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Structural Role of Samarium Ions in the Doped Lithium Borate Glasses: Optical and Radiation Shielding Studies
H. M. Zahran, A. M. Abdelghany, Y. M. Moustafa, Meawad M. Elkholy and G. El-Damrawi
Samples of parent lithium borate glasses of basic composition (70B2O3-30Li2O) mol% in addition to other samples that contain the gradual increase of samarium oxide (Sm2O3) at the expense of boron oxide were synthesized and characterized to investigate structural modifications, optical activation, and enhanced radiation shielding. Adding Sm2O3 caused progressive conversion of trigonal BO3 units to tetrahedral BO4 units due to charge compensation requirements, disrupting the borate network. This was evidenced by FTIR spectra showing systematic band shifts and intensity variations indicating structural changes. The fraction of 4-coordinated boron rose linearly from 0.35 to 0.54 with increasing Sm2O3 content. UV/vis absorption spectra revealed growing the f-f transition peaks of Sm3+ and charge transfer bands with Sm2O3 content. Glass density and the effective atomic number increased markedly with Sm2O3 doping, elevating gamma radiation attenuation 2-3 fold across diagnostic to radiotherapy energies due to the high samarium atomic mass and abundant outer electrons. Sm3+ containing lithium borate glasses thus demonstrate tunable structure, visible emission, and radiation shielding by optimal Sm2O3 additions between 2.5-15 mol%. Potential applications in optical devices and radioprotective materials can leverage these benefits.
Keywords: Lithium borate glass, samarium oxide, FTIR, radiation shielding, N4