Uric aicd, a natural product of purine metabolism, can precipitate under physiologic conditions in a variety of anhydrous, hydrated and salt pforms leading to symptoms associated with kidney stones and gout. The evolution of these physiologic deposits is a multi-step process that operates on several different length scales. This talk will describe our efforts to address some of the key steps in the solution-mediated phase transformation of metastable uric acid dihydrate to anhydrous uric acid using a combination of X-ray diffraction, thermal analysis and optical microscopy techniques. The kinetics suggest that the interconversions between uric acid forms is very sensitive to the initial method under which the metastable phase was prepared as well as the composition of the solution in which it transforms.

Zinc silicate (Zn₂SiO₄) has gained significant interest as a multifunctional material with several applications. In this study, we demonstrate a method to synthesize Zn₂SiO₄ nanotubes by exploiting Kirkendall effect at nanoscale. The reaction proceeds through interdiffusion of Zn²⁺ from ZnO nanorods into the chemically-synthesized Stöber-SiO_2shy; shell. Using in-situ heating in the TEM, we have monitored the nucleation and coalescence of the Kirkendall voids in the ongoing process. While heating the samples ex-situ in air leads to microstructural evolution that is similar to the in-situ experiments, there is a significant difference in the samples heated under reducing conditions. Heating the ZnO@SiO₂ nanostructures in a reducing atmosphere (95% Ar + 5% H₂) leads to the formation of amorphous silica nanotubes owing to etching of ZnO in H₂ atmosphere. Moreover, eletron-beam was also found to affect the course of the reaction, by sintering the tubes at higher temperature, thereby damaging the desired tubular morphology. Thus, this ambience-dependent thorough understanding of the relevant diffusion processes for the ZnO-SiO₂ diffusion couple at nanoscale presents a general conceptual platform to fabricate different multifunctional one-dimensional hollow nanostructures. These two materials, namely the Zn₂SiO₄ and SiO₂ nanotubes can respectively be used as cathode and anode materials for Li-ion battery.

Pulsed Laser Deposition (PLD) is a physical vapor deposition technique to fabricate a wide range of high quality thin film materials for the next generation devices such as solar-cells, MEMS and OLED&’s. This research is focused on in situ growth front monitoring between subsequent deposition pulses using an high speed Atomic Force Microscope (AFM). A scientific instrument is under development, in which a fast AFM (<10s /frame, 512*512 pixels) is combined with a PLD system, with special attention to a fast and accurate transfer and approach (<1s) mechanism¹. Using this instrument, we intend to repeatedly monitor the developing surface during growth (repositioning repeatability +/-60nm) with AFM at typical deposition conditions for complex oxides, nitrides and metals. In the case of PLD, the deposition and growth are separated in time, and therefore the above instrument aims to monitor the decay in adatom density after each laser pulse.
The described technique is an improvement of an earlier instrument, which demonstrated that it is feasible to combine in situ AFM with PLD in above manner².
This scientific instrument will help to improve the fundamental understanding of the kinetic growth during PLD. In addition, the approach to monitor the same surface area using AFM shortly after a chemical, biological or physical modification on a separated position has the potential to become widely accepted. Here, we present the design and test results of the current setup and our future plans to improve the scan rate and resolution further. This work is supported by NanoNext NL and in strong collaboration with Leiden Probe Microscopy (LPM)
¹ W.A. Wessels, J.J. Broekmaat, R.J.L. Beerends, G. Koster & G. Rijnders, Fast and gentle side approach for atomic force microscopy. Rev. Sci. Instru. 84, 123704 (2013)
² J.J. Broekmaat, In-situ growth monitoring with Scanning Force Microscopy during Pulsed Laser Deposition, PhD Thesis ISBN 978-90-365-2655-5, University of Twente, 2008

Since the discovery of quasicrystals in an Al-Mn alloy, quasiperiodic ordering states have been found in hundreds of intermetallic alloys, soft materials, oxide film, and even dense stacking of hard tetrahedra. Extensive studies have provided explicit knowledge for understanding and modeling the atomic arrangements in intermetallic quasicrystals. Mackay, Bergman or Cd-Yb icosahedral clusters were believed to be building blocks of three-dimensional (3D) icosahedral quasicrystals (IQC). Computer simulations showed that a dodecagonal quasicrystal seed nucleus grew through assimilation of icosahedral clusters in a supercooled liquid. However, the fundamental questions concerning why quasicrystals form, and how they nucleate and grow, are still unclear experimentally on the atomic scale, especially for 3D intermetallic IQCs.
Intermetallic quasicrystals are usually formed in undercooled liquids or frozen supercooled liquids (i.e. metallic glasses) both containing icosahedral atomic clusters that formed in liquids at higher temperature. A hexagonal phase without large icosahedral clusters in a Zn₆₅Mg₂₅Y₁₀ alloy transformed into IQC upon heating at 873 K which is around the melting point of the alloy, consistent with the law of entropy-optimized arrangement of atoms benefiting the stability of quasicrystals at high temperatures. However, it remains a challenge to realize solid-state crystal-to-quasicrystal transformation at relatively low temperatures when entropy doesn&’t predominate the free energy.
We found that Zn₆Mg₃Y icosahedral quasicrystals started to nucleate and grow epitaxially on Zn₃MgY crystals in Mg matrix of a Mg-Zn-Y alloy at about 573 K during in situ heating on a transmission electron microscope (TEM). Interdiffusion resulted in segregation of Y and Zn in Mg at the Mg/Zn₃MgY interfaces, which then triggered tetrahedral atomic rearrangement in Mg to form icosahedron pairs with surface distorted icosahedra of Zn₃MgY. The icosahedron pairs are tiny embryos of icosahedral quasicrystals. The interfacial icosahedron pairs inherited the same interconnectivity of those in the interior of Zn₃MgY, minimizing the nucleation barrier for icosahedral quasicrystal nanoparticles, lattice mismatch and distortion, and interfacial energy. The solid-state icosahedral ordering at lower temperatures sheds new light on understanding the nucleation and growth of quasicrystals.
In addition, In situ TEM observations showed the dynamical processes of eutectic IQC to W and H transformations at 688 K during heating, and the H to W transformation at 623 K on cooling. Quantitative analysis of the in situ transformation process reveals that both of the growth of H and W are diffusion-controlled growths, which agree with Avrami&’s model. These results provide useful information for microstructural optimization in order to improve the mechanical properties of Mg-Zn-Y alloys.

Fundamental understanding of metal oxidation has received extensive interest due to its significant importance in many fields including high temperature corrosion, catalytic reactions, and thin film processing. However, many fundamental questions still remain unresolved concerning the early stages of oxidation, which is inaccessible by the traditional surface science and ‘‘bulk&’&’ materials science techniques. A detailed understanding of the early-stage oxidation is often complicated by surface inhomogeneities caused by the presence of surface defects such as steps. In this work, through the use of in-situ transmission electron microscopy (TEM) we observe that the presence of surface steps leads to the decomposition of the oxide overlayer at the growth front, thereby resulting in oscillatory oxide film growth. Using density-functional theory (DFT) total energy calculations and ab initio molecular dynamics (AIMD) simulations, we show that oxygen adsorption on the lower terrace destabilizes the oxide film formed on the upper terrace that leads to oxide decomposition. Our results reveal the unique role of surface defects in oxide film growth and may have broader implications for understanding the fundamental process governing gas-surface reaction kinetics as modulated by atomic defects on a solid surface.

In many countries a significant legacy of radioactive wastes exists. The strategy for radioactive waste management includes, for intermediate level wastes, containment in a Geological Disposal Facility (GDF) in the deep sub-surface which typically will contain cementitious materials. Interaction of groundwater with the cement and wastes will form a plume of hyperalkaline leachate (pH 13 - 10) [1]. Under these conditions, thermodynamic modelling predicts that U(VI) solubility will be limited (ppb or lower) and controlled by equilibrium with alkali and alkaline-earth uranates [2]. In addition to transport in the dissolved phase, colloidal transport of radionuclides may be significant [3]. However, the potential formation of hexavalent uranium (U(VI)) colloids has received little interest despite the observation that U(VI) will be stabilised at elevated pH conditions relative to U(IV) [4]. Here, we focused on the formation and characterisation of such colloidal phases.
Charactersiaterion of colloidal particles using conventional extraction and separation techniques (e.g. filtration) can be challenging for suspended nanoparticles (i.e. <10nm). In this study we have utilised in situ time resolved Small Angle X-ray Scattering (SAXS) to characterise the formation of U(VI) oxide nanoparticles from a synthetic cement leachate (pH asymp; 13) with 10-60 ppm U(VI), and their aging over 2.5 years. Experiments were performed on beam line I22 of the Diamond Light Source. The results show the colloids consisted of 1.5 - 1.8 nm nanoparticles with a proportion of 20 - 60 nm aggregates which form within a few hours. In addition, the colloid remained stable for at least 2.5 years, and in the presence of several mineral phases (e.g. calcite). X-ray absorption spectroscopy in combination with TEM showed that the nanoparticles had a clarkeite (Na/K/Ca-uranate) type structure.
The presented results have clear and hitherto unrecognised implications for the mobility of U(VI) in cementitious environments, in particular those associated with the geological disposal of nuclear waste.
[1] Small and Thompson (2009) Scientific Basis for Nuclear Waste Management 1124, 327-332 [2] Gorman-Lewis et al (2008) J. Chem. Thermodyn. 40, 980-990 [3] Silva and Nitsche (1995) Radiochim. Acta. 70-1, 377-396 [4] Gaona et al (2012) Appl. Geochem. 27, 81-95

The direct growth of carbon nanotubes (CNTs) from bulk stainless steel enables the economical production of corrosion-resistant hierarchical materials with exceptional surface area as well as high thermal and electrical conductivity. Such direct growth has been achieved previously on stainless steel, typically through air annealing or acid treatment prior to synthesis, but often suffers from relatively poor yield, alignment, and lack of control over CNT morphology, preventing the realization of diverse applications ranging from heat exchangers to filtration membranes and capacitors. Previous work has suggested the importance of nanoscale roughness on the stainless steel surface as well as the removal of the steel&’s native chromium oxide outer layer. However, these findings result primarily from ex-situ studies and the exact role that they play, if any, in CNT growth remains unclear. Furthermore, how stainless steel geometry affects CNT growth has not been studied. We present the first direct observations of CNT growth from stainless steel using lattice fringe imaging and electron energy loss spectroscopy in an environmental transmission electron microscope. We will show how the sequential oxidation and reduction of the surface, and associated mechanical forces, lead to the formation of loosely bound, discrete nanoparticles that nucleate and grow CNTs. Among other findings, our in-situ study demonstrates that CNT growth can proceed from Fe-Cr and Fe-Ni alloy particles, and that CNT growth does not require the removal of the chromium surface oxide. We subsequently use the understanding gained from these detailed observations to improve CNT yield and morphological control on diverse stainless steel geometries through sequences of pre-treatments in oxidizing, reducing, and inert atmospheres. In addition to enabling the manufacture of CNT/stainless steel hybrids, these mechanisms are applicable to the general direct growth of CNTs from bulk metal substrates and will help to realize this new class of hierarchical materials.

The exceptional thermal stability, tunable porosity, unique shape-selectivity, and high acidity of zeolites contribute to their frequent use as catalysts and adsorbents. The inability to a priori control crystal growth, however, often yields materials with undesirable physicochemical properties. Approaches capable of selectively tailoring zeolite size, morphology, and/or crystal structure can lead to dramatic improvements in their performance. Given the application of zeolites in areas of biofuels, methane conversion, and CO₂ sequestration, there exists a need to expand the fundamental understanding of zeolite growth as well as design synthetic routes to optimize their properties. In this talk, we will discuss a new advancement in atomic force microscopy (AFM) that has enabled us to image zeolite surface growth in situ under realistic synthesis conditions (i.e., high temperature and long duration). AFM offers unparalleled insight of dynamic processes governing zeolite growth at near-molecular resolution [1]. We used in situ AFM to characterize zeolite surface growth over the course of 10 - 30 hours of continuous scanning. A systematic study of silicalite-1 revealed that growth occurs by two concurrent mechanisms: a classical route (i.e., molecule addition) and a non-classical pathway defined by the addition and subsequent rearrangement of amorphous precursor particles. These studies have been expanded to other zeolite crystal structures. We will discuss these findings and place their significance within the broader context of other zeolite crystal structures that are believed to grow by a variety of different pathways.
[1] A.I. Lupulescu and J.D. Rimer, In Situ Imaging of Silicalite-1 Surface Growth Reveals the Mechanism of Crystallization, Science 344 (2014) 729-732

Functional materials based on complex oxides in thin film form offer new and exciting strategies for meeting many of our outstanding energy challenges through systematic control of layer sequencing, strain, etc. However, synthesis of such oxide films can be a major challenge even when utilizing reactive molecular-beam epitaxy (MBE), a powerful deposition technique that is often regarded to allow the construction of materials atomic plane by atomic plane. To understand the fundamental physics of oxide growth by reactive MBE, we present in situ surface x-ray scattering results of the homoepitaxial growth of SrTiO₃ thin films on (001)-oriented SrTiO₃ substrates. By comparing sequential deposition (alternating Sr and Ti monolayer doses) with that of co-deposition of Sr and Ti, both in a background of oxygen pressure, we find drastically different growth pathways. While the co-deposition is marked by the usual roughening-smoothing transition associated with the completion of each layer, sequential deposition demonstrates strong islanding of the SrO monolayer followed by a smoothing transition during the TiO₂ layer deposition. Using in situ x-ray specular reflectivity and surface diffuse x-ray scattering during growth, an area detector simultaneously recorded both the specular x-ray scattering connected to out-of-plane atomic positions and the diffuse x-ray scattering associated with in-plane correlations. During growth of SrTiO₃ by co-deposition, where the fluxes of Sr and Ti are roughly equal, the specular intensity at the half-order position is at a minimum while the diffuse intensity is at a maximum. This is consistent with a 2D island growth mode with unit-cell-high SrTiO₃ islands that nucleate/grow on the terraces and coalesce before the next layer starts. For the case of sequential deposition, the scattering indicates that the SrO grows as islands and then restructures into SrTiO₃ unit cells during the growth of the TiO₂ to form an atomically flat layer. Theoretical calculations indicate that the growth of a single monolayer of SrO layer is thermodynamically preferable, so kinetic processes cause the formation of SrO islands. However, smoothing of SrO bilayer islands during the deposition of TiO₂ to form perovskite SrTiO₃ is energetically favorable. A detail comparison of sequential deposition and co-deposition will be presented, demonstrating the power of quantitative x-ray probes for understanding the process of thin film synthesis.
Work at Argonne, including the Advanced Photon Source, is supported by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

Scalable synthesis of 2D materials such as graphene and hexagonal boron nitride h-BN by chemical vapour deposition (CVD) has generated considerable research interest. However, the growth mechanisms of graphene and h-BN during CVD remain poorly understood. Simplistic models of elemental solubility of the constituent elements (eg: C, B etc.) in metallic catalysts eg: Ni (high solubility - precipitation from bulk) and Cu (low solubility - surface reaction) have so far been speculatively proposed based on ex-situ experiments while critical in-situ experimental evidence remains elusive. [1,2]
Here, using a combination of high-pressure process, time and depth resolved in-situ X-ray photoelectron spectroscopy (XPS) at the BESSY II synchrotron in Berlin [1,2] and in-situ X-ray diffraction (XRD) at the ESRF synchrotron in Grenoble, [1,2] we study the behaviour of polycrystalline transition metal catalyst films and foils during CVD at industrially relevant CVD conditions, i.e. pressure (~0.001 - 0.5 mbar) and extreme temperatures (800-1000^oC).
These complementary in-situ XPS and XRD experiments allow us to identify the chemical state/phase of the catalyst and the elemental species at any point of time during CVD. This allows us to observe elemental incorporation into the 2D material structure on the catalyst surface as it happens. The growth mechanisms of these 2D nanostructures is found to be predominantly isothermal along with some precipitation on cooling for both Ni[3] and Cu[3], i.e. we observe the detailed dynamics of the catalytic behaviour during growth as a complex interplay of isothermal and precipitation based growth mechanisms with kinetic effects playing an important role.
We highlight the use of our in-situ approach as a generic framework to study the growth other 2D and 1D nanostructures during CVD.[4]
References:
1. Kidambi et al. Nano Letters (submitted)
2. Kidambi et al. Nano Letters 13 (10), 4769-4778 (2013).
3. Kidambi et al. J. Phys.Chem. C. 116, 42, 22492-22501 (2012).
4. Kidambi et al. PSS RRL. 5, 9, 341-343 (2011).

Nucleation is the seminal process in the formation of ordered structures ranging from simple inorganic crystals to self-assembled macromolecular matrices. Yet due to its inherent dynamics much of what we know about nucleation comes from observations of the products rather than the processes. Consequently, in situ techniques of imaging and spectroscopy are critical to developing a foundational framework to describe this key step in materials synthesis. Molecular scale observations of structural and morphological evolution provide direct knowledge of nucleation pathways, while measurements of nucleation rates vs. temperature and supersaturation enable one to determine the kinetic and free energy barriers that define these pathways. Optical and force spectroscopic probes then establish the connection between this energy landscape and the underlying molecular interactions. Here we illustrate this approach to understanding nucleation by using in situ methods including AFM, TEM, and optical microscopy combined with FTIR and dynamic force spectroscopy (DFS) to investigate nucleation of ordered states in protein and mineral systems. TEM observations of calcium carbonate reveal the multiple complex pathways available to the system, due to the high driving force required to overcome the large free energy barrier to homogeneous nucleation of the stable phase. AFM and optical measurements of nucleation rates vs. supersaturation demonstrate that organic matrices can direct nucleation of a fixed phase by dramatically reducing these barriers. DFS measurements demonstrate that the underlying source of this control is the matrix-crystal binding energy. AFM studies of self-assembly in both the S-layer protein and collagen systems reveal the key role played by conformational transformations in controlling the pathways and kinetics of matrix assembly. The results demonstrate that the pathway to the final ordered state often passes through transient, less-ordered conformational states. Thus the concept of a folding funnel with kinetic traps used to describe protein folding is also applicable to nucleation of ordered protein matrices. Finally, both AFM and TEM studies of matrix mineralization illustrate the strong control that ion-matrix binding has in defining the location of mineral nucleation. Taken together, these results provide new insights into the mechanisms and pathways controlling nucleation of ordered states in biomolecular and biomineral systems.

Molecular beam epitaxy (MBE) is a thin film growth method that allows to synthesize high-quality, single-crystalline layers with defined thickness and stoichiometry. During MBE the elements to form the layer are provided as elemental vapor with defined flux in an ultra-high vacuum environment. This setup enables a simple chemistry that is free from incorporation of impurities and free from unwanted reactions and their products.
The MBE growth of oxides is realized by subliming the oxidic source material or evaporating the source metal and providing an oxidizing flux (molecular oxygen or an oxygen plasma).
This contribution demonstrates the in-situ investigation of the MBE of La₂O₃, In₂O₃, and Ga₂O₃ during growth.
In particular, the nucleation and phase formation was analyzed by in-situ reflection-high-energy electron diffraction (RHEED) and x-ray diffraction (XRD) of La₂O₃ oxide growth. The nucleation of the cubic polymorph on Si(111) substrate was followed by the formation of the bulk-stabile hexagonal phase as determined by XRD, wheras the growth rate could be measured using RHEED oscillations.
In-situ RHEED was also used to investigate the nucleation of In₂O₃ on ZrO₂:Y(001) substrates as function of growth temperature and O/In flux ratio. A regime of fast nucleation was able to realize continuous films whereas the opposite regime of suppressed nucleation could be used to grow isolated islands.
The growth of Ga₂O₃ on Al₂O₃ was investigated by in-situ laser reflectometry to determine the growth rate and by line-of-sight quadrupole mass spectrometry to identify the desorbing species. Measuring the (positive or negative) growth rate as function of Ga and oxygen flux and the identification of the desorbing species helped identifying the chemical reactions at play. These are: 2Ga+3O->Ga₂O₃ and 4Ga+Ga₂O₃ ->3Ga₂O.
Being not limited to oxides, these examples demonstrate the suitability of molecular beam epitaxy for many different types of in-situ measurement.

