Structure and thermochemical study of strontium sodium phosphate glasses

• Phosphate glasses with the formula (100-x)NaPO3-x SrO were prepared by melt quenching technique.
• Density measurement, Thermal analysis and chemical durability of the glasses were studied with increasing SrO content.
• Structural investigations were performed by FTIR and 31P NMR MAS spectroscopy.
• Dissolution of glasses in H3PO4 solution was performed in a C-80 microcalorimeter.

Phosphate glasses having the general formula (100-x) NaPO3-x SrO with an O/P ratio varying between 3 and 3.25 were synthesized by melt quenching technique. The glasses are studied in order to determine the influence of SrO addition on the structural and physical-chemical properties. Density, glass transition and crystallization temperatures increase with SrO content, showing the shrinking and reticulation of phosphate network. The chemical durability of the glass series is enhanced by the substitution of Na2O and P2O5 by SrO. Fourier Transform Infrared Spectroscopy and 31P Magic Angle Spinning Nuclear Magnetic Resonance spectroscopies revealed the depolymerisation of the glass network by the decrease of middle chain units to create end chain units species. Calorimetric study of the dissolution of glasses in acid solution shows a decrease of the dissolution enthalpy when the SrO is added.