Cr_2MC(M=Al,Ga)的电子结构、弹性和热力学性质的第一性原理研究  

First-principles investigations on the electronic,elastic and thermodynamic properties of Cr_2MC(M=Al,Ga)

作　　者：杨则金[1] 令狐荣锋[2] 程新路[3] 杨向东[3] 

机构地区：[1]浙江工业大学理学院,杭州310023 [2]贵州师范学院物理与电子科学学院,贵阳550018 [3]四川大学原子与分子物理研究所,成都610065

出　　处：《物理学报》2012年第4期332-343,共12页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10974139;10964002;11104247;11176020);贵州省科学技术基金(批准号:黔科合J字[2009]2066号和LKS[2009]07);贵州省高层次人才科研条件特助项目(批准号:TZJF-2008年-42号);浙江省教育厅科研项目(批准号:Y201 121807)资助的课题~~

摘　　要：本文使用第一性原理的GGA/RPBE方法研究了Cr_2MC(M=Al,Ga)的电子结构、弹性和热力学性质.研究发现两个化合物的体积压缩性几乎相同,并且证实了在0—50GPa范围内c轴始终较a轴更难以压缩并且结构始终是稳定的.通过对内坐标的研究发现了Cr_2AlC中Cr离子的内坐标始终大于Cr_2GaC中Cr离子的内坐标.使用准谐德拜模型得到的体弹模量在0GPa下随着温度的升高而减小,而在300GPa下则随着温度的升高而增大.对德拜温度的研究发现Cr_2GaC的值小于Cr_2AlC的值,而对热膨胀系数、Gr(u|¨)neisen参数、熵和热容的计算发现Cr_2GaC的值大于Cr_2AlC的值.对电子结构的分析发现Cr_2GaC的s和p电子在费米能级处的值大于Cr_2AlC的s和p电子的值,而其他离子的电子分布几乎一致.We investigate the electronic,elastic and thermodynamic properties of nanolaminate Cr_2MC（M=Al,Ga） by using the ab initio pseudopotential total energy method.Our results show that they have shown almost identical volume compressibilities.The axial compressibility investigations show that the c axis is always stiffer than a axis.The internal coordinate calculations revealed that the values of Cr atoms in Cr_2AlC are always larger than those in Cr_2GaC.The elastic constants calculations demonstrated the structural stability within 0—50 GPa.The obtained bulk moduli by quasi-harmonic Debye model observed that the bulk moduli of Cr2MC（M=Al, Ga）decrease with temperature at 0 GPa,but increase at 300 GPa.We also found that the Debye temperatures of Cr_2GaC are always smaller than those of Cr_2A1C at any conditions.However,the opposite cases can be found in thermal expansion coefficients,Griineisen parameter,entropy and heat capacity when comparing their respective counterparts between Cr_2GaC and Cr_2AlC.The electronic density of states and energy band distribution demonstrated that the Cr_2MC（M=Al,Ga） have shown similar profiles with the only exception of the more localized s and p electrons in Cr_2GaC than their respective counterparts in Cr_2AlC.

关 键 词：第一性原理 电子结构 弹性 热力学性质 

分 类 号：O469[理学—凝聚态物理]