High ionic conductivity of Lu₂O₃–TiO₂ co-doped Bi₂O₃ ceramics

In this study, a promising electrolyte material Bi_0.76Lu_0.16Ti_0.08O_1.5+δ (abbreviated as '8T16LSB') with high oxygen ion conductivity was obtained by co-doping with Lu₂O₃ and TiO₂ into Bi₂O₃. The phase composition, microstructure, and conductivity of TLSB ceramics were respectively investigated by x-ray diffraction, scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). XRD results exhibited that the sintered TLSB ceramics with an unchanged total doping concentration of 24 mol.% existed as a cubic fluorite structure. SEM results showed that the TLSB pellets were relatively dense. The relationship between temperature and conductivity showed that the 8T16LSB ceramic exhibited the highest conductivity of 0.56 S cm⁻¹ at 700 °C, which was higher than the value of 0.37 S cm⁻¹ for the representative single-doping Er_0.4Bi_1.6O₃ (abbreviated as '20ESB'). The results certified that the electrochemical performance of Bi₂O₃ was promoted by the co-dopant of Lu³⁺and Ti⁴⁺. (paper)