Esmaspäeval, 22. Sept. 2014. kell 16.15 toimub Physicumis Ravila 14C, 3. korruse seminariruumis D312
Väike materjalifüüsika ja spektroskoopia seminar nr. 178
Dr. Jiri A. Mares, Institute of Physics, AS CR, Cukrovarnicka 10, 162 00 Praha 6, Czech Republic
Multicomponent (Lu,Y,Gd)3(Ga,Al)5O12 garnet – new kind of scintillating materials
An intense research of heavy lutetium based Ce3+-doped aluminum garnet scintillating crystals as Lu3Al5O12 (LuAG) started around year 2000 [1,2]. Besides Ce3+ dopant also Pr3+ one started to be studied from year 2004 in LuAG, especially [2,3]. Ce3+ and Pr3+-doped LuAG crystals were prepared by a Czochralski method but from year 2008 also single crystalline layers were grown by a liquid phase epitaxy (LPE) method .
A few years ago a technique called “bandgap engineering” was developed in Japan . This technique allows to prepare so called multicomponent garnets of composition of Ce3+-doped (Lu,Y,Gd)3 (Ga,Al)5O12. Both single crystals and single crystalline layers were prepared [4,5]. These Ce3+-doped multicomponent garnets are characterized by higher Light Yield compared with Ce3+-doped Lu or Y aluminum garnets (up to ~ 50000 ph/MeV against ~ 25000 ph/MeV, respectively) . The highest Light Yield was observed on Gd3Ga3Al2O12:Ce3+ (GGAG:Ce) Czochralski grown crystal ; this crystal is also characterized by a good energy resolution of ~ 5.5 % at 662 keV energy of 137Cs radioisotope. Broad emission spectra of GGAG:Ce and similar multicomponent garnet (Lu,Y,Gd)3(Ga,Al)5O12:Ce crystals are lying in the visible range peaking in the green range (~ 510-530 nm) and they agree with those of LuAG:Ce and YAG:Ce garnets.
In this talk I will present the newest results of scintillating properties of Ce3+-doped multicomponent garnets (Radioluminescence spectra, Photoelectron and Light Yields, Energy resolution, and Proportionality measured using a HPMT multiplier under excitation of various radioisotopes ).
 M. Nikl, E. Mihokova, J.A. Mares, A. Vedda, M. Martini, K. Nejezchleb and K. Blazek,
Phys. Stat. Sol. A181 (2000) R10.
 M. Nikl, A. Yoshikawa, K. Kamada, R. Nejezchleb, C.R. Stanek, J.A. Mares and K.
Blazek, Prog. In Cryst. Growth and Characterization 59 (2013) 47.
 J.A. Mares, A. Beitlerova, M. Nikl, A. Vedda, C. D’Ambrosio, K. Blazek and K.
Nejezchleb, phys. stat. sol. (c) 4 (2007) 997.
 P. Prusa, M. Kucera, J.A. Mares, M. Hanus, A. Beitlerova, Z Onderisinova and M. Nikl,
Opt. Mat. 35 (2013) 2444.
 P. Prusa, K. Kamada, M. Nikl, A. Yoshikawa and J.A. Mares, Rad. Meas. 56 (2013) 62.
 J.A. Mares and C. D’Ambrosio, Opt. Mat. 30 (2007) 22.