Abstract: Cobalt aluminate ( CoAl2 O4 ) ceramic pigment powders were fabricated by co-precipitation method. Compositions, morphologies and valence state of CoAl2 O4 ceramic pigment powders were characterized by XRD, SEM and XPS. Effects of Co/Al ratio, pH value and calcination temperature on color properties of the samples were also investigated. Finally, coloration mechanism of the pigment was discussed. The results show that the resulting samples are of the typical spinel structure. The blue CoAl2 O4 ceramic pigment with high chroma was obtained when the Co/Al ratio is 0. 7∶2, pH value is 11 and calcination temperature is 1200 ℃. And, the color change of CoAl2 O4 ceramic pigments is mainly related with the valence of Co elements in the products. CoAl2 O4 ceramic pigments contain Co3 O4 ( Co4+) when the Co content or pH of the precursor solution is high, then crystal lattice distortion could be occured when Co3 O4 entered into the CoAl2 O4 to form a solid solution, resulting in a green ceramic pigment.

Key words: Cobalt aluminate ( CoAl2 O4 ) ceramic pigment powders were fabricated by co-precipitation method. Compositions, morphologies and valence state of CoAl2 O4 ceramic pigment powders were characterized by XRD, SEM and XPS. Effects of Co/Al ratio, pH value and calcination temperature on color properties of the samples were also investigated. Finally, coloration mechanism of the pigment was discussed. The results show that the resulting samples are of the typical spinel structure. The blue CoAl2 O4 ceramic pigment with high chroma was obtained when the Co/Al ratio is 0. 7∶2, pH value is 11 and calcination temperature is 1200 ℃. And, the color change of CoAl2 O4 ceramic pigments is mainly related with the valence of Co elements in the products. CoAl2 O4 ceramic pigments contain Co3 O4 ( Co4+) when the Co content or pH of the precursor solution is high, then crystal lattice distortion could be occured when Co3 O4 entered into the CoAl2 O4 to form a solid solution, resulting in a green ceramic pigment.