Abstract
Using the solid state reaction method, we synthesize the Ca 0.88 Al 2 Si 2 O 8 :Eu 2+ 0.12 phosphor powders at different sintering temperatures ranging from 1100 to 1500 °C. From X-Ray diffraction patterns, we confirmed that all the samples acquired mixed CaAl 2 Si 2 O 8 (triclinic), CaAlO 4 (Monoclinic) and SiO 8 (Hexagonal) phases. For the Ca 0.88 Al 2 Si 2 O 8 :Eu 2+ 0.12 phosphors, the excitation spectra exhibited an unresolved broad band in the range from 200 to 420 nm and maximum intensity at 350 nm. The emission spectra of CaAl 2 Si 2 O 8 :Eu 2+ show broad band ranging from 400 to 560 nm and maximum wavelength is found to be at around 440nm, which can be ascribed to the electric-dipole-allowed 4f 6 5d 1 - 8 S 7/2 (4f 7 ) transition of the Eu 2+ ions. The Commission International De I-Eclairage 1931 (CIE 1931) chromaticity coordinates for Ca 0.88 Al 2 Si 2 O 8 :Eu 2+ 0.12 phosphors are calculated and represented at (0.168, 0.144).
Highlights
Light emitting diodes (LED) are the promising candidates for generation solid lighting material owing to their lower energy consumption, high brightness, environmentally-friendliness, fast switching, small in size, longer lifetime and high efficiency, which starts to approach the theoretical limits[1,2]
A series of solid solutions containing isostructural members with slightly different size cations as hosts, such as MAl2Si2O8 (M = Ca, Sr, Ba) would be an ideal system to study the effect of crystal chemical variation on the luminescence of Eu2+ ions, and may offer possibilities for commercial application [18, 19]
Miller indices were assigned to the reflection peaks in the diffraction patterns by comparing the data obtained from the samples
Summary
Light emitting diodes (LED) are the promising candidates for generation solid lighting material owing to their lower energy consumption, high brightness, environmentally-friendliness, fast switching, small in size, longer lifetime and high efficiency, which starts to approach the theoretical limits[1,2]. White light emitting diodes (WLEDs) are usually fabricated with blue InGaN LED chips and yellow phosphors such as Ce3+ doped yttrium aluminum garnet (Y3Al5O12:Ce3+), Eu2+ doped oxynitrides, and Eu2+/Ce3+ doped silicate based materials[3,4,5,6]. The alkaline-earth materials of MAl2Si2O8 (M = Ca, Sr, Ba) have drawn much attention for their good luminescence properties [15,16,17]. Lifetime and CIE chromaticity coordinates of CaAl2Si2O8:Eu2+ have been be discussed with PL spectra behaviour
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