Investigation of electrical conductivity and oxygen relaxation behavior for BaBi0.98Sr0.02Nb5-xTixO15 ceramics

Abstract

Abstract BaBiNb5O15-based oxide ion conductors have shown promise for solid fuel cell applications at medium temperatures. In this study, the grain conductivity of the BaBi0.98Sr0.02Nb5−xTixO15−δ (x = 0.02, 0.04, 0.05, 0.06, 0.08) specimens was fabricated using conventional solid-state synthesis to thoroughly examine their electrical characteristics and oxygen relaxation tendencies. With increasing the Ti content, the bulk conductivity of the BaBi0.98Sr0.02Nb5−xTixO15−δ samples showed a trend of increasing first and then decreasing. When the doped Ti content reached 5 mol%, the highest bulk conductivity of BaBi0.98Sr0.02Nb5−xTixO15−δ samples can be got, 5.27×10− 5 S/cm at 773 K. According to the dielectric relaxation spectroscopy measurement, the BaBi0.98Sr0.02Nb4.95Ti0.05O15−δ sample exhibits the higher moveable oxygen vacancy concentration and mobility of oxygen vacancies. This could be the possible reason that there is the highest bulk conductivity in the BaBi0.98Sr0.02Nb4.95Ti0.05O15−δ sample. Additionally, the influence of sintering temperature on the electrical properties of the BaBi0.98Sr0.02Nb4.95Ti0.05O15−δ compound was investigated. When the BaBi0.98Sr0.02Nb4.95Ti0.05O15−δ sample is sintered at a temperature of 1423K, it exhibits the best bulk conductivity and total conductivity.