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

Abstract

Nd-doped BaCeO ₃ have been obtained from homogeneous coprecipitated oxalates when calcined at temperatures T≥1000 °C. Ball-milling of the calcined powders well disperses the agglomerates and consequently has a beneficial effect in 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 ofT≥1400 °C. By controlling the processing variables it was possible to obtain near fully dense Nd-doped BaCeO ₃ ceramics with homogeneous microstructure at a sintering temperature as low as 1300 °C. Electrical conductivities of the sintered samples were measured in dry and moist air and in hydrogen in the temperature range 500–800 °C using complex impedance techniques. Much higher proton conductivity was obtained in this work compared with previously reported values, in which the samples were prepared from traditional ceramic methods.