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Luminescence properties of cerium doped Y3Al5O12 nanopowders and nanoceramic
|Vladimir Pankratov 1, Larisa Grigorjeva 1, Donats Millers 1, Tadeusz Chudoba 2, Witold Łojkowski 2|
1. Institute of Solid State Physics, University of Latvia, 8 Kengaraga, Riga LV-1063, Latvia
Nanostuctured Y3Al5O12 (YAG) doped by various rare-earth ions is perspective raw material for transparent scintillating and/or laser ceramics. The nominally pure as well as cerium doped YAG nanocrystals (nanopowders) with the grain size ~20 nm and higher were obtained by co-precipitation methods. Translucent cerium doped YAG nanoceramic samples were sintered from nanopowders by means of high pressure and low temperature technique. Nominally pure and doped nanopowders and nanoceramics have been studied by means of time-resolved luminescence spectroscopy. Luminescence measurements were carried out using three different excitation sources: pulsed synchrotron radiation at the SUPERLUMI station at HASYLAB (DESY, Hamburg), the pulsed electron beam (270 keV, 10ns, 1012 el/pulse), pulsed lasers (266 nm, 337 nm and 532 nm).
It was shown that nanaoceramic’s sintering processes have a strong influence on luminescence properties of the material. In fact it was detected that nanostructured cerium doped YAG ceramic has worse luminescence intensity comparing to luminescence intensity for the starting nanopowder. Decay kinetics of cerium related emission could be approximated by sum of two exponents (fast and slow) in all nanoobjects studied. It was shown that the intensities ratio of fast and slow components is significant parameter. This parameter shows a relative concentration of impurity ions on the nanoparticle’s surface. The model proposed is based on the assumption that the distribution of impurity ions is different in a single crystal, nanopowders and nanoceramics and it is suggested that quenching processes on grain borders of nanopowders and nanoceramics play a key role.
The comparison of luminescence properties for nano- and single- crystals shows that nanosized YAG may offer an advantage in respect to single crystal and further investigation and production of nanocristalline YAG are perspective.
Presentation: Poster at E-MRS Fall Meeting 2007, Acta Materialia Gold Medal Workshop, by Vladimir Pankratov
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-14 14:58 Revised: 2009-06-07 00:44