Synthesis and Spectral Characterization of Vanadium Substituted Hexaniobates

Abstract

Reaction of aqueous solution of sodium vanadate with potassium niobate at different pH gives three well defined compounds viz., K₇HNb₃V₃O₁₉·3H₂O (I), K₇HNb₂V₄O₁₉·5H₂O (II) and K₇HNbV₅O₁₉·H₂O (III). Powder X-ray diffraction analysis shows that the three compounds to be isomorphous with the 'parent' compound, (K₇HNb₆V₃O₁₉·15H₂O) (IV). On the basis of IR and Raman spectra, [Nb₂V₄O₁₉]^8- is assigned to have cis-configuration (C₂V symmetry) and [Nb₃V₃O₁₉]^8- to have facial configuration (C₃V symmetry).