Understanding the spatiotemporal evolution of populations of carbon nanotubes (CNTs) during the growth of vertically aligned "forests" by chemical vapor deposition (CVD) is key to engineering their morphology and properties. Hence, in situ characterization of the successive stages of the growth process is sought after. Previously, it was shown that Synchrotron X-ray scattering and absorption can provide valuable quantitative information about the morphological evolution and population dynamics of CNTs within a forest. However, the initial stages of nanoparticle formation and CNT nucleation are more elusive and cannot be inferred directly from transmission X-ray measurements. Grazing incidence X-ray scattering was also used to study the dynamics of catalyst film dewetting, but decoupling the scattering signal from catalyst nanoparticles and CNTs becomes challenging upon CNT nucleation. To further elucidate the early nucleation behavior of CNTs, we carry out in situ and operando experimental studies of CNT growth in an environmental transmission electron microscope (TEM). Real-time imaging of particle formation and CNT nucleation shows a characteristic S-shaped kinetics that span a few second, highlighting the non-instantaneous nature of nucleation. Although further studies are needed to identify the differences between active nanoparticles and inactive nanoparticles, results show that inactive nanoparticles that do not bear CNTs are generally encapsulated inside a graphitic coating. In situ TEM images also show the mechanical interactions between neighboring CNTs during the crowding stage that leads to the build-up of alignment in the forest morphology. Moreover, electron energy loss spectroscopy (EELS) is used to infer the kinetics of carbon deposition upon the introduction of the hydrocarbon gas (acetylene) to the reactor. Our findings indicate that tuning the catalyst annealing and growth conditions can modulate the "popping" kinetics of nanoparticles to enable instantaneous nucleation of CNTs and therefore the growth of uniform functional CNT forests.

Our work on in situ studies of the atomic mechanisms of material reactions by high resolution transmission electron microscopy has now been extended to environmental (ETEM) investigations (e.g. [1]). This technique will be reviewed and recent applications discussed. Our research has focused on simple reactions with a single pure gas and some recent results will be presented.
The oxidation of matter is a basic process with broad implications. Here we demonstrate in situ observations of the oxidation of carbon nanotubes being developed as field emission sources for X-ray medical imaging purposes. The oxidation mechanism is quite different than had been previously proposed but is easily demonstrated by the ETEM [2].
Likewise, hydrogen storage is promising for possible future energy applications, and so the reaction of hydrogen gas with candidate materials has fundamental importance. Following prior work on hydrogenation of magnesium/palladium thin films [3], we have extended this investigation to the hydrogenation of magnesium films with palladium nanoparticles. The formation of magnesium hydride in the ETEM is demonstrated, as is the utility of a new vacuum transfer specimen holder.
It is clear from both these studies that the imaging electron beam can influence the observations. Accordingly, protocols have been established whereby any possible influence of the electron beam is avoided, and these procedures will be discussed.
[1] Sinclair, R., In Situ High-Resolution Transmission Electron Microscopy of Material Reactions, Mats. Res. Bull., 38, 1065-1071, 2013
[2] Koh, A.L., Gidcumb E., Zhou, O., Sinclair, R, Observations of Carbon Nanotube Oxidation in an Aberration-Corrected Environmental Transmission Electron Microscope, ACS Nano, 7 (3), 2566-2572, 2013
[3] Chung, C.J., Lee, S.C., Groves, J.R., Brower, E.N., Sinclair, R., Clemens, B.M., Interfacial Alloy Hydride Destabilization in Mg/Pd Thin Films, Phys. Rev. Lett, 108, 106102 1-4, 2012

As a stable 2-dimensional material, graphene has been extensively studied. Currently, most of explanations on growth mechanisms are based on the experimental results after graphene formation, and the direct observation on the whole growth process is still lacking. To produce single-crystal graphene as large as possible and finally control its growth, the deep understanding on the growth mechanisms is indispensable. By in situ technique, it is possible to observe the whole process including the morphology change of the substrate surface, formation of graphene crystal and so on during growth. In situ scanning tunneling microscopy (STM) analyses have showed this process at atomic scale [1]. Complementary to in situ STM, in situ scanning electron microscopy (SEM) observation provides a larger field of view, which may help us to better understand the growth mechanisms [2].
In this study, the whole graphene growth process on polycrystalline Cu substrate is observed by in situ SEM. The morphology changes of Cu surface and graphene structures formed under various conditions are carefully investigated. The influences of experimental parameters including temperature and growth time on the layer number of graphene as well as its quality are also discussed. According to our experimental observations, graphene is not created directly on the surface of Cu substrate but on an adsorbed gas layer over the surface, which is formed during graphene growth. The removal of this gas layer leads to the disappearance of graphene from SEM observation. Therefore, to finally obtain high quality graphene, the adsorbed gas layer on the surface of substrate has to be carefully considered. This result may suggest a possible direction for future research on graphene formation.
References
[1] Niu, T.; Zhou, M.; Zhang, J.; Feng, Y.; Chen, W. J. Am. Chem. Soc.135, 8409 (2013).
[2] Kidambi, P. R. et al. Nano Lett.13, 4769 (2013).
Corresponding Author: Huafeng Wang
Tel: +81-3-5228-8244, Fax: +81-3-5261-1023
E-mail: [email protected]

Platinum-alloy nanoparticles are a system of great interest for fuel cell electrocatalysis and magnetic applications. Fine-tuning their structure to enhance catalytic activity and durability is crucial to commercialize fuel cell systems. In an ongoing attempt to reduce the mass loading of platinum (Pt) in proton exchange membrane fuel cells, there has been a tremendous research till date; constantly suggesting that a nanoscale alloying of Pt with 3d transition metals is a more viable option. Pt-Fe nanoalloys, in particular, have gathered much attention in recent years not just as a better catalyst to Pt/C, but also because of its magnetic properties that are deployable in ultra-high density information storage [1]. However, a nanoscale phase transformation of an ensemble of alloy nanoparticles, polydispersed in both their size and composition, results in an assortment of materials with miscellaneous properties [2]. Controlling their collective evolution and probing the interplay between compositional segregation and atomic-ordering is therefore imperative, and demands, full-fledged understanding at the atomic scale. Traditionally, a bulk approach has been followed in this respect, by deriving inference from ex-situ thermal treatments, before and after. Given the inherent dynamicity associated with nanoscale processes, an atomic-perspective is hence so far not been possible. Looking beyond, here we demonstrate an in-situ atomic-resolution imaging and spectroscopy — on single Pt-Fe alloy nanoparticles — over the course of thermal treatment [2].
Same particle was tracked all through and a combination of atomic-resolution STEM-HAADF imaging and STEM-EEL spectroscopy was performed. While our STEM-HAADF results clearly demonstrate evolution of particle shape, size, ordering and sintering kinetics (ripening and coalescence) over the course of heat treatment, the EELS maps reveal new insights into the segregation process. Additionally, we have stumbled across a new phenomenon that comes to play as a consequence of interaction of nanoparticles with their chemical environment and our results bear witness to its unique role in creating unusual structures (unicore-multishells, as an instance) at the nanoscale. We illustrate through a model as to how these dynamic processes can collectively lead to the formation of various nanoalloy configurations. We believe that a dedicated attempt to understand the nanoscale phase transformation as this, is central to fine-tune the catalytic properties of alloyed-Pt nanoparticles in general, and hence could redefine a new methodology to synthesize next generation fuel cell nanocatalysts.
References
[1] Prabhudev, S.; Bugnet, M.; Bock, C.; Botton, G. ACS Nano 7 6103-6110 (2013)
[2] Prabhudev, S.; Bugnet, M.; Zhu, G-Z.; Bock, C.; Botton, G. (submitted)

As materials are reduced to the nanometer length scale, pseudomorphic phases can be stabilized. Thin films provide ideal systems to understand this phase stability because of their near atomic level control of thickness coupled to a high surface area; this creates tailored materials with high surface area-to-volume ratios. Thin films are also susceptible to significant epitaxial strains during growth which can contribute to the effects of interfacial energy reduction for the stabilized these pseudomorphic phases. Using an in situ laser reflectometry technique, the stress evolution of growing thin films was captured in real-time to understand how intrinsic growth stresses relate to phase stability. These associated growth stresses provide insights into adatom mobility during deposition. In the present work, this in situ technique has been utilized to elucidate the pseudomorphic bcc to ‘bulk&’ hcp stability of Ti in either a Ti/Nb or Ti/W multilayer. For Ti/Nb, the bcc phases have near equivalent lattice parameters whereas a significant deviation in bcc lattice parameters exist in the Ti/W system. During the initial growth, the Ti layers grew bcc with a tensile-stress state behavior. Upon reaching a critical thickness, a distinct change in stress occurred. The hcp Ti layer exhibited a relatively neutral stress change upon further growth. The subsequent deposition of either Nb or W resulted in the stress state of the film became very compressive. Atom probe tomography revealed significant intermixing through the Ti/Nb interfaces with segregation of Ti to the Nb grain boundaries. This intermixing resulted in a modification to the thermodynamic energies required for pseudomorphic stabilization. These experimental results have been compared to a hydride Molecular Dynamics + Monte Carlo simulation of the deposition process to clarify the intrinsic role of interfacial energy and strain that contributes to the bcc Ti stabilization. The simulations are compared to both the atom probe characterization and real-time, in situ stress evolution of the multilayer. This work has been supported by NSF-DMR-1207220.

Electric double-layer capacitors, or supercapcitors, store charge via polarization of the electrode-electrolyte interface of a very high specific surface area electrode and a suitable electrolyte. Traditionally, the predicted evolution of the electrified interface during the critical stages of charge and discharge almost exclusively considers the active role of the electrolyte: i.e., transport, proximity, and arrangement of ions approaching the electrode surface. Using in situ soft x-ray absorption spectroscopy and complementary ab initio modeling, we demonstrate that the electrode can also undergo complex, reversible, and highly influential structural transformations through the investigation of nanostructured carbon aerogel (CA) electrodes operating in prototypical electric double-layer capacitors. Profound bias- and time-dependent evolution of the electronic structure under applied bias connotes both surface distortion and specific adsorption. Simulations are leveraged to discriminate mechanisms for the observed dynamic structure and bonding of CAs within functioning supercapcitors and provide fundamental insights for charge storage models required for the rational design of electrodes with tailored architecture. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

For lithium ion battery, a range of materials has a high theoretical capacity and it is very often that this type of material is prone to cause the fast capacity fading of the battery. To address this problem, a range of microstructural designing concepts has emerged, most notably such as composites based on nanowires, nanotubes, and nanoparticles as well as in combination with surface structural and chemical modifications. For a lot of cases, the nanoscale designing concept is inspired and verified by direct in-situ imaging or spectroscopic analyzing of structural and chemical evolution of the materials under dynamic operating condition. In this presentation, we will explore the behavior of both native oxide layer and aluminum glycerol (ALGL) coating on silicon nanoparticle upon cyclic lithiation/delithation. We discovered that upon initial lithiation, the native oxide layer converts to Li₂O, which essentially increases the impedance and exert mechanical confinement on the particle, resulting in incomplete lithiation/delithiation or inactive particle. This study clarifies the role of the native oxide on silicon nanoparticle on cycle performance and provides vivid picture of how coating layer works on preserving capacity.

The current efforts to improve the OPV device performance almost exclusively employ spin-coating of the active materials in a protected atmosphere, with efficiencies now reaching 12% for small area devices on the order of millimeter squares. The fabrication conditions by which these very high electrical efficiency cells are currently produced generally cannot be simply transferred to a large-scale roll-to-roll industrial production scheme. The efficiency discrepancy between organic solar cells produced in the laboratory and large-scale devices manufactured in a roll-to-roll printing process need to be addressed before the commercialization of large area printed OPV devices. Correlating the process conditions, the morphology and electrical performance of the OPV devices are critical for solving the challenge of mass-producing high efficient large area organic solar cells.
To solve the above mentioned grand challenge, we developed a mini roll-to-roll compatible printing setup for organic solar cells with the capability to follow the film formation during solvent dry in situ with small and wide angle X-ray scattering at Stanford Synchrotron radiation facility. By using this set-up, time resolution down to 10ms was achieved to probe the drying kinetic and crystallization process of the organic semiconductor materials. This set-up also allows to use multiple inks that being delivered to the roll-to-roll printer head with different composition of the active layer between the donor and acceptor materials. We printed a variety of different BHJ OPV materials (both polymer fluorine systems and all polymer systems) on the flexible ITO/PET substrates and characterized the print process using in situ small/wide angle X-ray scattering (SAXS, WAXS). Wide range process parameters were investigated in details during R2R coating process, including solvent quality, drying temperature, shearing speed, blend ratio of donor and acceptor materials, additives, in order to obtain the optimized OPV morphology. By extracting the peak intensity, full widths at half maximum (FWHM) and peak position, rich information about the drying process as well as dried film are obtained. Finally the morphology of the OPV devices are correlated to electrical performance of the device (e.g. V_OC , Jsc , FF, PCE), thus shed light on the best protocol for drying process to obtain the highest possible efficiency for the R2R coating of OPV materials on flexible substrates.

Understanding the nanoscale changes that occur in battery materials and interfaces is critical to improve battery reliability, safety, and efficiency. Direct visualization of the material dynamics during cycling is now possible with miniature cells in a transmission electron microscope (TEM), and here we describe the development of a custom hermetically-sealed TEM liquid cell that allows electrochemical control in realistic aprotic electrolyte environments relevant to Li-ion and other high voltage battery chemistries. In particular, imaging phenomena related to the electrode/electrolyte interface such as solid-electrolyte interphase (SEI) formation from electrolyte decomposition requires a sealed liquid cell. Here we demonstrate the liquid cell operation with lithium electrodeposition and stripping with precise electrochemical control and awareness of the TEM electron beam effects.
The liquid cell design consists of a thin, electron-transparent liquid cavity confined between two silicon nitride membranes microfabricated on silicon chips. Multiple current collector electrodes (W or Al) on the bottom chip allow a variety of experiments on the same platform as well as facile assembly of nanoparticles via dielectrophoresis. Sealable fluid fill ports on the top chip enable a variety of electrolytes, and the stand-alone design permits electrochemical testing independent of the TEM holder.
To demonstrate Li electrodeposition, the cell was filled with 1:1 ethylene carbonate:dimethyl carbonate with 1 M LiPF₆ electrolyte and sealed with epoxy. The electrodes were nanopatterned Ti patches on W electrodes masked with Al₂O₃ such that a small, controlled working electrode area was fully viewable in the TEM. Applying a pA-level galvanostatic current resulted in clear, reversible Li electrodeposition on the Ti electrode, and features in the well-defined chronopotentiometry corresponded to specific events seen in the micrographs.
The electron beam damage was minimized in scanning (STEM) imaging mode with a low pA-level beam current, but some beam-induced effects were still evident. The Li deposition morphology grown while irradiated in-operando always formed circular/spherical deposits, while more crystalline/dendritic deposits were seen with the beam off during deposition and subsequent in-situ imaging. Additionally, growth of a beam-induced SEI was clearly visible with prolonged exposure. Knowledge of the deposition morphology and beam effects gives a deeper understanding of Li electrodeposition and progress towards suppression of detrimental dendrite formation.

Understanding the evolution of the electrochemical constituents of a battery during discharge can offer detailed information about state of charge as well as failure mechanisms. However, typical methods of characterizing the internal components of batteries are often only applicable post mortem. Previous work has used energy-dispersive x-ray diffraction (EDXRD) spectroscopy to image discrete volumes within Zn-MnO2 “alkaline” batteries, and has shown the evolution of the internal components during discharge. Most notably, the oxidation of the anode from Zn to ZnO has been quantified as a function of state of charge. Recently, there has been popular interest in the tendency of an alkaline AA battery to bounce after being dropped on its end when discharged to full capacity, compared to a flat landing with minimal bounce when the battery is as-received. This bounce test presents a non-destructive method of assessing the material properties of the battery, and thus the state of the electrochemical constituents.
In this work, we present an explanation for this bouncing, and quantify it by measuring the coefficient of restitution (COR) of alkaline AA batteries as a function of depth of discharge (DOD). The COR is shown to be constant at low DOD, but then begins to rise rapidly at 20% DOD, finally saturating at a value of 0.63 +/- 0.05 at 50% DOD. We have found this rise and saturation to correlate strongly to EDXRD spectra, showing that increase in COR corresponds to the formation within the anode of a contiguous pathway of ZnO particles from the separator to the current collector. The saturation is best explained due to densification of the anode core to a porous ZnO solid. SEM microscopy of as-received and fully-discharged batteries has confirmed this process. Of note is the sensitivity of the COR to the amount of ZnO formation, which rivals the sensitivity of in situ energy-dispersive x-ray diffraction spectroscopy.
Building from these results, we present a method similar to the Split Hopkinson Pressure Bar experiment, in which a compressive impulse is applied to a metal bar and the resulting strain wave is measured before and after transmittance through a sample. We show that the speed of the strain wave within an alkaline cell varies with state of charge, and therefore that acoustic determination of state of charge is possible. We also present 1-D wave simulations to support the results from the Split Hopkinson Pressure Bar experiment. Based on these results, we suggest future methods that can incorporate a transducer/detector system in which the state of charge of a cell can be measured in situ without interruption of the battery system operation.

A mechanistic understanding of the electrochemical reactions that occur at battery electrodes is needed to provide a scientific underpinning for the design of new electrode materials. The development of the in-situ open-cell transmission electron microscopy (TEM) technique - using either an ionic liquid or Li₂O electrolytes - has made it possible to track dynamic structural and morphological changes that occur within individual nanostructures at high tempo-spatial resolutions [1,2]. However, the direct use of conventional liquid electrolytes, which have high vapor pressure, is inconducive for the high vacuum environment of TEM. We will demonstrate the utility of the liquid-cell technique to observe charge/discharge processes at electrodes in real time. This has the advantage of being flexible enough to utilize any standard liquid electrolyte, thereby allowing the direct exploration of both electrode-electrolyte interfacial reactions as well as structural and morphological changes. We have studied conversion-based iron fluorides, such as FeF₂ as a model system. Iron fluorides are promising candidates to replace current intercalation-based cathode materials (e.g. LiCoO₂ and LiFePO₄; capacities <160 mAh/g), because of their ability to accommodate more than one electron per transition metal, thus resulting in higher specific capacities (>500 mAh/g) [2, 3]. We performed in-situ TEM studies of lithium reactions within individual crystalline FeF₂ nanorods, directly visualizing such conversion process in the bulk as phase nucleation and transformation, as well as related interfacial phenomena. In contrast to rapid lithium diffusion on the FeF₂ rod surface [2], lithium diffusion into the bulk was severely impeded. Moreover, there was a preferential orientation-dependent diffusion of lithium, accompanied by an anisotropic volume expansion during lithiation. A detailed understanding of the orientation dependence of the lithium transport across electrolyte-solid interface and through the bulk of FeF₂ nanorods will be discussed.
[1] Huang et al., Science330 (2010) 1515.
[2] Wang et al., Nat. Commun.3 (2012) 1201.
[3] Wang et al., J. Am. Chem. Soc. 133 ( 2011) 18828.
This work is financially supported by Northeastern Center for Chemical Energy Storage, an Energy Frontier Research Center funded by the U.S. DOE, BES under award number DE-SC0001294, and the LDRD at Brookhaven National Laboratory. Research carried out at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886.

When polycrystals are dispersed in the matrix, such as a solution or vapor, it is readily observed that particles larger than those of average size grow, accompanying the dissolution of smaller particles into the matrix at the same time. This particle coarsening process has generally been referred to as Ostwald ripening. As the entire microstructure of polycrystalline materials consists of both growing and shrinking crystals, scrutiny of shrinking (or evaporating) characteristics is essential for a complete understanding of the kinetic evolution of microstructure. Recent advances in transmission electron microscopy (TEM) enable atomic-scale imaging for direct visualization of lattice defects, phase transition, and structural evolution. In particular, a variety of techniques have been utilized for real-time observations in TEM, providing unexpected and new experimental findings in LiFePO₄ (S.-Y. Chung et al., Nature Phys.5, 68 (2009); Nano Lett.12, 3068 (2012); J. Am. Chem. Soc.135, 7811 (2013)). By capturing real-time in situ high-resolution electron micrographs at high temperatures, in this presentation we demonstrate the evaporation behavior of LiFePO₄ crystals embedded in a solid crystalline matrix, instead of crystals in a vapor, during recrystallization. Low-energy grain boundaries between an embedded nanocrystal and a matrix are clearly observed transitioning into comparatively high-energy surfaces before substantial evaporation begins, creating unavoidable free energy instability at the early stage of evaporation. Additionally, post-transition evaporation behavior is discussed in terms of the local strain field distribution inside the crystal and the anisotropic grain-boundary energy. This study suggests that the initial energy instability induced by the boundary transition strongly influences the overall evaporation rate of crystals that are geometrically confined by a solid phase.

