Color and Vanadium Valency in V‐Doped ZrO ₂

The distribution and chemical states of vanadium in V‐doped ZrO 2 were studied to clarify the origin of the color of vanadium‐zirconium yellow pigment in comparison with vanadium‐tin yellow pigment. ESCA data and measurements of lattice constants of V‐doped ZrO 2 revealed that vanadium was dissolved mainly as V 4+ substituting for Zr in ZrO 2 lattice, and its solubility limit was 0.5 wt% as V 2 O 5 . It was found that the yellow color of vanadium‐zirconium yellow was produced predominantly by the dissolved vanadium and that the contribution of vanadium oxide on ZrO 2 grains to the yellow color was about 1/30 of that of the dissolved vanadium when compared on the basis of equimolar quantity of vanadium. Most of the undissolved vanadium oxide was in an amorphous or a poorly crystallized state.