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Crystal growth of Pr:(Lu,Gd,Y)3(Al,Ga)5O12 by micro pulling down method and their scintillation properties

Akira Yoshikawa 1,2Kei Kamada 2Yasuhiro Shoji 1Shunsuke Kurosawa 1,2Yuui Yokota 2Petr Prusa 3Martin Nikl 1,3

1. Institute for Materials Research, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan
2. New Industry Creation Hatchery Center, Tohoku University, Aoba-yama 6-6-10, Aoba-ku, Sendai, Miyagi, Sendai 980-8579, Japan
3. Czech Academy of Sciences, Institute of Physics, Cukrovarnicka 10, Prague 16253, Czech Republic


Praseodymium ion Pr3+ exhibits fast 5d-4f emission in several host materials; such systems can be applied to obtain crystal scintillators with high figures of merit. Recently, our group intensively examined the scintillation properties of several Pr-doped compounds. Among those materials, Pr:Lu3Al5O12(Pr:LuAG) was found with the highest figure of merit due to high density (6.7g/cm3), high light yield (approximately 20000 photon/MeV by using PMT), good energy resolution, and a very fast 5d-4f emission decay time (20 ns)[1]. On the other hand, aluminum garnet hosts such as Y3Al5O12 (YAG) and LuAG have electron traps related to anti-site defects. A thermoluminescence (TSL) measurement in LuAG:Ce has identified electron traps associated with LuAl3+ defects, which are responsible for glow curve peaks within 120–200K. Such shallow trapping states in the LuAG host slow down scintillation decay kinetics, and considerable amount of slower decay components was found[2]. To optimize the performance of LuAG-based scintillator towards its intrinsic limits, understanding and control of such kind of defects through manufacturing technology are of crucial importance. Recently, Our group reported that Ga substitution of the Al site and Y substitution of the Lu site in Pr:LuAG suppress such defect and reduce slower decay components.  In this study, Pr: (Lu,Y,Gd)3(Ga,Al)5O12 single crystals were grown by the micro-pulling down (μ-PD) method. Example photographs are shown in Fig.1. Luminescence and scintillation properties were measured. The substitution phenomenon in the Lu3+ sites with Y3+ and Gd3+, and Al3+ sites with Ga3+ + in garnet structure has been studied. In the case of Pr: (Lu,Y)3(Ga,Al)5O12 series, Pr3+5d-4f emission within 300-400nm accompanied by weak Pr3+ 4f-4f emission in 480-650nm are observed in Ga 0-60 at.% substituted samples(Fig.2). Ga 80 at.% substituted sample shows only Pr3+ 4f-4f emission. In the case of Pr: (Lu,Gd)3(Ga,Al,Sc)5O12 series, strong Pr3+ 4f-4f emission in 480-650nm are observed accompanied by weak Pr3+5d-4f emission within 300-400nm and Gd3+4f-4f emission in 312nm. (Lu,Y)3(Ga,Al)5O12 series shows higher light output than that of Pr: (Lu,Gd)3(Ga,Al)5O12 and Pr: (Y,Gd)3(Ga,Al)5O12series. The light output of Pr1%:Lu1Y2Ga2Al2O12 sample was almost same as that of Cz grown Pr:LuAG standard. Two-component scintillation decay shows 16.9ns (90%) and 88.0ns (10%) using the PMT and digital oscilloscope. Details will be reported in the presentation.

Fig.jpg[1] K. Kamada , T. Yanagida, K. Tsutsumi, Y. Usuki, M. Sato, H. Ogino, A. Yoshikawa, et al., IEEE Trans. Nucl. Sci., 2009, Volume 56, Issue 3, pp. 570 – 573, Jun,  2009  [2] M. Nikl, Yoshikawa, et al., Phys.StatusSolidi(a)202, pp.201-207, Jan. 2005


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Presentation: Oral at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, Topical Session 6, by Akira Yoshikawa
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-04-15 08:41
Revised:   2013-07-18 20:18