马丁石-石过渡的路径
Tim Schaffrinna1, Victor Milman2, Björn Winkler3
1Institute of Geosciences, Goethe University, Frankfurt, Germany.
Scientific reports
|February 14, 2024
概括
应力诱导的马氏体转变使石英能够在较低的压力下转化为石. 这种原子化路径揭示了关键的剪切平面和压力不变反应屏障,证实了在特定应力条件下的coesite形成.
科学领域:
- 地质物理学 地质物理学
- 材料科学 材料科学 材料科学
- 晶体学 晶体学是指结晶学.
背景情况:
- 石英和coesite是二氧化的多态,具有不同的晶体结构.
- 石英和coesite之间的过渡通常发生在高压下.
- 了解相位过渡对于地质学和材料科学至关重要.
研究的目的:
- 为了确定石英和coesite之间的应变诱导的马氏体过渡的原子化机制.
- 为了确定这个过渡的最小原子移位和转换单元.
- 调查应力和压力在coesite形成中的作用.
主要方法:
- 使用密度函数理论进行原子路径计算.
- 对石英-石过渡的反应屏障的计算.
- 在马氏体变化过程中对不变的剪切平面的分析.
主要成果:
- 确定了24个配方单位的最小转换单元,用于无扩散的马氏体转换.
- 发现了两个不变剪切平面家族,接近{101}和{122},与撞击数据一致.
- 反应屏障 (150 meV/原子) 是压力不变的高达5 GPa.
- 在应力石英中,在明显低于水静电平衡压力的压力下证实了coesite的形成.
结论:
- 在亚固体条件下,应变可以诱导石英-石 martensitic 过渡.
- 已识别的路径和剪切平面为冲击石英中缺陷结构提供了洞察力.
- 这些发现表明,coesite可以在非水静压力条件下形成,压力低于以前认为的压力.
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