在高压下,GeO2玻璃的四面体-六面体-八面体转变
1Center for High Pressure Science and Technology Advanced Research, Beijing 100193, People's Republic of China.
概括
高压转化二氧化 (GeO2) 玻璃结构. 一个五重协调的六面体GeO5单位成为主导,在八面体GeO6的形成之前,揭示了一个新的过渡途径.
科学领域:
- 凝聚物质物理学 凝聚物质物理学
- 地质科学 地质科学
- 材料科学是一种材料科学.
背景情况:
- 在SiO2和GeO2玻璃中,压力诱导的结构转变对于理解凝聚物质物理学和地质科学至关重要.
- 在这些转型中,五重协调的结构单位在这些转型中的作用仍然不明确.
- 高压玻璃结构的实验性确定具有挑战性.
研究的目的:
- 调查高压下在GeO2玻璃中五倍协调结构单元的存在和作用.
- 为了阐明GeO2玻璃中压力诱导的结构过渡机制.
- 为了使实验发现与理论模拟相协调.
主要方法:
- 全面的 *ab initio* 分子动力学 (AIMD) 模拟.
- 模拟结果与高压X射线吸收细结构 (HP-XAFS) 实验数据的比较.
- 分析局部结构单元 (多面体) 作为压力的函数.
主要成果:
- 五重协调的六面体GeO5单位 (Ge) 随着压力增加而突然出现,达到多面体的40%左右.
- 六倍协调的八面体GeO6单位 (Ge) 起初是可以忽略不计的.
- [5]Ge成为15-25GPa范围内的主导物种,在Ge.Ge的形成中发挥了关键作用.
结论:
- 在GeO2玻璃中的高压转变不是简单的四面体-八面体转移.
- 提出了一个四面体-六面体-八面体过渡路径,六面体Ge单位是一个关键的中间体.
- AIMD模拟为了解玻璃结构中复杂的高压现象提供了有价值的工具.
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