The effect of doping on oxygen conductivity performance of Na0.5Bi0.5TiO3 compounds

Abstract

The three different doped (Na, K and Mg) Na0.5Bi0.5TiO3 compounds were prepared. The grain conductivity of the doped Na0.5Bi0.5TiO3 compounds shows: Na-doping > K-doping > Mg-doping. Using the dielectric relaxation spectroscopy, the relaxation parameters can be obtained: ENa = 0.61 eV, EK = 0.64 eV and EMg = 0.68 eV. In the Na-doped Na0.5Bi0.5TiO3 compound, there exists the lowest activation energy, best oxygen vacancy mobility and the disorder decrease of A-site sub-lattice in the Na0.5Bi0.5TiO3 compound from the Na-doping on the A (Bi3+)-site, which are the possible reasons for the higher grain conductivity in the Na-doped Na0.5Bi0.5TiO3 compound. In the Mg-doped Na0.5Bi0.5TiO3 compound, despite the worst oxygen vacancy mobility, the concentration of mobilizable oxygen vacancies is almost highest, which can be adopted to increase the mobilizable oxygen vacancy concentration of the Na-doped Na0.5Bi0.5TiO3 compound. For the Na0.5Bi0.5TiO3 compound, the further improvement of the electrical performance can be expected for the slight amount Mg-doping on the Ti4+-sites in the Na-doped Na0.5Bi0.5TiO3 compound, which is meaningful to obtain the higher oxide ionic conductivity in the Na0.5Bi0.5TiO3 compounds.