γ-radiation-induced centers in irradiated perovskite SrCeO3 and their role in thermally stimulated reactions: Fluorescence, thermally stimulated luminescence, electron paramagnetic resonance and shielding studies

Abstract

One promising host for actinide radioactive wastes is orthorhombic perovskite-type oxide. Perovskite SrCeO₃ ceramic was synthesized by nitrate-fuel combustion, which includes the organic fuel glycine. Powder X-ray diffraction was utilized to determine the structural features, and γ-radiation-induced changes and shielding properties were investigated in perovskite SrCeO₃. In a mixed-phase sample, a bright sky-blue luminescence was observed, and two thermoluminescence (TL) peaks were seen in irradiated SrCeO₃ ceramic. Electron paramagnetic resonance (EPR) spectrum in γ-irradiated SrCeO₃ ceramic had contributions from five defect centers. Center I having an isotropic g-value equal to 2.0283, is ascribed to an O⁻ ion, while center II with an axial g-tensor with principal values g_|| = 2.0224 and g_⊥ = 2.0068 is determined as an O₂⁻ ion. O⁻ ion relates to the TL peak at 215 °C. Center III with a g-value equal to 2.0009 is identified as an F⁺ center and is related to the 185 °C TL peak. The defect center associated with center IV is also identified as an F⁺ center. An additional defect center in the higher field region of the spectrum is assigned to an F⁺ center, and the center results from an F-center (oxygen vacancy with two electrons). The mass attenuation coefficients, effective atomic numbers, and half-value layer thicknesses concerning shielding property effectiveness were computed and it was found that the perovskite SrCeO₃ ceramic provided superior γ-shielding properties.