Synthesis and characterization of new environmentally-friendly pigments based on cerium phosphate

New yellow-green pigments based on cerium orthophosphate were synthesized by the solid-state reaction in order to develop ecological and environmentally-friendly specific pigments. The pigments were obtained by doping alkaline earth metal ions into a cerium orthophosphate lattice to form their solid solutions. The products were characterized by using X-ray powder diffraction, UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, and colorimetric assessment. From these results, it has been evidenced that the formation of solid solution is necessary to have color coordinates in the synthesized pigment samples. Since the color of the pigments was almost the same yellow-green in all solid solution samples, the origin of the coloration was attributed to the appearance of the principal broad absorption band corresponding to the 4f-5d electron transition of Ce3+ and the additional O-2p-Ce-4f charge transfer transition of Ce4+ by the doping of alkaline earth ion into CePO4 lattice.