Controllability over the size, shape, composition and surface properties of nanoparticles is imperative to achieve enhanced catalysis in energy conversion and storage systems. Equally important is to gain insights into the native chemical environment and various dynamic mechanisms that come into play during the actual catalyst reaction processes. Particularly in the case of proton exchange membrane (PEM) fuel cells, the nanocatalyst degradation is a serious limiting factor for commercialization. Although structural degradation of nanoparticles has been extensively studied in the past through various ex-situ electrochemical methods, employing an in-situ technique can greatly improve our understanding of the mechanisms involved during electrochemical cycles. In-situ imaging through liquids is certainly a promising approach for exploring biological and materials processes in their native operating environment [1]. This report describes our recent findings on simultaneous investigation of both, the structural evolution and electrochemical responses of platinum-iron (Pt-Fe) nanoalloy catalyst particles, using an in-situ liquid cell inside a TEM. In-situ studies were conducted using a Protochips flow cell with 50 nm thick silicon nitride viewing windows spaced about 250 nm apart. Through identical location imaging over the course of several potential cycles, we illustrate how the coarsening mechanisms, including nucleation and the growth, are not uniform, both in space and in time scale. The growth rate was, interestingly, found to be both site- and potential-dependent. Further, these particles were found to exhibit considerably different behaviors when attached to an electrode as opposed to when isolated in the bulk of the electrolyte. In addition to experimental characterization results, we demonstrate this with a numerical model studying the distribution of current density, which relates to the rate of electrode reactions in the electrochemical cell. An increased current density was observed near the working electrode that was found to be decreasing as we moved towards the counter electrode. In addition, we observe current density hot spots between particle aggregates. We expect higher electrochemical reaction rates to occur at areas with increased current density. However due to the highly localized nature of this effect, we do not expect it to influence the electrochemical reaction rates in regions beyond a few microns away from the particles. In summary, with Pt-Fe nanoalloy system as a candidate material, we demonstrate that the in-situ structural characterization of nanocatalysts under electrochemical bias and inside the native electrolyte environment provides much deeper insights into the catalyst degradation mechanisms compared to the routine ex-situ electrochemical studies [2].
References
[1] N. de Jonge and F. Ross, Nature Nanotechnology 6 (2011) 695.
[2] Prabhudev. S, et.al. ACS Nano 2013, 7, 6103-6110

We will present in-situ scanning electron microscope (SEM) observations of the growth and dissolution of Li islands/whiskers through solid electrolyte interfaces coated with a metal current collector as a function of current density during charge-discharge processes.
A great deal of attention has been paid to the development of next-generation-rechargeable batteries that may store several times more energy than commercial Li-ion batteries. The research on all-solid-state-lithium batteries (SSLB) has been significantly propelled by advancements in techniques to decrease solid/solid interface resistivity and new discoveries of solid Li⁺ ionic electrolytes.
Inorganic solid electrolyte blocks Li dendrite growth if Li metal is used as the negative electrode. This is certainly attractive because the theoretical energy density of Li metal (2060 Ah L^-1) is much greater than those of presently commercialized negative electrodes (< 1000 Ah L^-1). Moreover, there are also other advantages of using ceramic electrolyte: (1) non-flammability; (2) simplified battery pack design due to no risk of electrolyte leakage; (3) longer cycle and calendar life compared to organic liquid electrolyte.
Amorphous electrolyte plays a key role in blocking Li growth from the anode for using Li metal as the negative electrode in SSLB. It is thus important to study how Li metal grows and dissolves through amorphous solid electrolyte interfaces during charging and discharging. Extensive studies of electrochemical Li deposition and dissolution have not sufficiently been devoted to solid electrolyte systems.
Since solid electrolytes are not volatile, conventional electron microscope techniques can be applied for observations of in-situ electrochemical experiments using this class of electrolytes.
We have studied the electrochemical Li deposition and dissolution under galvanostatic condition (50 mu;A cm^-2 to 1.0 mA cm^-3) using an amorphous electrolyte of lithium phosphorous oxynitride (LiPON)¹. Li deposition invokes non-uniform nucleation that leads to whisker-like growths on a LiPON layer. Consequently, analyzing every step of Li growth trajectories at fixed sites during charge-discharge processes is an important step toward understanding the mechanisms of non-uniform Li growth. We will discuss the mechanism of Li nucleation at solid/solid interfaces under significant strain-confinements due to a rigid electrolyte, which are different from liquid/solid interfaces.
The authors thank the Advanced Low Carbon Technology Research and Development Program (ALCA) of the Japan Science and Technology Agency (JST) for the financial support.
1. M. Motoyama, M. Ejiri, and Y. Iriyama, Electrochemistry,82, 364 (2014).

It is widely assumed about heterogeneous catalysts, that they are rigid and neither lost nor deactivated (ideally) during operation. They can be pre-determined in their function by a rational synthesis based on crystal structures.
Although this conjecture is true for the bulk phases of such catalysts we have now learned that the functional surface of heterogeneous catalysts is not rigid and not pre-determined directly by synthesis. Performance catalysts activate in contact with their feeds and respond to temporal changes of the local chemical potential.
The contribution exemplifies this new concept in catalysis and gives examples^[1] of how in-situ controlled synthesis can be used to optimize the response of a performance catalyst to its desired activation.
[1] a B. Frank, T. P. Cotter, M. E. Schuster, R. Schlögl, A. Trunschke, Chem. Eur. J. 2013, 19, 16938-16945; b M. Sanchez Sanchez, F. Girgsdies, M. Jastak, P. Kube, R. Schlögl, A. Trunschke, Angew. Chem. Int. Ed. 2012, 51, 7194-7197; c M. Eichelbaum, M. Hävecker, C. Heine, A. Karpov, C.-K. Dobner, F. Rosowski, A. Trunschke, R. Schlögl, Angew. Chem. Int. Ed. 2012, 51, 6246-6250.

Liquid cell Transmission Electron Microscopy (TEM) allows imaging through liquids with high spatial and temporal resolution has attracted significant interest in recent a few years. Many different areas have been explored including nanoparticle growth, materials corrosion, electrode-electrolyte interfaces, diffusion in liquids, etc. In this talk, I will first present our study on nanoparticle shape evolution during solution synthesis. Both growth by monomer attachment and nanoparticle coalesce have been observed. The growth mechanisms and shape controlling factors have been identified with the assistance of theoretical calculation. Second, I will show our progress in the study of electrochemical processes by the development of electrochemical liquid cells. At the end, the electron beam effects in the liquid cell study will be discussed.

Transition metal oxides (TMOs) have attracted attention for solid oxide fuel cell, gas sensor and catalytic applications. The energetics of the oxygen reduction reaction at the cathode is the key determinant for solid oxide fuel cell functionality. Although oxygen diffusion in cathode materials, including the path oxygen ion takes through the lattice, has been studied by DFT [1], it is still difficult to investigate diffusion mechanism experimentally, especially at atomic resolution. Recently, it became possible to characterize oxygen vacancy distribution and vacancy ordering at an atomic scale in the static case using quantitative aberration-corrected STEM. [2] In this study, we take this approach to the next level by observing lattice dynamics of phase transition from perovskite LaCoO₃ to brownmillerite LaCoO_2.5 with atomic resolution. We also perform DFT calculations to confirm the energetically favorable ion trajectories in LaCoO₃ based on the local atomic structure which is obtained by in-situ experiments.
We find that while before electron beam exposure films do not show any signs of vacancy ordering, they nevertheless contain a substantial amount of vacancies; the ordering is quickly induced by electron beam exposure. In the case of LCO film, beam exposure leads to a sequence of different phases, starting from disordered perovskite LaCoO_3-x to eventually brownmillerite La₂Co₂O_5-x, which is similar to the phase evolution observed in the bulk [3]. Specifically, we directly observe the evolution of the sequence of octahedral (O) and tetrahedral (T) layers from 4:1 (OOOOT) to 2:1 (OOT) and finally 1:1(OTOT), which shows the oxygen vacancy motion along lateral direction as well as vertical direction during the transition from 4:1 to 2:1. When oxygen vacancies travel from one adjacent layer to another in the out-of-plane direction for a film, metastable configurations are sometimes observed. Motion of oxygen ions induced a cascade of changes in the positions of nearby La and Co atoms, as well asin the tilt patterns of the adjacent CoO₆ octahedra. Kinetics of the V_o ordering as well as pathways to uncovering the exact atomic mechanism of oxygen vacancy ordering in LaCoO₃-x at an atomic scale will be discussed.
* Research supported by the U.S. Department of Energy (DOE), Basic Energy Sciences (BES), Division of Materials Sciences and Engineering, and through a user project supported by ORNL&’s Center for Nanophase Materials Sciences (CNMS), which is sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. DOE.
References
[1] A. Chroneos, Energy Environ. Sci. 4, 2774 (2011)
[2] Young-Min et al., Nat. Mater. 11 888 (2012)
[3] Ole H. Hansten et al., J. Mater. Chem. 8(9) 2081 (1998)

Pulsed laser deposition (PLD) is a well-established technique in fabrication of thin film of inorganic materials, eg. metals. Moreover PLD was also shown as successful technique in preparation of some organic materials, eg. molecular materials for optolectronics. PLD profits from its simplicity, modesty, versatility and flexibility. Varying deposition conditions, ie. fluence, laser repetition rate, ambient pressure, substrate and its temperature, one can easily influence nucleation and the growth of thin film and consequently its properties. The in-situ monitoring of optical or electrical properties allows sophistically control such processes. We chose zinc phthalocyanine (ZnPc) and silver as organic and inorganic material examples, respectively, to demonstrate benefits obtained of the implementation of the in-situ monitoring. These materials possess a great potential for application in optoelectronic devices, eg. OLEDs and solar cells.
We investigated, using in-situ monitoring of absorbance measurement in UV-VIS spectral range, the growth of ZnPc in vacuum on suprasil quartz substrates at room temperature. The effect of laser fluence (in the region from 10 mJ.cm^-2 to 100 mJ.cm^-2) and laser repetition rate of 50 Hz and 200 Hz on ZnPc film growth and properties was evaluated. In-situ monitoring revealed the growth rate and β-polymorph of ZnPc film.
The growth of silver ultra thin film on fused silica and ZnPc substrates was characterized using in-situ monitoring of electrical properties. Electrical conductivity and I-V curve were measured by four-wire technique. We demonstrated that we could estimate the point of coalescence and influence the growth mode in the real-time as well as the subsequent evolution of the surface roughness and control.
The optical properties of the films were ex-situ characterized by spectral ellipsometry and morphology was examined by SEM and AFM.

Electron microscopy of nanomaterials in liquid state is essential for providing precise information about dispersibility, aggregation and agglomeration of nanomaterials in their native environment (solvents, or buffers). Moreover, to determine exact shape and size of nanomaterials in liquid is very important and useful. Drying/freezing of the samples is the traditional way to do the electron microscopy of the colloidal nanoparticles and bio-nanomaterials in liquid. However, this approach of sample preparation, sometimes, induces structural damages, and changes the aggregation and agglomeration of the nanomaterials. In this work, we report the application of K-kit for liquid state TEM characterization of gold nanoparticles/polystyrene nanobeads, and CMP slurry nanoparticles in liquid. Resolution and image quality of these nanoparticles in liquid are found to be comparable with those in dry state. Furthermore, K-kit was demonstrated as a high resolution solution for investigating liquid state dynamic processes in TEM. Examples of the dynamic changes of polystyrene nanobeads in PBS buffer solution and wet chemical growth of gold nanoparticles are presented in this work.

The chemical and physical properties of oxides depend sensitively on the phase, microstructure, atomic termination, stoichiometry and defects, all of which can be modified by oxide reduction. A fundamental understanding of the microscopic processes of the reduction of metal oxides is indispensable to obtain controllable functionalities of the oxide. Hematite (α-Fe₂O₃) exhibits a wide range of functionalities and has been demonstrated as catalysis, gas sensing, water splitting, dye solar cells, etc. However, the variable oxidation states of iron results in a fairly complicated phase diagram of iron oxides with several easily interchangeable phases, which makes it a challenge in understanding the reduction mechanism of hematite. We have obtained three different kinds of nanostructures of hematite, i.e., one-dimensional nanowires, two-dimensional nanoblades and nanobelts. By employing in-situ transmission electron microscopy, we studied the microscopic processes of the reduction of nanostructured hematite, i.e., one-dimensional nanowires, two-dimensional nanoblades and nanobelt,s, by hydrogen gas at elevated temperatures. Our results reveal that the reduction proceeds via heterogeneous, topotactic nucleation of lower oxides of iron, which results in various hybrid nanostructures of iron oxides. We showed that α-Fe₂O₃ nanowires can be reduced to γ- Fe₂O₃ nanowires_, followed by transformation to Fe₃O₄, i.e., α-Fe₂O_{3 -->} γ- Fe₂O_{3 -->} Fe₃O_4. The comparative study of the reduction of Al₂O₃-coated α-Fe₂O₃ is also performed to understand the effect of surface confinement on the oxide reduction processes.

We have tested graphene as electron transparent window material for environmental cells dedicated for ambient pressure XPS spectroscopy and electron microscopy of interfaces under atmospheric pressure liquid and gaseous samples. These windows have thicknesses comparable or smalle compared to the effective attenuation length of 200-1000 eV electrons what allow to conduct interfacial spectroscopy of fully hydrated or gaseous samples . Based on this unique combination of properties and on recent developments in graphene fabrication and transfer protocols we demonstrate the capability to perform in situ electron microscopy and XPS spectroscopy studies of the dynamic electrochemical processes taking place at liquid electrolyte-solid interface.

Liquid cell transmission electron microscopy enables observation of processes in liquids with good spatial and temporal resolution, yielding information that is complementary to that available from light microscopy, scanning probe microscopy and scattering techniques. Here we discuss its application to electrochemical deposition, measuring local structure and growth rate during the formation of metal films from aqueous electrolytes. Control of the morphology of electrochemically deposited films is critical for creating high quality coatings and high performance structures for interconnects, sensors, magnetic storage devices and batteries. Liquid cell electron microscopy can give detailed information on morphology evolution as a function of electrolyte composition, electrode geometry and current/voltage parameters. We will show in movies the progression of the growth front during deposition in different materials systems, and quantify the onset of growth instabilities such as dendrites. Parameters of the growth front such as roughness, local velocity and curvature allow us to test models for growth instabilities and examine the effect of surfactants, electrode geometry and modulation of the applied voltage. We will consider some experimental issues, including electron beam artifacts and the effect of the thin liquid layer on diffusion, and discuss the extent to which microscopy can help to guide the fabrication of specific morphologies by electrochemical deposition.

Tungsten trioxide (WO₃), the most commonly used chromogenic material, has been investigated since the 1960s. In an electrochemical cell arrangement the transmission characteristics of WO₃ thin films can be reversibly changed by application of an external electric field. For this reason it is widely used for electrochromic (EC) devices, such as "smart windows", which can be employed for efficient fenestration for buildings due to the ability of switching the transmittance of light and solar energy. WO₃ is a cathodic EC material, meaning that it changes its color upon ion insertion, e.g. H⁺ or Li⁺ ions. Although WO₃ has been extensively studied since its EC properties were discovered, the mechanism responsible for the coloration/bleaching effect is still unclear and part of recent scientific discussion. In this work we provide some new insights into the coloration mechanism by studying nanocrystalline tungsten thin films combining electrochemical and analytical techniques such as UV-Vis, Raman, x-ray photoelectron spectroscopy as well as x-ray diffraction.
By employing in situ transmission spectroscopy at a fixed spectral band pass during electrochemical experiments, such as cyclic voltammetry, we identified a two-step insertion process for both protons and lithium ions, of which one step exhibits significantly lower coloration efficiency than the other. To obtain a better understanding of the insertion process we analyzed inserted WO₃ thin films at different stages using UV-Vis and x-ray photoelectron spectroscopy. Our analyses show that the first step denotes the reduction from initial W^VI+ to W^V+ and the second step the reduction of W^V+ to W^IV+. We found that the blue coloration in tungsten oxide is not present for all oxidation states of tungsten but rather mainly for W^IV+. That is, crystalline WO₃ only shows a significant transmission change when it is reduced to the W^IV+ state.
Furthermore, we present an experimental setup for spectrally and spatially resolved in situ intercalation/diffusion experiments. A compact three-electrode cell with the WO₃ film as working electrode is attached to a microscope system, a subtractive double spectrometer and a CCD. Patterning the thin film with a translucent electrochemically inactive layer separates certain areas of the WO₃ film from the liquid electrolyte. Upon application of an external electric field ions from the electrolyte are inserted into the uncovered WO₃ parts and diffuse into the covered areas. Due to time controlled CCD data acquisition diffusion/migration processes can be studied with a high spatial and time resolution.

Effects of superimposed thermal and electric fields on the densification behavior of 8% yttria doped zirconia (8YSZ) of 200 nm particle size was studied as a function of applied electric field strength in the range 143-320 V/cm and 20 ^oC/min heating rate using time-resolved in situ high temperature EDXRD with a polychromatic 200 keV synchrotron probe where spectra were collected with 2 second intervals. The isothermal densification occurred in the 790-930 ^oC range, which resulted in 95-98 % of the theoretical density with discontinues current draw up to 3 A through samples. No local melting at particle-particle contacts was observed in scanning electron micrographs, implying densification was due to solid state mass transport processes. It was found that the higher the applied electric field on sample, the temperature at which densification and the current draw occur, decreases. During current draw, anomalous elastic volume expansion of unit cell by 1% to 3% range is observed. It was found that time dependence of (211) and (112) peak widths depict a decrease at these a singularities at 790 ^oC-930 ^oC , which is not related to a phase transformation. We attribute the reduction in densification temperature and time to ultrafast ambipolar diffusion of species arising from the superposition of mass fluxes due to Fickian diffusion, thermodiffusion (Soret effect), and electromigration, which in turn are a consequence of a superposition of chemical, temperature, and electrical potential gradients. On the other hand, we propose defect pile-up at particle-particle contacts and subsequent tunneling as a mechanism creating the “burst-mode” discontinuous densification at the singularities observed at 790 ^oC and 930 ^oC.

We report on the discovery of anomalous lattice expansion and related defect phenomena in 8% yttria doped zirconia (8YSZ) particulate matter of 250 nm median particle size under superimposed thermal and electric fields. We carried out in situ high temperature EDXRD with a polychromatic 200 keV synchrotron probe. Densification occurred in the 876-905thinsp;°C range, which resulted in 97% of the theoretical density. No local melting at particle-particle contacts was observed in scanning electron micrographs, implying densification was due to solid state mass transport processes. The maximum current draw at 905thinsp;°C was 3 A, corresponding to instantaneous absorbed power density of 570thinsp;W/cm³. Densification of 8YSZ was accompanied by anomalous elastic volume expansions of the unit cell by 0.45% and 2.80% at 847thinsp;°C and 905thinsp;°C, respectively. The anomalous expansion at 905thinsp;°C at which maximum densification was observed is characterized by three stages: (I) linear stage, (II) anomalous stage, and (III) anelastic recovery stage. The densification in stage I (184thinsp;s) and II (15thinsp;s) was completed in 199thinsp;s, while anelastic relaxation in stage III lasted 130thinsp;s. The residual strains (ε) at room temperature, as computed from tetragonal (112) and (211) reflections, are ε₍₁₁₂₎thinsp;=thinsp;0.05% and ε₍₂₁₁₎thinsp;=thinsp;0.13%, respectively. Time dependence of (211) and (112) peak widths (β) show a decrease with both exhibiting a singularity at 905thinsp;°C. Moreover, parameterized Warren-Averbach analysis revealed an anisotropic and abrupt increase in (101) and (110) coherently diffracting domain size from 32 and 21 nm to 88 and 128 nm, and a decrease in d-spacing variation (DSV) from 0.72% and 0.64% to 0.44% and 0.52%, respectively, while burst-mode densification occurred. The CCDS and DSV exhibit time-dependent recovery to their initial state upon cool down from 905 ^oC to RT under zero E-field. Through thermokinetic computations we show that the observed anomalous lattice expansion and the accompanying changes in coherently diffracting domain size is not a consequence of thermal expansion due to Joule heating. The results provide direct proof of a new oxygen vacancy transport modality under the action of the simultaneous fields in particulate matter which we call the burst mode transport leading to burst mode densification.

