Effect of precursor solution parameters on the formation of yttria stabilized zirconia coatings on yttria stabilized bismuth oxide substrates

Abstract

A useful intermediate temperature solid oxide fuel cell design could be the utilization of yttria doped bismuth oxide (YDB) ceramics as electrolyte supports, which would also enable the use of high-performing nanocomposite thin film electrodes. However, to prevent the reduction of YDB down to metal upon contact with hydrogen, a thin, chemically stable ionic conductor ceramic coating must be applied onto the fuel side of the anode. In this work, we aim to determine the optimum parameters to fabricate dense and crack-free yttria-stabilized zirconia (YSZ) doped zirconia coatings onto sintered yttria doped bismuth oxide (YDB) ceramics by a facile, cost effective polymeric precursor method, for the first time in the literature. We have found that the most commonly used Zr source, zirconium oxychloride octahydrate, i) reacts with the YDB substrate to form bismuth yttrium oxychloride and ii) results in crack formation due to reduced extent of polymerization unless the solution is fed with nitric acid. Meanwhile, the use of zirconium oxynitrate hydrate forms dense, crack free thin films. Both thin films had low conductivities, in the range of 10-6 S/cm at 600 degrees C, likely, due to the lack of crystallization in their as-deposited state. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.