The effect of dual substitution of Na and Al on ionic conductivity of Na0.5Bi0.5TiO3 ceramics

Abstract

Abstract The Na and Al dual substitution Na0.5Bi0.5TiO3 samples were synthesized by the conventional solid-state reaction method. The oxygen ion conductivity and migration in the Na0.54Bi0.46Ti1−xAlxO2.96−x/2 (x = 0.02, 0.04, 0.06 and 0.08) samples were investigated. The grain conductivity and relaxation activation energy of the Na0.54Bi0.46Ti1−xAlxO2.96−x/2 samples show the trend of declining-rising-declining with the increase of Al-doped content. The highest grain conductivity can arrive at 0.0016 S/cm for the Na0.54Bi0.46Ti1−xAlxO2.96−x/2 (x = 0.06) sample at 673 K and the corresponding activation energy is about 0.80 eV, which are the lowest results of oxygen ion diffusion in the Na0.54Bi0.46Ti1−xAlxO2.96−x/2 (x = 0.02, 0.04, 0.06 and 0.08) samples. The mobile oxygen vacancy content decreases with increasing Al-doping content in the Na0.54Bi0.46Ti1−xAlxO2.96−x/2 compounds. The sudden change of grain conductivity in NBT-Na4Al6 sample may be from the lower activation energy and better oxygen vacancy mobility. These results are helpful to improve the electrical performance by doping methods.