Effects of gamma-irradiation on Al_2O_3 crystals grown under reducing atmosphere

摘要

Gamma-ray irradiation-induced color centers in Al_2O_3 crystals grown by temperature gradient techniques (TGT) under a strongly reducing atmosphere were studied. The transition F~+ → F takes place during the irradiation process. Glow discharge mass spectroscopy (GDMS) and annealing treatments show that Fe~(3+) impurity ions are present in the crystals. A composite (F~+ -Fe~(3+)) defect was presented to explain the origin of the 255 nm band absorption in the TGT-Al_2O_3 crystals.