Síntese e caracterização de partículas nanométricas predecessoras de óxidos mistos de TixOy/AlmOn, pelo método sol-gel

Abstract

The sol-gel method consists of the transition from a sol system to a gel system through hydrolysis and condensation reactions. This method is widely used due to its versatility in obtaining simple or multicomponent nanometric particles, with high control in synthesis reactions and low temperature heat treatments. This method was used to obtain TixOy / AlmOn lyophilized sols with different percentages of the titanium oxide precursor (10%, 15% and 20% by mass). The lyophilized sols were characterized by thermal analysis, x-ray diffraction and Rietveld analysis, scanning electron microscopy, x-ray dispersive energy spectroscopy, transmission electron microscopy, particle size analysis and adsorption and desorption nitrogen analysis. These analyzes were performed in order to obtain information about the thermal behavior, present phases, particle size and uniformity of the samples. The obtained results indicate that the sol-gel methodology used promoted the synthesis of TixOy / AlmOn mixed oxide predecessors with spherical predominance, nanometric particles, and high dispersion of the present phases, with low crystallinity. Additionally, the amount of TixOy precursor had an influence on the size of the synthesized particles as well as on the crystallite size of the present phases. In the proportion of 20% of TixOy in AlmOn, smaller particles and therefore larger specific area were obtained. In this context, the average size of TiO2 crystallites increased with increasing amount of this precursor.