Raman Spectrum of Vanadium-Zirconia Yellow Pigment

Monoclinic vanadium-zirconia yellow pigments were prepared by gelling mixtures of zirconium n-propoxide and vanadyl acetylacetone. The nature of interactions between the host ion and the foreign cation in the vanadium-zirconia pigment was investigated in order to contribute to a better understanding of the origin of this pigmenting system using Raman scattering measurements. The Raman spectra of powdered samples of the vanadium-zirconia pigment recorded between 100 and 1400cm(-1) show the peaks at 991, 701, and 403cm(-1) assigned to the asymmetric and symmetric stretching and bending vibrations of the V4+=O bonds, respectively. The assignment of these peaks was discussed by comparison with Raman spectra of vanadium oxides and on the basis of V-O bond distances deduced from the Hardcastle and Wachs equation and from the valence state of the vanadium cation calculated by Brown in the valence sum rule. This suggests that the V4+ cations replace Zr4+ in sevenfold coordinated site in the monoclinic zirconia structure. The V4+ cation allowing the d-d electronic transition is related to the origin of the lemon yellow coloration.