Preparation of doped BaZrO3 and BaCeO3 from nanopowders

To lower the calcining and sintering temperatures of 16 at% Y-doped BaZrO3 (BYZ), Gd-doped BaCeO3 (BGC) and Smdoped BaCeO3 (BSC), nanopowders of BaCO3 and either (i) yttria stabilized zirconia, (ii) Gd2O3 and CeO2 or (iii) Sm2O3 and CeO2, were used as starting materials, respectively. BYZ powders were prepared by two mixing methods (i.e. ball milling and magnetic stirring), followed by calcination at 1050–1250 °C, while BSC and BGC powders were prepared by ball milling and calcined at 1050 °C. The results reveal that the ball milling and magnetic stirring methods yield similar results for BYZ powder preparation. By adding 1 wt% ZnO nanopowder, the average relative densities of BYZ pellets were increased from ∼70% to ∼96% at the sintering temperatures of 1300 °C. Thus, with the utilization of nanopowders and ZnO as a sintering aid, the calcining and sintering temperatures were lowered to 1050 °C and 1300 °C, respectively, while still attaining the relative bulk densities of both BYZ and BGC higher than 95.7%. However, since the relative bulk density of BSC reached only 93% even sintered at 1400 °C, ZnO was not an effective sintering aid for the BSC fabrication.