Solvothermal synthesis and characterization of cobalt blue pigment

A novel low-cost solvent-thermal method was proposed for the preparation of cobalt blue (CoAl 2 O 4 ) pigments. The effects of solvent composition , reaction time, reactant molar ratio, and reaction temperature on the structure and tone of the synthesized pigments were investigated. The results revealed that the optimal process conditions for the synthesis of uniform, vibrant cobalt blue pigments were obtained when the volume ratio of alcohol-water was 1:1, the molar ratio of Co 2+ to Al 3+ was 1:3, the reaction time was 4 ​h, and the reaction temperature was 200 ​°C. This solvothermal synthesis method is mild, cost-effective, and easily controllable, thus making it highly suitable for industrial applications.