Preparation and characterization of La1-xSrxMnO3+δ (0≤x≤0.6) powder by sol-gel processing

La1-xSrxMnO3+delta oxides with 0 less than or equal to x less than or equal to 0.6 were synthesized via sol-gel route (Pechini process). The gel decomposition as studied by several thermal analysis methods. After calcination at 1000 degreesC of the dried gels, the oxides were characterized by X-ray diffraction, thermal analyses, transmission and scanning electron microscopies and chemical analyses. In order to correlate the Mn4+/Mn3+ ratio with the symmetry of the structure and the particle size, the nonstoichiometry level at room temperature, delta, was determined by two methods: chemical titration and temperature programmed reduction. It is shown that a negative correlation exists between the strontium content and the nonstoichiometry level. i.e., at low Sr content the oxygen content is higher. To define the best material composition for use as a solid oxide fuel cell (SOFC) cathode. a comparison as made between values at room temperature and SOFC operating temperature (1000 degreesC). (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.