DEDICATÓRIA Dedico essa Tese a ele, meu querido mestre, Prof. Dr. Pérsio de Souza Santos, uma pessoa notável e atenciosa, um profissional incomparável e brilhante, para sempre guardarei a lembrança de seus ensinamentos, sua paixão pelos estudos e seu carinho. A ele, minha eterna admiração e respeito, um muito obrigado por todo o auxilio na composição dessa Tese e pelas ricas experiências compartilhadas; foi uma honra tê-lo conhecido. Saudades. ABSTRACT The synthesis of nanoparticles with

more »

... led morphology is of increasing interests in the field of Materials Science. Due to this motivation, the main objective was the synthesis and characterization of boehmite pseudoboehmite presenting one or two nanoscale dimensions. The method of synthesis used to obtain fibrillar pseudoboehmite is based on the reaction of an aluminum alkoxide in aqueous acetic acid. For the preparation of boehmite, a single synthesis method, the hydrothermal synthesis, was used with three different precursors: a pseudoboehmite, an organic salt (aluminum monohydroxide diacetate) and the aluminum trihydroxide gibbsite, the latter in two forms: a commercial gibbsite and a gibbsite synthesized that utilizes iodine as activator. The pseudoboehmites and boehmites obtained were characterized by X-ray diffraction and scanning electron microscopy. Some samples of pseudoboehmite and boehmite were characterized by differential thermal analysis and by vibrational spectroscopy in the infrared region. Pseudoboehmites were obtained with fibrillar morphology (anisometric elongated particles); for boehmites, different morphologies were produced (according to the precursor and the synthesis conditions employed in their production): fibrillar (two dimensions in nanoscale), nanoplates (one dimension in nanoscale) and particles with cubic symmetry (no dimensions in nanoscale). The presence of acetate ion in hydrothermal synthesis was instrumental in the formation of boehmite with plate morphology. nanocrystals: hydrotermal synthesis and structural characterization. Journal or crystals growth 283; 553-562, 2005.