A novel route to synthesize metal titanium phosphate ceramic pigments: Co, Ni, and Cu-incorporated α-Ti(HPO4)2⋅H2O from ilmenite

Solid-state reaction of α-Ti(HPO4)2·H2O (α-TiP) and acetates of Co, Ni, or Cu at 500 °C and 800 °C produce a number of different metal titanium phosphate (MTiP) inorganic pigments with different colors and shades. At a given metal to α-TiP ratio and calcination temperature, the reaction produces several types of pigments such as phosphates M0.5TiO(PO4), M0.5Ti2(PO4)3, M2P2O7, and M3(PO4)3 (M = Co, Ni, and Cu) with a unique color. α-TiP, an iron free base material was prepared by digestion of high-grade natural ilmenite beach sand (FeTiO3) with 85 wt% H3PO4 at 120 °C. TGA, XRD, SEM/EDX, Diffuse reflectance UV–vis, and Raman spectroscopy techniques were used for characterization. Synthesized MTiP pigments after enameling at a single fire glazing at 1100 °C for 45 min exhibit vivid colors, ranging from purple, yellow, and green with different shades.