Synthesis of Co-free inorganic blue pigments based on turquoise blue glaze

Glass mixtures based on turquoise blue glaze were synthesized by the conventional ceramic method, and their color properties were investigated as environmentally friendly Co-free inorganic blue pigments. Samples showed coloring from light blue to black depending on their compositions. The bluest color was observed for 0.60 BaO·0.20 Li2O·0.20 Na2O·0.45 Al2O3·2.50 SiO2 in a 20 wt % CuO sample heated at 900°C, which had the following color parameters: (L*a*b*) of L* = 41.9, a* = −4.5, and b* = −14.2. The a*, b* values are comparable to those of commercial Co-based blue pigments. Since the glass mixtures do not include cobalt oxide as a raw material, it should be an attractive alternative to conventional Co-based inorganic blue pigments.