X_(2)MnSc(X=Ni,Cu,Pd,Pt,Ag和Au)合金晶体结构和弹性常数的第一性原理计算  

First-principles calculation of crystal structure and elastic constants of X_(2)MnSc(X=Ni,Cu,Pd,Pt,Ag and Au)alloys

作　　者：李春梅 姜博 周金萍 LI Chunmei;JIANG Bo;ZHOU Jinping(College of Physical Science and Technology,Shenyang Normal University,Shenyang 110034,China)

机构地区：[1]沈阳师范大学物理科学与技术学院,沈阳110034

出　　处：《沈阳师范大学学报（自然科学版）》2023年第5期402-407,共6页Journal of Shenyang Normal University:Natural Science Edition

基　　金：辽宁省教育厅基本科研项目(LJKMZ20221472)。

摘　　要：全d族Heusler合金作为一种新型的多功能材料,有望改善传统非全d族Heusler合金Ni_(2)MnGa易脆、不易加工等不良的力学性能。基于第一性原理密度泛函理论,采用精确Muffin-Tin轨道方法,系统计算研究了全d族Heusler合金X_(2)MnSc(X=Ni,Cu,Pd,Pt,Ag和Au)在0 K下的晶体结构、四方晶格变形、磁矩和弹性常数。研究结果表明,相比XA和fcc结构,这些全d族Heusler合金在L21结构下的电子总能均更低,表明它们均具有该立方稳定结构。当L2_(1)-X_(2)MnSc合金发生四方晶格变形时,体系的电子总能总是高于该立方结构,因而它们均不能发生马氏体相变。L2_(1)-X_(2)MnSc合金的总磁矩均主要源于Mn原子;当X=Ni,Pd和Pt时,它们也贡献较小磁矩,而与Sc原子类似,X=Cu,Ag和Au则均可视为非自旋极化的。L2_(1)-X_(2)MnSc合金的弹性常数均符合立方晶系力学稳定性要求,且Pt_(2)MnSc合金的体弹性模量与剪切模量的比值(B/G)、泊松比(ν)均明显高于Ni_(2)MnGa合金,因而其有望具有更良好的力学性能,从而在工程上具有更广泛的应用潜能。研究结果有望为全d族Heusler合金X2MnSc力学性能的优化设计提供理论参考。As a new multifunctional material,all-d-metal Heusler alloys are expected to improve the poor mechanical properties of the traditional non-all-d Heusler alloy Ni_(2)MnGa,which is brittle and difficult to machine.This paper systematically calculates and studies the crystal structure,tetragonal lattice deformation,magnetic moment and elastic constant of all-d-metal Heusler X_(2)MnSc(X=Ni,Cu,Pd,Pt,Ag and Au)alloys at 0 K using the exact Muffin-Tin orbitals method based on first-principles density generalization theory.The results show that the total electron energy of these all-d-metal Heusler alloys in L2_(1) structure is lower than that of XA and fcc structures,indicating that they all have this cubic stable structure.When the L2_(1)-X_(2)MnSc alloys undergo tetragonal lattice deformation,the electron energy of the system is always higher than the cubic structure,so none of them can undergo martensitic phase transition.The total magnetic moment of L2_(1)-X_(2)MnSc alloys is mainly derived from Mn atoms;when X=Ni,Pd and Pt they contribute less,while similarly to the Sc atoms,X=Cu,Ag and Au can be considered non-spin-polarized.The elastic constants of the L2_(1)-X_(2)MnSc alloys meet the requirements for the mechanical stability of the cubic lattice and the ratio of bulk modulus to shear modulus(B/G)and Poisson's ratio(ν)of Pt_(2)MnSc are significantly higher than Ni_(2)MnGa,thus are expected to have better mechanical properties and wider potential applications in engineering.The results are expected to provide a theoretical reference for the optimal design of the mechanical properties of the all-d-metal Heusler X_(2)MnSc.

关 键 词：第一性原理 晶体结构 弹性常数 全d族Heusler合金 

分 类 号：O469[理学—凝聚态物理]