Influence of Ba2+ on the optical property of cobalt blue

Ba-doped cobalt blue pigment was prepared by calcination method and precipitation method to investigate the influence of Ba2+ on cobalt blue. X-ray diffraction analysis shows that there existed BaAl2O4 in CoAl2O4 prepared by calcination method. Ultraviolet spectrum analysis shows that the reflectivity of the sample prepared by calcination method was changed obviously at a wavelength of 439 nm, while the reflectivitiy of the sample prepared by precipitation method increases obviously at 439 and 600 nm. The influences of milling time of raw materials and calcining temperature on reflectivity of cobalt blue were analyzed. The results show that the sample containing 1.5 wt% BaO possesses a good optical property when the raw materials are milled for 8 h and then calcined at 1250 °C for 8 h. The coloring ability of the precipitated sample is poor.