MECHANICAL INSTABILITIES IN ALPO4

被引：25
作者：
KESKAR, NR
CHELIKOWSKY, JR
WENTZCOVITCH, RM
机构：
[1] UCL ROYAL INST GREAT BRITAIN, LONDON W1, ENGLAND
[2] UNIV LONDON UNIV COLL, DEPT GEOL SCI, LONDON WC1E 6BT, ENGLAND
来源：
PHYSICAL REVIEW B | 1994年 / 50卷 / 13期
关键词：
D O I：
10.1103/PhysRevB.50.9072
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
Pressure-induced amorphization has been observed in isostructural oxides such as alpha-quartz (SiO2), GeO2, and alpha-berlinite (AlPO4). Here we focus on the mechanical behavior of alpha-berlinite under pressure. We have computed the second-order elastic constants of alpha-berlinite and applied the Born stability criteria. Our analysis reveals an elastic instability associated with soft shear modes. We have also computed the phonon spectrum of alpha-berlinite as a function of pressure. A soft phonon mode corresponding to the shear instability is observed at the Brillouin-zone edge. We have analyzed the displacements of cations associated with the soft phonon modes in alpha-quartz and alpha-berlinite. They exhibit the same qualitative behavior. This strongly suggests that the mechanism of amorphization is similar in these materials.
引用
收藏
页码：9072 / 9078
页数：7
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