Role of Ti in the luminescence process of Al2O3:Si,Ti |
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Authors: | P.S. Page B.C. Bhatt S.V. Godbole |
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Affiliation: | a Radiological Physics and Advisory Division, Bhabha Atomic Research Center, Mumbai-400 085, India b Radio Chemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai-400 085, India |
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Abstract: | Al2O3:Si,Ti, prepared under oxidizing condition at high temperature, gives PL emission around 430 nm when excited with 240 nm. The Al2O3:C, TL/OSL phosphor, also shows emission around 430 nm, which corresponds to characteristic emission of F-center. Thus, to identify the exact nature of luminescent center in Al2O3:Si,Ti, fluorescence lifetime measurement studies were carried out along with the PL,TL and OSL studies. The PL and TL in Al2O3:Si,Ti show emission around 430 nm and the time-resolved fluorescence studies show lifetime of about 43 μs for the 430 nm emission, which is much smaller than the reported lifetime of ∼35 ms for the 430 nm emission (F-center emission) in Al2O3:C phosphor. Therefore, the emission observed in Al2O3:Si,Ti phosphor was assigned to Ti4+ charge transfer transition. Fluorescence studies of Al2O3:Si,Ti do not show any traces of F and F+ centers. Also, Ti4+ does not show any change in the charge state after gamma-irradiation. On the basis of the above studies, a mechanism for TSL/OSL process in Al2O3:Si,Ti is proposed. |
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Keywords: | Al2O3:Si,Ti Time-resolved luminescence Lifetime measurements Thermoluminescence |
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