Raman and optical spectroscopy study of iron-bearing bio-relevant phosphate glasses: Assessment of γ-ray irradiation effects

Abstract

Glasses with 50P2O5-30CaO-(20 – x)Na2O-xFe2O3 (x = 0.1, 1, 5, 10 mol%) compositions were prepared by melting, and characterized by X-ray diffraction, Raman scattering, and optical spectroscopy. The glasses were subjected to γ-ray irradiation and structural and optical properties evaluated via Raman, absorption, and photoluminescence spectroscopy. The pristine glasses were X-ray amorphous, whereas Raman spectroscopy indicated Fe2O3 depolymerizes glass structure. Absorption spectroscopy showed that iron occurred largely as Fe3+ with Fe2+ revealed at high iron contents. Following γ-ray irradiation, the Raman features were preserved supporting lack of structural alteration. Radiation-induced defects were detected optically for 0.1 mol% Fe2O3 but prevented at higher concentrations. Bluish luminescence ascribed to electron centers was detected under 265 nm excitation for 0.1 mol% Fe2O3 similar to the irradiated host exhibiting ms-scale decay. The optical properties of γ-irradiated glasses at higher iron contents were like the pristine, supporting an increase in glass network resistance against gamma radiation.