First-principles study on electronic structure, magnetic and dielectric properties of Cr-doped Fe_3C  

作　　者：YANG Jian-ping CHEN Jin LI Wei HAN Pel-de GUO Li-na 杨建平;陈津;李伟;韩培德;郭丽娜(College of Materials Science and Engineering, Taiyuan University of Technology)

机构地区：College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China

出　　处：《Journal of Central South University》2016年第9期2173-2181,共9页中南大学学报（英文版）

基　　金：Project(51174252)supported by the Joint Funds of the National Natural Science Foundation of China

摘　　要：The first-principles calculations were performed to investigate the electronic structure, magnetic and dielectric properties of Cr-doped Fe_3C, in comparison to those of pure Fe_3C and Cr_3C. The obtained results show that the thermodynamic stability of Crdoped Fe_3C becomes weaker in terms of the larger formation enthalpy, on the contrary, the metallicity and covalency are found to strengthen to some extent. The magnetic moments of Fe_3C, Fe_(11)CrC_4(g), and Fe_(11)CrC_4(s) are respectively 21.36 μB/cell, 16.92 μB/cell, and 17.62 μB/cell, and in Fe_(11)CrC4(g) and Fe_(11)CrC_4(s), the Fe of Wyckoff positions of 8d and 4c is substituted by Cr. The local magnetic moment of Cr at 8d site is larger than that at 4c site in the doped structure, which is opposite to that of Fe. In low frequency band, the permittivity follows the ranking of Fe_(11)Cr C_4(s)>Cr_3C>Fe_(11)Cr C_4(g)>Fe_3C. Once exceeding a certain frequency, the sequence will be broken. Besides the electron transition, the polarization of atoms also makes a contribution to the dielectric properties.The first-principles calculations were performed to investigate the electronic structure, magnetic and dielectric properties of Cr-doped Fe3C, in comparison to those of pure Fe3C and Cr3C. The obtained results show that the thermodynamic stability of Cr-doped Fe3C becomes weaker in terms of the larger formation enthalpy, on the contrary, the metallicity and covalency are found to strengthen to some extent. The magnetic moments of Fe3C, Fe11CrC4（g）, and Fe11CrC4（s） are respectively 21.36 μB/cell, 16.92 μB/cell, and 17.62 μB/cell, and in Fe11CrC4（g） and Fe11CrC4（s）, the Fe of Wyckoff positions of 8d and 4c is substituted by Cr. The local magnetic moment of Cr at 8d site is larger than that at 4c site in the doped structure, which is opposite to that of Fe. In low frequency band, the permittivity follows the ranking of Fe11CrC4（s）〉Cr3C〉Fe11CrC4（g）〉Fe3C. Once exceeding a certain frequency, the sequence will be broken. Besides the electron transition, the polarization of atoms also makes a contribution to the dielectric properties.

关 键 词：Cr-doped Fe3C electronic structure magnetic properties dielectric properties 

分 类 号：TG141[一般工业技术—材料科学与工程]