Preparation and coloring mechanism of MAl2O4/CoAl2O4/quartz sand (M = Ca or Ba) composite pigments

The doping of divalent metal ions is considered as a feasible strategy for reducing the consumption of expensive cobalt source and regulating the color performance of CoAl2O4 pigments. However, it may be controversial for formation of solid solution in the system of MAl2O4/CoAl2O4 (M = Ca or Ba) due to the bigger differences in ionic radius and coordination number between Ba2+ (or Ca2+) and Co2+, and thus the coloring mechanism of CoAl2O4...