Perovskite-type complex oxides ABO3 （A=Sr, La; B=Mn, Fe, Co） were prepared by citric acid method. The degradation of water-solubilized dyes was carried out using the mixed oxides as photocatalyst. The surface absorbed oxygen was analyzed using X-ray photoelectron spectroscopy （XPS）. The results indicated that there was a relationship between the photocatalytic activity and the content of the surface absorbed oxygen. The higher the content of the surface absorbed oxygen was, the better the performance of the photocatalyst.
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.
The complex fluoride, KNiF3, with perovskite structure was synthesized by refluxing KF and Ni（NO3）2·6H20 in ethanediol. The samples were characterized by X-ray diffraction（XRD）, transmission electron microscopy（TEM）, X-ray photoelectron spectroscopy（XPS）, and ultraviolet-visible diffuse reflectance speetroseopy（UV-Vis DRS）. The results indicate that the mean diameter of KNiF3 particles is about 30-60 nm and the oxygen content in the samples is ≤5%. The prepared KNiF3 shows obvious absorption peaks at 400-830 nm.
