Effect of Phosphate Doping on Electric Properties and Chemical Stability of Ba4Ca2Nb2O11 Protonic Conductor

Conductivity of perovskite phosphate-substituted solid solutions of Ba4Ca2Nb2 P-x O-x(11) (0.0 <= x <= 0.5) was studied as a function of temperature, partial pressure of oxygen and water vapors. It is proved that the studied systems are protonic conductors at the temperatures below 600 degrees C in the atmosphere with elevated content of water vapors (pH(2)O = 1.92 x 10(-2) atm). Introduction of the tetrahedral [PO4] group in the complex oxide matrix of Ba4Ca2Nb2O11 results in an increase in the oxygen-ionic (dry air, pH(2)O = 1.91 x 10(-4) atm) and protonic conductivities (wet air, pH(2)O = 1.92 x 10(-2) atm). Is it found that the doping causes a considerable increase in chemical stability of phases with respect to carbon dioxide.