Supported transition metal nanoparticles are important class of materials used extensively in catalytic applications due to their high surface to volume ratio and high concentration of low coordinated atomic sites. When exposed to high temperatures and gas environment, there is a range of thermally activated processes that can lead to morphological, structural and surface transformation, and the ability to characterize the catalytic nanoparticles under in-situ conditions is critical for rationalization of structure-property relationship, and thus essential for future advancement of catalytic technologies. In the current work, we will present atomic level in-situ TEM observations of Pd nanoparticles during exposure to elevated temperature and oxidizing environment. The in-situ observations were performed with environmental FEI Titan 80-300 equipped with a CEOS C_s -image corrector operated at 80kV and 300kV. In particular, the work will focus on the characterization of oxide nucleation and growth, and identifying the crystallographic features of Pd metal-oxide transformation. We will also show how coherency strains from the substrate play role in inhibiting phase transformation, and show that a distinct chemical interaction with the substrate can lead to significant changes in the initial stages of oxide formation. The obtained observations will be placed in the context of classical theory of oxidations. As a part of this presentation, we will also describe a gas control unit that enabled us to carry out switching between well-controlled mixtures of gasses, and demonstrate the use of this system to study gas-induced transformations at the atomic scale. This research is part of the Chemical Imaging Initiative at Pacific Northwest National Laboratory. The work was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by DOE&’s Office of Biological and Environmental Research and located at PNNL.

In order to improve the understanding of catalytic processes, information about the surface structure and the catalytic behavior of the active materials has to be gleaned. In particular, synergistic effects between the local structure and composition have to be considered and are, in fact, frequently observed.
A thorough description of such effects at the atomic scale remains challenging. Field emission techniques, including field ion microscopy (FIM) and field emission microscopy (FEM), are especially suited for studying these effects: the nanosized metal tip used as a sample represents a good model for a single catalytic nanoparticle. Furthermore, such high-field studies can be performed during an ongoing catalytic reaction by real-time imaging and in direct space. Nanoscale lateral resolution is achieved and provides information about the local surface composition in a time-resolved manner. Reaction-induced structural changes of the surface of the catalyst can also be assessed with step-site resolution in FIM mode. FEM is based on the emission of electrons from the sample, which can be locally affected by the presence of adsorbates. Local variations of the work function are detected in the form of a brightness pattern and the surface composition of the sample can be qualitatively investigated during the ongoing catalytic process, allowing for the determination of the elementary processes.
In this work, we study the morphological and structural changes occurring over platinum samples after oxygen exposure. The effects of reconstruction on the local catalytic activity of the NO₂ hydrogenation reaction are also investigated. For this purpose, the microscope is run as an open nanoreactor. Accordingly, the chemical system is kept far from its thermodynamic equilibrium, a necessary condition to observe nonlinear spatiotemporal behaviors. Aperiodic and highly periodic oscillations of various complexity have been reported for the NO₂+H₂ reaction on platinum, as well as the propagation of chemical waves on a single facet of the nanocrystal. This proves the robustness of dissipative, nonlinear behaviors down to the nanoscale. The velocity of the observed waves is of the order of a few mu;m/s, which is in good agreement with previous studies of catalytic reactions at the mesoscale.
As a conclusion, we show that nanoparticle dynamics must be accounted for in models describing the nonlinear features of catalytic reactions and, more generally, included in the description of catalytic properties of nanosized particles.

A key requirement for future applications of graphene is the development of scalable, economic production methods. Catalytic growth techniques are highly promising for achieving this, however the underlying mechanisms have yet to be fully understood, and control over the material structure and quality thus remains rudimentary.
Here, we apply complementary in situ techniques to develop a detailed, multi-scale understanding of catalytic graphene growth on polycrystalline Ni catalysts. We focus on technologically relevant low temperature (le;600°C) exposures to gaseous hydrocarbons,[1,2] and vacuum annealing (le;600°C) of Ni/solid-carbon stacks[3] We combine time- and depth- resolved X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction/Reflectivity (XRD/XRR), and Scanning Tunnelling Microscopy (STM) to probe the structural and chemical properties of graphene and the catalyst during growth.[1,2,3,4] We show that graphene forms directly during isothermal hydrocarbon exposures, whilst the contribution of precipitation upon cooling is minor. Similarly, for Ni/tetrahedral amorphous carbon (ta-C) stacks, graphene growth is found to occur predominantly during ramping up and annealing by C dissolution and diffusion through the catalyst. A detailed growth rationale is established from these measurements, and we relate this to the understanding of the growth kinetics we have previously developed.[5] Further systematic growth studies on other polycrystalline transition metal catalyst foils (Co, Cu, Pt) demonstrate that the growth behaviour broadly resembles that on Ni, highlighting the generality of our model.
Based on this, we introduce several approaches to control the structural properties of the graphene produced. Catalyst alloying is demonstrated as a means of improving graphene growth by tuning reactivity and selectivity. We show that alloying Au with Ni results in an order of magnitude increase in graphene domain sizes,[1,5] enabling monolayer graphene growth at 600°C of comparable uniformity and quality to that reported for Cu-based growth at >900°C. For the catalytic transformation of solid C sources, we introduce C diffusion barriers as a general and simple method to prevent premature C dissolution during temperature ramping, significantly improving the graphene produced. A thin Al₂O₃(1-3 nm) barrier inserted into a Ni/ta-C stack enables growth of uniform monolayer graphene at 600°C, with domain sizes >100 mu;m, and a Raman D/G ratio of <0.07.[3]
The understanding of the growth process developed is broadly relevant to catalytic graphene growth on a wide range of catalysts, and the ability to rationally engineer the growth process highlights the importance of our approach.
(1) Weatherup et al. Nano Lett. 2011, 11, 4154-4160
(2) Weatherup et al. ChemPhysChem 2012, 13, 2544-2549
(3) Weatherup et al. Nano Lett. 2013, 13, 4624-4631
(4) Patera et al. ACS Nano 2013, 7, 7901-7912
(5) Weatherup et al. ACS Nano 2012, 6, 9996-10003

SiO₂-coated gold nanorods (SiO₂-GNRs) are of broad of interest because they have better thermal stability than uncoated GNRs. Thermal stability of GNRs is a key issue for photothermal heating and other applications that involve exposure of GNRs to high intensity light because uncoated GNRs will revert into spherical shapes, usually at temperatures below 250 °C, in both air and in solution. As the GNR aspect ratio decreases, the optical properties change, and the redshift in the longitudinal surface plasmon resonance (LSPR) vanishes. Here, we report the thermal stability of SiO₂-GNRs under different environments and compare with uncoated GNRs. When we measuere by in situ TEM (pressure of ~10^-5 Pa), SiO₂-GNRs maintain their rod shape within the SiO₂ shells at temperatures up to 1200 °C, which exceeds the bulk melting temperature of Au. Uncoated GNRs maintain their shape but sublime into the vacuum at ~900 °C. For comparison, during heating on TEM substrates in a furnace under ambient atmosphere, SiO₂-GNRs become spherical at ~700 °C, while uncoated GNRs become spherical at temperatures below 400 °C. The environment in which the samples are heated critically affects their stability.

The mass transport at liquid catalyst and nanowire (NW) interface is critical in understanding the vapor-liquid-solid growth mechanism in III-V semiconductor nanowires. Here, through in-situ high resolution transmission electron microscope observation, we show the oscillatory dissolution and precipitation process at the liquid catalyst/NW interface in InAs NW coated by amorphous carbon during heating. The NW morphology during precipitation indicates that nucleation occurs at the liquid/solid interface or liquid/solid/amorphous carbon triple point, under which condition the formation of zinc blende nuclei is preferred. The precipitation process observed at atomic resolution advances the basic understanding of mass transport between the liquid and solid phases.

Electrical wind force is an important element in electrical switching behaviors of phase-change materials. It has been reported that the electrical wind force influences the motions of dislocations, which determines the degree of order-disorder states existing in phase-change materials [1]. In this presentation, we discuss electrical wind force-driven behaviors occurring in phase-change materials. At first, we report atomic mass-transport behaviors as DC voltage biases are applied in line-shape Ge₂Sb₂Te₅ (GST) devices. As the electrical current density reached 3-4 MA/cm² by DC voltage bias, a directional mass transport was identified by forming asymmetric surface morphology on the line-shape GST devices. By electric current, Joule-heating raised the temperature up to ~300 ^oC, implying that the mass transport of GST occurs in hexagonal phase (solid state) regime. In second, we extend the roles of electrical wind force to electrical switching behaviors of GST. We studied the effects of electrical voltage pulses on crystalline-to-amorphous phase transition of GST by in situ transmission electron microscopy (TEM). Electrical voltage pulse plays a critical role by creating dislocations through heat shock process: Rising edge of the pulse produces vacancies by heating, whereas during rapid cooling, atomic vacancies are condensed into dislocation loops. As the dislocations feel the electrical wind force, they become mobile and glide in the direction of hole-carrier motion. Continuous increase in the density of dislocations moving unidirectionally leads to dislocation jamming, which eventually induces the crystalline-to-amorphous phase transition. We interpret it through one-dimensional traffic model in which the increase of dislocation density exceeding a certain threshold point induces a catastrophic jamming of dislocations. Density functional theory (DFT) calculations of generalized-stacking-fault (GSF) energy show that basal plane of GST hexagonal phase provides favorable pathways of dislocation motions. Our understanding about dislocation-templated amorphization suggests that the transition from crystalline to amorphous states in phase-change materials may not require a melting process.
[1] S.W. Nam et al, Science, 336, 1561-1566 (2012)

Conventional and cryogenic transmission electron microscopy (TEM) are key techniques for the real-space imaging of soft matter at the nanometer scale.¹ Still, these techniques can only produce snapshots, and not reveal the true dynamics of a system that will give insight in the dynamic interactions between the different components. In contrast, the application of liquid phase TEM (LP-TEM), using 200-500 nm thick cells with electron transparent (generally SixNy) windows allows the dynamic monitoring of events in liquid samples, thus avoiding the need for specimen preparation at every time point.²
Currently LP-TEM still has some limitations, e.g. the interaction of the electron beam with the fluid is a matter of concern as it may induce free electrons in the liquid by and also gradients in temperature and pH (due to water decomposition), and beam induced deposition of nanoparticles is also often observed. Indeed, many of the reported experiments so far have either a) used the electron beam to drive the processes under investigation, b) have imaged objects rather than processes, or c) reported on the effects of the electron beam on the events observed.
Here, we exploit these beam-sample interactions to write silica nanostructures in aqueous medium. By applying a focused electron beam in STEM mode we can control the localized deposition of fused silica nanostructures with defined thickness from a solution of monodisperse silica nanoparticles. The thickness of the deposits is linear with the applied electron dose. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) demonstrate that the deposited patches are a result of the merging of the original 20 nm-diameter nanoparticles, and that the related surface roughness depends on the electron dose rate used. Using this approach, sub-micrometer scale structures are written on the SiN in liquid by controlling the electron exposure as function of the lateral position. The observed process could be useful in future work for the direct writing of three dimensional nanoscale silica structures in liquid.

Liquid cell electron microscopy is a powerful tool to study nanoscale phenomena in liquids in situ. However, energy transferred from the fast-moving electrons to the irradiated medium generates radical and molecular species; for water these include hydrogen, oxygen, hydrated electrons and hydrogen peroxide. These species may influence phenomena under study in liquid cell electron microscopy. In particular, the formation of bubbles composed of radiolytic gaseous species can strongly affect imaging. Additives to the initial solution are known to alter radiolysis product formation. Here we examine the effect of hydrogen peroxide, an important additive in oxidation and reduction reactions, on the production of radiolytic species in liquid cell electron microscopy. We computed the concentrations of radiolysis products as functions of initial hydrogen peroxide concentration, beam current, beam size, time, and position relative to the beam center. These calculations predict that the concentration of hydrogen increases as the concentration of hydrogen peroxide increases. Bubble nucleation is a function of the saturation concentration, which is fixed by the pressure within the device during observation. The pressure inside the device was controlled during the filling of our closed cell, the nanoaquarium, and then estimated in situ by considering the deflection of the silicon nitride windows based on transmitted beam intensity. The predictions are consistent with experimental observations in a liquid cell indicating that the presence of hydrogen peroxide lowers the critical dose rate required to nucleate bubbles as a result of the higher radiolytic production of hydrogen.

Acknowledgements: The study was supported, in part, by the National Science Foundation through grants 1129722 and 1066573. Device fabrication was carried out at the Cornell NanoScale Facility (NSF Grant ECS-0335765), a member of the National Nanotechnology Infrastructure Network.

The Nd₂Fe₁₄B magnets with excellent properties have extended the applications in the field of motors for Hybrid Electric and Electric Vehicles. It is well known that the Nd₂Fe₁₄B magnets without doping dysprosium (Dy) show decrease of coercivity at elevated temperatures. Development of the Nd₂Fe₁₄B magnets which can use at elevated temperature is expected. Therefore, in order to reduce deterioration of coercivity of Nd₂Fe₁₄B magnets at elevated temperatures, it is important to observe the generating site of reverse magnetic domains in Nd₂Fe₁₄B magnets. In this study, we observed thermal and magnetic field demagnetization process in polycrystalline Nd₂Fe₁₄B magnets by transmission electron microscopy (TEM) / Lorentz microscopy.
Nd₂Fe₁₄B polycrystalline samples with average grain size of below 800 nm were prepared by HDDR process. Thin foils suitable for TEM observations were#12288;prepared by a focused ion beam (FIB) thinning method#12288;(Hitachi FB-2100). TEM observations were carried out in a HF-3300EH at the temperature range from room temperature to 523K.
After magnetization by external magnetic field of 2.0 T, the magnetic domain walls were observed by the Fresnel mode with in situ heating. At 498K, reverse magnetic domains were observed in thin foil sample. The observed reverse magnetic domain would indicate the beginning of thermal demagnetization.
Similar observations were repeatedly conducted without (condition 1) and with applying an external reverse magnetic field of 25 mT (condition 2) using the same thin foil. As the results, the reverse domains were revealed to be generated at lower temperature under the condition 2 than under the condition 1. Moreover, in the case of condition 2, the reverse domains were found to be generated nearly the same region.
Acknowledgement: This work has been supported by Future Pioneering Projects /Development of magnetic material technology for high-efficiency motors from Japanese Ministry of Economy, Trade and Industry

We are utilizing synchrotron based in situ small- and wide-angle X-ray scattering (SAXS and WAXS respectively) to study the structural variation during continuous tensile mechanical testing of melt blown Linear Low Density Polyethylene (LLDPE) films. These experiments allow us to link the true macro-scale mechanical response of the films with the continuously evolving film morphology. Clear differences in the morphological evolution are observed between samples strained along the processing machine direction (MD) or the transverse direction (TD) of the films.
At large macroscopic strains, the growth of a new lamellae-amorphous morphology occurs, the dimensions of which are independent of strain. When strained in the TD direction, this characteristic dimension is shown to be independent of the choice of processing conditions under which the films were melt blown. This behavior however is absent in the samples strained along the MD where the processing conditions affect the dimensions of the structural feature at high strains. The large strain TD characteristic dimension therefore reflects an inherent behavior of the specific polyethylene. Exploiting correlation analysis of the SAXS data, the length scale contributions of the crystalline and amorphous factions to the characteristic dimension can be extracted. Coupling these results with the average branch distribution along the backbone we observe a relationship between the characteristic dimension at high strain and the distribution of low molecular weight branches and the resulting branch spacing along the backbone of the LLDPE. These structural insights will potentially allow correlations of mechanical performance parameters to the polymer molecular architecture in these polyethylenes.

Use of a tilted fiber Bragg grating (TFBG) as a sensing device for the monitoring of metal-organic chemical vapor deposition (MOCVD) for a variety of group 11 ultrathin films has been employed. Mechanistically, a TFBG-polarized transmission amplitude spectrum in the near-infrared (NIR) range works as a real-time film sensing platform by undergoing attenuation under finite changes to the surrounding refractive index (SRI) as a film nucleates and grows. Moreover, the polarization mode (S or P) of core-guided light interrogating the growing film provides accurate real-time information about the growth profile of metal thin films deposited from single-source precursors developed in our lab. Use of MOCVD affords many advantages over other line-of-sight techniques such as physical vapor deposition (PVD) due to its ability to uniformly coat complex surfaces such as optical fibers. The MOCVD of anisotropic (polarization-dependent) and isotropic (polarization-independent) ultrathin gold films from gold (I) guanidinate ([Au(NⁱPr)₂CNMe₂]₂) and gold (I) iminopyrrolidinate ([Au(Me₂-^tBu-ip]₂) compounds, respectively, has been explored extensively. Atomic force and scanning electron microscopies as well as an ensemble of both soft and hard (synchrotron radiation) x-ray spectroscopies were employed to corroborate a variety of the TFBG-extracted thin film metrics (e.g. thickness and growth rate) obtained in-situ. This TFBG-based ellipsometer has also been employed to probe the nucleation and growth of silver and copper films from the analogous M(I) guanidinate (M=Ag, Cu) precursors. Use of a dielectric pre-coating on the TFBG, particularly for its enhancement of the TFBG&’s SRI sensitivity and polarization-dependence properties, was also considered. The broad scope of work already achieved with the TFBG employed as a highly robust and tunable deposition monitoring tool will be discussed, as well as further applications of the coated TFBG as an evanescent field-based sensor.

Due to its potential for weight savings, aluminum alloys are an attractive alternative to steels in applications such as the automobile industry. However, difficulties associated with the deformation behavior of these alloys has limited their application in practice. A primary example is serrated flow seen in the stress/strain curves during straining of Al-Mg alloys in certain strain rate and temperature regimes due to the Portevin-Le Chatelier (PLC) effect. This effect is generally associated with the diffusion of solute Mg atoms to dislocations, which act to pin the dislocations, resulting in plastic strain occurring in bursts. Macroscopically, this effect has been well characterized over a wide range of materials and testing conditions. The underlying dislocation structures and mechanisms responsible have not received the same level of scrutiny. In order to characterize these interactions, Al 5xxx samples were strained in situ in the scanning electron microscope (SEM) and the transmission electron microscope (TEM). Combined electron backscatter diffraction (EBSD) and electron dispersive X-ray spectroscopy (EDS) analysis in the SEM showed high local Mg concentrations forming which correlated to regions of high deformation. In situ TEM straining showed that these higher Mg concentrations led to Mg clustering in front of a crack tip. Interactions with glissile dislocations resulted in discontinuous dislocation propagation. The results are discussed in terms of potential impact on the PLC effect.

Scanning transmission electron microscopy (STEM) coupled with electron energy loss spectroscopy (EELS) can identify changes of composition as well as bonding environment with atomic resolution. However EELS measurements made with sub-nm spatial resolution impose demanding experimental and instrumentation requirements. This is a particularly important consideration for in situ measurements when the environment is less stable and phenomenon such as sample drift increases. An alternative approach using STEM has been identified to track changes of oxidation state in ceria (CeO₂) with sub-nm spatial resolution. Moreover because the experimental protocol is less complex it facilitates measurements on time scales that would be untenable otherwise. This technique was qualified through the use of EELS, in situ experiments, and image simulations. Using this approach the oxidation and reduction behavior of CeO₂ nanoparticles were studied. Changes to the nanoparticles were stimulated locally and globally either by using the electron beam directly or by exposing the particles to oxidizing and reducing conditions in an environmental transmission electron microscope. The results of these experiments will be discussed.

