Impact of glass matrix Sb2O3-NiO-Na2O-B2O3 on the structure, optical, ligand field characteristics and radiation shielding parameters of borate glass system

This work presents the impact of the glass matrix Sb2O3-NiO-Na2O-B2O3 on the structure, optical and ligand field parameters of Ni cations inside this glass system. Also, the radiation shielding properties of this glass system were investigated. The Sb2O3 concentrations varied from 0 to 18 mol%, while Na2O and NiO were fixed at 19.6 and 0.9 mol%, respectively. The structural analyses confirmed that the glass density changed from 2.13 to 2.76 g/cm(3), the molar volumes increased from 31.88 to 39.18 cm(3)/mol and N-4 ratio (tetrahedrally coordinated boron atoms) decreased from 41.16% to 29.65% with further Sb2O3/B2O3 contents. The brown color of the glass samples and the absorption band at 419-427 nm also showed that Ni2+ cations in the form of NiO6 units are present in this glass system. Furthermore, additional Sb2O3/B2O3 contents moved the fundamental absorption edge toward higher wavelengths, reducing optical band gaps from 3.32 eV to 2.89 eV. Furthermore, the nonlinear refractive index increases with the increased Sb2O3/B2O3 ratios. Also, Ni ions' ligand field splitting and Racah parameters showed different behaviors. In detail, the ligand field splitting showed decreased behavior from 7434 cm(-1) to 7408 cm(-1), whereas the Racah parameters showed increased behavior from 907 cm(-1) to 942 cm(-1). The obtained results support the tendency of the bonds between the Ni ions and their environments toward an ionic nature. Besides, the radiation shielding investigations showed enhanced parameters with further Sb2O3 additives. Further, with increasing Sb2O3 from 0 mol% to 18 mol%, there are increases in the mass attenuation coefficient values. The improved radiation shielding parameters of the studied glass samples propose them for ionizing radiation shielding applications.