Stability of BaCe0.8Gd0.2 O 3 in a H 2 O ‐Containing Atmosphere at Intermediate Temperatures

Barium cerate‐based electrolytes have been extensively studied for intermediate‐temperature (600 to 800°C) solid‐state ionic devices because of their high ionic conductivities at these temperatures. However, the long‐term stability of these materials under the conditions of intended applications, such as in a water vapor‐containing atmosphere, has been controversial in recent literature. In this study, a gadolinium‐doped barium cerate, , has been tested in an atmosphere containing 50 volume percent water vapor at 600 and 700°C for 1000 h. X‐ray diffraction, transmission electron microscopy, differential thermal analysis, and electrochemical measurements indicate that there is no creditable evidence to suggest an observable decomposition of to and under the testing conditions for up to 1000 h, further confirming the stability of the material under fuel cell conditions demonstrated by others.