Observation of Amorphous-To-Crystalline Transition at the Single-Atom Level

The amorphous-to-crystalline transition is fundamental to many physical, chemical and biological phenomena, but is a challenging process to study at the atomic scale. An approach to overcome this challenge is atomic electron tomography (AET) (1). AET combines high-resolution tomographic tilt series with advanced computational algorithms to resolve the three-dimensional (3D) atomic structure of materials without assuming crystallinity (2). We have recently advanced AET to determine the 3D atomic structure of amorphous materials and characterize the short- and medium-range order of the 3D atomic arrangement (3,4). In this talk, I will present our most recent results on the application of AET to observe the amorphous-to-crystalline transition in 3D at the atomic resolution. By using a carbothermal shock method (5), we trapped high entropy alloy nanoparticles at different stages of crystallization. We then used AET to determine the 3D atomic structure of the high entropy alloy nanoparticles as a function of crystallization. By quantitatively characterize the 3D atomic arrangement inside a large number of nuclei, we observed crystal nucleation pathways at the single-atom level. We expect that these experimental results not only open the door to study the amorphous-to-crystalline transition at the atomic scale, but also could transform our fundamental understanding of nucleation and crystal growth.<br/><br/>1. J. Miao, P. Ercius and S. J. L. Billinge. Atomic electron tomography: 3D structures without crystals. <i>Science</i> <b>353</b>, aaf2157 (2016).<br/>2. J. Zhou, Y. Yang, Y. Yang, D. S. Kim, A. Yuan, X. Tian, C. Ophus, F. Sun, A. K. Schmid, M. Nathanson, H. Heinz, Q. An, H. Zeng, P. Ercius & J. Miao<i>.</i> Observing crystal nucleation in four dimensions using atomic electron tomography. <i>Nature </i><b>570</b>, 500-503 (2019).<br/>3. Y. Yang, J. Zhou, F. Zhu, Y. Yuan, D. Chang, D. S. Kim, M. Pham, A. Rana, X. Tian, Y. Yao, S. Osher, A. K. Schmid, L. Hu, P. Ercius and J. Miao. Determining the three-dimensional atomic structure of an amorphous solid. <i>Nature </i><b>592</b>, 60–64 (2021).<br/>4. Y. Yuan, D.S. Kim, J. Zhou, D.J. Chang, F. Zhu, Y. Nagaoka, Y. Yang, M. Pham, S. J. Osher, O. Chen, P. Ercius, A. K. Schmid and J. Miao. Three-dimensional atomic packing in amorphous solids with liquid-like structure. <i>Nature Mater.</i> <b>21</b>, 95–102 (2022).<br/>5. Y. Yao, Q. Dong, A. Brozena, J. Luo, J. Miao, M. Chi, C. Wang, I. G. Kevrekidis, Z. J. Ren, J. Greeley, G. Wang, A. Anapolsky and L. Hu. High Entropy Nanoparticles: Synthesis-Structure-Property Relationships and Data-Driven Discovery. <i>Science</i> <b>376</b>, eabn3103 (2022).