The concentrations of impurities in BaZr0.85Y 0.15O3-δ were qualitatively measured by GD-MS, and the concentrations of carbon, nitrogen, sodium, silicon, sulfur, chlorine, hafnium, and platinum were found to be more than 100 ppm. Among these identified impurities, we investigated the influence of sodium and silicon on grain boundary resistance of BaZr0.85Y0.15O3-δ. It was found that silica or silicate precipitated at grain boundary of BaZr0.85Y0.15O3-δ and prevented the proton conduction of BaZr0.85Y0.15O3-δ at the grain boundary, but sodium did not affect either bulk or grain boundary resistance. Also, we investigated which steps of the applied procedure causes the increase in the silicon concentration of BaZr0.85Y 0.15O3-δ during the synthesis process of the widely-used solid state reaction method. Drying the powder in atmospheric air and using the heated glass flask were found to be major problems. With this knowledge, we reduced the silicon concentration of sintered BaZr 0.85Y0.15O3-δ to 120 ppm.
- Barium zirconate
- Grain boundary