Abstract
Highly intense, long persistent Sr4Al14O25:Eu2+,Dy3+ blue-green phosphor with different B3+, Eu2+, Dy3+, and Ag+ contents was prepared by solid-phase reaction at various temperatures in reductive atmosphere of 10% H2 in N2. The effects of synthesis parameters like calcination temperature and time, calcination environment, effect of stoichiometry of the host composition, and additives like addition of boron and rare earth ions (Eu, Dy) were studied in detail. Results revealed that the phosphor containing ~40 mol% H3BO3 showed dense and pure Sr4Al14O25 phase with higher emission intensity, but in the samples containing less than 20 mol% H3BO3 mixed phases consisting of Al2O3, SrAl12O19 and SrAl2O4 were observed, while in higher H3BO3 content, SrAl2B2O7 phases predominated. When the stoichiometry of Al/Sr was 3.7, the best phosphorescence and afterglow were noted. The phosphor containing 4 at.% of Eu and 8 at.% of Dy, and 3 at.% Ag exhibited the maximum initial intensity of 5170 mcd·m−2 and the longest persistency of greater than 30 hours over the value of 5 mcd·m−2, higher than the commercial products and applicable for various display applications involving indoor as well as outdoor uses.
Highlights
Phosphor materials with long afterglow is a kind of energy storing materials that can absorb UV-visible light from sun light, and gradually release the absorbed energy in the darkness at a certain wavelength [1]
In this paper, the systematic examination regarding composition of starting materials, rare earth ions (Eu2+, Dy3+), flux (H3BO3), charge compensator ions, reduction temperatures/time, and reduction atmosphere on the Sr4Al14O25 phosphor have been explained in detail
B0.2 and S4A7B0.4 respectively, that came from the weight loss in γ-alumina as well as the decomposition of boric acid present in the mixture
Summary
Phosphor materials with long afterglow is a kind of energy storing materials that can absorb UV-visible light from sun light, and gradually release the absorbed energy in the darkness at a certain wavelength [1]. Strontium aluminates doped with Eu divalent ion (SAE) have been investigated as an efficient phosphor that has high quantum efficiency and good stability, indicating their good practical prospects [4,5,6,7,8]. These phosphors have decay time ranging from nanosecond to tens of seconds and were used as important constituents of light emitting devices, fluorescent lamps, plasma display panels, and lamps for medical applications [9]. In this paper, the systematic examination regarding composition of starting materials, rare earth ions (Eu2+, Dy3+), flux (H3BO3), charge compensator ions, reduction temperatures/time, and reduction atmosphere on the Sr4Al14O25 phosphor have been explained in detail
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