科研之友
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摘要
Eu3+ (2, 5, 7 and 10 at.%) activated SrWO4 phosphors were prepared via a polyol synthesis route at low temperature (similar to 150 degrees C) under urea hydrolysis. X-ray diffraction studies of all Eu3+ doped samples corroborate good crystallinity with a tetragonal scheelite-type structure of the SrWO4 phase. The value of strain was obtained in the range similar to 0.003 to 0.004 for as-prepared (ASP) and samples annealed at 900 degrees C. Vibrational modes were studied using IR and Raman Spectroscopy. Photoluminescence studies of Eu3+ doped SrWO4 samples were carried out under 266, 394 and 464 nm excitations. An intense red emission was observed with a strong peak at similar to 613 nm due to D-5(0) -> F-7(2) transition under 266 nm. Effect of annealing at 900 degrees C on the photoluminescence properties of samples has been studied and it was found that luminescence intensity increases up to similar to 9 times (for 10 at.% Eu3+-doped SrWO4) on annealing as compared to the corresponding as-prepared sample. High asymmetric ratios (A(21)) similar to 6-13 were observed demonstrating it to be a red emitter. Calculated CIE co-ordinates of these Eu3+ doped samples under 266 nm excitation for ASP and annealed at 900 degrees C are x = 0.65 & y = 0.34, which are closer to the standard of NTSC (x = 0.67 & y = 0.33). These studies reveal that SrWO4:Eu3+ nanophosphors can be used as potential red emitting phosphors for the development of white LEDs.
- 出版日期2014
