Sol–gel synthesized calcium borate glass and glass–ceramics: effect of CrCl3 doping on structure, mechanics, and gamma-ray shielding efficiency

This study presents the synthesis and characterization of chromium chloride-doped calcium borate glasses and glass ceramics. Samples with the nominal composition 55CaO-(45-x)B2O3-xCrCl3 (where x = 0, 1, 2, and 3 mol%) were successfully prepared via the sol-gel method. X-ray diffraction (XRD) analysis confirmed that the specimens retained an amorphous nature following calcined at 500 °C for 4 h. However, a distinct transition to a glass-ceramic phase was observed upon increasing the temperature to 700 °C. Morphological characteristics were analyzed using field emission scanning electron microscopy (FESEM). FTIR spectroscopy revealed a progressive increase in the fraction of tetrahedral units (BO4), rising from 43 to 46% with increasing CrCl3 content, which increased the rigidity of the prepared glass samples. The radiation shielding efficiency was computationally evaluated using the Phy-X/PSD online software. The results demonstrated that CrCl3 integration effectively reduced the half-value layer (HVL), the tenth-value layer (TVL), and the mean free path (MFP). At 0.04 MeV, the HVL, TVL, and MFP values decreased from 0.336 cm, 1.115 cm and 0.484 cm for the 0CrCaB to 0.252 cm, 0.839 cm, and 0.364 cm for the 3CrCaB sample, respectively. In contrast, the mass attenuation coefficient increased from 0.803 cm2/g for the 0CrCaB to 0.883 cm2/g for the 3CrCaB sample. Furthermore, the mechanical properties were theoretically calculated using the Makishima–Mackenzie model. Young’s modulus (Y) increased from 66.137 to 108.00 GPa, bulk modulus (B) increased from 47.619 to 90.720 GPa, shear modulus (S) increased from 26.069 to 41.488 GPa, and microhardness (H) increased from 4.023 to 5.4878 GPa. The density progressively increased from 2.57 to 3.11 g/cm3 with rising CrCl3 content, while the molar volume simultaneously decreased from 24.19 cm3/mol to 20.85 cm3/mol. These findings suggest that the synthesized samples can potentially be used as radiation shields.