Pnnm-CrB_(4)的高压物理性质探究

Investigation of the Physical Properties for Pnnm-CrB_(4)under High Pressure

本文采用广义梯度近似(GGA)的PBE(Perdew-Burke-Ernzerhof)形式,利用基于密度泛函的赝势平面波法研究了四硼化铬(CrB_(4))的晶体结构属性和弹性性能。计算得到的Pnnm-CrB_(4)平衡结构参数与现有的实验数据和其他理论结果吻合较好。另外,本文还研究了高压条件下Pnnm-CrB_(4)的弹性常数C_(ij)、体模量B、剪切模量G及弹性模量E。根据Pnnm-CrB_(4)在高压下的泊松比σ及B/G分析了其在高压下的韧脆性。为了详细地研究Pnnm-CrB_(4)的弹性各向异性,本文还计算了剪切各向异性因子A_(1)、A_(2)、A_(3)及线性体模量的各向异性因子B_(a)、B_(b)、B_(c)。同时,本文还估算了Pnnm-CrB_(4)的维氏硬度H_(V)。最后,根据Pnnm-CrB_(4)的态密度及分态密度详细分析了其力学及弹性性能机制。

The crystal structure and elastic properties of chromium tetraboride(CrB_(4))were investigated by pseudopotential plane-wave methods within the Perdew-Burke-Ernzerhof(PBE)form of generalized gradient approximation(GGA).The calculated equilibrium structural parameters of Pnnm-CrB_(4)are in good agreement with the available experimental data and other theoretical results.Moreover,the elastic constants C_(ij),bulk modulus B,shear modulus G and elastic modulus E under high pressure were calculated,and the toughness and brittleness of Pnnm-CrB_(4)under high pressure were analyzed with the Poisson ratioσand B/G.To study the elastic anisotropy of Pnnm-CrB_(4)in detail,the anisotropic factors A_(1),A_(2),A_(3)for shear and B_(a),B_(b),B_(c)for the directional bulk modulus were also calculated.The Vickers hardness H_(V)of Pnnm-CrB_(4)was estimated at the same time.Finally,the total and partial density of states of Pnnm-CrB_(4)under high pressure were studied so as to have a better understanding of the mechanical and elastic properties of Pnnm-CrB_(4).