Gamma irradiation effects on optical, luminescent, and electrical properties of CeO₂, Ho₂O₃, and Sm₂O₃ doped...

A series of undoped and rare-earth oxide-doped borophosphate glasses (CeO₂, Ho₂O₃, Sm₂O₃) was successfully synthesized via melt-quenching and annealing techniques, with x-ray diffraction confirming their amorphous nature through characteristic broad halos devoid of sharp crystalline peaks. Ultraviolet-visible (UV-Vis) absorption spectra of the undoped base glass revealed prominent UV bands at 265 nm and 330 nm before gamma irradiation, which persisted post-75 kGy exposure with only modest intensity reductions, indicating subtle radiation-induced modifications in defect states without profile disruption. CeO₂-doped glasses exhibited three strong UV peaks at 220, 260, and 327 nm. At the same time, Ho³⁺-doped variants displayed a UV band at 295 nm alongside visible-NIR transitions at 418, 451, 482, 539, 644, 894, 1146, and 1944 nm from ⁵I₈ ground state excitations; Sm₂O₃-doped glasses showed distinct f-f transitions at 354, 403, 470, 920, 1064, 1221, 1365, 1474, and 1520 nm. Photoluminescence analysis highlighted intrinsic features such as a 330 nm excitation and 408 nm emission in CeO₂-doped glasses, three excitation peaks (350, 364, 387 nm) and emissions at 487 and 573 nm in Ho₂O₃-doped glasses, and seven excitation peaks (345-475 nm at λ_ex = 598 nm) in Sm₂O₃-doped glasses, all exhibiting characteristic intensity decreases post-irradiation. CIE 1931 chromaticity coordinates positioned CeO₂-doped emissions in bluish-purple, Ho₂O₃-doped in green (0.275, 0.405 pre-irradiation), and Sm₂O₃ -doped in reddish-orange regions. Electrically, AC conductivity showed a slight decrease followed by an increase with rising temperature across compositions, DC conductivity displayed non-monotonic behavior with a minimum at 384 K, and real dielectric permittivity (ε') was elevated at low frequencies due to space charge polarization. Overall, gamma irradiation induced only minor effects on optical and electrical properties, attributable to dopant-driven structural modifications like non-bridging oxygen formation and enhanced charge carrier pathways via modifier ions, underscoring the radiation resilience and potential of these glasses for luminescent, photonic, and radiation-resistant applications.