The oxidation states of titanium and niobium in compounds of composition SnxNbTiP3O12 (0 < x ⩽ 0.50) : an XPS study

The oxidation states of titanium and niobium in compounds of composition SnxNbTiP3O12 (0 < x ⩽ 0.50) have been examined by X-ray photoelectron spectroscopy. The incorporation of tin as Sn2+ within the NbTiP3O12 structure results in the partial reduction of Ti4+ to Ti3+ and of Nb5+ to Nb4+. The Ti 2p and Nb 3d core levels are characterized by high binding energies, suggesting highly ionic character in the TiO and NbO bonds.