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Study of undoped and doped zirconia nanocrystals luminescence
|Krisjanis Smits 1, Donats Millers 1, Larisa Grigorjeva 1, Janusz D. Fidelus 2, Witold Łojkowski 2|
1. Institute of Solid State Physics, University of Latvia, 8 Kengaraga, Riga LV-1063, Latvia
The study of time-resolved luminescence of undoped as well as europium and praseodymium activated zirconia free standing nanocrystals was carried out. The different excitation sources (e-beam, x-ray, lasers 4.66eV and 3.67eV, deuterium lamp) were used in experiments. The intrinsic defects related and activator luminescence bands were observed. The luminescence dependence on activators concentration is shown. The excitations in zirconia are mobile, so with increasing of activator concentration the intrinsic defects related luminescence band intensity decreases and activator luminescence intensity increases until it reaches the saturation. The thermal treatment of ZrO2 nanocrystals in vacuum resulted in the change of luminescence. It is proposed that the ZrO2 nanocrystals recombinative luminescence intensity reduction is due to the oxygen loss from nanocrystals in vacuum. The relative intensities of luminescence bands due to transitions 5D0 - 7F1 and 5D0 - 7F2 of Eu3+ activated zirconia nanocrystals shows that significant fraction or Eu3+ is incorporated in low symmetry sites. The Eu3+ luminescence excited by a laser showed that this luminescence decay kinetics depends on both activator and intrinsic defects concentration in nanocrystals. The difference of intra-centre and recombinative luminescence was observed. The use of different excitation sources allow to determine role of direct excitation of luminescence centers, energy transfere by excitons to these centres and band carriers trapping involved in the creation of excited states of luminescence centres. The mechanisms of excited state creation and the possible models of luminescence centers in the nanocrystals will be discussed.
Presentation: Poster at E-MRS Fall Meeting 2007, Acta Materialia Gold Medal Workshop, by Krisjanis Smits
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-11 16:08 Revised: 2009-06-07 00:44