LAUSR

Bi0.85−xCa0.15ZrxO1.5−δ (0.12 ≤ x ≤ 0.24) oxygen ion conductors were synthesized by solid-state reaction method. Small quantities of CaZrO3 and Ca0.15Zr0.85O0.85 second phases were observed on the grain boundaries of the Bi0.85−xCa0.15ZrxO1.5−δ matrix with cubic fluorite structure. The lattice parameter a of Bi0.85−xCa0.15ZrxO1.5−δ lay within the range of 5.512 Å to 5.525 Å. The conductivity of all the Bi0.85−xCa0.15ZrxO1.5−δ samples increased with temperature. The Bi0.70Ca0.15Zr0.15O1.5−δ sample exhibited the highest conductivity of 0.05 S/cm at 750°C. The typical impedance spectra of the Bi0.85−xCa0.15ZrxO1.5−δ samples showed that the main resistance resulted from charge-transfer polarization at low temperatures, while the grain-boundary resistance dominated when the temperature was increased to above 600°C because of the CaZrO3 and Ca0.15Zr0.85O1.85 second phases appearing at grain boundaries.