PROTON CONDUCTION IN CA-SUBSTITUTED AND SR-SUBSTITUTED LAPO4

LaPO4 with nominally 5 atom% Ca or Sr was synthesised using co-precipi tation, cold-pressed to bars, and sintered at 1300 degrees C. The elec trical conductivity in wet air was mainly protonic up to approximately 900 degrees C; it increased with increasing humidity and decreased wh en protons were replaced by deuterons in situ by equilibrating the sam ples in air containing D2O. Above 900 degrees C the proton conductivit y fell and a native conductivity contribution became dominant.