Effect of γ-irradiation and annealing on defects behaviors in transparent MgAl₂O₄ ceramics

Transparent MgAl₂O₃ ceramics was exposed to ⁶⁰Co γ-ray with doses from 0.1 kGy to 3500 kGy and isochronally annealed. The samples were studied by PAT, UV-VIS and FT-IR. Before irradiation there is an absorption peak at 3360 cm^-1, which is induced by the V_OH^- center. There is a broad optical-absorption band at 370 nm, which is due to V-type color centers absorption in MgAl₂O₄ ceramics after irradiation. The V-type color centers can be destroyed by heat treatment. The results show that vacancy clusters in the samples can be split into single-vacancies in the process of γ-irradiation and the single-vacancies can be aggregated again in the process of annealing. The γ-ray with low doses decrease transmittance of the samples from ultra violet to infrared region. With the increasing of the dose, however, it induces a thermal effect to increase the infrared transmittance of the samples.