Determination of the Thermal Expansion Coefficient of the Nanoparticles with In Situ Electron Energy Loss Spectroscopy

Our ability to determine the local temperature of a sample inside the electron microscope column is key in measuring the effects of electron-sample interaction and controlling the beam-induced sample changes. Temperature dependence of the plasmon resonance energy of the material can be used to map the local temperature of the material at the nanoscale [1-2] and to determine its thermal expansion coefficient [3]. In this work, we will study the behavior of plasmon energy of In and BaTiO₃ nanoparticles across the phase transition temperature. We will compare the performance of several nanoparticles (Al, Si, In, SrTiO₃, BaTiO₃) as a nano-thermometer for high-temperature measurement. In addition, we will also utilize a novel approach of non-contact thermometry based on the combination of low-loss electron energy-loss spectroscopy (EELS) with the free electron model to measure the thermal expansion coefficient (TEC) of nanoparticles at the nanoscale. Finally, we will explore the effects (if present) of the particle size, oxygen vacancies, and contamination on this approach of measuring the thermal expansion coefficient as well as the local temperature.<br/><br/>References:<br/>[1] Mecklenberg et al., Sci. 347, 6222(2015)<br/>[2] Mecklenberg et al., Phys. Rev. Applied 9, 014005(2018)<br/>[3] Hu et al., Phys. Rev. Lett. 120, 05590(2018)<br/>[4] This work was supported by the National Science Foundation (DMR-1831406).