Stellhorn Jens Rüdiger, Hosokawa Shinya, Kohara Shinji
Department of Applied Chemistry, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, 739-8527, Japan.
Department of Physics, Kumamoto University, 2-39-1 Kurokami, Chuo, Kumamoto, 860-8555, Japan.
Anal Sci. 2020 Jan 10;36(1):5-9. doi: 10.2116/analsci.19SAR02. Epub 2019 Dec 20.
Local- and intermediate-range atomic structures were investigated on amorphous phases of an ordinary phase-change material, GeSbTe (GST), and an exotic one, CuGeTe (CGT), by using anomalous X-ray scattering close to K absorption edges of each element to find a fast amorphous-crystalline phase-change mechanism. The obtained data were analyzed by using reverse Monte Carlo modeling to obtain partial structure factors, partial pair distribution functions, and three-dimensional atomic configurations. Ring statistics were carefully examined to clarify the similarity and difference compared with the corresponding crystal structures, and it was found that amorphous GST has a number of four-membered rings indicating fragments of crystal structure, and amorphous CGT has a remarkable number of three-membered rings showing a collapse of crystal structures composed of purely six-membered rings. A persistent homology analysis was carried out and long-range ring structures of the constituent elements were observed in the amorphous phase, which may originate from fragments of crystal structures with a long-range periodicity.
通过使用接近各元素 K 吸收边的反常 X 射线散射，研究了普通相变材料 GeSbTe（GST）和一种特殊相变材料 CuGeTe（CGT）非晶相的局部和中程原子结构，以寻找快速的非晶-晶态相变机制。利用反向蒙特卡罗建模对所得数据进行分析，以获得部分结构因子、部分对分布函数和三维原子构型。仔细研究了环统计，以阐明与相应晶体结构相比的异同，发现非晶态 GST 有许多表明晶体结构片段的四元环，而非晶态 CGT 有大量表明由纯六元环组成的晶体结构崩塌的三元环。进行了持久同调分析，并在非晶相中观察到了组成元素的长程环结构，这可能源于具有长程周期性的晶体结构片段。
