物理化学学报 >> 2000, Vol. 16 >> Issue (06): 512 -516 .doi: 10.3866/PKU.WHXB20000607

研究论文 上一篇    下一篇

正磷酸铝高压下相变的分子动力学模拟

徐桦, 邵俊   

  1. 常熟高等专科学校化学系,江苏常熟 215500|上海大学化学系,上海 201800
  • 收稿日期:1999-09-24 修回日期:2000-01-10 发布日期:2000-06-15
  • 通讯作者: 徐桦

Molecular Dynamics Simulation of the Phase Transition of α-berlinite under High Pressure

Xu Hua, Shao Jun   

  1. Department of Chemistry,Changshu College,Changshu 215500|Department of Chemistry,Shanghai University,Shanghai 201800
  • Received:1999-09-24 Revised:2000-01-10 Published:2000-06-15
  • Contact: Xu Hua

摘要:

在300K、-20GPa至40GPa范围内,对正磷酸铝系统进行了定温定压分子动力学模拟.随着压力不断增加,正磷酸铝中的磷氧四面体基本不变,只是各向同性稍有压缩 ;铝氧四面体变得越来越畸变,但铝对氧的配位数仍保持4. 所计算的晶胞压缩率与现有实验数据符合良好,晶格常数a比c减少得更厉害. 在 +20GPa处发生了一级相变,对径向分布函数分析的结果表明,这主要是铝氧四面体中氧 氧位置发生滑移的结果. 从高压下回到零压,模拟表明又回复到原来的晶体结构. 在 -15GPa下,晶体结构崩溃. 对所得结果进行了讨论.

关键词: 分子动力学模拟, 正磷酸铝, 压力诱导相变

Abstract:

A Molecular dynamics simulation of the behavior of α-berlinite (AlPO4) was performed between -20 GPa to 40 GPa at 300 K. With increasing pressure, the PO4 tetrahedron almost keeps unchanged, while the AlO4 tetrahedron becomes more and more distorted, but both P and Al continue to keep four coordinated with oxygen in the pressure region studied. The lattice constant a is more compressible than c and the calculated cell edge compressibilities are in good agreement with the experimental data available in low pressure region. An amorphous solid is formed at about 20 GPa and this glass, when releasing the pressure to zero, will transform back to its original crystal structure. The crystal structure can remain under tension until -15GPa.Further tension will make the crystal structure collapse.

Key words: Molecular dynamics simulation, α-berlinite, Pressure-induced amorphization