Synthesis and characterization of new environmentally benign tantalum-doped Ce sub(0.8Zr) sub(0).2O sub(2 yellow pigments: Applications in coloring of plastics)

New inorganic pigments having the general formula Ce sub(1-(x+y)Zr) sub(x)Ta sub(yO) sub(2)+[delta] (x ranges from 0.15 to 0.2 and y ranges from 0 to 0.05) displaying colors ranging from white to yellow have been synthesized by a traditional solid-state route, as viable alternatives to lead, cadmium and chromium based yellow toxic inorganic colorants. The products were characterized by X-ray powder diffraction, UV-vis diffuse reflectance spectroscopy and CIE-L*a*b* 1976 color scales. The coloring mechanism is based on the strong absorptions of the pigments in the visible region under 500 nm, which could originate from the additional energy level between O sub(2p valence band and the Ce) sub(4)f conduction band by forming a hybrid orbital of Ta sub(5d and O) sub(2)p. The designed yellow pigments consist of non-toxic elements and further found to be thermally and chemically stable. The pigments were also found to be suitable candidates for the coloration of plastics.