Composition engineering of Tb3-xGdxAl5-yGayO12:Ce single crystals and their luminescent, scintillation and photoconversion properties

The luminescence, scintillation, and photoconversion properties of the single crystals of Ce3+ doped Tb3-xGdxAl5-yGayO12 (x = 0-1.5; y = 2-2.5) mixed garnets, grown by the micro-pulling-down (mu-PD) method, are investigated as a function of the Tb/Gd ratio with the aim of development of phosphor-convertors of white LED and scintillators. The partial Tb3+ substitution by Gd3+ cations leads to the suitable change of the crystal field splitting of the 5d energy levels of Ce-3 ions due to different sizes of the Gd3+ and Tb3+ cations. For this reason, the cation engineering enables to improve the luminescence and scintillation characteristics of Tb3-xGdxAl5-yGayO12 crystals due to increasing the efficiency of Gd3+ -> Tb3+ -> Ce3+ cascade energy transfer observed in these solid solutions. We have shown that from all the crystals under study, the Tb3-xGdxAl5-yGayO12:Ce (x = 1-1.5) crystal is the best promising candidate for the photoconversion and scintillation applications. (C) 2020 Elsevier B.V. All rights reserved.