Nb掺杂对TiO_2/NiTi界面电子结构影响的第一性原理计算

Effect of Nb doping on electronic structure of TiO_2/NiTi interface:A first-principle study

采用基于密度泛函理论的第一性原理平面波超软赝势方法,计算了Nb掺杂对TiO2/NiTi界面电子结构的影响.体系生成能的计算结果表明,4种TiO2/NiTi界面结构中,NiTi中Ti原子和TiO2中O原子相邻的界面,即Ti/O界面的生成能最大,结构最稳定.在Ti/O界面结构优化的基础上,态密度、电荷分布以及集居数的计算结果均表明:Nb原子取代界面上的Ti原子后,界面原子之间的结合力增强,且界面附近的基体和氧化层中原子之间的相互作用也增加,有利于促进NiTi合金抗氧化性能的提高.

The electronic structure of pure and Nb doped TiO2/NiTi interface have been calculated with the first-principle ultrasoft pseudopotential approach of the plane wave based on the density functional theory aiming at examining the effect of Nb on the electronic structure of the TiO2/NiTi interface. The formation energy calculation results show that the structure with Ti-terminated NiTi matrix and O-terminated TiO2 layer （Ti/O interface） is the most stable one among the four possible interface structures. Based on the optimized Ti/O interface model, the calculation results of the partial density of states, charge population and bond order suggest that the introduction of Nb on the interface strengthens the atomic interactions on the interface, as well as the interactions between the matrix and the oxidation layer in the neighborhood of the interface, which results in the improvement in the interfacial adhesion and the oxidation resistance of NiTi intermetallic compound.