Synthesis and characterization of vanadium-containing ZrO2 solid solutions pigmenting system from gels

Abstract

A procedure is reported for the synthesis of vanadium-doped zirconia pigmenting system with different vanadium loadings which permitted their complete formation and further characterization. Monoclinic vanadium-zirconia solid solutions were prepared by gelling mixtures of zirconium n-propoxide and vanadyl acetylacetonate and studied over the range of temperature up to 1300 °C. Succesive steps of the reactions leading to the final monoclinic vanadium-zirconia solid solution phase were investigated by X-ray powder diffraction. It was found that the formation of the monoclinic solid solution took place by a phase transformation from a phase with the structure of tetragonal zirconia. The transformation temperature of metastable tetragonal to monoclinic phase was found to be governed by the nominal vanadium amount. Measurements of lattice parameters of monoclinic vanadium-zirconia solid solutions as a function of the nominal vanadium amount revealed that vanadium was dissolved in the zirconia lattice. Energy dispersive X-ray microanalysis and lattice parameters variation indicates that the maximum amount of vanadium into the monoclinic zirconia lattice was about 5 mol % of vanadium (3.7 wt % as V2O5). UV-Vis diffuse reflectance of monoclinic V-ZrO2 solid solutions indicated that vanadium was dissolved as V+4 and that the color of vanadium-zirconia yellow pigments was produced by the dissolved vanadium.