Electronic origin of shearing in M2AC (M = Ti, V, Cr, A = Al, Ga)

被引:53
作者
Sun, ZM
Music, D
Ahuja, R
Schneider, JM
机构
[1] Rhein Westfal TH Aachen, Mat Chem, D-52074 Aachen, Germany
[2] Univ Uppsala, Dept Phys, Condensed Matter Theory Grp, S-75121 Uppsala, Sweden
关键词
D O I
10.1088/0953-8984/17/46/001
中图分类号
O469 [凝聚态物理学];
学科分类号
070205 ;
摘要
We have studied shearing in M(2)AC (space group P6(3)/MMC, prototype Cr2AlC), where M is Ti, V and Cr, and A is Al and Ga, using ab initio calculations. These compounds can be described as interleaved layers of MC and A. As Ti in Ti2AlC is substituted by V, c(44) increases by 24.3%. Increasing the transition metal valence electron concentration further, through a substitution of V by Cr, results in 2.2% decrease of c(44). The electronic origin of this c(44) versus valence electron concentration dependence may be understood by analysing the decomposed band structure: in the vicinity of the Fermi level, we find two types of dd bonding. One contributes to shearing (t(2g) + e(g) symmetry or MC-MC coupling) and the other does not (e(g) symmetry). We provide evidence that filling of the transition metal dd bonding states with the t(2g) + e(g) symmetry may be responsible for the behaviour of c(44). The results presented enable tailoring of the shear properties Of M(2)AC phases.
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收藏
页码:7169 / 7176
页数:8
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