第一性原理研究压力对Ni-Mo二元化合物力学性能和电子结构的影响

First-principles Study of Mechanical Properties and Electronic Structures of the Nickel-molybdenum Binary Compounds Under Pressure

采用基于密度泛函理论的第一性原理方法研究压力对Ni-Mo二元化合物Ni_4Mo、Ni_3Mo(DOa)、Ni_3Mo(DO_(22))、Ni_2Mo力学性能和电子结构的影响。研究表明:0~40 GPa压力范围内,随着压力的增大,相对体积V/V_0不断减小且趋势减缓;形成热均为负值,且随着压力的增大形成热减小,说明增大压力可提高化合物的合金化能力;体积模量B、剪切模量G、杨氏模量E、拉梅常数λ、硬度H的计算结果表明压力可提高4种化合物的抗变形、抗压缩能力及硬度。另外,B/G和泊松比v表明所有化合物均为延性和塑性的;进行态密度的分析,阐明增大压力可提高4种化合物的稳定性及硬度。

The effects of high pressure on mechanical properties and electronic structures of Ni-Mo binary compounds （Ni_4Mo, Ni_3Mo（DOa）, Ni_3Mo（DO_（22））, Ni_2Mo） have been studied by first-principles calculation based on density functional theory. The results show that the values of V/V_0 decrease with the pressure increasing and the rates of change decrease gradually. The formation enthalpy is negative, and it decreases with pressure increasing, indicating high pressure can enhance the ability of alloying. The calculated results of bulk modulus （B）, shear modulus （G）, Young＇s modulus （E）, Lama constant （λ） and hardness （H） illustrate that pressure can increase the resistance to deformation, compression resistance and hardness of four compounds. In addition, ratio of bulk modulus to shear modulus （B/G） and poisson＇s ratio （v） show that all the compounds are ductile and plastic. The state density was also analyzed to explain the physical origin of the pressure effect on four compounds. It is suggested that the increasing pressure can improve the stability and hardness of all compounds.