Ceramic pigments obtained by sol-gel techniques and by mechanochemical insertion of color centers in Al2O3 host matrix

Nanocrystalline pigments for ceramic glazes have been obtained by mechanochemical insertion of Fe and Ti in an α-Al2O3 host matrix (Fe and Ti oxides were reduced by high energy milling with metallic Al with subsequent formation of additional Al2O3 by oxidation of Al(0)). The powders have been characterized by X-ray diffraction, laser granulometry and by surface area and porosity measurements. Sol-gel techniques have also been used in order to obtain pigments with pure Al2O3 and Cr or Fe/Ti-doped Al2O3. Pigments have been prepared using Al(III)-alkoxides or Al(III)-inorganic salts, obtaining products with different characteristics in the two cases. Pigments have been studied by X-ray diffraction, surface area and porosity measurements and by the analysis of electrochemical reactivity in aqueous suspensions. Coloring properties of pigments obtained by mechanomaking and by sol-gel techniques have been tested in ceramic glazes; their properties have also been analyzed by insertion in ceramic bodies for glazed gres (porcelain) technology.