Effect of neutron irradiation of colorless sapphire (leucosapphire) single crystals on their absorption and luminescence spectra |
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Authors: | I Kh Abdukadyrova |
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Institution: | (1) Institute of Nuclear Physics, Academy of Sciences of Uzbekistan, pos. Ulugbek, Tashkent, 702132 |
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Abstract: | Features of the thermoradiative changes in the optical absorption and luminescence spectra of leucosapphire (colorless sapphire)
crystals irradiated by neutron fluences within the range 5·1015 to 5·1019 cm−2 have been studied in the visible region. The stepwise character of these processes was established as well as the basic steps
involved in bleaching the induced color of the wafers as a result of isochronal annealing. Some anomalies have been observed
in the temperature dependence of the optical density of the 460–620 nm bands, the activation energies for the color centers
as well as the color center concentrations have been calculated, and the nature of the radiation-induced centers has been
analyzed. An analytical expression is proposed to describe the accumulation kinetics for the centers during irradiation of
the crystals by reactor neutrons. It is concluded that there is an interconnection between, for example, the 460 nm color
centers and the 540 nm luminescence centers, and that there is a common mechanism for the process of radiation-induced defect
formation, initially responsible for their formation in the crystal. The possible effect of reabsorption of radiation on the
behavior of the Y(Φ) curve in the irradiated material is discussed.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 247–251, March–April, 2007. |
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Keywords: | optical spectrum thermoradiative process irradiation crystal generation center step |
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