Caracterização térmica e estrutural de pós e filmes finos de BaTiO3 sintetizados via método Pechini

Abstract

Amorphous oxides are chemical compositions whose atomic or molecular configuration does not follow a periodicity like it happens with crystals, which are essentially constituted by oxygen atoms, which has to be the most electronegative element, and other elements. The barium titanate (BaTiO3), amorphous oxide obtained through this work has tetragonal structure, in ambient temperature, similar to the cubic structure of perovskite (ABO3), it is widely used in electronic devices and ceramic technology industry because of their ferroelectric properties, thermoelectric, piezoelectric and optical properties, such as photoluminescence. Nowadays the researches are focused on this last property of barium titanate, once it has a great potential on electro optical application. The preparation of the oxides was the starting point on this work in order to obtain thin films. The specific desirable features of a thin film, are usually related to intrinsic characteristics of the used precursors, being these characteristics powerfully influenced by the techniques of acquisition of these precursors. This project began with the synthesis of BaTiO3 powder by polymeric precursor method, ordinarily called the Pechini Method, which consists on the formation of a tridimensional inorganic net via chemical reactions that happen in solution and on relatively low temperatures. These powders were characterized via Thermal Analysis - TG / DSC and analysis X-Ray Diffraction - XRD. After that, it was started the process of preparation of BaTiO3 thin films, through the Pechini Method either. The obtained films were characterized through the techniques of Scanning Force Microscope - SFM and Photometry: Absorbance. The powders and thin films of BaTiO3 were successfully obtained by the polymeric precursor method, Pechini method, a method that was easily reproducible and low cost, there are signs that reveal nanometer dimensions for the post. Changes in color are perceived in the film due to pH change and agglomerations of particles are all the movies, to a greater or lesser number. Since the surface roughness change significantly with increasing annealing temperature of the thin films