Glass-forming ability and the structure of glasses in the BaO-WO3-P2O5 system

Abstract

The purpose of this work was to prepare and study new glasses from the system BaO-WO3–P2O5 focusing on their basic physical properties and studying their structure by Raman and 31P NMR spectroscopies in five compositional glass series. The glass transition temperature increases in all compositional series with increasing WO3 content. The 31P MAS NMR spectra of the glasses revealed depolymerization of the phosphate network. In the Raman spectra of glasses with a low WO3 content, two strong vibrational bands at 885 and 945 cm−1 were assigned to the vibration of WO and W-O− bonds in tungstate structural units. In glasses with a high WO3 content, a broad band at 820–841 cm−1, ascribed to W-O-W bonds, indicated the formation of clusters composed of WO6 units. Raman spectra also revealed partial transformation of WO6 units into WO4 units in glasses with a low P2O5 content.