Water interaction with metal oxides is of great interest in a number of technological applications of these materials: catalysis, corrosion, electrochemistry, biology, environment protection and atmospheric chemistry. [1, 2] Both the strength of the interaction (hydrophilicity) and the tendency of water to dissociate strongly depend on the nature of the oxide. We have studied the interaction of water with the (001) surface of LaMO₃ perovskites (M = Cr, Mn, Fe, Co, Ni). We found that the LaO terminated surface is more reactive, while for both LaO and MO₂ terminated surfaces the reactivity depends on the transition metal. The results have been correlated with the different hydrophilic behavior measured by contact angle measurements.[3] The tendency of water to dissociate has been also analyzed in connection with the different acid-base properites of the surfaces.
The spectroscopic properties (IR and XPS) were also computed thereby providing a reference for in-situ characterization. In particular, the different species present at the oxide surface exposed to water—comprised of molecular water, hydroxyl groups, and carbonate—have been identified by comparing the experimental XPS spectra [4] with the computed core-levels shift.
REFERENCES:
[1] Thiel, P. A.; Madey, T.E. “The interaction of water with solid surfaces: fundamental aspects” Surf. Sci. Rep. 1987, 7, 211-385.
[2] Henderson, M. A. “The interaction of water with solid surfaces: fundamental aspects revisited” Surf. Sci. Rep. 2002, 46, 1-308.
[3] Stoerzinger, K. A.; Hong, W. T.; Azimi, G.; Crumlin, E. J.; Biegalski, M. D.; Bluhm, H.; Varanasi, K. K.; Shao-Horn Y. “The reactivity of perovskites with water: role of hydroxylation in wetting and catalysis” in preparation 2014
[4] Stoerzinger, K. A.; Hong, W. T.; Crumlin, E. J.; Bluhm, H.; Biegalski, M. D.; Shao-Horn, Y. "Water Reactivity on the LaCoO₃ (001) Surface: An Ambient Pressure X-ray Photoelectron Spectroscopy Study" under review 2014.

The process and kinetics of carbide precipitation upon tempering of an Fe-10Cr-0.15C (wt.%) alloy fabricated from high-purity components has been studied. Differential scanning calorimetry reveals three exotherms in a temperature range of 100-7000C. Using advanced electron microscopy and with the aid of simulation using the MatCalc software, the exothermic processes have been interpreted. Cementite precipitated first upon tempering at temperature as low as 2000C; M₇C₃ and M₂₃C₆ appear at higher temperatures, precipitating at approximately the same time but on different sites (M₇C₃ within grains and laths and M₂₃C₆ on grain and lath boundaries). Subsequently, the more stable M₂₃C₆ coarsens at the expense of M₇C₃, which dissolves. The first exotherm was interpreted as being related to the precipitation of cementite whilst the other two overlapping exotherms were interpreted as relating to the concurrent precipitation of M₇C₃ and M₂₃C₆, and the coarsening of M₂₃C₆, respectively. In-situ SEM and TEM observation is being conducted in order to obtain a more precise understanding and further validate the use of MatCalc simulation in interpreting DSC results.

Inkjet printing technology is a fast growing technology with a widespread field of applications. Although this technology is known since the 1950s it really started its multi field development in the 1970s. Since then many new applications for inkjet printing were added to the field of classical graphical printing. Advantages of the technique are manifold: Various materials can be placed precisely on specific surfaces, micro sized structures can be printed and cost reduction is achievable as well by using this technique in large-scale production. For this purpose, it is necessary to have a closer look on the process-parameters and their influence on the ink quality and stability.
Inline process surveillance based on Near Infrared Spectroscopy (NIR) is commonly used in pharmaceutical industry, where the adsorption spectra of functional groups are determined. In an inkjet ink production process this method is not used so far, although there is a huge lack on information concerning chemical reactions, interactions and on the parameters influencing them. By implementation of NIR methods determination of these information becomes potentially feasible.
The aim of this study is the buildup of an inline surveillance system during the ink production process of UV-curing inkjet inks based on NIR. Hence, data on the chemical reactions during the various process steps are obtained that are not available at present. Investigating the parameter limits and interactions on the molecular level is important not only in respect of production quality. Results will give a basis for optimization in terms of environmental sustainability, cost reduction and process operation. Direct and/or indirect determinations of the values for inter- and intramolecular crosslinkage, zeta-potential, temperature, pH, particle size, pressure and viscosity, for example, are done. Furthermore the inline process surveillance gives the possibility to immediately take actions if parameters are outside the limits. This leads to improved production results.
The authors acknowledge funding by the Austrian research promotion agency FFG within the ImprovInk project (843641).

In the present study, we carried out the detection of C₂H radical in conventional hot filament chemical vapor deposition (HFCVD) reactor using REMPI spectroscopic method during microcrystalline diamond thin film deposition using CH₄(0.4%) + H₂ gas mixture. The gas mixture was passed by the reactor at 100 sccm of flow rate and at total gas mixture pressure of 20 Torr while the filament (Re) temperature was 2760 K. The absolute calibration of the used REMPI method was carried out by direct photodissociation of C₂H₂ by the radiation of excimer ArF laser (lambda;_exc = 193 nm) at the room temperature and bulk acetylene pressure of 0.5 Torr. Photodissociation quantum yield of acetylene at 193 nm excitation wavelength radiation is about 1. We as well carried out systematic measurements of the C₂H radical concentration space distribution between filament and substrate surface and CH₄ concentration dependences of such a radical concentration as a function of the distance between filament and substrate. We made a comparison of our results with the literature data as well as we proposed for C₂H radical formation mechanism based on the obtained experimental data. We propose that the main channels of the C₂H radical formation are the H substitution in CH_m by CH_n species where m and n are 1, 2 and 3. Values of the estimated kinetic parameters of the proposed model were compared with those of the literature. We found the acceptable agreement between our kinetic parameters and those available in the literature which means that the proposed mechanism is reasonable. From our analysis, we obtained the phenomenological coefficient γ of the C₂H radical heterogeneous decay on the substrate surface to be close to 1. This indicates that our radical of interest plays some important role in the heterogeneous chemical processes of the microcrystalline diamond deposition in the HFCVD reactor.

The initial formation stages (i.e., island nucleation, growth, and coalescence) set characteristic length scales during growth of thin films from the vapor phase. They are, thus, decisive for morphological and microstructural features of films and nanostructures such as surface roughness, island size and separation, and thickness required to form conductive (in the case of metallic films) and continuous films.¹ Each of the initial formation stages has previously been well-investigated separately for the case of Volmer-Weber growth,^2,3 but knowledge on how and to what extent each stage individually and all together affect the microstructural evolution is still lacking. Here we address this question by systematically studying the growth evolution of Ag on SiO₂ from pulsed vapor fluxes⁴ all the way from nucleation to formation of a continuous film. By combining in situ spectroscopic ellipsometry measurements, ex situ AFM imaging and kinetic Mote Carlo simulations we establish the effect of the vapor flux time domain on the scaling behavior of characteristic growth transitions (elongation transition, percolation and continuous film formation). Our data reveal a pulsing frequency dependence for the characteristic growth transitions, where the nominal transition thickness decreases with increasing pulsing frequency up to a certain value after which a steady-state behavior is observed. This scaling behavior is shown to result from differences in island sizes and densities that, in turn, are determined solely by the interplay between the characteristics of the vapor flux and time required for island coalescence to be completed. In particular, our data provide evidence that the steady-state scaling regime of the growth transitions is caused by island growth that hinders coalescence from being completed.
¹ M. Ohring. Materials science of thin films. Academic Press, San Diego, 2nd edition (2002).
² T. Michely and J. Krug. Islands, mounds and atoms: Patterns and processes in crystal growth far from equilibrium. Springer, Berlin (2004).
³ J. E. Greene. Thin film nucleation, growth, and microstructural evolution: An atomic scale view. Elsevier Inc., Oxford (2010).
⁴ Pulsed vapor fluxes are generated by the plasma based deposition technique high power impulse magnetron sputtering. See: D. Magnfält, V. Elofsson, G. Abadias, U. Helmersson and K. Sarakinos. J. Phys. D: Appl. Phys. 46, 215303 (2013).

This paper has reported the beneficiation and characterization of gold from Itagunmodi gold ore in Atakumosa West LGA in the State of Osun Nigeria using cyanide solution obtained from cassava and commercially available sodium cyanide analar grade. Cyanide solution extracted from cassava variety TMS 30572 leaves obtained from Obafemi Awolowo University (O.A.U) Research and Teaching Farm was discovered to have the highest free cyanide (CN^-) among the ten different cassava varieties evaluated. The samples were exposed to varied concentrations from 0.25% to 2.00% CN at intervals of 0.25% CN from cyanide solution obtained from cassava and commercially available sodium cyanide analar grade.
The result showed that after 24 hours of cyanidation and concentration of 2% CN on 10 g gold ore concentrate, the analar grade sodium cyanide yielded 0.123 g while the cassava based cyanide yielded 0.098 g. The performance of analar grade sodium cyanide is greater than cassava based cyanide by a difference of 0.25%.

The discovery of two-dimensional (2D) materials stimulates intense interests and research in their novel structures and emerging new physical phenomena. It has been demonstrated both by theory and experiment that a 2D monolayer is not an ideally flat sheet, but a film with ripples that minimize its surface energy, an intrinsic feature of 2D material in reality [1, 2]. Direct visualization and monitoring the ripples of the monolayers is an important way to reveal the novel mechanical properties of the material, for instance, the propagation of mechanical waves on monolayers. However, it is still challenging to directly observe the ripple structures and their dynamical behavior.
In this present work, we used medium-angle annual dark-field (MAADF) imaging in a scanning transmission electron microscope (STEM) to directly visualize ripples on CVD-grown monolayer MoSe₂ at the nanometer scale. We found that the MAADF imaging intensity of the Se₂ columns correlated linearly with the displacement between the top and bottom Se atoms in projection because of electron channeling. Such displacement results from titling of the monolayer with respect to the incident electron beam due to the presence of ripples. By mapping out the gradually changing tilting components of each atomic column in an atom-resolved image, the 3D morphology of the monolayer can be reproduced. Moreover, time-series imaging reveals that the ripples propagate through the monolayer under the excitation of the electron beam, representing the breathing of the monolayer film.
[1] J. C. Meyer, et al, The structure of suspended graphene sheets, Nature, 446, 60-63 (2007)
[2] J. Brivio, et al, Ripples and layers in ultrathin MoS₂ membranes, Nano Letter, 1 (12), 5148 (2011)

In-situ observation by transmission electron microscopy (TEM) on behavior of metal nanoparticles with sub 10nm has been performed for the study on nucleation and growth in initial stage of thin film growth or on nanoparticle aggregation as a temperature. It has been revealed that Au nanoparticles with several nanometer scale move, rotate, change the crystal structure and aggregate each other without heating of the samples under the e-beam irradiation in TEM. The behavior of Au nanoparticles under the e-beam irradiation has been explained by temperature increment by e-beam irradiation or charging by inelastic scattering of electron such as secondary electron generation, ionization etc.
We observed the behavior of Au nanoparticles on pure carbon and SiO membrane under the e-beam irradiation. Au nanoparticles sputtered and the target thickness was about 0.5 nm. Average diameter and areal density of Au nanoparticles was about 3 nm and 4 #/(10nm*10nm), respectively. In situ observation of Au nanoparticles in TEM with 200kV was performed for 5 hr and recorded to video file. Electron flux was 1.5*10⁵ e/nm²sec.
The behavior of Au nanoparticles on pure carbon and SiO as e-beam irradiation time was extremely different. Au nanoparticles on SiO membrane travel and aggregate after 15min of e-beam irradiation. The nanoparticle size increased with the increase of the irradiation time. After 2hr, Au nanoparticles grow up to about 5 nm and the density of Au nanoparticle decrease to 1 #/(10nm*10 nm). However, during e-beam irradiation of 4 hr, Au nanoparticles on pure carbon did not actively move and then, particle size and density did not change. In this presentation, we will show the movie on the behavior of Au nanoparticles under the e-beam irradiation and discuss about quite different behavior of Au nanoparticles on different substrate for a long time e-beam irradiation.

Proteins are the molecular machines that carry out the vast array of functions needed for the survival and propagation of all cellular organisms. Many proteins form this machinery by folding into functional building blocks that self-assemble into extended networks to deliver complex functions ranging from photosynthesis, to CO₂ separation, selective ion transport, and tissue mineralization. Inspired by protein recognition and self-assembly in nature, various synthetic proteins and peptides have been exploited to mimic both properties. However, the application of protein- and peptide-based materials is problematic, because they exhibit poor stabilities against thermal and chemical degradation.
Peptoids, or poly-N-substituted glycines, were recently developed with aims to mimic both the structure and functionality of peptides and proteins, and bridge the gap between biopolymers and bulk polymers. As with peptides, sequence-specific peptoids can be efficiently and cheaply synthesized by using automated solid-phase synthesizer. Moreover, peptoids exhibit much higher thermal and chemical stabilities than proteins and peptides. In contrast to peptides and proteins, peptoids are much less complex, yet they can still encode unique side-chain diversity for self-assembly and molecular recognitions. The lack of backbone hydrogen bonding is an advantage of peptoids for the design of self-assembling materials because it allows the explicit introduction of interactions through the side chains, thereby leading to structures with high predictability.
In this talk, we report our efforts to exploit peptoids to mimic both assembly and mineralization functions of peptides and proteins. In situ AFM imaging was used to directly observe peptoid self-assembly and peptoid-promoted calcite crystal growth in real time. Specifically, we demonstrated that 12-mer peptoids self-assemble into ordered materials both in solutions and on substrates. Assembled materials include two-dimensional (2D) porous networks, free-floating 2D crystalline nanosheets, 1D nanoribbons and 0D micelles. Similar to peptide and protein self-assembly, peptoid self-assembly is highly sequence-specific, and pH sensitive. Our in situ AFM imaging results showed that peptoid-peptoid and peptoid-substrate interactions played critical roles in the assembly of peptoid-based biomimetic materials. We also demonstrated that peptoids are able to mimic acidic proteins commonly presented in natural biominerals for dramatic controls over both calcite morphology and growth kinetics. By designing peptoids with controllable balance between electrostatic and hydrophobic interactions, we were able to tune calcite morphology and the degree to which growth was accelerated.

Colloidal particles are often regarded as building blocks for creating new materials, so guiding them to form specific structures is crucial. In carefully chosen systems, observation of the assembly process is possible in real-time using fluorescence confocal microscopy. Here we assemble a cellular network starting from a colloid-stabilized emulsion of partially miscible liquids. Network formation is induced by the disappearance of the continuous phase via evaporation, a process that can be followed in detail [1]. The particles are driven into a cellular network as the droplets are squeezed together. Re-mixing of the liquid phases eventually occurs, leaving a stable structure surrounded by a single fluid phase. We relate this formation process back to the underlying phase behaviour of the partially miscible liquids.
We then apply our understanding to create a non-aqueous (oil-in-oil) Pickering high internal phase emulsion (HIPE) stabilized by chemically modified fumed silica [2]. In this case, a 75 vol % ethylene carbonate (EC)-rich internal phase is emulsified in 25 vol % p-xylene (xylene)-rich continuous phase using interfacial nanoparticles. Incorporating polystyrene (PS) into xylene enables one-step formation of PS-filled HIPEs in place of a multi-step polymerization of the continuous phase. Here, drying the pure HIPE results in the selective removal of xylene and coalescence of EC-rich droplets. By contrast, with the PS in the xylene-rich continuous phase, we show that EC-rich droplets can be retained even though the xylene is evaporated off, and a new semi-solid composite containing both liquid phase and solid phase is formed.
References:
[1] N. Hijnen and P.S. Clegg, Mater. Horiz., 1, 360 (2014)
[2] D. Cai, J.H.J. Thijssen and P.S. Clegg, ACS Appl. Mater. Interfaces, In Press, DOI: 10.1021/am501328r

In nanoparticle synthesis it is common practice to add organic ligands during the synthesis to control final nanoparticle size and shape. This results from the fact, that the ligands change the crystallization kinetics as well as the reaction path. Ab initio electronic structure simulations by Alivisatos et al. show how the binding energies of different ligands influence the relative growth rates of unlike crystal facets of CdSe nanoparticles [1]. For the model system ZnO in non-aqueous sol-gel processes a multitude of studies exists with a variety of synthesis parameters and organic ligand molecules, all with the general aim to develop a substantiated nucleation model. The experimental procedures employed so far cannot reveal the evolution of crystallinity [2]. Therefore, we performed in-situ pair distribution function (PDF) experiments with a zinc concentration of 30 mM in ethanol in a flow cell setup at synchrotron PDF beamlines, adding ligands of different binding strengths at 7 mM, namely acetate, dimethyl-L-tartrate and 1,5-diphenyl-1,3,5-pentanetrione. The reaction was initiated by the addition of the organic base tetramethylammonium hydroxide [3]. The ligands not only result in different particle sizes of 6 and 2.5 nm in the powders, but also show distinct differences in the ZnO nucleation pathways. These have in common the existence of identical tetrahedral primary precursors Zn₄OAc₆ [4]. Moreover, we find a common magic-sized cluster (MSC) of 13 Å in diameter. However, the ripening time of the primary precursors until they form 13 Å MSCs differs as well as their further reaction path. For the weakly binding ligand acetate, the MSCs subsequently form continuously growing crystalline particles as other precursors and MSCs can attach and restructure more readily. For the two studied strongly binding ligands, the MSCs are highly stable and undergo oriented attachment without immediate restructuring. Only upon the agglomeration of about seven MSCs the agglomerate is large enough to restructure to spherical 2.5 nm particles. These in-situ experiments are the first to show the feasibility of in-situ PDF measurements at concentrations as low as 30 mM. Further, they proof directly the previous theoretical findings that nanoparticle nucleation and growth is strongly influenced by the binding strength of organic ligands.
[1] Puzder A., Williamson, A. J., Zaitseva, N., et al., Nanoletters Vol. 4, No. 12 (2004), 2361
[2] Ludi, B. & Niederberger, M.,. Dalton Trans. 2003, 42, 12554
[3] Wood, M. Giersig, M. Hilgendorff, A., et al. Aust. J. Chem. 56, p. 1051, 2003.
[4] Spanhel, L. and Anderson M. A., J. Am. Chem. Soc. 113 (1991), 2826

The interplay between mineral and organic species is central to the control of numerous organisms over biomineral formation. Deciphering the underlying mechanisms requires in vitro studies in which the physical and chemical parameters can be well controlled.
Along these lines, self-assembled monolayers (SAMS) - single-layered molecular assemblies in height adsorbed on surfaces organized into large laterally ordered domains - have shown to be a great tool for understanding formation and involved energetics of mineral growth in contact with an organic templating stucture (so-called matrix-mediated mineralization). Amongst essential findings, previous work on calcium carbonate (CaCO₃) (one of the most abundant biominerals), has indicated that such an organic template is able to control nucleation rates by lowering interfacial energies and corresponding free energy barriers, indicating a more kinetically determined pathway of mineral formation [1].
Using negatively charged polyelectrolyte polystyrene sulfonate (PSS) as a proxy for a bio-organic mediator, here we investigate organic-mediated crystallization of CaCO₃. Hereto for TEM purposes, a Hummingbird commercial liquid flow holder cell was utilized, containing two Si/Si₃N₄ wafers with electron transparent Si₃N₄ membranes. To induce mineral growth in the liquid cell, we use a calcium source (CaCl₂) with or without PSS in combination with the ammonium carbonate diffusion method, where the latter increases supersaturation in the system by the diffusion of CO₂/NH₃ gas into the solution.
Without the organic PSS additive as a control reaction, we observe rapid, ubiquitous nucleation and growth of vaterite in both liquid TEM/AFM when exposing the CaCl₂ to the carbonate source in a diffusion regime of minutes. However, when we add the PSS as organic mediator, both techniques reveal a more complex pathway during the initial stages of formation: Primarily PSS globules are formed containing a large amount of Ca²⁺, where these ions interact with sulfonate groups (as evidenced by FTIR). Subsequently these globules adsorb onto the substrate. After about 45 minutes diffusion in the TEM fluid cell, the real-time nucleation of amorphous calcium carbonate was observed and captured. Nucleation and growth was in this time regime only observed at places of adsorbed globules, implying a stark contrast with respect to the control reaction without the PSS: We observe a more controlling, stabilizing role of the organic PSS in the form of globules towards ACC. We furthermore are able to deduce a detailed quantification of the system in terms of supersaturation, concentrations etc. and conclude that the PSS is able to serve as a suitable biomimetric matrix for localized, predominantly kinetically controlled, crystallization of calcium carbonate.
[1] Nielsen, M.H. et al., Faraday Discuss., 2012, 159, 105-121

In this presentation we describe the use of a temperature responsive polymer to regulate DNA-interactions at nanoparticle interfaces. A series of thermo-responsive pNIPAAm-co-pAAm polymers have been synthesized with low critical solution temperatures (LCST) ranging from 37-65 ^oC. These polymers have been co-grafted onto nanoparticles containing single stranded oligonucleotides (ssDNA). The thermo-responsive behavior of the polymer allowed for regulating the accessibility of the sequence-specific hybridization between complementary DNA functionalized AuNPs, leading to controllable assembly kinetics, unique morphology and new phase behavior. In particular this presentation will describe a recent synchrotron small angle X-ray scattering (SAXS) study that probed the assembled crystals thermal response and phase behavior. The role that DNA length and structure, as well as polymer conformation plays in the observed properties will be discussed.

