Color hue controlling of blue ceramic pigments with low cobalt contents via crystal field engineering

Ceramic pigment is the most basic chromogenic substance introduced into all ceramic coloring materials. In recent years, the development of ceramic pigments has been able to keep the quality and color stability of ceramics even after 1300 °C. Studies have proved that these ceramic pigments have good color performance under the tests of high temperature and acid and alkali resistance. In this paper, Co²⁺doped Mg_1-xAL_2-2xSi_xO₄;was prepared by high-temperature solid-state method. The main crystal phase and its content of the synthesized pigment were studied by X-ray powder diffraction (XRD), scanning electron microscope (SEM), fluorescence-spectrum (PL), diffuse reflection spectrum and precise analysis colorimeter. The crystal structure, chromaticity, acid and alkali resistance of ceramics and color rendering performance of glass of pigments doped with different amounts of Al were observed and tested. The results of XRD and Raman spectra show that MgSiO₄ is a perovskite-type ceramic pigment. The main crystalline phase of the pigment is MgSiO₄, and the secondary crystalline phase is MgAl₂O₄. Co²⁺ replaces Mg²⁺ to make the pigment yellowish brown. Impurities such as MgAl₂SiO₄ and MgAl₂O₄; will be produced when different amounts of Cu are doped at 1400 °C calcination temperature. However, at the calcination temperature of 1300 °C, the temperature will be compared, and it is not easy to produce impurities, indicating that the temperature limit is around 1300 °C. At 1400 °C, the color of the pigment becomes lighter with the increase of Al content, especially when the concentration is higher, the pigment is yellowish brown in glass. At 1300 °C, the color of the pigment has no obvious change with the increase of Al content, and the color of the pigment in the glass is yellow, and its good color rendering performance is consistent with that of the calcined sample. In the test of acid and alkali resistance of samples, hydrochloric acid (HCl) is used as the acid and sodium hydroxide (NaOH) is used as the alkali. The data obtained by the precise analysis colorimeter also shows that the corrosion resistance is good.