Infrared, Raman, and Electron Spin Resonance Studies of Vitreous Alkaline Tungsten Phosphates and Related Glasses

Abstract

Ternary phosphates are found to vitrify within large domains of compositions inside the phase diagrams P2O5–WO3–A2O (A = Li, Na). Structural approach of the highly modified glasses P2O5–A2MoO4–A2O (M = Mo,W) was investigated using various spectroscopic techniques such as infrared, Raman, and electron spin resonance (ESR). These glasses were found to contain MO6octahedra, MO4tetrahedra, M2O7dimers, PO4tetrahedra, and also P2O7or metaphosphate chains, depending on the composition considered. As shown in earlier studies, the glass network is progressively depolymerized as the content of A2O increases. ESR experiments were conducted on both X‐ray irradiated and unirradiated samples. Unirradiated glasses exhibit two ESR signals attributed to W5+ and Mo5+ centers that are octahedrally coordinated. Irradiation of these glasses induces new paramagnetic centers ascribed to the phosphorus–oxygen–hole–center and peroxy radicals. The M5+ concentration depends strongly on the sample composition and temperature. ESR parameters are determined using a computer simulation approach adapted for vitreous materials.