Investigation of proton conducting BaZr0.9Y0.1O2.95 : BaCe0.9Y0.1O2.95 core–shell structures

Abstract

Barium zirconate shows better chemical and mechanical stability than the corresponding cerate, but lower protonic conductivity largely due to resistive grain boundary contributions. In this work we attempted to reduce the grain boundary resistance of BaZr_0.9Y_0.1O_2.95 starting from a core–shell modification of its grain with a thin film of BaCe_0.9Y_0.1O_2.95. The resultant core–shell material was characterised by X-ray powder diffraction (XRD), thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM). Impedance spectroscopy performed on the material in wet 5% H₂/Ar atmosphere showed a significant reduction in terms of both bulk and grain boundary resistances of the initial barium zirconate when modified with a thin film of barium cerate. As by thin films modification the total conductivity of the sample increases by about one order of magnitude, this surface modification concept appears to be a promising way to control the grain boundary properties for a given material.