Structure of molybdenum-phosphate glasses by X-ray photoelectron spectroscopy (XPS)

Highly-concentrated molybdenum-phosphate glasses with analyzed compositions of Mo greater than 0.65 have been studied by X-ray photoelectron spectroscopy (XPS) and magnetization measurements. 1 eV shifts in the binding energies of P2p, P2s, Mo3d, and Mo3p from their respective values in P₂O₅ and MoO₃ can be accounted for by changes in the next nearest neighbor environment of the P and Mo atoms upon the mixing of the two glass formers. The O1s spectrum is deconvoluted into two peaks with the lower-energy peak being associated with the oxygen atoms of the non-bridging P=O structure as well as from various M-O bonds and the higher-energy peak with the bridging oxygen atoms of the P-O-P structure. From the amount of Mo⁶⁺ reduced to Mo⁵⁺, as determined from the magnetization results, the variations in the areas of these O1s peaks are discussed in terms of an existing structural model based on this binary glass being composed of a mixture of the structural groupings which occur in the crystalline phases of the MoO₃:P₂O₅ system.