Effect of replacing B2O3 with CuO on the structural, optical absorption, thermal, mechanical, and gamma-ray shielding properties of B2O3–Bi2O3–K2O glass

This paper delves into the effect of replacing B₂O₃ with CuO on the structural, optical absorption, thermal, mechanical, and gamma(γ)-ray shielding properties of four CKB glasses formulated as (65-y)B₂O₃–15Bi₂O₃–20K₂O-yCuO (where y = 0, 0.3, 0.6, and 1.2 mol%). The glasses were created using the melt-quenching technique, and their non-crystalline structure was verified by X-ray diffraction (XRD) analysis. Fourier-transform infrared (FTIR) spectroscopy identified several structural groups, predominantly consisting of BO₃, BO₄ units, and B–O–B linkages. Thermal properties, assessed via Differential Scanning Calorimetry (DSC), indicated that the glass transition temperature was highest for the 0.3 mol% CuO sample (CKB0.3), demonstrating enhanced thermal stability in comparison to other compositions. Density measurements correlated positively with CuO concentration, peaking at 1.2 mol%, while molar volume, boron molar volume, oxygen packing density, and boron-boron separation distances showed a decreasing trend with increased CuO concentration. UV–Vis absorption spectroscopy indicated a decline in the optical energy gap and an increase in Urbach energy, attributed to the conversion of BO₃ into BO₄ units in the glass matrix. Mechanical properties, evaluated using the Makishima-Mackenzie model, demonstrated enhancements in elastic moduli and micro-hardness with rising CuO concentration. The γ-ray shielding properties (γ-RPs) were examined at energies of 0.662, 1.173, and 1.333 MeV, revealing that both the linear attenuation coefficient and effective atomic number reached their maximum values at 1.2 mol% CuO (CKB1.2). While CKB1.2 exhibited excellent mechanical and γ-ray shielding performance, CKB0.3 excelled in thermal stability and demonstrated γ-ray shielding efficiency comparable to CKB1.2. This suggests that CKB0.3 is a promising candidate for radiation shielding applications requiring a balanced combination of thermal stability and effective γ-ray attenuation properties, particularly at 0.662 MeV.