Thermal-Expansion Behaviors and Mechanisms for Ca- or Sr-Doped Lanthanum Manganite Perovskites under Oxidizing Atmospheres

The thermal expansion behavior and mechanism of A‐site‐deficient lanthanum manganite perovskites, , and alkaline earth metal (AE)‐doped lanthanum manganite perovskites, , under oxidizing atmospheres have been investigated. The average linear thermal expansion coefficients of the AE‐doped lanthanum manganites decreased with increasing Ca content up to 20 mol % and with increasing Sr content up to 10 mol %, and then increased. During the thermal cycle measurement, the perovskite samples and the perovskites (0 ≤ x ≤ 0.3) shrank, while no anomalous shrinkage behavior was observed for the samples. From the results of high‐temperature X‐ray diffraction analysis, no dependency of cell volume of the perovskites on aging time at selected temperatures and on thermal cycles was observed. © 2000 The Electrochemical Society. All rights reserved.