La_2Zr_2O_7弹性常数及最低热导率的第一性原理计算

First Principle Calculation of Elastic Constant and Minimum Thermal Conductivity of La_2Zr_2O_7 Ceramic

采用基于第一性原理的赝势平面波法计算了新型热障涂层陶瓷材料La2Zr2O7的弹性常数和热力学性质。计算结果表明:优化后的La2Zr2O7的晶格常数为1.0934 nm,当O(48f)的位置参数为0.329时其晶胞总能量最低;由计算得到的三个弹性刚度张量C11,C12,C44、体弹性模量B和剪切模量G可知La2Zr2O7的结构非常稳定;La2Zr2O7的杨氏模量E=201.50GPa,泊松比为0.274,同性系数为0.733,具有一定的脆性;计算得到的La2Zr2O7德拜温度为619.4K,等容比热为274.3J.mol-1.K-1,最低热导率为1.31W.m-1.K-1,与利用激光脉冲法在1473K测得的热导率1.55 W.m-1.K-1相比,相差15.48%。

Elastic constant and thermodynamic properties of La2Zr2O7 ceramic which are used for thermal barrier coating have been calculated by using the first principle pseudopotential method. These results show that the lattice parameter of optimized crystal structure is 1. 0934 nm, and the cell energy is the lowest when the x （ positional parameter of O （48f）） is 0. 329. The La2Zr2O7 ceramic have high structure stability from the results of elastic constant C11 , C12, C44, bulk modulus and shear modulus. The Young＇ s modulus E is 201. 50GPa, and the Poisson＇s ratio is 0. 274, the isotropy coefficient is 0. 733 which means that La2Zr207 ceramic with some brittleness. The Debye temperature is 619.4K and the specific heat is 274.3J·mol-1·K-1. The minimum thermal conductivity of La2Zr2O7 ceramic is 1.31W·m-1K-1, while the experiment value measured by laser pulse method is 1.55 W·m-1K-1, its error is 15. 48%.