Anisotropy of elasticity and minimum thermal conductivity of monocrystal M_4AlC_3(M=Ti,Zr,Hf)  

作　　者：丁艾玲 李春梅 王瑨 敖靖 李凤 陈志谦 

机构地区：[1]Faculty of Materials and Energy,Southwest University

出　　处：《Chinese Physics B》2014年第9期314-320,共7页中国物理B（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.51171156);CSTC2012GGYS5001,CSTC2013JCYJYS5002

摘　　要：The elastic constants, elastic anisotropy index, and anisotropic fractional ratios of Ti4AlC3, Zr4AlC3, and Hf4AlC3 are studied by using a plane wave method based on density functional theory. All compounds are characterized by the elastic anisotropy index. The bond length, population, and hardness of the three compounds are calculated. The degrees of hardness are then compared. The minimum thermal conductivity at high temperature limitation in the propagation direction of [000l] （0001） is calculated by the acoustic wave velocity, which indicates that the thermal conductivity is also anisotropic. Finally, the electronic structures of the compounds are analyzed numerically. We show that the bonding of the M4AlC3 lattice exhibits mixed properties of covalent bonding, ionic bonding, and metallic bonding. Moreover, no energy gap is observed at the Fermi level, indicating that various compounds exhibit metallic conductivity at the ground state.The elastic constants, elastic anisotropy index, and anisotropic fractional ratios of Ti4AlC3, Zr4AlC3, and Hf4AlC3 are studied by using a plane wave method based on density functional theory. All compounds are characterized by the elastic anisotropy index. The bond length, population, and hardness of the three compounds are calculated. The degrees of hardness are then compared. The minimum thermal conductivity at high temperature limitation in the propagation direction of [000l] （0001） is calculated by the acoustic wave velocity, which indicates that the thermal conductivity is also anisotropic. Finally, the electronic structures of the compounds are analyzed numerically. We show that the bonding of the M4AlC3 lattice exhibits mixed properties of covalent bonding, ionic bonding, and metallic bonding. Moreover, no energy gap is observed at the Fermi level, indicating that various compounds exhibit metallic conductivity at the ground state.

关 键 词：elastic property ANISOTROPY thermal conductivity electronic structure 

分 类 号：O469[理学—凝聚态物理]