Eu Luminescence in zirconia nanocrystals
|Krisjanis Smits 1, Donats Millers 1, Larisa Grigorjeva 1, Anatolijs Sarakovskis 1, Agnieszka Opalińska 2, Janusz D. Fidelus 2, Witold Łojkowski 2|
1. Institute of Solid State Physics, University of Latvia, 8 Kengaraga, Riga LV-1063, Latvia
The time – resolved luminescence of Eu3+ in a pure and Yttria – stabilized zirconia nanocrystals was studied. For luminescence excitation different excitation sources was used: tunable pulsed solid state laser NT342/3UV (pulse duration ~4 ns) from Ekspla (210-355nm; 420-2300nm) with Andor SR-303i-B spectrometer and YAG laser 4-th harmonic (pulse duration ~2 ns) with MDR3 grating monohromator, PMT and photon counting board for time resolution measurements. The size and phase was characterized with BET and XRD (Diffractometer X’Pert Pro MPD).
The zirconia nanocrystals were produced by the microwave driven hydrothermal method. The luminescence spectra shows typical (592nm- 5D0 – 7F1 and 613nm- 5D0 – 7F2) Eu3+ bands. With increase of europium concentration luminescence from host defects decreases, but Eu3+ luminescence increases. This indicates the energy transfer from host to dopant.
The increase of Eu concentration led to the appearance of additional 5D0 – 7F2 (electric dipole) luminescence band. It was showed this band is due to change of nanocrystal structure. The observed splitting as well as the decay kinetics of luminescence gave a strong witness that the Eu3+ in ZrO2 is incorporated in two different symmetry sites. The XRD spectrum confirms that with increase of Eu concentration tetragonal phase appears. The 5D0 – 7F2 transitions in the monoclinic and tetragonal phase zirconia have slightly different energies and this was confirmed by the luminescence excitation spectra – the monoclinic and tetragonal phases have different excitation spectra.
The work was partly supported by grants 05.0026 of LCS and no. N N508 0851 33 of MNiSW granted for the years 2007 – 2009
Presentation: Poster at E-MRS Fall Meeting 2008, Symposium I, by Krisjanis Smits
See On-line Journal of E-MRS Fall Meeting 2008
Submitted: 2008-05-19 16:23 Revised: 2009-06-07 00:48