Ni、Mo共掺杂对SnO2材料性能影响的仿真研究

针对AgSnO₂触头材料存在的不足,采用基于密度泛函理论的第一性原理对SnO₂、Ni单掺杂、Mo单掺杂以及Ni-Mo共掺杂SnO₂材料进行了电性能与力学性质的研究,计算了各体系的形成能、能带结构、态密度、弹性常数等各项参数。结果表明,掺杂后的材料可以稳定存在,且仍为直接带隙半导体材料。与未掺杂相比,掺杂后体系的能带结构带隙值减少,其中Ni-Mo共掺杂时的带隙值最小,载流子跃迁所需能量减少,极大地改善了SnO₂的电性能;由弹性常数计算了剪切模量、体积模量、硬度等参数,其中Ni-Mo共掺杂时的硬度大幅降低,韧性增强,有利于AgSnO₂触头材料后续加工成型,且其普适弹性各向异性指数最小,不易形成裂纹。综合各项因素,Ni-Mo共掺杂能够很好地改善SnO₂的性能,为触头材料的发展提供了理论指导。

Simulation Analysis of the Effect of Ni and Mo Co-Doping on the Properties of SnO2

For the deficiencies of AgSnO₂ contact material, the first-principle based on the density functional theory was used to study the electrical and mechanical properties of pure SnO₂, Ni doped SnO₂, Mo doped SnO₂ and Ni-Mo co-doped SnO₂. The parameters of every model, including the formation energy, energy band structure, density of state, elastic constant were obtained by the CASTEP module of Materials Studio software. According to the formation energy, the doped models can exist stably. After doped, every model′s valence band top and conduction band bottom are at the same point so the doped models are still the direct bandgap semiconductor materials. The Ni-doped SnO₂ is P-type doped semiconductor material, and the Mo-doped is the N-type as well as Ni-Mo co-doped SnO₂. With the introduction of the new impurity levels, the band gap is narrowed. Compared with the band structure of pure SnO₂, the doped models have a rising valence band and a declining conduction band so they have a smaller band gap, and the Ni-Mo co-doped SnO₂ has the smallest band gap. With the reduced energy for carrier transition, the electrical performance of SnO₂ is improved largely. What′s more, the shear modulus, volume modulus and hardness are obtained by the elastic constants. The hardness of Ni-Mo co-doped SnO₂ decreases significantly and its toughness is enhanced, which is conductive to the subsequent processing and forming of AgSnO₂ contact material. The Ni-Mo co-doped SnO₂ has the smallest universal elastic anisotropy index so the contact materials are not easy to form cracks. According to the calculation results, it turns out that the co-doping of Ni-Mo can improve the electrical and mechanical properties of SnO₂ better than single element doping, which provides theoretical guidance for the further development and research of contact materials.