Abstract
Two methods for the preparation of LaCoO 3 samples were used: thermal decomposition of La–Co citrate precursors obtained by freeze-drying of the corresponding solutions and by a solid state reaction. Microstructural characterization was made by electron paramagnetic resonance spectroscopy (EPR). For assignment of the EPR signals, La 1− x Sr x CoO 3 samples were used as EPR references. The LaCoO 3 oxides prepared from citrates and by a solid state reaction were shown to differ in respect of the mean oxidation state of the cobalt ions, the specific surface area and the particle morphology. EPR spectroscopy reveals for ex-citrate LaCoO 3 ferromagnetic Co 3+ and Co 4+ coupled ions. For LaCoO 3 samples obtained by a solid state reaction, EPR permits detecting Co 3O 4 impurities only.
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