Influence of {Ce3+ – Mg2+} pairs on the photo- and thermally stimulated luminescence of Mg2+ co-doped Gd3(Ga,Al)5O12:Ce single crystals.

Single crystals of Gd 3 (Ga,Al) 5 O 12 :Ce,Mg with different concentration of Mg2+ ions varying from 0 to 0.029 at.% are investigated by the X-ray diffraction, steady-state and time-resolved photoluminescence, and thermally stimulated luminescence (TSL) methods in a wide temperature range (77–510 K). The origin and structure of the luminescence centers are considered. The influence of Mg2+ ions on the structure of the Ce3+-related excited state, the processes taking place in this state, and the TSL characteristics is clarified. At low temperatures, the photoluminescence optical quenching in close {Ce3+ - Mg2+} pairs is found to be responsible for the light yield reduction accompanied with the acceleration of the luminescence decay kinetics. At room temperature, the luminescence quenching can be additionally caused by the thermal ionization of the 5d 1 excited state of Ce3+ ion, whose probability increases with the increasing Ga content. The conclusion is made that in order to create the fast scintillator with the maximum light yield, the concentration of intrinsic crystal lattice defects in Gd 3 (Ga,Al) 5 O 12 :Ce,Mg should be minimized, the optimum composition of the host should be chosen, and the balance between the concentrations of the doped Mg2+ and Ce3+ ions should be optimised. • Photo- and thermoluminescence and XRD of Gd 3 (Ga,Al) 5 O 12 :Ce,Mg crystals are studied. • Influence of Mg2+ ions on the Ce3+-related luminescence and excited states is clarified. • Optical quenching in close {Ce3+ - Mg2+} pairs results in the light yield reduction and accompanied with acceleration of the Ce3+ luminescence decay kinetics. • Ga3+ ions and intrinsic defects strongly influence the luminescence thermal quenching. • Optimum host composition and preferable Ce3+/Mg2+ concentration ratio are considered. [ABSTRACT FROM AUTHOR]