Colour modifiers of zirconium-vanadium pigments on a ZrO2 basis

The synthesis of yellow baddeleyite pigments involves a phase transition of ZrO2, which facilitates the process of incorporating vanadium chromophore into its lattice, and occasionally also modifiers, such as oxides of trivalent elements, either chromophoric or non-chromophoric. Depending on the type of the modifier used — an oxide of indium, yttrium, gallium or thallium — the yellow-green colour of the two-component ZrO2-V pigment may be changed smoothly into yellow or yellow-orange. The temperature of the synthesis of ZrO2-based pigments ranges from 1050 °C to 1325 °C, depending on the properties of the substrates, such as a non-oxide form of the materials — ZrOCl2, Zr(SO4)2, certain additives (e.g. Bi2O3). Raising the synthesis temperature over 1400 °C has no visible effect on the colour quality of the pigment, as it depends on the concentration of the vanadium chromophore in the ZrO2 structure. The article describes the effect of the synthesis temperature and modifying additives on the effectiveness of incorporating vanadium into the ZrO2 lattice and, consequently, on the colour properties of the pigment.