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Synthesis and luminescent properties of Sr2SiO4:Eu2+ co-doped with Ti4+ ions.
|Justyna Barzowska 1, Karol Szczodrowski 1, Krzysztof Anders 2, Ryszard Piramidowicz 2, Marek Grinberg 1|
1. University of Gdansk, Faculty of Mathematics, Physics and Information Science (UG-MFI), Wita Stwosza 57, Gdańsk 80-952, Poland
In this contribution luminescence and luminescence kinetics of Sr2SiO4:Eu2+ and Sr2Si0.95Ti0.05O4:Eu2+ are studied. The samples were synthesized using solid state method. Sr2SiO4:Eu2+ and Sr2Si0.95Ti0.05O4:Eu2+ have strong luminescence which consists of two partially overlapping broad bands with maxima at 480 nm and 570 nm. The bands are attributed to the 4f65d1 → 4f7 transitions in Eu2+ occupying in Sr2SiO4 crystal lattice two different Sr2+ sites, respectively ten-coordinated SI and nine-coordinated SII. Contribution of these two bands to the total luminescence can be controlled by choosing excitation wavelength.
Besides described above two strong emission bands, which decay in microseconds range, Sr2SiO4:Eu2+ exhibits also luminescence that lasts at room temperature for few seconds after stopping the excitation. The persistent luminescence is relatively weak at ambient conditions but can be easily seen in dark with eye. In the case of the samples co-doped with Ti4+ the persistent luminescence is significantly enhanced. We have proved that besides the concentration of Eu2+ and Ti4+ also the form of the titanium precursor used in synthesis influences on the persistent luminescence phenomenon observed in Sr2Si0.95Ti0.05O4:Eu2+ phosphor. For all investigated samples the persistent luminescence is dominated only by the one band with maximum at 570 nm, independently of the excitation wavelength. It leads to the conclusion, that traps responsible for long lasting luminescence of Sr2SiO4:Eu2+ observed at room temperature, deactivate directly and only through Eu2+ ions occupying nine coordinated SII sites.
Presentation: Poster at Nano and Advanced Materials Workshop and Fair, by Karol Szczodrowski
See On-line Journal of Nano and Advanced Materials Workshop and Fair
Submitted: 2013-07-19 14:35 Revised: 2013-07-19 14:35