The effects of phosphorus pentoxide additions on the thermal, rheological, and structural properties of sodium borosilicate glass

• The solubility limit of phosphorus pentoxide in a sodium borosilicate glass was between 3 and 4 mol%. BS-SEM suggested induced nucleation-type phase separation. Phosphorus increased decreased the transition temperature. viscosity at lower temperatures. Raman spectroscopy re-polymerised network. This research has characterized effects P 2 O 5 additions on physical, chemical, thermal, rheological properties structure SiO -B -Na glasses relevant to radioactive waste immobilization. Properties analysed include high-temperature viscosity, temperature (T g ) structure. X-ray diffraction (XRD) confirmed 3.0 4.0 mol% for onset crystallinity with formation Na PO 7 annealed bulk glasses; 5.0 unannealed (quenched) glasses. difference behaviour is attributed annealing being greater than T phase-separated, phosphate-rich droplet phases present glass, which promoted crystallization, where back scattered scanning electron microscopy (SEM) images that separation had occurred as liquid-liquid separation, there evidence like morphology containing 6.0 molar % . However, exact mechanism cannot be unequivocally nucleation growth based purely morphology. Differential Thermal Analysis (DTA) dilatometry showed modest increases increasing contents below crystallisation more substantial increase coinciding High-temperature measurements led samples highest displaying non-Newtonian consistent presence crystals melt 950 °C. spectra content resulted characteristic peak intensities 729 cm − 1 , 937 1000 1026 1109 1445 were associated phosphate species.