Effect of Bi2O3 on the physical, structural and gamma ray shielding properties of phosphate glasses inside the ternary P2O5-SrO-Bi2O3 system

Strontium phosphate glasses containing bismuth oxide were prepared using conventional melt-quenching technique. X-ray diffraction and differential scanning calorimetry (DSC) analysis suggests that stable ternary glasses of composition 70 P2O5-(30-x)SrO-xBi2O3 can be obtained for x = 5–25 mol%. This study examines such physical properties as the density, molar volume (Vm), glass transition temperature (Tg), and structural properties in the interest of explaining the effect on these glasses of Bi-Sr substitution. An almost linear increase in the density when the concentration of bismuth increases between x = 5 and x = 10 mol% followed by monotonic decreasing is noted. However, the calculated molar volume (Vm) behaves in exactly the opposite way. DSC curves showed that the glass transition temperature (Tg) decreases by 555 °C down to 490 °C as the concentration of Bi2O3 increases, due to the increase in the number of bridging oxygens. Structural investigations performed using IR spectroscopy revealed that the structure of the phosphate network contains predominately meta-phosphate (Q2) units, with contributions from pyrophosphate (Q1) and orthophosphate (Q0). The infrared spectra also revealed depolymerization of the phosphate chains in the glass system, with increased Bi2O3 concentration and the formation of P–O–Bi bonds. The study of the gamma ray shielding parameters showed that the prepared glasses can be used for shielding radiation applications.