Synthesis and characterization of new environmentally benign tantalum-doped Ce_(0.8)Zr_(0.2)O2 yellow pigments:Applications in coloring of plastics

摘要

New inorganic pigments having the general formula Ce_(1-(x+y))Zr_xTa_yO_(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_(2p)valence band and the Ce_(4f)conduction band by forming a hybrid orbital of Ta_(5d)and O_(2p).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.