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 mode'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 Modoped 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. [ABSTRACT FROM AUTHOR]