Full Length Article The temperature dependence studies of rare-earth (Dy 3 þ , Sm 3 þ , Eu 3 þ and Tb 3 þ ) activated Gd 3 Ga 3 Al 2 O 12 garnet single crystals K. Bartosiewicz a,b,n , V. Babin a , A. Beitlerova a , P. Bohacek c , K. Jurek a , M. Nikl a a Institute of Physics, CAS, Cukrovarnicka 10, Prague 6 16253, Czech Republic b Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, Praha 111519, Czech Republic c Institute of Physics, CAS, Na Slovance 1999/2, Prague 8 18221, Czech Republic article info Article history: Received 26 April 2016 Accepted 20 September 2016 Keywords: Gd 3 Ga 3 Al 2 O 12 Rare earth dopants Energy transfer Thermal quenching Single crystal abstract The luminescence properties of the Dy 3 þ , Sm 3 þ , Eu 3 þ and Tb 3 þ activated Gd 3 Ga 3 Al 2 O 12 (GGAG) single crystals were investigated as a function of temperature. The photoluminescence excitation, emission and decay kinetic analysis revealed an efficient energy transfer from Gd 3 þ ions towards all the Dy 3 þ , Sm 3 þ , Eu 3 þ and Tb 3 þ activators. The intensity ratio between electric dipole and magnetic dipole emission transitions in activator's ions suggested a high homogeneity of the host lattice grown by Czochralski technique. Only the Gd 3 Ga 3 Al 2 O 12 single crystal activated with Dy 3 þ ions exhibited a stable lumines- cence up to 800 K. The Sm 3 þ , Eu 3 þ and Tb 3 þ doped Gd 3 Ga 3 Al 2 O 12 single crystals showed the onset of the thermal quenching of luminescence at lower temperatures. We proposed three different models, very well-known from the literature, to explain the mechanisms responsible for thermal quenching of acti- vator's luminescence in Gd 3 Ga 3 Al 2 O 12 single crystal. & 2016 Elsevier B.V. All rights reserved. 1. Introduction Rare-earth aluminum garnets, having a general formula of RE 3 Al 5 O 12 (REAG, RE ¼ lanthanide and Y), are an important family of multi-functional materials. The YAG might be the best known garnet compound owing to its excellent chemical stability, high creep resistance, optical isotropy and particularly the ability to accept various trivalent RE 3 þ for diverse optical functionalities. In the bulk form, the YAG:Nd 3 þ single crystal is one of the most widely used solid laser material since its discovery in the 1960s [1]. However, soon the potential of Ce 3 þ doped YAG single crystal for fast scintillators was realized [2]. Cerium activated YAG and LuAG are well-known scintillators, where the former was widely applied a time ago in the cathodoluminescent detectors in electron microscopy [2], and the latter has undergone an intense research and development in the past decade [3]. Recently, a high quality Pr 3 þ activated YAG single crystal has shown an excellent scintil- lation properties [4], and the Pr 3 þ doped LuAG was also announced as a fast and efficient scintillator [5]. The YAG:Ho 3 þ and YAG:Er 3 þ are an important infrared solid laser materials for medical surgery [6]. In the powder form, RE-activated (Ce 3 þ , Eu 3 þ , Tb 3 þ etc.) YAG is being widely studied and used as a phosphor for fluorescent lamps, field emission displays and white LEDs [7,8]. The Y 3 Al 5 O 12 activated with Dy 3 þ is one of the candidates for thermographic phosphors that can be used for simultaneous non- intrusive measurement of the temperature and velocity fields in a high temperature flows of the combustion systems [9,10]. In the REAG host lattice, the rare-earth occupies a dodecahedral site with eightfold oxygen coordination, two of the five aluminum cations occupy octahedral sites and three occupy tetrahedral sites. The rare earth site can be replaced by the smaller Lu or the larger Gd or La ions, and Al can be replaced by the larger Ga 3 þ or the even Sc 3 þ . Two Al 3 þ can also be replaced by one Mg 2 þ plus one Si 4 þ or Ge 4 þ while maintaining the garnet crystal structure type, and many others substitution are possible [11]. The very wide solid solution compositional variation enables optimization of proper- ties. For example, the crystal filed interaction and the red shift can be manipulated enabling color tuning of emission [12]. In recent years, mainly Pr 3 þ and Ce 3 þ activated (Y,Gd) 3 (Ga , Al) 5 O 12 crystals have been intensively studied for application as a scintillating materials [3,12]. Interestingly, such host lattice doped with the other RE ions has been much less explored. However, GGAG material may hold a number of merits for optical applications: (i) the intrinsic 8 S 7/2 - 6 I J excitation transition of Gd 3 þ (usually cantered at  275 nm) can be utilized as a new excitation source for some types of RE activators, and enhanced luminescence may also by attained via an efficient energy transfer from Gd towards activators [8], (ii) the GGAG host lattice is more covalent than YAG due to lower electronegativity of Gd 3 þ (χ ¼ 1.20) than Y 3 þ Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jlumin Journal of Luminescence http://dx.doi.org/10.1016/j.jlumin.2016.09.053 0022-2313/& 2016 Elsevier B.V. All rights reserved. n Corresponding author at: Institute of Physics, CAS, Cukrovarnicka 10, Prague 6 16253, Czech Republic. E-mail address: bartosiewicz@fzu.cz (K. Bartosiewicz). Please cite this article as: K. Bartosiewicz, et al., J. Lumin. (2016), http://dx.doi.org/10.1016/j.jlumin.2016.09.053i Journal of Luminescence ∎ (∎∎∎∎) ∎∎∎–∎∎∎