Speaker
Description
Ce and Pr doped Lu3Al5O12 (LuAG) single crystals started to be systematically studied around year 2000 and 2004, respectively, see review [1]. Among their advantages there is stable crystal growth, relatively high density, fast decay due to allowed 5d-4f transitions of Ce3+ and Pr3+, good light yield, mechanical and chemical robustness and radiation hardness. Degradation of figure of merit of these single crystals is due to a number of electron traps arising around the antisite defects (shallow ones) and oxygen vacancies (deep ones). The former were overcame by the concept of multicomponent garnets, namely by the pushing down the bottom of conduction band by the Ga admixture and even more restricted by the divalent alkali earth ion codoping [1,2].
In some applications, even faster decay than is defined by the inherent transition dipole moment of Ce3+ or Pr3+ is required. Shortening of the luminescence lifetime of Ce3+ can be achieved, e.g. by partial ionization of its 5d1 state by tuning the energy barrier between 5d1 and bottom of conduction band [3] or it can be achieved by embedding a suitable acceptor center, which will have its excited state in resonance with 5d1 level of Ce3+ (Pr3+) and thus enables a nonradiative energy transfer away from 5d1 state. Such an energy transfer will accelerate the measured decay time of Ce3+ (Pr3+) emission and this acceleration can be observed in both photoluminescence and scintillation decays.
In this contribution, we report the exploitation of the latter principle in the acceleration of the primary decay component of LuAG:Pr3+,Dy3+ luminescence. Such an energy transfer is realized due to the overlap of 5d1-4f emission of Pr3+ within 300-380 nm with the 4f-4f absorption transitions of Dy3+, resulting in shortening of the leading decay component by 30-40%. We will report the luminescence and scintillation characteristics of such a doubly doped LuAG and describe the energy transfer process in the terms of the Förster-Dexter model.
- M.Nikl, A. Yoshikawa, K. Kamada, et al, Progr. Cryst. Growth Charact. Materials 59, 47 (2013).
- M. Nikl, K. Kamada, V. Babin, et al, Crystal Growth Design 14, 4827 (2014)
- O. Sidletskyi, Ia Gerasymov, D. Kurtsev et al, CrystEngComm (2017). DOI 10.1039/c6ce02330d.
