Effect of sol–gel method on colour properties of the classical cobalt olivine (Co₂SiO₄) ceramic pigment

Abstract

A sol–gel method based on (H ₂ S _{2 5}) _{a q} as silicon precursor in the presence of NaCl and KCl mineralizers was used for the synthesis of the classical cobalt olivine (Co ₂ SiO ₄ ) ceramic pigment. The effect of this synthesis route on the colour properties was studied. Highly pure olivine phase was obtained after firing at 1200^∘C for 3 h. The resulting powders exhibited very intense violet colour, while their addition at only 1 wt% to an industrial transparent glaze was enough to produce a very intense blue–violet colouration. Based on the aspect of glazed ceramics, addition of pigments even at 0.5 wt% to the glaze resulted in a very interesting colour and opacity. By this appropriate minimization of the used pigment amount without compromising the colouring properties required during application, the obtained Co olivine could be more efficient, less toxic and less expensive.