(1. 中南大學(xué) 物理科學(xué)與技術(shù)學(xué)院，長(zhǎng)沙 410083；
2. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 應(yīng)用基于密度泛函理論的平面波贗勢(shì)方法計(jì)算16H金屬硅化物Zr5Si3及Zr3Ti2Si3的基態(tài)晶格參數(shù)，得出彈性常數(shù)、體彈性模量、彈性模量、剪切模量及泊松比等彈性性質(zhì)。利用彈性常數(shù)計(jì)算德拜溫度、格林奈森常數(shù)，并在德拜-格林奈森模型基礎(chǔ)上計(jì)算這兩種金屬硅化物的各向異性熱膨脹系數(shù)，由此得出Zr5Si3的a、c方向各向異性熱膨脹系數(shù)(高溫時(shí))分別為8×10−6和15×10−6，對(duì)Zr3Ti2Si3(高溫時(shí))分別為11×10−6和13×10−6，與實(shí)驗(yàn)基本相符。根據(jù)方向體彈性模量、方向彈性模量及重疊布居數(shù)討論兩種材料各向異性熱膨脹不同的原因。
關(guān)鍵字: 第一原理計(jì)算；熱學(xué)性質(zhì)；彈性性質(zhì)；金屬硅化物
（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
