Structural and electrical properties of BaCe(Ti,Y)O3 protonic conductors

Abstract

Barium cerate exhibits high protonic conductivity, especially when doped by suitable trivalent ions. A possible approach to get the protonic conductor stable in the presence of CO2 with relatively high protonic conductivity is the preparation of solid solutions of BaCe1−xMexO3−δ (Me=Zr, Ti) doped simultaneously with acceptor ion. In this work selected properties of series of Ba(Ce0.95Ti0.05)1−yYyO3−δ (0≤y≤0.2) materials prepared by solid-state reaction method were investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM) and direct current (DC) electrical measurements, including open cell voltage (OCV) measurements of electrochemical cells were used as experimental techniques. Structural studies have shown materials crystallized in orthorhombic Pmcn phase with the solubility limit of Y in Ba(Ce0.95Ti0.05)1−yYyO3−δ higher than 20at.%. The DC conductivity measurements accompanied by the potentiometric OCV measurements of solid state electrochemical cells in controlled gas atmospheres (containing H2, O2 and H2O) and temperatures (500–800°C) allowed determination of total electrical conductivity and transference numbers of oxygen, protonic and electronic defects in prepared materials. The introduction of Y increases total electrical conductivity and transference numbers for protonic defects, which was correlated with structural changes.