Preparation of Nd-doped BaCeO3 proton-conducting ceramics by homogeneous oxalate coprecipitation

Nd-doped BaCeO3 was obtained from homogeneous coprecipitated oxalates when calcined at temperatures of 1000 C and above. Ball-milling of the calcined powders thoroughly disperses the agglomerates, thereby having a beneficial effect on the densification process. The calcination temperature has a major influence on the sintering process and powders calcined at 1100 C possess good sinterabilities. The pressure applied to press the green pellets has no apparent influence on the sintered density at sintering temperatures of 1400 C and above. By controlling the processing variables, it was possible to obtain near fully dense Nd-doped BaCeO3 ceramics with homogeneous microstructure at a sintering temperature as low as 1300 C. Electrical conductivities of sintered samples were measured in dry and moist air and in H2 in the temperature range 500-800 C using complex impedance techniques. A much higher proton conductivity was obtained compared with previously reported values, in which the samples were prepared from traditional ceramic methods, making this material a promising candidate as an electrolyte for moderate-temperature solid oxide fuel cells. 15 refs.