Papers by Author: M. Dondi

Abstract: Ceramic pigments with Cr-doped sphene structure (CaSn1-xCrxSiO5, CaTi1-xCrxSiO5) were synthesized by both spray drying an aqueous solution of precursor salts plus further calcining the resulting powders and conventional ceramic method. The thermal evolution of products was studied by X-Ray Powder Diffraction (XRPD). The powder morphology and chemical composition were analyzed by SEM-EDX. The color efficiency of pigments was evaluated by colorimetric analysis (CIELab system). Results showed that the spray drying process decreased the maximum firing temperature and increased the color efficiency of Cr-doped sphene pigments therefore enhancing a higher reactivity of powders compared with the solid state process.

Abstract: Ink-jet printing is becoming a leading technology for traditional ceramics, due to its capacity of reproducing highly resolved and customized images on tile surfaces. Nano-sized inks, produced by the polyol synthesis route, proved to fulfil the printing requirements, tailoring their chemico-physical properties (e.g. viscosity, surface tension) on industrial ink-jet devices, so representing a major breakthrough in the quadrichromy process.

Abstract: Nanocrystalline titania pigments were produced by a novel synthesis route consisting of a high temperature forced hydrolysis in a coordinating high-boiling solvent. The effect of synthesis conditions as well as doping with Cr, Sb and V on the particle size and on the anatase-to-rutile transformation was studied by temperature-resolved synchrotron powder diffraction. The experiments were performed directly on as-synthesized low concentration suspensions of titania nanoparticles (up to 230°C) and on dried titania nanoparticles (up to 950°C). Crystallite size of as-synthesized nanoparticles is in the 5 to 50 nm range, being affected by the synthesis conditions as well as by doping and exhibits a slow-rate coarsening trend with temperature. The anatase-to-rutile transformation is drastically influenced by both synthesis conditions and doping. In particular, doping affected the anatase-to-rutile transformation rate, while the synthesis conditions influenced the phase composition, causing the appearance of brookite.