A new potential electrolyte Ba11W4O23: Novel structure and electrical conductivity

Ba11W4O23 (or Ba1.75(BaW)O5.75) has a derivative perovskite (ABO3) structure with vacancies ordered in the A-sublattice, but disordered in the O-sublattice, suggesting the potentiality as an oxide ion electrolyte. Electrical conductivities of Ba11W4 − xTaxO23 − 0.5x were characterized as functions of temperature, oxygen activity, water vapor activity, and composition x (= 0.1, 0.5, 1.0, 2.0). It has been found that the compound is indeed an oxide ion conductor, over a wide oxygen activity range, with a moderate ionic conductivity, compared with the conventional electrolyte oxides. The conductivity is little dependent on x, but for x = 1 where an appreciable depression of the conductivity occurs. The oxide also exhibits a proton conductivity at temperature below 800 oC.