The γ-radiation-induced defects in natural topaz samples were investigated by using electron paramagnetic resonance spectroscopy in the X-band frequency (9.72GHz). The most intense electron paramagnetic resonance lines were identified as being due to the paramagnetic impurities, Fe3+ and Ti3+, and complexes: (PO4)0 and (AlO4)0. The growth of the electron paramagnetic resonance lines for 60Co γ-ray doses up to 5kGy, and the thermal stability of these lines at 100 to 600C were studied. The results suggested that the hole center, (AlO4)0, and the electron centers, Ti3+ and (PO4)0, were involved in the recombination process which occurred around 200C and was responsible for the destruction of the brown color and for thermoluminescent emissions in this temperature region. It was concluded that the (AlO4)0 probably acted as a recombination center, while the Ti3+ and (PO4)0 centers acted as traps.

Paramagnetic Radiation-Induced Defects in Gamma-Irradiated Natural Topazes. E.G.Yukihara, E.M.Yoshimura, E.Okuno: Nuclear Instruments and Methods in Physics Research Section B, 2002, 191[1-4], 266-70

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