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, La1-xMnO3 (0 < x less than or equal to 0.1), and alk aline earth metal (AE)-doped lanthanum manganite perovskites, La(1-x)AE(x)M nO(3) (AE = Ca and Sr, 0 less than or equal to x less than or equal to 0.4) , under oxidizing atmospheres have been investigated. The average linear th ermal expansion coefficients of the AE-doped lanthanum manganites decreased with increasing Ca content up to 20 mol % and with increasing Sr content u p to 10 mol %, and then increased. During the thermal cycle measurement, th e La1-xMnO3 (0 less than or equal to x less than or equal to 0.1) perovskit e samples and the La(1-x)AE(x)MnO(3) perovskites (0 less than or equal to x less than or equal to 0.3) shrank, while no anomalous shrinkage behavior w as observed for the Li(0.6)AE(0.4)MnO(3) 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 w as observed. (C) 2000 The Electrochemical Society. S0013-4651(99)05-043-0. All rights reserved.