Processing and mechanical behavior at elevated temperatures of directionally solidified proton conducting perovskites

High-temperature proton conducting perovskite oxides have been fabricated by directional solidification using a laser-heated floating zone (LHFZ) method. Several families of compositions were selected: SrCe1−xYxO3−δ (with x = 0.1, 0.2), BaCe1−xMxO3−δ (with M = Y, Yb and Ca; x = 0.05, 0.2), Sr3Ca1.18Nb1.82O9−δ, SrZr0.8Y0.2O3−δ and SrTi0.95Sc0.05O3−δ. The resulting microstructures were characterized by electron microscopy and X-ray diffraction. The compounds exhibit a singular microstructure consisting of strongly textured crystalline cells surrounded by an intercellular amorphous phase. Compressive mechanical tests were performed at elevated temperatures in air at constant strain rate to evaluate the creep resistance. The results are discussed in terms of ionic radius, degree of aliovalence and content of dopant cations.