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中国物理学会期刊

Cr2MC(M=Al, Ga)的电子结构、弹性和热力学性质的第一性原理研究

CSTR: 32037.14.aps.61.046301

First-principles investigations on the electronic, elastic and thermodynamic properties of Cr2MC(M=Al, Ga)

CSTR: 32037.14.aps.61.046301
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  • 本文使用第一性原理的GGA/RPBE方法研究了Cr2MC(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050 GPa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Cr2AlC中Cr离子的内坐标始终大于Cr2GaC中Cr离子的内坐标. 使用准谐德拜模型得到的体弹模量在0 GPa下随着温度的升高而减小, 而在300 GPa下则随着温度的升高而增大. 对德拜温度的研究发现Cr2GaC的值小于Cr2AlC的值, 而对热膨胀系数、Grneisen参数、熵和热容的计算发现Cr2GaC的值大于Cr2AlC的值. 对电子结构的分析发现Cr2GaC的s和p电子在费米能级处的值大于Cr2AlC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 Cr2MC(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 Cr2AlC are always larger than those in Cr2GaC. The elastic constants calculations demonstrated the structural stability within 050 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 Cr2GaC are always smaller than those of Cr2AlC at any conditions. However, the opposite cases can be found in thermal expansion coefficients, Grneisen parameter, entropy and heat capacity when comparing their respective counterparts between Cr2GaC and Cr2AlC. The electronic density of states and energy band distribution demonstrated that the Cr2MC(M=Al, Ga) have shown similar profiles with the only exception of the more localized s and p electrons in Cr2GaC than their respective counterparts in Cr2AlC.

     

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