压力对六角密堆结构金属锂弹性的影响  

Pressure Effects on the Elastic Properties of the hcp Lithuim

作　　者：陈长波[1] 崔田[1] 刘志明[1] 邹广田[1] 韦孟伏[2] 陈长安[2] 

机构地区：[1]吉林大学超硬材料国家重点实验室,吉林长春130012 [2]中国工程物理研究院,四川绵阳621900

出　　处：《高压物理学报》2005年第4期331-336,共6页Chinese Journal of High Pressure Physics

基　　金：国家自然科学基金委员会-中国工程物理研究院联合资助项目(10276016);2003年度教育部优秀青年教授资助计划;2004年度教育部新世纪优秀人才支持计划;国家重点基础研究规划项目(2001CB711201)

摘　　要：采用密度泛涵理论第一原理赝势方法,利用应力和应变的关系计算了压力下六角密堆结构金属锂的弹性常数。计算结果显示,C12、C13随着压力的增加而线性增加,而压力对C44和C66的影响并不大。在各个压力点C33值都要比C11的值大,表明金属锂在z方向的硬度要比x、y方向的硬度大。还发现在理论预测的结构相变区域,C11和C33有一个跳跃。通过对压缩波各向异性参数Δp和剪切波各向异性参数Δs1、Δs2的计算发现,零压下Δp=1,并且高压下Δp值也接近1,表明压缩时金属锂表现出各向同性。Δs1、Δs2值远离1,并且随着压力的增加这种远离趋势不断增强,表现很强的剪切弹性各向异性。还讨论了压力对Cauchy关系和相对弹性常数的影响。The elastic constants of bulk lithium with hexagonal close-packed （hcp） structure under high pressures have been calculated, by using Density Functional Theory and the relationship between stress and strain. From our results, C12 and C13 increase linearly with pressures, but pressure effects on C44 and C66 are not obvious. At each pressure, C33 is bigger than C11, indicating rigidity of lithium in z direction is harder than that in x, y direction. It has been found that C11 and C33 have step-like changes in the phase transition zone. The results of the compressional wave anisotropy （△p） show that △p is equal to 1 at zero pressure and still near 1 under high pressure, meaning hcp lithium have the compressional elastic isotropy. The shear wave anisotropy （△s1, △s2） are away from 1 and this tendency increases with the increasing of pressure, showing the shear elastic anisotropy. Pressure effects on the Cauchy relations and the normalized elastic constants of hcp lithium are also discussed in this paper.

关 键 词：第一性原理 弹性常数 压力效应 金属锂 弹性各向异性 

分 类 号：O343[理学—固体力学]