Study on the effect of Nb doping on the phase transition temperature of VO2

The application of VO₂ is limited by its phase transition temperature from metal to insulator. In this work, a two-step hydrothermal method was applied to explore the thermodynamic properties of Nb-doped VO₂. In this way, the temperature of metal-to-insulator transition was largely reduced from 71°C for pure VO₂ to 34°C for Nb-doped VO₂. Furthermore, based on the first principles calculation, we investigated the lattice and electronic performances for pure and Nb-doped VO₂. The calculations indicated that the difference between monoclinic and metallic structure of Nb-doped VO₂ became less than those of pure VO2, which was caused by the displacement of Nb atom. This change played a key role on decreasing the phase transition temperature. In addition, the results of density of states showed that conductivity of Nb-doped VO₂ didn’t change too much.