高压下V_(2)B_(3)结构稳定性及物理性质的研究

Study on structural stability and physical properties of V_(2)B_(3)under high pressure

用密度泛函理论的第一性原理计算方法,分析压强为0~100 GPa的V_(2)B_(3)稳定性、物理性质。电子交换相关函数用近似一般梯度(GGA)形式,价电子波函数用赝势(PAW)法处理。计算了弹性模量、切变模量、电荷密度、态密度、能带结构和压强间的变化关系。结果表明:常压下V_(2)B_(3)为正交结构,随压力增加,稳定性增加,未发生相变;常压下维氏硬度高达39.4 GPa,随压力增加,硬度提高,是一种潜在的超硬材料;高压下V_(2)B_(3)具有金属性,是脆性材料。计算与试验结果吻合,为超硬材料的进一步研究提供理论指导。

The structural stability and physical properties of V_(2)B_(3)at a pressure range of 0-100 GPa were systematically studied by first principles calculation method based on density functional theory.The electron exchange correlation function was treated in the form of approximate general gradient(GGA),and the valence electron wave function was treated by pseudopotential(PAW)method.The relationship among elastic modulus,shear modulus,Young’s modulus,charge density,state density,band structure and pressure was calculated.The results show that V_(2)B_(3)has an orthogonal structure under atmospheric pressure,and it’s stability getting better with increasing pressure.Vickers hardness can be as high as 39.4 GPa under atmospheric pressure,which increases with the increase of prsssure,suggesting that it’s a potentially superhard material.V_(2)B_(3)is a brittle material with metallic properties under high pressure.The calculated results are in good agreement with the experimental results,which provides a theoretical guidance for the further research on superhard materials.