Abstract: We characterized Na_0.52Bi_0.48-2xLi_xSr_xTi_0.99Mg_0.01O_3-δ（x=0,0.005,0.010,0.015) polycrystalline oxygen ion conductors prepared at a sintering temperature of 1 000 ℃ by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectrum, and AC impedance spectroscopy to study the effect of the co-doping concentration of Li⁺ and Sr²⁺ on the crystal structure, microstructure and electrochemical properties of the series of the samples. The results show that with increase of co-doping concentration of Li⁺ and Sr²⁺, no obvious impurity peaks were observed in all samples, and the unit cell parameters and unit cell volumes first decreases and then increases with the increase of doping concentration. When x=0.010, the grain conductivity reaches its maximum value, which is about twice that of the undoped sample. When x=0.010, the apparent grain-boundary conductivity and the macroscopic grain-boundary conductivity of the sample reach their optimal values, which are superior to other doped samples.

Key words: perovskite structure, solid-state method, oxygen ion conductor, conductivity, co-doping