Shi Rui, Tanaka Hajime
Department of Fundamental Engineering, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
Sci Adv. 2019 Mar 1;5(3):eaav3194. doi: 10.1126/sciadv.aav3194. eCollection 2019 Mar.
Tetrahedral amorphous materials such as SiO, GeO, Si, Ge, C, and chalcogenides are extremely important in nature and technology. It is known that covalent bonding favors local tetrahedral order in these materials. However, how to extract information on this structural order from the scattering function has remained elusive. By analyzing the structure of simulated SiO and experimental data of various tetrahedral materials, we show that the lowest wave number peak, known as the first sharp diffraction peak (FSDP), and a few higher wave number ones in the scattering functions come from the characteristic density waves of a single tetrahedral unit. FSDP is thus a direct measure of the tetrahedrality. This finding opens the door for long-awaited experimental access to the characterization of disordered amorphous structures.
诸如SiO、GeO、Si、Ge、C和硫族化合物等四面体非晶材料在自然界和技术领域都极为重要。众所周知，共价键有利于这些材料形成局部四面体有序结构。然而，如何从散射函数中提取有关这种结构有序性的信息仍然难以捉摸。通过分析模拟的SiO结构和各种四面体材料的实验数据，我们表明，散射函数中最低波数的峰，即所谓的第一尖锐衍射峰（FSDP），以及一些较高波数的峰，来自单个四面体单元的特征密度波。因此，FSDP是四面体性的直接度量。这一发现为长期以来期待的对无序非晶结构进行表征的实验研究打开了大门。
