Synthesis of La_(1-x)Sr_xMnO3 powders from different precursors.

摘要

Different precursor powders (carbonates,oxalates,citrates) of strontium-doped lanthanum manganites have been prepared by soft-chemistry methods.After calcination,these precursors lead to mixed oxides with the perovskite-like structure La_xSr_(1-x)MnO3.The size,the morphology,and the non-stoichiometry coefficient of the oxide powders depend on those of precursor as well as on the thermal treatment conditions.Thermal analysis studies of the precursors' thermolysis show that only the citrates are really 'mixed'.Thus the perovskite phase is obtained from 600 °C instead of 850 °C using oxalate or 900 °C using carbonate precursors.Moreover,only the citrate method allows us to vary the morphology,the specific surface area,and the non-stoichiometry of the oxide powder in a wide range.