During the asexual stage of their lifecycle, the malaria parasites reside in the erythrocytes, where they catabolize hemoglobin and release Fe(II) heme. The released heme oxidizes to toxic Fe(III) hematin, which is sequestered as crystalline hemozoin. Several antimalarial drugs are assumed to act by inhibiting the crystallization of hematin. Despite extended efforts, the mechanisms of hematin crystallization and its inhibition remain elusive. Here we demonstrate that the crystallization of hematin occurs at physiologically relevant rates in citric buffer-saturated octanol, which mimics a lipid sub-phase in the parasite, and does not occur in aqueous solvents. We show that crystal growth follows a classical mechanism whereby new crystal layers are generated by two-dimensional nucleation and grow by the attachment of solute molecules to the steps. The generation of layers is governed by the thermodynamics of crystallization. Chloroquine (CQ), a common antimalarial drug, fully arrests growth by inhibiting both the rate of nucleation of new layers and the velocity of their growth at concentrations 2 mu;M (ca. 100× lower than that of hematin), likely by adsorbing on the terraces between steps, but is ineffective at 0.25 mu;M. The sensitivity of CQ action to its solution concentration may be at the basis of the increased resistance of the malaria parasites to this drug. The high efficacy of CQ in inhibiting layer generation and growth suggests that adsorption on crystal surfaces may be its main mode of antimalarial action. This insight into the CQ mechanism can form the basis of the design of novel antimalarials that absorb strongly to the hemozoin crystal surfaces.

To date, the discovery of the protein corona phenomenon has revolutionised the way we analyse the nanomaterials aimed for use in biomedical applications [1]. With advances of nanotechnology, many novel material structures are arising, and their impact in the field of biology and nanomedicine is becoming very important [2]. Here we investigate, describe and define the impact of protein presence on the formation of Bi-based nanomaterials and complex nanoparticle structures
Tip sonicated Bi₂O₃ dispersed in phosphate buffer characterised using Transmission Electron Microscopy (TEM) and Differential Centrifugal Sedimentation (DCS) showed that the NMs had a mean particle diameter between 70-100 nm. DCS analysis of incubated Bi₂O₃ particles with 10% Bovine Serum Albumin showed no protein adsorption. However, gel electrophoresis showed that protein was present on the NM surface. DCS analysis of Bi₂O₃ NM/protein dispersions yielded both positive and negative mean diameter shifts dependent on the protein used. The HR-TEM analysis revealed a complex structure of Bi₂O₃ particles, i.e. demonstrating that each 70-100 nm sized particle consisted of agglomerates of ca. 5 nm sized smaller particles. This phenomenon was observed only in NMs dispersed in proteins solutions. Oxidation of the particles with H₂O₂ enabled the deagglomeration of the particle composites yielding single particles of 5 nm diameter. This work shows unusual behaviour of Bi₂O₃ nanoparticles only when exposed to proteins, as confirmed using other Bi-based material as controls. We conclude that the protein corona plays not only an important role in influencing biological endpoints, but also in the formation of complex nanostructures.
[1] Monopoli, M., et al.,. Nature Nano, 7, p 779-786 (2012)
[2] Bertrand, N., et al., Advanced Drug Delivery Reviews, 2014. 66(0): p. 2-25.

Continuous manufacturing of fine chemicals and pharmaceuticals using microfluidic platforms are currently researched due to their advantageous heat and mass transfer rates compared to traditional batch processes. However, these platforms can be irreversibly clogged due to precipitation of inorganic crystals which form as byproducts of reactions. The Palladium catalyzed C-N coupling reaction is desirable for pharmaceutical applications, but forms stoichiometric amounts of inorganic salt which then precipitate and clog the microreactor. The clogging behavior can occur within minutes, causing the reaction to end. In this work, we utilize a model Palladium catalyzed C-N coupling reaction to show enhanced control of solid formation. We study how the crystal formation impacts eventual clogging through in situ pressure drop and optical measurements. We avoid microreactor clogging by tailoring the morphology of inorganic crystal formation, achieved through a combination of nucleation control and other mechanical means. We demonstrate the formation of crystal aggregates that can flow through the reactor without causing clogging or undesirable pressure drops, and study the impact of growing crystal aggregate size on clogging behavior. The design strategy for ensuring reaction optimization without microreactor clogging with the use of in situ optical and pressure measurements will be presented.

The kinetic adsorption profile at DNA-gold nanoparticle (AuNPs) interface is probed by following the binding and organization of thiolated linear DNAs and aptamers of varying chain lengths (15, 30, 44, and 51 mer) to the surface of AuNPs (13.0 ±1.0 nm diameter). A systematic investigation utilizing dynamic light scattering has been performed to directly measure the changes in particle size during the course of a typical aging-salting thiolated DNA/AuNP preparation procedure. We discuss the effect of DNA chain length, composition, salt concentration, and secondary structure on the kinetics and conformation at DNA-gold interface. The adsorption kinetics is chain-length dependent, composition independent, and not diffusion rate limited for the conditions we report here. The kinetic data supports a mechanism of stepwise adsorption of thiols to the surface of AuNPs and reorganization of the thiols at the interface. Very interestingly, the kinetic increases of the particle sizes are modeled accurately by the pseudo second-order rate model, suggesting that DNAs could possess the statistically well-defined conformational evolution. Together with other experimental evidence, we propose a dynamic inner-layer and outer-tail (DILOT) model to describe the evolution of the DNA conformation after the initial adsorption of a single oligonucleotide layer. According to this model, the length of the tails that extend from the surface of AuNPs and are capable for hybridization or molecular recognition can be conveniently calculated. Considering the wide applications of DNA/AuNP conjugates, the results should have important implications for in sensing and DNA-directed nanoparticle assembly.

On many synchrotron X-ray scattering beam lines performing on-line, or in-situ, experiments has become routine. To be able to follow the unfolding of structural changes in real-time with a combination of techniques has therefore become a valuable tool in the tool chest of material scientist.
The DUBBLE beamlines at the ESRF attract a user community with a wide range of materials science interests. One of the main areas of research is in the field of polymers where crystallization studies of semicrystalline polymeric materials have been staple experiments for many years. In recent years these experiments have evolved from purely using under-cooling as trigger for the crystallization to experiments where, beside temperature, parameters like pressure, cooling rate and shear fields have been applied. Examples of the more challenging experiments will be given.
Liquid crystal displays have been an ubiquitous part of daily life and even though competing technologies have become available it is likely that the low power consumption and well established processing technology will keep these displays relevant for many years to come. However, what actually happens during the rotation from the liquid crystalline material when the field is changed is still not well known. Although normally the orientation of the liquid crystalline director in a working device is changed by applying an electric field magnetic fields do allow for more control over the experimental conditions. a serious drawback is that here fields are required which require superconducting magnets. On-line experiments on the switching behavior in magnetic fields have given important insights in the relation between temperature and cell thickness.
The occurrence of radiation damage is well known on synchrotron radiation beamlines. Especially in soft condensed matter research. What is less well known is that X-rays can also interfere in crystallization processes in hard condensed matter in such a way that the crystallization is either enhanced via the creation of nucleation sites or by aiding the formation of larger metallic entities by reducing the metallic ions via photo electrons.
Examples of these three topics will be given.

Recent interest in synthesizing and studying charged interfaces in oxide heterostructures has been driven by the realization that charge mismatch at insulating interfaces can be used to drive the formation of emergent interfacial states. Many of the proposed mechanisms for the origin of these emergent properties are linked to the valance state of individual cations in the layers of the heterostructure. In the cubic perovskite structure of a material such as SrTiO₃, the A-site cations have a +2 valence and the B-site cations have a +4 valence, resulting nominally neutrally charged (001) planes. For materials in which both the A-site and B-site cations have a +3 valence, such as LaGaO₃, individual pseudo-cubic (001) lattice planes are charged. The need to compensate this charge at the hetero-interface is a potential origin of novel interfacial properties. Exploring the properties of these interfacial states requires the ability to synthesize materials with sub-monolayer control of growth behavior, resulting in detailed understanding of how polar surfaces grow. This talk will focus on describing results of recent in situ x-ray studies at Sector 12ID-D of the Advanced Photon Source of the epitaxial growth behavior of polar LaGaO₃ thin films on the nominally charge-neutral TiO₂-terminated (001) surface of SrTiO₃. We utilize in-situ grazing incidence surface x-ray scattering to monitor and control the growth of films via 90 degree off-axis rf magnetron sputtering. We will compare films grown from a single LaGaO₃ target with films grown by either alternating deposition from two separate cation sources (La₂O₃ and Ga₂O₃) or co-depositing from these same two sources. These results will be discussed in the context of identifying new pathways and methods for the synthesis of novel charged interfacial states.

Functional materials are key to the development of advanced devices. To archive high performance of the devices, the relevant chemical or physical properties of functional materials need to be optimized, by tuning their structural or compositional features, such as chemical composition, phase composition, defect density, particle morphology, etc. It is critically important to understand the synthesis process of materials in great details and therefore to apply appropriate controls in the synthesis process.
Hydrothermal and solvothermal methods are widely used to synthesize a variety of functional materials, such as zeolites, noble metal catalysts and solar cell materials. However, because hydrothermal and solvothermal syntheses commonly require the use of thick-walled metal reactors to accommodate the high pressure generated by the solvents at elevated temperatures, it is extremely challenging to investigate the reactions in real time. Benefiting from the high flux, high intensity and high penetration depth of synchrotron generated X-ray, an experimental setup was successfully built up at National Synchrotron Light Source (NSLS), which allows us to collect powder diffraction patterns in situ during the hydrothermal or solvothermal synthesis. A number of functional materials for energy conversion and storage applications have been studied with this method, including phosphates, oxides and metals. The observations on the nucleation, crystal growth and phase transformation of these materials will be presented, as well as the results from complimentary analytical techniques such as transmission electron microscopy (TEM) and electrochemical analysis. The results provide novel insights on materials formation in solution environments.

A unique phenomenon in the area of porous solids is flexibility in the solid state. In recent years a new class of porous solids was discovered showing step-wise huge volume changes (more than 240 %) during gas uptake. These gas-triggered crystal-to-crystal transformations (also called gating crystals) show a unique porosity switch from a closed pore (cp) to an open pore (op) form, a cooperative step-wise transition, with a high potential for applications in switchable catalysts, filters, threshold sensors, or stimulus induced drug delivery.
However, so far only a limited number of such compounds are known, and more important, the underlying principles responsible for such a high degree of flexibility are not understood, which is essential to explore the applicability of such networks in separation and catalysis further.
A novel experimentation environment was developed at the synchrotron (BESSY, Berlin) for X-ray diffraction studies in parallel to physisorption using various gases and temperatures. The equipment can monitor the pronounced structural changes of step-wise volume changes in MOFs. As an example, pore opening and closing mechanisms in DUT-8 (DUT = Dresden University of Technology) will be discussed. The compound shows a pronounced gating behavior and high degree of porosity (ca. 2000 m²/g surface area) and recognition effects: Gases with a high adsorption enthalpy in general tend to open the MOF, while weakly adsorbing species cannot trigger the pore opening. Small differences in the open structure can be detected depending on the gas adsorbed. As a valuable extension, in situ EXAFS measurements will be reported for the first time giving astonishing insights in changes in the metal-oxide cluster structure during the transformation.

Electrochemical Capacitors (ECs) are a class of energy storage devices that fill the gap between high-energy-density batteries and high-power-density electrostatic capacitors. However, the development of ECs has been hindered by the lack of cost-effective electrode materials having high energy density. Fundamental research on the charge-storage mechanism during redox reactions is a key step towards development of transition metal oxide (TMOs) electrodes for EC devices. Here, syntheses and measurements of MnO2 nanolayers and Mn3O4 nanoparticles have been presented. Particularly, in situ studies of the charge-storage mechanism of both materials during the redox process are conducted using synchrotron-based X-ray diffraction (XRD) and absorption spectroscopy (XAS) techniques: (i) in situ XRD is used to study the changes of crystalline structure caused by the intercalation/de-intercalation of ions during redox reaction; (ii) in situ XAS is used to study the changes of electronic state of Mn component during redox reactions. These measurements can provide fundamental understanding about the optimal electrode structure that can facilitate the change-transfer reactions via maintaining a stable electrode/electrolyte interface.

Small-angle X-ray scattering (SAXS) is a powerful tool to obtain information on the size, shape, orientation and arrangement of nanoscaled soft matter. SAXS has - in comparison to concurrent or complementary techniques - the particular advantages of easy sample preparation, high resolution in reciprocal space and a good statistical accuracy of the collected data. The main advantage, however, is the possibility to perform in-situ measurements to follow the evolution of nanostructures at different temperatures and/or loads, in different environments or under processing conditions.
To show the potential of the method, selected examples of hybrid materials are presented, ranging from sol-gel derived silica,¹ functionalized silica and mixed metal oxide systems to polymeric ionic liquids (POILs) and pseudo block copolymers (PBCs).
For all these materials, in-situ SAXS measurements offer the unique possibility to follow the structural evolution during synthesis and post treatment. The isothermal crystallization process was followed by SAXS for two different systems (pure silica and PBCs) and characterized by Avrami&’s kinetics theory. In case of POILs, temperature dependent in-situ SAXS measurements were performed, which allowed the determination of order-order (OOT) and/or order-disorder (ODT) transition temperatures and the relaxation time.² The structural recovery of the POILS caused by the re-establishment of ionic bonds is discussed with respect to self-healing in biological tissues.³
Fig.1 Differently ordered nanostructures in polymeric ionic liquids (from P. Zare et al., Macromolecules 45 (2012) 2074.
¹ M.Weinberger, T.Fröschl, S.Puchegger, H.Peterlik, and N.Hüsing:
Silicon 1 (2009) 19-28.
² P.Zare, A.Stojanovic, F.Herbst, J.Akbarzadeh, H.Peterlik, and W.H.Binder:
Macromolecules 45 (2012) 2074-2084.
³ J.Akbarzadeh, S.Puchegger, A.Stojanovic, H.O.K.Kirchner, W.H.Binder, S.Bernstorff, P.Zioupos, and H.Peterlik:
Bioinspired, Biomimetic and Nanobiomaterials, DOI: 10.1680/bbn.14.00007.

A garnet-type fast Li-ion conductor Li₇La₃Zr₂O₁₂ (LLZO) with bulk conductivity around 10^-4 S cm^-1 at 298K is a potential candidate of the solid electrolyte material for an all-solid-state rechargeable lithium-ion battery with significant improved stability, durability and safety. The cubic phase (Ia-3d) of undoped LLZO is stable at high temperature and transforms to a tetragonal phase (I41/acd) with low Li-ion conduction when cooled down. Dopants are therefore applied to stabilize the cubic structure. In order to unravel the dopant&’s effects on the synthesis, stabilization and properties of LLZO, we carried out the in-situ neutron diffraction measurements of Al-doped LLZO, Zn-doped LLZO and undoped LLZO using neutron diffraction to monitor the structural evolution. Thanks to the capability of differentiating multiple phase and catching light atoms by neutron scattering, it is revealed that the cubic garnet was formed at 700~800 °C and stable at 1000 °C, accompanied with the presence of the secondary phases: perovskite-type LaAlO₃ along with Al-doped LLZO, and pyrochlore-type La₂Zr₂O₇ along with Zn-doped LLZO and undoped LLZO. The cubic phase is stabilized until room temperature in both doped LLZO while undoped LLZO encounters the phase transition to tetragonal phase at about 625 °C. Rietveld refinement on the neutron diffraction patterns quantitatively reveals the phase evolutions along the temperature scale. The dopant sites in garnet and its influence on the Li vacancy are also resolved.

Carbon fiber exhibits a unique combination of material properties, including high tensile strength and modulus, low weight, high temperature resistance, and low thermal expansion, that has made it an ideal choice as a structural component in light-weight composites for a wide range of applications from aerospace to sports equipment. The unique properties of this material are a direct consequence of its constituent highly-oriented graphitic microstructure, which is typically obtained commercially through controlled pyrolysis of either polyacrylonitrile (PAN) or mesophase pitch-based precursor fiber, but can also be produced from non-traditional relatively inexpensive precursors, including polyethylene (PE). Measurement of the characteristics of the graphitic microstructure, such as orientation, domain size, and interlayer spacing as a function of processing conditions is thus critical to understand structure-property-process relationships for these very different starting materials.
This presentation will describe the design and operation of a custom high-temperature tensile device that, when combined with synchrotron wide-angle x-ray diffraction (WAXD), enables us to observe in situ and in real time the microstructural transformation from carbon fiber precursor to high-modulus carbon fiber. Specifically, this tensile device heats fiber bundles at a variable rate from 25 °C to greater than ~2300 °C, while simultaneously applying tensile stress, and monitoring the resulting fiber strain. Synchrotron WAXD patterns obtained as a function of temperature reveal the conversion to graphitic microstructure, and provide key insights into the physical processes that occur during carbonization and high-temperature graphitization. Experiments conducted using PAN-, pitch-, and PE-derived fiber precursors reveal stark differences in the carbonization and high-temperature graphitization behavior among these three precursor types.

In situ X-ray diffraction (XRD) measurements have been performed during InAs quantum dot (QD) and cap layer growth on GaAs(001) by molecular beam epitaxy (MBE).
Tuning the emission wavelength of InAs QDs on GaAs(001) to 1.3 mm for telecommunication applications has already been realized. However, further redshifting the wavelength to 1.55 mm remains a challenge. While bandgap engineering predicts it to be possible, for instance, by using InGaAs cap instead of GaAs [1], 1.55 mm emission is yet to be reported. In contrast, it has been shown that eliminating the cap layer can induce a large emission redshift, and has been attributed to strain [2]. XRD is one of the few techniques that can observe lattice strain on the nm scale, and has been successfully employed for the study of strain during GaAs capping on InAs QDs [3]. In this study we performed in situ XRD measurements during modulated InGaAs capping to discuss the development of the strain in the system.
The experiments were performed at SPring-8 (BL11XU), Japan, using an MBE-X-ray diffractometer (MBE-XRD) system. The InAs QDs are grown on GaAs(001) at a substrate temperature of 470°C after buffer layer growth. The InAs growth rate is 0.017 ML/s. The X-rays 10 keV in energy with incident angle of 0.2° were reflected by the (220) planes and monitored by a CCD detector during the InAs QD and cap layer growth. The total amount of InAs deposition for the QDs was 2.5 ML, and the 30 nm-thick modulated cap layers of GaAs and In_0.09Ga_0.91As were grown.
XRD images were obtained by CCD in which the two orthogonal axes correspond to the in-plane lattice constant and the outgoing angle a, respectively. XRD intensity transients from different relative lattice constants, normalized by that of GaAs, at an interval of 0.01 are used to investigate the strain variation during capping.
The XRD intensities from almost all lattice constants decrease monotonously with increasing cap thickness during 4 nm GaAs followed by 26 nm InGaAs, similar to that during 30 nm-thick GaAs capping. In contrast, the intensities from large lattice constant components (~1.05) decrease with cap thickness, while those from small lattice constants (~1.01) first decrease, then increase, and decrease again during 4 nm InGaAs followed by 26 nm GaAs as well as 30 nm-thick InGaAs. These results suggest that the strain induced is mainly determined by the initial stage of capping. The growth mechanisms and development of the lattice strain will be discussed.
This work was supported by the Strategic Research Infrastructure Project, MEXT, Japan. The XRD experiments were performed at BL11XU of JAEA at SPring-8 under the Nanotechnology Platform Project, MEXT, Japan.
[1] W. H. Chang, et al., Appl. Phys. Lett. 86 (2005) 131917.
[2] H. Saito, et al., Appl. Phys. Lett. 73 (1998) 2742.
[3] M. Takahasi and J. Mizuki, J. Cryst. Growth 275 (2005) e2201.

