Síntese e caracterização do Tantalato de Cério

Abstract

The production, structural, optical and thermal characterization of Cerium Tantalate (CeTaO4) is inquired in this dissertation through Mechanical Milling (MM), X-Ray Diffraction (DRX), Differential Scanning Calorimetry (DSC), Heat Treatment (HT), Fluorescence X-Ray (FRX) and UV-Visible Spectroscopy (UV-Vis). The precursors Tantalum (Ta) and Cerium Oxide (CeO2) in powder form were ground for eight hours using a high-energy mil and every two hours of grinding, the characterization was made by XRD. In addition to the two precursor phases Ta and CeO2, a new phase, Ce2O3, was identified. The FRX identified (in addition to the precursor elements) approximately 1.5% of Iron (Fe), an element from the jar's feedstock through Mechanical Milling. An analysis of the DSC showed that the general behavior of the sample is exothermic. The temperatures determined from the DSC to the HT were: 500°C, 850°C and 1000°C. A one-hour threshold was used for all treatments. Tantalate structures were identified through the XRD after HT. In 500°C, the nanostructured CeTaO4 phase was suggested and in 1000°C the existing phases were CeTa3O9, FeTaO4 and CeO2. Through Uv-Vis spectroscopy, the samples, after HT in 500°C and 1000°C, showed a gap equal to 0 eV and after the same process at 750°C and 850°C, a gap of 3.2 eV and 2.2 eV, respectively.