Instability of BaCeO3 in H 2 O ‐Containing Atmospheres

Rare earth oxide doped is known to exhibit high protonic conductivity in the temperature range 500 to 900°C and is a potential electrolyte for use in hydrogen sensing and fuel cell applications. Prior work, however, has shown that may be thermodynamically unstable at low temperatures. In the present work, the stability of in an vapor containing environment was investigated by exposing powder and sintered samples to ∼430 Torr in the temperature range 500 to 900°C. All samples decomposed into and in relatively short periods of time at temperatures less than 900°C. Doped decomposed at a faster rate than the undoped . Sintered decomposed at a rate comparable to the powder samples. These results establish that is thermodynamically unstable when a critical vapor pressure is exceeded and that the rapid decomposition of both powder and sintered samples is the result of the high solubility of in which accelerates the kinetics of decomposition.