Abstract
Ternary phosphates are found to vitrify within large domains of compositions inside the phase diagrams P2O5-WO3-A2O (A = Li, Na). The structure of 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 MO6 octahedra, MO4 tetrahedra, M2O7 dimers, PO4 tetrahedra, and also P2O7 or metaphosphate chains, depending on the composition considered. As previously shown, the glass network is progressively depolymerised 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+ centres ascribed to the phosphorus-oxygen-hole-centre and peroxy radicals. The M5+ concentration largely depends on the sample composition and temperature. ESR parameters were determined using a computer simulation approach adapted for vitreous materials. 36 refs.