Color and Luminescence Centers in LuAG and Pr:LuAG Crystals Before and After 60Co γ-Irradiation


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Abstract

The absorption and thermoluminescence spectra and their relaxation in pure and praseodymium-doped LuAG crystals are comparatively studied to determine the contribution of intrinsic and impurity defects before and after irradiation by 60Co γ-quanta with an average energy of 1.25 MeV, dose rate of 0.8 Gy/s, and dose of 103 Gy at 310 K. The existence of intrinsic F+ defects with a typical absorption band at 375 nm and impurity Cr4+ centers absorbing at 285, 420, 490, and 595 nm in both LuAG and Pr:LuAG samples before irradiation is related to the crystal-growth technology and the impurity composition of the charge. An increase in the concentration of F+ and Cr4+ centers after γ-irradiation is caused by charging of neutral F centers and changing of the electronic state (valence) of Cr3+ impurity centers. Formation of antisite defect complexes LuAl3+–VO, which are responsible for a luminescence band at 335 nm, is suggested. The first broad peak at 340 K on the thermoluminescence curves of both samples after irradiation with a dose of 103 Gy is related to liberation of charge carriers from shallow trapping levels; thermal activation and radiative recombination with emitting centers begin at 310 K, which places the upper limit on the temperature range of application of these scintillation crystals.

About the authors

A. Kh. Islamov

Institute of Nuclear Physics; National University of Uzbekistan

Author for correspondence.
Email: akhatqul@inp.uz
Uzbekistan, pos. Ulugbek, Tashkent, 100214; Tashkent, 100174

E. M. Ibragimova

Institute of Nuclear Physics

Email: akhatqul@inp.uz
Uzbekistan, pos. Ulugbek, Tashkent, 100214

I. A. Khaiitov

Institute of Nuclear Physics

Email: akhatqul@inp.uz
Uzbekistan, pos. Ulugbek, Tashkent, 100214

R. R. Vil’danov

National University of Uzbekistan

Email: akhatqul@inp.uz
Uzbekistan, Tashkent, 100174

M. Z. Amonov

Institute of Nuclear Physics

Email: akhatqul@inp.uz
Uzbekistan, pos. Ulugbek, Tashkent, 100214

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