Brown ceramic pigments based on chromium(III)-doped titanite obtained by spray pyrolysis

摘要

Cr-doped titanite(CaTiSiO5)pigments were synthesized through spray pyrolysis of aerosols generated from aqueous solutions containing colloidal silica,calcium chloride,titanium(lV)oxychloride and chromium(III)nitrate.This process yielded amorphous powders with spherical morphology and broad size distribution(<10 mu m)after thermal decomposition at 600°C.The titanite phase was obtained by further calcination at 800°C without any addition of flux agents.The brown color of the pigments can be attributed mainly to the existence of Cr(IV)ions occupying both,octahedral positions of Ti(IV)and tetrahedral position of Si(IV),together with a small amount of Cr(III)present as Gr2O3.The optimum pigment obtained by this method corresponded to a Cr/titanite mole ratio of 0.04.