Effect of Humidity on Conductivity of Ba4Ca2Nb2O11 Phase and Solid Solutions Based on This Phase

The conductivity of the Ba4Ca2Nb2O11 phase and its solid solutions of the formulas Ba4.4Ca1.6Nb2O11 and Ba3.4Ca2.6Nb2O11 is studied as a function of the partial pressure of the water vapor at 2 x 10(-2)-3 x 10(-5) atm (log P-H2O = -1.7...-4.5) and temperatures of 400-600 degrees C. A model, which is based on the model of structural oxygen vacancies, is proposed for the quasichemical description, providing an adequate explanation of the experimental dependences log sigma(tot) = f(log P-H2O). It is shown that in the region dominated by the proton transport the log dependences of the conductivity on P-H2O have the slope of 1/3. Proton transport numbers are calculated at the given temperatures and pressures of the water vapor.