高压下c-Zr_3N_4弹性性质和热力学性质的第一性原理研究

Theoretical Calculations for Structural,Elastic and Thermodynamic Properties of c-Zr_3N_4 under High Pressure

利用平面波赝势密度泛函理论方法研究了高压下c-Zr3N4的结构性质和弹性性质,由此获得了c-Zr3N4在高压下的体弹模量、杨氏模量、剪切模量和泊松比等力学性质.高压弹性常数计算结果表明,在小于50 GPa下,c-Zr3N4没有发生相变,是力学稳定的,而且各向异性因子计算表明其具有弹性各向异性.此外,高压下c-Zr3N4的B/G计算结果表明,在此压强范围内,c-Zr3N4具有较好的延展性.最后利用准谐德拜模型研究了c-Zr3N4的热动力学性质,得到了其高压下的热容、德拜温度和热膨胀系数等参数.研究c-Zr3N4在高压下的弹性性质和热动力学性质,对实验研究具有一定的参考价值.

We have investigated the structural and elastic properties of c-Zr3 N4 at high pressures using generalized gradient approx- imation within the plane-wave pseudopotential density functional theory. The elastic constants as a function of the applied pressure, the bulk modulus, Young＇ s modulus, shear modulus, compressibility and Poisson＇ s ratio on the pressure p, are also successfully ob- tained. The superior mechanical properties indicate that c-Zr3 N4 is a potential candidate structure to be one of the ultra-incompressible and hard materials. The high pressure elastic constants indicate that c-Zr3N4 is mechanically stable up to 50 GPa. In addition, the cal- culated B/G ratio indicated that c-Zr3 N4 possesses ductile nature in the range of pressure from 0 to 50 GPa. The calculated elastic ani- sotropic factors suggest that c-Zr3N4 is elastically anisotropic. Through the quasi-harmonic Debye model, we have also investigated the thermodynamic properties of c-Zr3 N4.