Exposed to mechanical stress, silicon may phase transform, resulting in changes of crystallographic structure and material properties. Instrumented indentation testing (IIT) has been widely used to investigate the phase transformation of Si. However, in conventional indentation experiments, the structure and phase of Si is probed only after the completion of the indentation test (ex situ), which leaves the exact path of transformation to conjecture. In-situ electrical resistance measurements between a conductive probe tip and the indented Si surface can allow indirect observations of phase transformation, however, the unambiguous identification of phases is still very difficult with this method. In order to analyze the indentation-induced phase transformation directly, researchers at NIST developed an indentation device that is coupled with a Raman microscope to perform in situ spectroscopic analysis (in situ Raman microprobing and imaging) of mechanically strained contact area between the transparent sample and the indenter probe while conducting an indentation experiment. The talk reports on indentation-induced phase transformation processes studied by in situ Raman imaging of the deformed contact region of silicon, employing Raman spectroscopy-enhanced IIT. In this study, the spatial distribution of phases generated in transformation processes along with the strain field were qualitatively analyzed. This is, to our knowledge, the first sequence of Raman images documenting the evolution of the strain fields and changes in the phase distributions of a material while conducting an indentation experiment. The reported in situ experiments provide insights into the transformation processes in Si during indentation, confirming, and providing the experimental evidence for, some of the previous assumptions made on this subject. In this context, the developed experimental setup coupling indentation with in situ Raman microscopy has demonstrated its potential in advancing the understanding of deformation mechanisms and will provide a very useful tool in validating and refining contact models and related simulation studies.

In this work, we take advantage of in-situ transmission electron microscopy (TEM) to investigate thermally induced decomposition of the surface of Li_xNi_0.8Co_0.15Al_0.05O₂ (NCA) cathode materials that have been subjected to different states of charge (SOC). While unchraged NCA is stable up to 400 °C, significant changes occur in charged NCA with increasing temperature. These include the development of surface porosity and changes in the oxygen K-edge electron energy loss spectra, with pre-edge peaks shifting to higher energy losses. These changes are closely related to O₂ gas released from the structure, as well as to phase changes of NCA from the layered structure to the disordered spinel structure, and finally to the rock-salt structure. Although the temperatures where these changes initiate depend strongly on the state of charge, there also exist significant variations among particles with the same state of charge. Notably, when NCA is charged to x = 0.33 - the charge state that is the practical upper limit voltage in most applications - the surfaces of some particles undergo morphological and oxygen K-edge changes even at temperatures below 100 °C, a temperature that electronic devices containing lithium ion batteries (LIB) can possibly see during normal operation. Those particles that experience these changes are likely to be extremely unstable, and may trigger thermal runaway at much lower temperatures than would be usually expected. These results demonstrate that in-situ heating experiments are a unique tool to study not only the general thermal behavior of cathode materials, but also to explore particle-to-particle variations, variations that are sometimes of critical importance in understanding the performance of the overall system.

In-situ observation and fabrication of nanomaterials at nanometer-scales is very important to understand on the nano-scale phenomena associated with atomic movement, phase change, electrical or optical properties, and even reactions which take place in gas or liquid phases.
We have applied the in-situ observation technologies on 0D, 1D, and 2D nanomaterials, such as nano-pore, nano-cluster, nanowire, carbon nanotube, and graphene, et al. By using ultrathin membrane techniques and transition electron microscopy we have demonstrate various interactions; formation of solid state nano-pores in the ultrathin graphene[1], atomic inter-diffusion and phase changes in nanowire devices[2], direct observations of spatial movements of nanodroplets of metal trapped inside sealed carbon nanocontainers[3], et al.
References
1. ACS Nano, 7(6) 5008 (2013).
2. Advanced Materials, 23(16) 1871 (2011).
3. Scientific Reports, 3, 2588 (2013).

We present a novel MEMS-based method for controlled, top-down nano-fabrication of quench-condensed 2D or 1D thin films. Standard resist-based lithography is typically based on a series of deposition and etch steps. This approach is no longer feasible when fabricating devices comprised of a small number of atoms. Furthermore, the resist and etch step chemistries limit the types of materials compatible with such fabrication methods. We demonstrate how MEMS can be used to circumvent these limitations and fabricate structures made from a wide range of materials.
A dynamic MEMS aperture-shutter system controllably places a small number of atoms on a substrate [1]. Using multiple apertures and sources, subsequent depositions can be used to create complex structures in a manufacturable way. Since no lift-off or etch step is necessary, the deposition is the final fabrication step. This enables quench-condensed deposition and subsequent in-situ measurements in a cryostat. Annealing effects can be measured, controlled, and utilized through temperature cycling. For example, using a sequential quench-anneal deposition process, it has been shown that the resistivity of a silver thin film can be tuned over many orders of magnitude [2].
This novel “Fab on a Chip” [3] approach promises to enable new mesoscopic physics experiments. By using materials incompatible with resist-based lithography, it becomes possible to fabricate nano-scale devices and subsequently add a controlled number of impurities in situ, while simultaneously measuring the device. We present the current status of this technology, with a focus on the writer-shutter ensemble as well as provide examples of the quench condensed nano-structures that can be made.
[1] Imboden, Matthias, et al. "Atomic Calligraphy: The Direct Writing of Nanoscale Structures Using a Microelectromechanical System." Nano letters 13.7 (2013): 3379-3384.
[2] Arnason, S. B., and A. F. Hebard. "Ultra-thin silver films obtained by sequential quench-anneal processing." Thin Solid Films 518.1 (2009): 61-65
[3] Imboden, Matthias, et al. "Building a Fab on a Chip." Nanoscale 6.10 (2014): 5049-5062.

Probing the surface chemistry of a photoelectrocatalyst in situ presents a unique challenge in materials characterization. [1] A host of dynamic processes across several orders of magnitude both spatially and temporally occur at this interface and cause changes on the micro- and nanoscale. One such photocatalyst, n-doped SrTiO_3-δ (STO), perfectly exemplifies this complexity through its situation-dependent behavior. In neutral or basic media, illuminated STO can perform both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) but in acidic conditions, it is unable to perform such reactions at open circuit [2]. .
Here, Scanning electrochemical microscopy (SECM) is used to directly address electrochemistry at this surface using probes and techniques tailored to each phenomenon. SECM probe electrodes range in size from microns down to several nanometers and afford lateral resolution nearly equal to their radius. In the feedback mode of SECM, an electrochemical mediator is used to interrogate reactivity at an operating substrate electrode. The feedback current reflects the kinetics of the substrate reaction and in general a decrease in tip size can be used to probe faster kinetics, thus making SECM ideal for this study of fast competing photoelectrochemical processes at the catalyst surface. Using this adaptable instrument, the roles of adsorbed intermediates during photocatalytic water splitting [3] is being studied to better understand how their spatial distribution, mobility and redox potential affects reactivity. . Specifically, imaging reactivity of the surface with these probes elucidates the catalytic role of surface diffusion of adsorbed intermediates and its interplay with defects, co-catalysts and surface features. This spatially-resolved in situ knowledge is essential to the design and manufacture of next-generation solar materials. Here, an integration of SECM modes is used to deconvolve the many electrochemical processes at the STO-water interface through in situ measurements not available using other techniques.
1. A. Fujishima, X.T. Zhang, and D.A. Tryk: TiO2 photocatalysis and related surface phenomena. Surface Science Reports63, 515 (2008).
2. F.T. Wagner, G.A. Somorjai: Photocatalytic and photoelectrochemical hydrogen production on strontium titanate single crystals. Journal of the American Chemical Society102, 5494 (1980).
[3] D. Zigah, J. Rodriguez-Lopez, A.J. Bard: Quantification of photoelectrogenerated hydroxyl radical on TiO₂ by surface interrogation scanning electrochemical microscopy. Physical Chemistry Chemical Physics 14: 12764 (2012).

Ferroelectrics, possessing a reversible and spontaneous polarization, are an actively researched class of materials with a wide range of current and proposed applications. Ferroelectric switching is a complex process dependent upon domain nucleation and domain wall motion. These processes, occurring on short time scales and micron length scales, are difficult to experimentally quantify yet are crucial to ferroelectric applications. Techniques currently employed to study domain kinetics do not possess the spatial and temporal resolution needed to accurately observe these dynamic events. In this work, we utilize in-situ transmission electron microscopy (TEM) to study domain switching characteristics in Potassium Titanyl Phosphate (KTiOPO₄) and Barium Titanate (BTO₃) at temporal and spatial resolutions inaccessible to competing techniques. Samples were prepared using an FEI DB235 dual-beam focused ion beam and experiments were performed on a JEOL 2100 LaB₆ TEM, using a custom biasing holder designed by M. L. Taheri and Hummingbird Scientific. Both domain nucleation and domain wall motion were studied as functions of applied field and defect interactions. Our work provides valuable insights on polarization switching in BTO and KTP, unobtainable through conventional techniques. The in-situ TEM methods developed in this study can be applied to many other ferroelectric systems.

Adenosine triphosphate (ATP) is indispensable molecules for our life. Transformation from ATP to adenosine diphosphate (ADP) by enzyme catalyzed hydrolysis is essentially important chemical reaction. So far, X-ray diffraction study has revealed atomic structure of both nucleotides and enzyme by using their single crystal. Nuclear magnetic resonance spectroscopy has also revealed intermediate products and kinetics by using the deuterium substitution method. One of the best ways to observe actual situation of the biological molecules is in-situ observation in the aqueous solution. In this study we adopted transmission Fourier transform infrared (FT-IR) spectroscopy, which was one of the most popular and useful methods to identify chemicals and their vibrational states. It is, however, usually difficult to obtain the IR spectrum of aqueous solution because of its large absorption coefficient in mid-IR range. In order to avoid this conflict, we developed a new cell with a short optical path length which was adjusted to be about 1 micron meter by using a nickel foil spacer. The cell windows were diamond. Aqueous solution was flowed into the cell by using a pump for high-performance liquid chromatography. Temperature and pressure could be controlled.
It is well known that the ionization state of ATP in the aqueous solution depends on its pH value. As a first step, titration curves for the phosphoric acid (100 mM), adenosine monophosphate (AMP), ADP and ATP (40 mM) aqueous solutions were measured by adding sodium hydroxide solution. According to the appearance of equivalent point in the titration curves, ionization states were deduced. Corresponding transmission FT-IR spectra were observed with changing pH value. Systematic change of the peaks of P=O stretching vibration and P-O stretching vibration were observed and these peaks were decomposed. Then, three peaks due to P=O stretching vibration were assigned respectively α, β, γ and phosphate in an ATP molecule. Similarly, decomposed peaks of P-O stretching vibration could be assigned to specific bonds of P-O in an ATP molecule. In conclusion, systematic structure change of ATP with pH value could be deduced by present in-situ transmission IR spectroscopy for the aqueous solution.

Control of magnetic properties in ferromagnetic materials has been an overarching goal for potential applications in magnetic storage and spintronics devices. In this work we report reversible reduction in coercivity of Co/Pt multilayer thin films under DC biasing. We carried out in-situ focused MOKE measurement while the specimen is under DC bias. These experiments show a reduction in coercivity during the application of direct current. We propose this reduction is results from the electromigration induced stresses and resulting grain rotation.

The use of metallic nanomaterials for various pharmaceutical and biomedical applications is increasing worldwide. In this research, Fe₃O₄ nanoparticles (NPs) 10 to 15 nm in size were synthesized by thermal decomposition of iron acetylacetonate (III) in 1-octadecene in the presence of oleic acid as surfactant and oleylamine and 1,2 - dodecanediol as reducing agents. The morphology and size of the NPs were characterized by Transmission Electron Microscopy (TEM). The presence of magnetite and potential impurities were determined using X-ray diffraction (XRD). Organic capping molecules were characterized through infrared spectroscopy (IR). The saturation magnetization was determined from their hysteresis loop by using a vibrating sample magnetometer (VSM). The magnetic susceptibility of the colloidal suspension help in determining the concentration of magnetite. With this information, the reaction kinetics was obtained in situ. The NPs showed to have a very low polydispersity (0.06) and a magnetization saturation of 74 emu/g, which is very similar to the bulk material (84 emu/g), furthemore, the NPs hysteresis loop showed a superparamegnatic behavior, Fe₃O₄ NPs crystallographic nature was verified through the XRD pattern, which showed an inverse spinel structure. IR spectra displayed the typical vibrations of Fe-O as reported by Gillot et al. (1994) (510 cm^-1 and 400 cm^-1). This providen an indication of a transition of iron atoms in the cubic face-centered structure (Fd3m) in which there is not order in the vacancies. The relationship between magnetic susceptibility and Fe₃O₄ concentration showed a linear dependence, yielding a correlation factor of 0.99. Finally this correlation was used to determine the kinetics of the reaction, this one was showed sigmoidal behavior which is similar to the autocatalytic reactions. Therefore, the NPs grow followed an Ostwald ripening behavior, and a minimum initial concentration of magnetite in the reaction was required, which was produced by partial reduction of the precursor. Subsequently, the data were fitted to a Boltzmann double function model available in Origin software version 8.0, where the correlation factor obtained was 0.99. In conclusion, these nanoparticles were obtained with high cristallinity and low polydispersity. These particles are potential candidates for biomedical applications.

The selective growth of molecular crystal polymorphs has a significant impact on a variety
of industries including pharmaceuticals, energetic materials, foods and dyes. Heterogeneous
nucleation self-assembled monolayers (SAMs) offers a means to control polymorphism at the
earliest stages of crystallization. The Pechmann dye (E)-4,4&’-dimesityl-but-3-enolidylidene-but-
3&’-enolide (EDEE) crystallizes in two polymorphic forms concomitantly, blue-black needles and
scarlet prisms, from a variety of solvents. The blue-black needles are metastable and irreversibly
transform to the more stable red phase upon heating. Herein we report on the crystallization
of EDEE on a library of siloxane SAM templates. This study serves to highlight the effect of
monolayer chemistry on the material phase obtained, as well as the orientation and density of
crystals nucleated from various solvents.

Micromachined nanocalorimetry sensors have shown excellent performance for high-temperature and high-scanning rate calorimetry measurements. Here, we combine scanning AC nanocalorimetry with in-situ x-ray diffraction (XRD) to facilitate interpretation of the calorimetry measurements. Time-resolved XRD during in-situ operation of nanocalorimetry sensors using intense, high-energy synchrotron radiation allows unprecedented characterization of thermal and structural material properties. We demonstrate this experiment with detailed characterization of the melting and solidification of elemental Bi, In, and Sn thin-film samples, using heating and cooling rates up to 300 K/s. Our experiments show that the solidification process is distinctly different for each of the three samples. The experiments are performed using a combinatorial device that contains an array of individually addressable nanocalorimetry sensors. Combined with XRD, this device creates a new platform for high-throughput mapping of the composition dependence of solid-state reactions and phase transformations.

Galvanic replacement reactions using silver nanoparticles are useful methods for the synthesis of various metallic hollow nanostructures. These reactions are based on a combination of electrochemical potential difference and diffusion dynamics between distinct metals on the surface.
Metal ions such as gold (Au³⁺), platinum (Pt⁴⁺), and palladium (Pd²⁺) easily react with silver atoms (Ag⁰) in aqueous solution. Among these ions, the addition of gold ions into the silver nanocubes yields gold/silver hollow alloy nanostructures. These alloy nanoparticles have highly sensitive localized surface plasmon resonance (LSPR) peaks to detect structural and environmental changes, and lead to continuous shifts of the plasmon extinction maximum to the longer wavelength from 500 nm to 650 nm by compositional variation of gold and silver.
In the present study, we used dark field microscopy (DFM) to study the change of LSPR spectrum of individual Ag nanocube at a single particle level. When gold ions are added into Ag nanocubes, the replacement reaction is proceeded at a specific rate. We calculated the plasmon extinction maximum shift of the LSPR peak in time progress, and combined with the spectroscopic results to quantitatively measure the rate of compositional variation of gold/silver alloy.

Nanoscale crystal and thin film growth from the liquid phase have great importance for electrochemical reactions, nanoparticle formation and assembly, and liquid/gas wetting dynamics. Liquid cell transmission electron microscopy enables measurements of such growth. Here we examine a standard growth phenomenon that is known to be mediated via the electron beam, predicting beam effects with simulations and using the results to investigate the reaction mechanism.
The system we examine is the growth and dissolution of Au nanoparticles and films in a thin layer of HAuCl₄ solution. The electron beam is thought to form hydrated electrons that reduce soluble Au³⁺, precipitating Au as nanoparticles. By carrying out growth in a thin liquid layer, we ensure a 2D diffusion field and growth morphology, allowing quantitative modeling, and we can also use atomic force microscopy post-growth to measure the height of the structures. The Au morphology and deposition rate were measured as functions of beam current, cumulative dose, and liquid thickness. Radiolysis product concentrations were calculated using a kinetic model adapted for conditions relevant to transmission electron microscopy. Initially, faceted flat topped islands nucleate and grow up to 500 nm in diameter. Growth rate measurements of individual particles, with height determined post-growth, show that the volume increases linearly with time and also linearly with dose rate, once it exceeds a certain threshold. Growth rates do not depend on shape, or on proximity to other islands, suggesting that diffusion fields do not play a role in growth kinetics. At later times, clusters form with a more irregular morphology and growth slows, with a competing process of coalescence and dissolution of the clusters.
The linear relationship between growth rate and dose rate is unexpected based on standard simulations of water radiolysis, where the concentration of hydrated electrons shows a sublinear (exponent ~ 0.5) dependence on dose rate. However, simulations that include the experimental pH and Cl^- concentration do predict a near-linear dependence. This is consistent with the expectation that the production rate of hydrated electrons governs the kinetics, rather than diffusion of Au ions or radiolytic byproducts. We will discuss the implications of these results and simulations for modeling beam induced phenomena in other liquid cell growth experiments.
Acknowledgments
Device fabrication was carried out at the Cornell NanoScale Facility (NSF Grant ECS-0335765), a member of the National Nanotechnology Infrastructure Network. JHP and SK gratefully acknowledge funding from the National Science Foundation (NSF-GOALI: DMR-1310639). NMS and HHB were supported, in part, by Grants 1129722 and 1066573 from the National Science Foundation.

