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Concentration dependent fluorescence lifetime in nanocrystalline Y2O3:Eu phosphors
|Harald Kaps 1, Mohammad Lutful Arefin 2, Ulrich Herr 3, Heiko Paul 3|
1. Osram GmbH, Industriestraße, Herbrechtingen 89542, Germany
Nanocrystalline Y2O3:Eu powder was synthesized via chemical vapor reaction. X-ray diffraction revealed the structure of cubic yttria with crystallite sizes of about 5 nm. The Eu-dopand concentrations for the samples were determined by EDX-spectra and resulted in values in the range from 0.3% up to 16.5%.
Luminescence of the nanopowders was investigated by continuous and timeresolved UV fluorescence spectroscopy and compared to a microcrystalline Y2O3:Eu phosphor as a reference. Emission spectra show increasing intensity for higher doping concentrations. Compared to the microcrystalline material, however, the yield was significantly lower. The lifetime τ of the 5D0→7FJ transition in the nanocrystalline Y2O3:Eu was strongly enhanced in the lowest doped sample (3.71 ms for the 611 nm line) compared to the microcrystalline reference (1.07 ms). By increasing the Eu-content the lifetime τ decreased until reaching a value of 1.20 ms for the highest doping concentration.
The concentration dependent lifetime behaviour was interpreted by energy transfer between Eu ions among each other and between Eu ions and impurities as a competing process to the radiating 5D0→7FJ transition.
Presentation: Poster at E-MRS Fall Meeting 2006, Symposium C, by Harald Kaps
See On-line Journal of E-MRS Fall Meeting 2006
Submitted: 2006-05-05 13:42 Revised: 2009-06-07 00:44