Electric properties D 8000Sintering, Chemical Stability and Electrical Conductivity of the Perovskite Proton Conductors BaCe 0.45 Zr 0.45 M 0.1 O 3-δ (M: In, Y, Gd, Sm). -The title compounds are synthesized by solid state reactions of BaCO3, CeO2, ZrO2, and M2O3 (M: In, Y, Gd, Sm; alumina crucible, 1250-1650°C, 10 h) and characterized by XRD, SEM, and electrochemical impedance spectroscopy. The title ceramics are relatively stable in CO2, but a small amount of amorphous phases can form in boiling water. The optimum sintering temperature for maximizing the conductivity is 1600°C. At 800 °C, the total conductivities of BaCe0.45Zr0.45M0.1O3-δ (M: In, Y, Gd, Sm) ceramics in air are 0.5·10 -2 , 1.06·10 -2 , 0.82·0 -2 and 0.69·0 -2 S/cm, resp., and the corresponding activation energies are 79.8, 73.0, 71.6 and 66.5 kJ/mol.The high temperature proton conductors have a great potential for applications, such as steam electrolyzers, gas sensors, fuel cells, hydrogen pumps, and in reactors for synthesis of ammonia at atmospheric pressure. -(LV, J.; WANG*, L.; LEI, D.; GUO, H.; KUMAR, R. V.; J.