Sol gel synthesis of forsterite, M-doped forsterite (M = Ni, Co) solid solutions and their use as ceramic pigments

This work presents the synthesis of forsterite and M-doped forsterite solid solutions (Mg2−xMxSiO4; M = Ni, Co; x = 0.2, 0.4, 0.6, 0.8 and 1) for which the optical properties were investigated before and after enameling with an industrial transparent glaze in the aim to explore their potential as ceramic pigments. The different materials were prepared through the sol–gel process based on (H2Si2O5)aq as silicon precursor. Pure phases were obtained by calcination at 1000 °C (forsterite) and 1200 °C (pigments). Crystal field transitions of Ni2+ and Co2+ ions in octahedral M1 and M2 sites were the only source of green and violet colors of the pigments. The color stability was satisfactory for both Ni- and Co-pigments, although the latter underwent an appreciable dissolution in glaze. Moreover, the absence of secondary phases in the tested pigments yielded very good coloring performance, which further supports their high potential use as ceramic pigments.