Obtenção da LaCoO3 pelo processo de decomposição térmica de quelatos coprecipitados

Abstract

Currently, studies with rare earth metal oxides with perovskite structure have been carried out due to their interesting properties, such as high electronic and ionic conductivity, and their potential applications in batteries, fuel cells, catalysts, gas sensors, chemical sensors, among others. This work presents the results obtained to obtain LaCoO3 from the thermal decomposition of cobalt and lanthanum 8-hydroxyquinolinates obtained by the coprecipitation method, at final pH of 5 and 9, and in acetone or acetic acid medium. The complexes were characterized by X-ray diffraction (XRD), Infrared Region Absorption Spectroscopy (FTIR), Atomic Absorption (AAS), Elemental Analysis (AE) and Scanning Electron Microscopy (SEM). The thermogravimetric analysis (TGA), Derived Thermogravimetry (DTG) and Differential Thermal Analysis (DTA) in different heating and atmosphere ratios up to 800 ºC were performed. The oxides obtained by thermal decomposition were characterized by XRD, FTIR and ASA. By studying the thermal behavior, it was observed that the samples presented three stages of thermal decomposition under a synthetic air atmosphere and five steps under N2 atmosphere, it was still possible to observe that the percentage of final residue for pH 9 was higher than the final residue at pH 5, but the final decomposition temperatures were lower in pH 5. Results showed higher efficiency of the process of obtaining LaCoO3 for pH 9 in both reaction media, characterized by XRD, with an average yield of 93%.