Pressure-induced amorphization in crystalline silica: Soft phonon modes and shear instabilities in coesite
Pressure-induced amorphization in crystalline silica: Soft phonon modes and shear instabilities in coesite
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DOI：
10.1103/physrevb.61.3303
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发表时间：
2000-02
影响因子：
3.7
通讯作者：
D. Dean;R. Wentzcovitch;N. Keskar;J. Chelikowsky;N. Binggeli
中科院分区：
文献类型：
--
作者：
D. Dean;R. Wentzcovitch;N. Keskar;J. Chelikowsky;N. Binggeli
石英和密切相关的材料将在压力下从晶态转变为非晶态。在这里，我们研究柯石英，高压形式的二氧化硅，也经历压力诱导非晶化。我们发现柯石英，像石英，具有剪切不稳定性密切耦合到一个带边声子软化的压力下相媲美的非晶化转变。这些功能的共性强烈表明，剪切和声子软模式之间的耦合起着重要的作用，压力诱导的非晶化。这种机制与马氏体相变中观察到的机制相似。在高压下产生的相的密度，从可变的细胞形状的分子动力学计算，遵循实验玻璃质区域加入柯石英stishovite。(c)2000年，美国物理学会。
Quartz and closely related materials will transform under pressure from crystalline states to amorphous forms. Here we examine coesite, a high-pressure form of silica which also undergoes pressure induced amorphization. We find that coesite, like quartz, possesses a shear instability closely coupled to a zone-edge phonon softening at pressures comparable to the amorphization transformation. The commonality of these features strongly suggests that a coupling between a shear and a phonon soft mode plays an important role in pressure induced amorphization. This mechanism is similar to that observed in martensitic transformations. The densities for the phases produced at high pressures, as calculated from variable cell shape molecular dynamics, follow the experimental glassy region joining coesite to stishovite. (c) 2000 The American Physical Society.