Fabrication of Dense, Shaped Barium Cerate by the Oxidation of Solid Metal‐Bearing Precursors

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Abstract
Some rare‐earth‐doped alkaline‐earth cerates (e.g., Nd2O3‐doped BaCeO3) are proton conductors that can act as solid state electrolytes in hydrogen or steam sensors, hydrogen pumps, steam electrolyzers, and fuel cells. In the present study, dense tapes of neodymia‐doped barium cerate were produced by the oxidation of malleable Ba‐CeH3‐Nd2O3precursor tapes. Precursor tapes were produced by cold‐rolling either blended or milled mixtures of Ba, CeH3, and Nd2O3 within a silver can. X‐ray diffraction, electron microprobe analyses, and thermogravimetric analyses were used to study the phase transformations resulting from heat treatments conducted at 300° to 900°C in pure, flowing oxygen. Barium peroxide and cerium dioxide, produced during oxidation at ≤300°C, reacted at ≤500°C to form barium cerate. The rate of formation of barium cerate depended on the degree of milling of the solid metal‐bearing precursor powder. Dense barium cerate tapes were obtained after heat treatment at 1080°C.