Tuning of luminescence properties by controlling an aid-sintering additive and composition in Na(Ba/Sr/Ca)PO4:Eu2+ for white LEDs. Issue 36 (21st April 2017) - Bai, Qiongyu
Abstract : A series of Na(Ba/Sr/Ca)PO4 :Eu 2+ phosphors were prepared via a high-temperature solid-state reaction method. Abstract : A series of Na(Ba/Sr/Ca)PO4 :Eu 2+ phosphors were prepared via a high-temperature solid-state reaction method. When the phase of NaCaPO4 :Eu 2+ was pure, the luminescence of Eu 2+ was enhanced by doping the sintering-aid additive NaCl ( t ), and it showed a maxima at t = 0.03. For NaCaPO4 :Eu 2+ with 0.03NaCl, the XRD patterns, and emission and decay spectra demonstrated that Eu 2+ ions occupied two different Ca sites with different coordination ( i.e., eight and seven coordination). Therefore, two green emission bands at 510 and 542 nm were observed, and the emission band ranging from 480 to 510 nm had a weaker intensity. To obtain a cyan-broad emission, Ba 2+ or Sr 2+ were introduced into NaCaPO4 :0.01Eu 2+ . The substitution of small Ca 2+ ions by large Ba 2+ or Sr 2+ ions induced a decreased crystal field splitting of Eu 2+ ions, which resulted in various full width at half maximum and a blue shift. The colors varied from green (0.1996, 0.4380) to blue (0.1578, 0.0978) under the same excitation. Overall, the phosphor has promising applications for use in white LEDs.