(1. 中南大学 物理科学与技术学院，长沙 410083；
2. 中南大学 材料科学与工程学院，长沙 410083)
摘 要: 应用基于密度泛函理论的平面波赝势方法计算16H金属硅化物Zr5Si3及Zr3Ti2Si3的基态晶格参数，得出弹性常数、体弹性模量、弹性模量、剪切模量及泊松比等弹性性质。利用弹性常数计算德拜温度、格林奈森常数，并在德拜-格林奈森模型基础上计算这两种金属硅化物的各向异性热膨胀系数，由此得出Zr5Si3的a、c方向各向异性热膨胀系数(高温时)分别为8×10−6和15×10−6，对Zr3Ti2Si3(高温时)分别为11×10−6和13×10−6，与实验基本相符。根据方向体弹性模量、方向弹性模量及重叠布居数讨论两种材料各向异性热膨胀不同的原因。
关键字: 第一原理计算；热学性质；弹性性质；金属硅化物
（1. School of Physics Science and Technology, Central South University,
Changsha 410083,China;
2. School of Materials Science and Engineering, Central South university, Changsha 410083, China）
Abstract: A first-principles study on elastic and thermal properties of intermetallic silicides with 16H crystal structure, Zr5Si3 and Zr3Ti2Si3, was done, using the pseudopotential plane-wave method in the framework of the density-functional theory. The equilibrium lattice parameters of ground state at 0 K were calculated. The elastic constants, bulk modulus, elastic modulus, shear modulus, and Poisson’s ratio were obtained. Debye temperature and Grüneisen parameters were calculated from elastic constants. The anisotropic coefficients of thermal expansion (CTE) for a and c axes of Zr5Si3 and Zr3Ti2Si3 were calculated based on Debye-Grüneisen model. For Zr5Si3 (at high temperature), they are 8×10−6 and 15×10−6, respectively; for Zr3Ti2Si3 (at high temperature), they are 11×10−6 and 13×10−6, respectively. The results are in agreement with available experimental data. According to the calculated directional bulk modulus, directional elastic modulus and overlap population, the cause of different anisotropic CTE in these two systems was discussed.
Key words: first-principles calculations; thermal properties; elastic properties; intermetallic silicides
