Abstract: Rutile Ti_1-2xCr_xMo_xO₂ (x=0, 0.05, 0.10, 0.15, 0.20) pigments were synthesized by solid-state reaction method with TiO₂, Cr₂O₃ and MoO₃ as the main raw materials. The effects of Cr/Mo co-doping amount and calcination temperature on the phase structure, color performance and microstructure of obtained Ti_1-2xCr_xMo_xO₂ pigments were investigated. The results show that the same amount of Cr/Mo co-doping of 5%~15% mole fraction led to single-phase rutile pigments of black color, which can promote the phase transformation from anatase to rutile. Furthermore, the introduction of Mo is beneficial for improving the solid solubility of Cr in TiO₂ lattice. With the increase of Cr/Mo co-doping content, the blackness (L^* value) of the sample decreases first and then increases, while the redness (a^* value) and yellowness (b^* value) both show an opposite trend. When the calcination temperature is 950~1 100 ℃, the change of chromatic parameters of the samples is relatively small. The Ti_0.70Cr_0.15Mo_0.15O₂ pigment calcined at 1 100 ℃ shows the best color performance of black, and its L^*, a^* and b^* values are 24.41, 2.12 and -2.53, respectively. The obtained rutile pigments also have good color performance and chemical stability in ceramic glaze. The main mechanism to produce black color could be attributed to the lattice distortion of rutile TiO₂ and charge defects caused by appropriate Cr/Mo co-doping, thus absorbing most visible light.

Key words: TiO₂, rutile structure, black pigment, solid-state reaction method, chromium and molybdenum co-doping, color performance, stability