Structural and Electrochemical Properties of Dense Yttria-Doped Barium Zirconate Prepared by Solid-State Reactive Sintering

Abstract

For practical utilization of proton-conducting ceramic fuel cells and electrolyzers, it is essential to lower the sintering temperature and processing time of BaZrO3-based proton conductors. We investigated the effect of sintering temperature and time on the structural and electrochemical properties of dense BaZr0.8Y0.2O3- (BZY) prepared by a solid-state reactive sintering process, using NiO as a sintering aid. The sintered BZY prepared from the micronized precursor powder exhibited a density higher than 93%, and an average grain size in the range of 0.6 to 1.4 m. The orthorhombic BaY2NiO5 phase was also observed in the sintered BZY from the combined conventional and synchrotron X-ray diffraction measurements. Electrochemical impedance spectroscopy showed that the total proton conductivities of BZY can be modulated by sintering temperature in a wet reducing atmosphere. The maximum total ion transport number achieved was 0.89 at 600 degrees C, and the maximum power density of the symmetric BZY electrolyte supported cell with Pt electrodes was 5.24 mWcm(-2) at 900 degrees C.