Unravelling the Mechanism of Pressure Induced Amorphization of Phase Change Materials
Unravelling the Mechanism of Pressure Induced Amorphization of Phase Change Materials
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DOI：
10.1103/physrevlett.102.205502
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发表时间：
2009-05-22
影响因子：
8.6
通讯作者：
Parrinello, M.
中科院分区：
文献类型：
--
作者：
Caravati, S.;Bernasconi, M.;Parrinello, M.
基于从头算分子动力学模拟，我们确定了压力诱导Ge（2）Sb（2）Te（5）非晶化的原子机制。模拟结果表明，在压力作用下，立方Ge（2）Sb（2）Te（5）中出现了同极Ge/Sb键，并产生了相对于晶轴旋转45 °的方环，其形成是由于Te原子填充相邻Ge/Sb化学计量空位的空隙而引起的。这些拓扑缺陷的浓度随着压力增加到21 GPa，在该系统是不稳定的，并转化为与实验一致的非晶相。
Based on ab initio molecular dynamics simulations, we identify the atomistic mechanism of the pressure induced amorphization of Ge(2)Sb(2)Te(5). The simulations reveal that homopolar Ge/Sb bonds appear in cubic Ge(2)Sb(2)Te(5) under pressure, giving rise to square rings rotated by 45 degrees with respect to the crystalline axis whose formation is induced by the displacement of Te atoms filling the voids of neighboring Ge/Sb stoichiometric vacancies. The concentration of these topological defects increases with pressure up to 21 GPa at which the system is destabilized and transforms into an amorphous phase in agreement with experiments.