Study on reaction mechanism of low temperature preparation of nanocrystalline LaCoO3-λ

Perovskite-type oxide nanocrystalline LaCoO3-λ was prepared using the citrate method. The structure and morphology of the sampies were characterized by powder X-ray diffraction （XRD） and transmission electron microscopy （TEM）. The intermediate products were analyzed by thermal gravimetric and differential thermal analysis （TG-DTA） technology. The results showed that nanocrystalline LaCoO3-λ with a granula of 30-50 nm had a cubic perovskite structure. The reaction mechanism of low temperature preparation was suggested as follows： the metal complex was first formed by the combination of metal ion and citric acid; and then it decomposed into an aconitic acid complex, followed by an oxycarbonate, and finally a perovskite-type oxide.