Fast Atomic-Scale Chemical Imaging of Crystalline Materials and Dynamic Phase Transformations

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• 作者：Ping Lu ; Ren Liang Yuan ; Jon F. Ihlefeld ; Erik David Spoerke ; Wei Pan ; Jian Min Zuo
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：April 13, 2016
• 年：2016
• 卷：16
• 期：4
• 页码：2728-2733
• 全文大小：475K
• 年卷期：0
• ISSN：1530-6992

文摘

Atomic-scale phenomena fundamentally influence materials form and function that makes the ability to locally probe and study these processes critical to advancing our understanding and development of materials. Atomic-scale chemical imaging by scanning transmission electron microscopy (STEM) using energy-dispersive X-ray spectroscopy (EDS) is a powerful approach to investigate solid crystal structures. Inefficient X-ray emission and collection, however, require long acquisition times (typically hundreds of seconds), making the technique incompatible with electron-beam sensitive materials and study of dynamic material phenomena. Here we describe an atomic-scale STEM-EDS chemical imaging technique that decreases the acquisition time to as little as one second, a reduction of more than 100 times. We demonstrate this new approach using LaAlO₃ single crystal and study dynamic phase transformation in beam-sensitive Li[Li_0.2Ni_0.2Mn_0.6]O₂ (LNMO) lithium ion battery cathode material. By capturing a series of time-lapsed chemical maps, we show for the first time clear atomic-scale evidence of preferred Ni-mobility in LNMO transformation, revealing new kinetic mechanisms. These examples highlight the potential of this approach toward temporal, atomic-scale mapping of crystal structure and chemistry for investigating dynamic material phenomena.