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 (V_m), glass transition temperature (T_g), 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 (V_m) behaves in exactly the opposite way. DSC curves showed that the glass transition temperature (T_g) 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.