Elaboration du titanate d’aluminium par la méthode sol-gel.

Abstract

The sol- gel method is a very attractive technique for elaborating materials, since it is known to be able to synthesize, at low temperature, bothnanometric powders ormaterials with finemicrostructure. Moreover,it ensuresa high chemicalpurity and homogene it y and also controls, in an accurate manner, themorphology of the synthesizedmaterials. The main advantage of aluminum titanate (Al2TiO5) is its low thermal expansion coefficient which gives it a very good resistance to thermal shock. It also has a high chemical inertness, good thermal insulation, and high electrical resistance. These properties make it very interesting as materials in various applications such as carindustry, aluminum foundry, and as blindage material in the nuclear fusion reactors. OurStudy relates, therefore, the synthesis of aluminum titanate by the sol-gel method and its characterization. Nanoparticles of aluminum titanate were synthesized. The preparation of theprimary solutions,with an acidpH, are polymerizedat80°Canddriedat 120°Cfor 24 hours. Calcining the xerogel was performed at different temperatures from 650 to 1150°C with a step of 50°C, maintainingfor two hours. The obtained results, by X-ray diffraction , show that the crystallization of the product starts from 650°C with the appearance of titanium oxide (anatase) which disappears around 900°C. The best crystallization is obtained for the heat treatment at 950°C which indicates the presence of Al2TiO5, with very weak peaks of corundum and titanium oxide in rutile form. Beyond1050 °C, thespectral analysisonlyrevealsthe presence of phases resulting from the decomposition of aluminum titanate. Scanning electron microscope observations of samples, treated at 950°C, show that the particle size is of the order of 50 nanometers. The nanoparticles size has been also calculated from the X-ray diffraction spectra, using the Scherrer formula. The obtained results are consistent with those of the electron microscopy. The nature of the phases present at different temperatures was confirmed by Raman spectroscopy.