Polyamorphism of GeO2 Glass at High Pressure,Physica Status Solidi (B) - Basic Solid State Physics

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Polyamorphism of GeO2 Glass at High Pressure
Physica Status Solidi (B) - Basic Solid State Physics ( IF 1.5 ) Pub Date : 2020-04-03 , DOI: 10.1002/pssb.202000052
Xinguo Hong _{1,

2} , Matt Newville ₃

Affiliation

Polyamorphism of network‐forming SiO₂ and GeO₂ glasses at high pressures is a puzzling topic in condensed matter physics and has long‐standing interest because of their important geophysical and geochemical implications. Molecular dynamics simulations suggest that there are multiple amorphous–amorphous transitions at high pressure with parallel high‐pressure crystalline counterparts. However, it is very challenging to experimentally distinguish the pressure‐induced subtle change in the amorphous state at high pressure. Recently, a high‐pressure X‐ray absorption fine structure (HP‐XAFS) method is developed using a diamond anvil cell (DAC) to measure the local structure of polyamorphs in GeO₂ glass at high pressure. The results indicate that GeO₂ glass shows multiple polyamorphs at high pressure with a local structure, in general, similar to their high‐pressure crystalline states in the first coordination shell but with increasing differences in the distant coordination shells. Three pressure‐induced polyamorphs in GeO₂ glass are recognized unambiguously at high pressure, i.e., α‐quartz‐like, rutile‐like, and pyrite‐like amorphous structures. The obtained knowledge of these polyamorphs is helpful for understanding the mechanisms of network compression behavior and physical properties of SiO₂ and GeO₂ glasses and melts under extreme conditions.

中文翻译：

GeO2玻璃在高压下的多晶现象

在高压下，网络形成的SiO ₂和GeO ₂玻璃的多态性在凝聚态物理中是一个令人费解的话题，并且由于其重要的地球物理和地球化学意义而引起人们的长期关注。分子动力学模拟表明，在高压下存在多个非晶态-非晶态转变，并伴有平行的高压结晶态对应物。但是，通过实验区分高压下压力诱导的非晶态细微变化是非常具有挑战性的。最近，开发了一种使用金刚石砧盒（DAC）的高压X射线吸收精细结构（HP-XAFS）方法，用于在高压下测量GeO ₂玻璃中多晶型物的局部结构。结果表明，GeO ₂玻璃在高压下显示出多个多晶型，具有局部结构，通常与第一配位壳中的高压晶态相似，但远处的配位壳中的差异越来越大。在高压下可以清楚地识别出GeO ₂玻璃中的三种压力诱导的多晶型物，即α-石英，金红石和黄铁矿的非晶结构。获得的这些多晶型物的知识有助于理解SiO ₂和GeO ₂玻璃在极端条件下的网络压缩行为和物理性质的机理。

更新日期：2020-04-03

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