First-principles investigations on structure stability, elastic properties, anisotropy and Debye temperature of tetragonal LiFeAs and NaFeAs under pressure ☆
First-principles investigations on structure stability, elastic properties, anisotropy and Debye temperature of tetragonal LiFeAs and NaFeAs under pressure ☆
复制标题
DOI：
10.1016/j.jpcs.2017.01.014
复制
发表时间：
2017-05
影响因子：
4
通讯作者：
Lili Liu;Gang Xu;Anrong Wang;Xiaozhi Wu;Rui Wang
中科院分区：
文献类型：
--
作者：
Lili Liu;Gang Xu;Anrong Wang;Xiaozhi Wu;Rui Wang
采用第一性原理结合均匀形变方法研究了LiFeAs和NaFeAs四元结构的二阶和三阶弹性常数。从LiFeAs和NaFeAs的二阶和三阶弹性常数中得到了有效的二阶弹性常数。进一步研究了高压下的Pugh模量比、泊松比、维氏硬度、弹性各向异性和德拜温度。随着压力的增大，材料的塑性增大，硬度减小，且NaFeAs的塑性优于LiFeAs，硬度始终低于LiFeAs。对于LiFeAs和NaFeAs，沿{100}面的剪切各向异性因子A {100}沿着迅速减小，沿{001}面的剪切各向异性因子A {001}沿着增大.
First-principles methods combined with homogeneous deformation methods are used to investigate the second-and third-order elastic constants of LiFeAs and NaFeAs with tetragonal structure. The effective second-order elastic constants are obtained from the second-and third-order elastic constants for LiFeAs and NaFeAs. Pugh's modulus ratio, Poisson's ratio, Vickers hardness, elastic anisotropy and Debye temperature under high pressure are further investigated. The ductility increases and the hardness decreases with pressure, and the ductility of NaFeAs is better than that of LiFeAs and the hardness of NaFeAs is always lower than that of LiFeAs. For LiFeAs and NaFeAs, the shear anisotropy factor A {100} along the {100} plane decreases quickly and the shear anisotropy factor A {001} along the {001} plane increases with increasing pressure.