Effects of Γ-Irradiation and Thermal Annealing on Photo-thermal-refractive Glass

Photo-thermal-refractive (PTR) glass was irradiated with gamma-ray at the total dose of 0.35, 1, 10 and 100 kGy, respectively, and then annealed. Irradiation mechanism of the photo-thermal-refractive glass was studied by absorption spectroscope, luminescence spectroscope and electron paramagnetic resonance. The results showed that the absorption of the gamma-irradiated PTR glass in the visible light was mainly caused by the Ag-0, silver molecular clusters Ag-2, Ag-3, silver nanoparticles Ag-m(0), and non-bridge oxygen hole center HC1 and HC2. Under different doses of gamma-ray irradiation, valence state of the ions (Ag+, Ce3+) in the glass matrix changed. At the same time, non-bridged oxygen bonds in the glass matrix broke, generating non-bridged oxygen hole defects HC1, HC2 and Ag-0. With the increase of the radiation dose, silver molecular clusters Ag-2 and Ag-3 generated, and the concentration of HC2 center in the glass matrix increased, resulting in enhanced absorption near 639 nm. After being irradiated and annealed at 250 degrees C, HC1 and HC2 defect centers was bleached. Silver molecules appeared after annealing at 430 degrees C, of which absorption peak had a redshift and was broadened with the increase of annealing duration.