Novel environment-friendly yellow pigments based on praseodymium(III) tungstate

The novel environment-friendly inorganic yellow pigments, (Pr1-xCex)(2)W2O9+delta (0 <x <= 0.12) with the monoclinic structure, were synthesized and their color properties were investigated. The (Pr1-xCex)(2)W2O9+delta (0 < x <= 0.12) samples showed brilliant yellow color by doping trivalent Ce3+ into the Pr2W2O9 lattice due to the optical absorption in blue light region caused by the 4f -5d transition of Ce3+. According to the XPS and Rietveld analysis results, cerium ions in the crystal lattice have two different oxidation states of 3+ and 4+, in which the rate of each oxidation state is 58%:42%, and the Ce3+ and Ce4+ ions are preferentially occupied the PrO9 and the PrO8 polyhedral sites, respectively. Among the samples prepared, the (Pr0.90Ce0.10)(2)W2O9+delta pigment exhibited the most vivid yellow hue with high color durability for light and acid/base solutions.