The recent discoveries of inorganic solid electrolytes with large Li⁺ ionic conductivities have greatly propelled the research on all-solid-state lithium batteries. Solid electrolyte blocks Li dendrite growth toward the cathode if Li metal is used as the negative electrode. This is certainly attractive because the theoretical energy density of Li metal (2060 Ah L^-1) is much greater than those of presently commercialized negative electrodes (e.g. graphite). It is hence important to understand how Li metal grows and dissolves through solid electrolyte interfaces in the charge-discharge processes [1]. We will present in-situ scanning electron microscope (SEM) observations of charge-discharge reactions for Li metal anode at electrode/amorphous solid electrolyte interfaces.
The most part of the electrolyte (1.25 cm × 1.25 cm) is a mirror-polished Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) sheet (OHARA Inc.) with a thickness of 150 mu;m. The top and bottom surfaces of a LATP sheet were sputter-coated with lithium phosphorus oxynitride (LiPON) layers with thicknesses of 3.0 mu;m. The working electrode is a Cu film deposited by pulsed laser deposition (PLD) onto a 5.0-diameter-circular area in the center of the top LiPON surface. The counter electrode is a 2-3-mu;m-thick-Li film on the bottom LiPON surface. Electrochemical Li deposition and dissolution were conducted in a Keyence VE-9800 SEM under galvanostatic conditions. Li deposition/dissolution are carried out at 50 mu;A cm^-2 to 3 mA cm^-2. The total charges are 180 mC cm^-2 to 720 mC cm^-2. These charge amounts correspond to plating of 242-to-968-nm-thick Li films if the plated films formed contiguous solid thin films.
During the first charge, a thin Cu film was cracked by a number of Li nuclei grown under the Cu film. Li islands subsequently grew above the Cu film through the cracks. Hence, the LiPON layer effectively blocked the Li growth toward the cathode. The number density of Li nucleation was saturated after Li deposits appeared through the Cu film. The Li number density increased with current density, whereas the critical Li island diameters to break a Cu film did not depend on current density.
The coulomb efficiency on dissolution at 1.0 mA cm^-2 (cutoff voltage: 1.5 V) was 80-85% at the first cycle. For subsequent cycles, the coulomb efficiencies on dissolution were always approximately 98%, which is not yet as high as those for graphite negative electrodes in liquid electrolytes (>99%) [2]. We will discuss where the rest of charge dissipates in every charge-discharge cycle for our solid-state battery.
The authors thank the Advanced Low Carbon Technology Research and Development Program (ALCA) of the Japan Science and Technology Agency (JST) for the financial support.
1. M. Motoyama, M. Ejiri, and Y. Iriyama, Electrochemistry, 82, 364(2014).
2. A. J. Smith, J. C. Burns, S. Trussler, and J. R. Dahn, J. Electrochem. Soc.,157, A196(2010).

Fast switching behavior of 90^o domain wall under an electric field in the epitaxial tetragonal (100)/(001)-oriented Pb(Zr_0.4Ti_0.6)O₃ (PZT) films grown on (100)_cSrRuO₃//(100)KTaO₃ substrates was investigated using in-situ synchrotron X-ray diffraction in conjunction with a high-speed pulse generator set up. 004 peak (c-domain) positions shifted to a lower angle under an electric field, indicating an out-of-plane lattice elongation. On the other hands, 400 peak (a-domain) position shifted to an opposite direction (higher angle) indicating that the lattice may be shrinking under an electric field. Moreover, 90^o domain switching from (100) to (001) was observed by the present high-speed pulse in width within 20 nsec. This 90^o domain switching and the out-of-plane lattice constant under an electric field result in the change of the misoriented angles from the substrate surface normal for both of a- and c-domains. These results indicate the realization of high speed piezoelectric MEMS.
This research was partially supported by JSPS Kaken Grant Numbers 26220907.

A new synthesis route of obtaining nanocomposites, consisting of manganese oxides nanocrystallites embedded in reduced graphene oxide spherical matrix, is reported [1]. This process is based on annealing of dried amorphous xerogel precursor prepared by a simple and low cost sol-gel method. The starting material consists of lithium and manganese salts mixed together with citric and acetic acids aqueous solution. During the initial annealing process, carried out in vacuum and intermediate temperatures of about 350°C, the nanocomposites start to change the morphology from shapeless grains into hollow spheres with diameters anywhere between several nanometers up to few micrometers depending on the precursor grains size. The final product structure depends on subsequent annealing conditions. In particular, depending on the ambient atmosphere, heating above the crystallization temperature (about 450°C) can cause the formation of either MnO or LiMn₂O₄ nanoparticles in the carbonaceous matrix, which are important materials for lithium-ion batteries applications as anodes or cathodes, respectively. Interestingly, the structure of the carbonaceous matrix can be controlled by changing the temperature of the synthesis. For instance, heating the material above 800°C can result in the formation of graphene-related structures, such as reduced graphene oxide.
Here, we will present in situ TEM and Raman study of the formation mechanism of these new type nanocomposites. For comparison, samples of different compositions, including managanese salt/organic precursors, lithium salt/organic precursors and pure organic precursors, were prepared. In situ TEM annealing was used to directly observe the nanocomposite formation process and to explain its mechanism. A series of example nanocomposites were produced and used for subsequent detailed analysis using several techniques including HRTEM, SAED, EELS, EDX and Raman spectroscopy. The study indicates that the gaseous decomposition products of lithium organic precursor are accountable for the hollow spheres formation and the citric acid serves as a graphene-like framework precursor. HRTEM and EELS measurements were used to monitor the evolution of the carbon structure and it was observed that that carbonaceous matrix changes from amorphous carbon into graphene-like material, depending on annealing temperatures. The final products were also analyzed by means of Raman spectroscopy, which confirmed that under certain synthesis conditions, reduced graphene oxide can be produced using a simple sol-gel method.
[1] J.Jasinski, D. Ziolkowska, M. Michalska, L. Lipinska, K.P. Korona, M. Kaminska, RSC Adv. 3, 22857 - 22862 (2013)

Using fluorine-doped tin oxide (FTO) has several advantages over other transparent conductive oxide (TCO) films, like indium tin oxide (ITO). It is chemically inert under atmospheric environment and mechanically stronger. It is also less expensive than other TCO materials. It is ideal for many applications such as energy-saving windows for buildings, thin film photovoltaics, and other opto-electronic devices. Characterization and in-line monitoring of FTO/SiO₂/SnO₂/Glass processing are important to ensure product quality in both composition and layer thicknesses. Spectroscopic ellipsometers and spectroscopic reflectometers are non-destructive techniques that are suitable for in-line or in-situ monitoring of this process. For this setup, a spectroscopic ellipsometer will be used to build baseline models which are then implemented into a multiple channel spectroscopic reflectometer for in-line control purposes. Aside from optical models, a long term stability study on both layer thickness and color parameters of layer stacks will be presented.

Electrical contacts are made to silicon solar cells through Ag lines printed onto the Si and then quickly fired. The Ag-Si contact formation begins with printing a mixture of Ag powder, glass frit (mixture of metal oxide such as PbO, B₂O₃, Bi₂O₃ and ZnO) and an organic binder over the antireflection coating (SiN_x), which is subsequently rapidly fired up to about 800 0C in a process that takes10s of seconds. It is known that the frit allows the paste to react with and burn through the anti-reflective coating such that the metal can react with underlying c-Si during firing. However, the precise phase transformations/evolutions between the Ag, Si, SiN_x, and frit constituents giving rise to optimal Ag-Si contacts are not well understood, since this process happens over a very short period of a few seconds (typically ~10 s) during the rapid thermal processing (RTP). While there are several proposed mechanisms for Ag-Si cell contact formation during rapid thermal processing, there is no in-situ characterization of the actual processing conditions. We have characterized the Ag-Si cell contact formation under realistic processing conditions using an in-situ rapid thermal processing, X-ray diffraction setup. The facility utilizes synchrotron X-rays to track structural phase evolution during processing. A large fast area detector is used to gather a large angular range of the diffraction pattern with 100 milliseconds time resolution. It is demonstrated that the phase evolution/reaction sequence depends on the heating ramp rate. The phase evolution and reaction pathways during the Ag-Si cell contact formation processing and role of frit constituent will be discussed.

We demonstrate direct evidence that the strain variation induced by local lattice distortion exists in the surface layers of ZnO and SnO₂ nanowires by coupled in situ scanning transmission electron microscopy (STEM) and digital image correlation (DIC) techniques. The localized change of surface atomistic configuration is responsible for the observed reduction of elastic modulus and hardness in ZnO and SnO₂ nanowires. We found that humidity and electron beam radiation remarkably affect the mechanical behavior and function performance of nanostructures. The mechanical properties such as elastic modulus vary significantly at different humidity levels and electron beam radiation doses, in turn affecting the function performance of the nanostructures which utilize the elastic modulus as the function base. The functions of mechanically damaged nanostructures can be recovered by self-healing in the nanostructures in situ over a period of time. This talk also presents new nanostructure health monitoring and self-healing concepts and new guidelines for designing and fabricating nanostructures and their devices with improved reliability.

The application of block copolymer self-assembly towards membrane separations has received significant attention over the past several years due to the potential for significantly improved performance. In particular, the combination of self-assembly and non-solvent induced phase separation (SNIPS)¹ produces integral isoporous membranes. Using this facile and industrially scalable method, membranes have been fabricated from a variety of block copolymers, including poly(styrene-b-4-vinyl pyridine),² poly(styrene-b-N,N-dimethylaminoethyl methacrylate)³ and poly(isoprene-b-styrene-b-4-vinyl pyridine).⁴ These SNIPS membranes exhibit exceptional fluxes and high-resolution separations, as well as the capacity for post-functionalization, leading to temperature-dependent performance and charge-based separations. While functional membranes can be fabricated, a detailed understanding of their formation mechanism has yet to be fully elucidated. To further understand the formation mechanism in these SNIPS membranes, in situ block copolymer membrane formation that relies on self-assembly of doctor bladed solutions was observed using grazing incidence small-angle X-ray scattering (GISAXS). The evaporation dependent evolution of a disordered to an ordered structure in a film of the triblock terpolymer poly(isoprene-b-styrene-b-4-vinyl pyridine) dissolved in 1,4-dioxane and tetrahydrofuran was observed. The GISAXS pattern of the film exhibited Bragg spots consistent with an ordered structure around the experimental membrane evaporation time. Projections of the GISAXS patterns were consistent with solution small angle X-ray scattering. Such in situ methods offer the potential to optimize the key parameter of evaporation time in the production of isoporous integral block copolymer membranes.
(1) Dorin, R. M.; Marques, D. S.; Sai, H.; Vainio, U.; Phillip, W. A.; Peinemann, K. V.; Nunes, S. P.; Wiesner, U. ACS Macro Lett.2012, 1, 614.
(2) Peinemann, K. V.; Abetz, V.; Simon, P. F. Nat Mater2007, 6, 992.
(3) Schacher, F.; Ulbricht, M.; Muller, A. H. E. Adv. Funct. Mater.2009, 19, 1040.
(4) Phillip, W. A.; Dorin, R. M.; Werner, J.; Hoek, E. M. V.; Wiesner, U.; Elimelech, M. Nano Lett.2011, 11, 2892.

The objective of this work is to elucidate the deformation behavior of materials at high temperatures - an essential step toward the design and manufacturing of a new generation of high-temperature materials. To do this, we developed an experimental setup that allows us to heat the specimen while applying uniaxial tensile loading. High temperature at the specimen is achieved by ohmic heating while uniaxial tensile loading is applied using electro-thermal (chevron) actuator. This device is fabricated by MEMS based micro fabrication techniques. Specimen is cofabricated with the device that will remove any misalignment and gripping problems. We carried out in-situ transmission electron microscope (TEM) experiments on 75 nm Pt thin film specimen at high temperatures and observed grain boundary sliding induced edge cavitation as deformation and failure mechanism.

When a thin film is deposited, it typically undergoes a compressive-to-tensile-to-compressive
stress evolution. These changes can be measured in real-time using a laser reflectometry
technique that captures substrate curvature effects linked to these stresses. These changes in
stress states are associated with the adatom mobility on the substrate surface during deposition.
The initial stress is related to the atomic-scale migration into embryonic islands that form to
minimize surface area-to-volumetric energies; the subsequent tensile stress originates from the
elastic strain associated with the coalescence of these islands to minimize the grain boundary
energy; a return to a compressive stress state, for higher intrinsic mobility adatoms, during
post-coalescence is less understood. Using alloy metallic films, the origins of the secondary
compressive stress states are being explored using solid solutions. In the Cu(Ni) system, Ni
has been reported to weakly segregate to the grain boundaries. A series of Cu-rich Cu(Ni) alloy
films have been sputter deposited and the in situ stress measured during growth. As Ni is added
to these films, the growth stress of these alloy films becomes more compressive then either
of the elemental Cu or Ni thin films. With ever increasing Ni content, the compressive stress
moves towards the elemental stress states. This post-coalescence stress has been hypothesized
to be from the effect of the insertion of excess adatoms into the grain boundaries. Atom probe
tomography has revealed that Ni does indeed segregate to these boundaries and would support
the above theory. As the Ni content increased, the relative amount of Ni within the matrix to
that in the grain boundary increases, which seems to off-set further compressive stress increases.
From these findings, the use of solute segregation appears as a plausible means of tailoring the
intrinsic stress state of thin films. This work is supported by ARO-W911NF-13-1-0436.

Interfaces between semiconductors and metal oxides are important for a wide array of applications including surface passivation layers on solar cells and gate dielectrics. The electronic behavior of these interfaces can have a large influence on overall device behavior. Recently, atomic layer deposition (ALD) has emerged as a unique tool for the formation and study of oxides on semiconductors. ALD exhibits conformal deposition of a wide variety of compositions with precise thickness control through a binary reaction sequence. We utilize the temporally-separated chemical events that result in ALD growth to study the evolution of fixed charge at the interface between metal oxides and silicon. Here, the conductance across a silicon channel region was measured during ALD of aluminum oxide which yielded information about the effects of ALD chemistry on the charge carrier concentrations in the channel. In particular, we observed evidence for the formation of a small fixed negative charge (~5×10¹⁰ cm^-2) upon the first chemisorption of trimethylaluminum on the Si/SiO₂ surface. This magnitude of interfacial charge is consistent with other reports of un-annealed ALD alumina films deposited at low temperatures. Further growth of several nanometers of alumina continued to change surface charge density but changes diminished in magnitude relative to the first ALD cycle. These measurements provide a unique ability to monitor charge formation during deposition, and the possibility to engineer interfaces with controlled amounts of positive or negative charge. Such understanding and control of interfaces is critical for controlling the flat band voltage in gating applications and for field effect passivation in photovoltaics.

Electrolyte-gated (EG) thin film transistors make use of electrolytes, such as ionic liquids and ion gels, to replace conventional dielectrics in large area, flexible, printable electronic applications. (1) We previously demonstrated EG transistors based on organic semiconductor channels exhibiting current modulations of several orders of magnitude at relatively modest gate voltages (about 1 V), exploiting the exceptionally high capacitance of the electrical double layer formed at the electrolyte/transistor channel interface. (2) Different doping mechanisms, including electrostatic and Faradaic (the latter being commonly referred to in the electrolyte gating literature as electrochemical doping), have been proposed to explain the gating process in EG transistors. While both processes can be reversible, the former does not involve charge transfer and takes place in the immediate vicinity of the surface of the channel material, whereas the latter involves charge transfer and takes place in the bulk of the channel material.
We believe that the development/success of the EG transistor concept will depend, among others, on the operational stability of the device, in terms of the number of I/V cycles that is possible to record, at a certain sweeping rate within a well defined voltage range in a certain electrolyte.
We used Atomic Force Microscopy to follow in situ the behavior of the films during the doping-dedoping process, i.e. during insertion/removal of ions in/from the transistor channel. We selected as the channel materials conducting polymers (PEDOT:PSS), semiconducting polymers (MEH-PPV, P3HT) but also metal oxides (TiO₂ and WO₃). If polymers are prone to electrochemical doping, metal oxides can exhibit electrochemical (e.g. WO₃ in aqueous electrolytes) and (mainly) electrostatic (TiO₂) doping. Aqueous electrolytes, imidazolium-based ionic liquids and ion-gels, prepared from block copolymers and ionic liquids, were investigated. We will discuss the guidelines we extracted from our experiments to produce EG transistors with improved operational stability.
(1) G. Tarabella, F. M. Mohammadi, N. Coppede, F. Barbero, S. Iannotta, C. Santato and F. Cicoira, Chem. Sci., 2013, 4, 1395.
(2) J. Sayago, F. Soavi, Y. Sivalingam, F. Cicoira, and C. Santato, J. Mater. Chem. C doi: 10.1039/c4tc00864b.

The shape memory effect due to reversible martensitic transformation has been extensively studied in metallic shape memory alloys (SMAs). The low actuation stress (usually < 1GPa) and the narrow working temperature range of SMAs have encouraged the transition of study towards other shape memory materials such as ceramics. In our recent work on CeO₂ stabilized zirconia, we have demonstrated that small-scale, oligocrystalline and single crystalline structures can exhibit recoverable shape memory strains up to 3-7%. In this work we show for the first time that similar effects are possible in yttria stabilized zirconia (YSZ) ceramics, and are facilitated by doping with a small amount of titania to promote grain growth. In-situ compression tests on micromachined YSZ pillars show all the characteristic signatures of the shape memory effect with maximum strains up to 5% without fracture. The motion of martensitic boundaries has been directly observed, with martensitic transformation stresses as high as ~2.4 GPa. Such high transformation stress, large strain and good chemical and thermal stability offer unique advantages over many shape memory alloys.

We report the in situ formation and the characterization of individual nanowire memristors inside a transmission electron microscope. First the initial memristors are formed in situ by localized intense electron-beam irradiation on copper oxide nanowires. As a result the oxygen vacancies are generated as charge carriers. Then the in situ current-voltage measurements on nanowires show distinctive hysteresis characteristics of memristors. Such memristic behaviors can be well explained theoretically by an oxygen vacancy migration model. The presence of the oxygen vacancies will cause copper exist in different valance state which can be distinguished by the electron energy loss spectroscopy. Finally, combining with the use of scanning transmission electron microscopy, the in situ electron energy loss spectroscopy reveals the presence and migration of the oxygen vacancies during the in situ switching cycle of memristor to both either on and off state. These experimental results strongly support the theoretical model.

Through the installation of electron gun and photon detector, the in-situ photoemission and damage-free sputtering integrated analysis system are completely constructed. Therefore, this enables to accurately characterize the energy level alignments including unoccupied/occupied molecular orbital (LUMO/HOMO) levels at interface region of organic semiconductor/electrode according to depth position. Based on the organic semiconductors on Au and Ti, the LUMO/HOMO level transitions depending on electrode work function are clearly observed and the energy band diagram using directly measured results can be established. Furthermore, the effects of Ar gas cluster ion beam sputtering on the unoccupied/occupied states and the electron-injection barriers of transparent conducting electrodes are comprehensively studied.Through the installation of electron gun and photon detector, the in-situ photoemission and damage-free sputtering integrated analysis system are completely constructed. Therefore, this enables to accurately characterize the energy level alignments including unoccupied/occupied molecular orbital (LUMO/HOMO) levels at interface region of organic semiconductor/electrode according to depth position. Based on the organic semiconductors on Au and Ti, the LUMO/HOMO level transitions depending on electrode work function are clearly observed and the energy band diagram using directly measured results can be established. Furthermore, the effects of Ar gas cluster ion beam sputtering on the unoccupied/occupied states and the electron-injection barriers of transparent conducting electrodes are comprehensively studied.

The observation and evaluation of lattice defects such as vacancies, dislocations, and grain boundaries are very important in materials design. Electrical resistivity measurement is superior to electron microscopy for obtaining average microstructural information, including density and type of lattice defects. Electrical resistivity can generally be measured using a well-shaped cylindrical or tabular specimen. The dimensions of the specimen must be accurately measured in order to obtain the electrical resistivity from four-point DC electrical resistance measurements. This means that the resistivity cannot be measured in irregularly shaped specimens, for example, under tensile deformation. However, resistivity can be estimated using the empirical relationship. The purpose of this study was to determine Matthiessen&’s empirical relationship by using tensile-deformed specimens and to estimate changes in electrical resistivity during the tensile deformation of commercial-purity (CP) Ti. The electrical resistivities of tensile deformed Ti specimens were measured at 77 K (ρ₇₇) and 300 K (ρ₃₀₀) along the tensile direction using a direct current (DC) four-point method in order to determine Matthiessen&’s empirical relationship, ρ₇₇ = α/(R - 1) + β, R = ρ₃₀₀/ρ₇₇. Plots of ρ₇₇ versus 1/(R-1) showed a linear relationship, and the values of α and β were determined to be 0.9293 and -0.0837 (mu;Omega;m), respectively. Changes in ρ₇₇ during tensile deformation were estimated by substituting the resistance ratio R into Matthiessen&’s empirical relationship. In elastic deformation region, no remarkable change was confirmed in the resistivity. This means the density of dislocation hardly changed. On the other hand, electrical resistivity increased drastically around the yielding. It indicates much dislocation was introduced around here. The dislocation density was calculated to be 2.32×10¹⁴m^-2 by the electrical resistivity. In addition, annihilation of vacancies just after tensile deformation could be also detected by the present electrical resistivity measurement.