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

A procedure is reported for the synthesis of vanadium-doped zirconia pigmen ting 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 v anadyl acetylacetonate and studied over the range of temperature up to 1300 degreesC. Succesive steps of the reactions leading to the final monoclinic vanadium-zirconia solid solution phase were investigated by X-ray powder d iffraction. It was found that the formation of the monoclinic solid solutio n took place by a phase transformation from a phase with the structure of t etragonal zirconia. The transformation temperature of metastable tetragonal to monoclinic phase was found to be governed by the nominal vanadium amoun t. Measurements of lattice parameters of monoclinic vanadium-zirconia solid solutions as a function of the nominal vanadium amount revealed that vanad ium was dissolved in the zirconia lattice. Energy dispersive X-ray microana lysis and lattice parameters variation indicates that the maximum amount of vanadium into the monoclinic zirconia lattice was about 5 mol % of vanadiu m (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 . (C) 2001 Kluwer Academic Publishers.