Mixed Ionic and Electronic Conductivity of Undoped and Acceptor-Doped Er[sub 6]WO[sub 12]

The ac conductivities of and 1% Ca-doped have been characterized as a function of oxygen and water vapor partial pressures in the temperature range 300– . Partial conductivities have been determined from the open-circuit voltage of , , and concentration cells. The materials exhibit n- and p-type electronic conductivity and oxygen ion and proton conductivity, depending on the conditions. Protons are the major ionic charge carriers in wet atmospheres below . Hydration thermodynamics and transport parameters have been determined under conditions where the acceptor doping is predominantly compensated by oxygen vacancies and protons.