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Luminescent properties of Li2 (Ca0.99, Eu0.01) SiO4: B3+ particles as a potential bluish green phosphor for ultraviolet light-emitting diodes

100%

Yao S. , Chen D.

Open Physics

2007

tom 5

nr 4

558-569

In our study, the 1% mol Eu2+ doped Li2CaSiO4: B3+ phosphors were prepared by the combustion method as fluorescent material for ultraviolet, light-emitting diodes (UV-LEDs) used as a light source. The properties of Li2 (Ca0.99, Eu0.01) SiO4: B3+ phosphors with urea concentration, doping boric acid and a series of initiating combustion temperature were investigated. The crystallization and particle sizes of Li2 (Ca0.99, Eu0.01) SiO4: B3+ has been investigated by using powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). Luminescence measurements showed that the phosphors can be efficiently excited by UV to the visible region, and exhibited bluish green light with a peak of 480 nm. The results showed that the boric acid was effective in improving the luminescence intensity of Li2 (Ca0.99, Eu0.01) SiO4: B3+ and the optimum molar ratio of boric acid to calcium nitrate was about 0.06. The optimized phosphors Li2 (Ca0.99, Eu0.01) SiO4: B0.063+ showed 180% improved emission intensity compared with that of the Li2 (Ca0.99, Eu0.01) SiO4 phosphors under ultraviolet (λex =287 nm) excitation.

Combustion synthesis and luminescent properties of green-emitting phosphor (Sr, Zn) Al2O4: Eu2+, B3+ for white light emitting diodes (WLED)

100%

Yao S.-S. , Li Y.-Y. , Chen D.-H. , Tang W.-J. , Peng Y.-H.

Open Physics

2009

tom 7

nr 1

96-101

In this study, the phosphors (Sr1−x , Znx)0.9(Al2−y , By)O4 doped 10 mol % Eu2+, were prepared by combustion method as the fluorescent material for white light emitting diodes (WLEDs), performing as a light source. The luminescent properties were investigated by changing the combustion temperature, the boron concentration, and the ratio of Sr to Zn. The luminescence, crystallinity and particle morphology were investigated by using a luminescence spectrometer, X-ray diffractometer (XRD) and transmission electron microscopy (TEM), respectively. The highest intensity of Sr0.9(Al2−y , By)O4: Eu0.12+ phosphor was achieved when the combustion temperature was 600° and the concentration of B3+ was 8 mol % of the aluminate. A new blue emission was observed when the high Zn concentration (x ⩾ 0.8), and this blue emission disappeared with the Zn concentration became lower than 0.8. The combustion method synthesized phosphor (Sr0.6, Zn0.4)0.9(Al1.92, B0.08)O4: Eu0.12+ showed 3.3 times improved emission intensity compared with that of the Sr0.9(Al1.92, B0.08)O4:Eu0.12+ phosphor under λex = 390 nm.

Nano-silica reinforced hybrid light-diffusing films with enhanced mechanical and thermal properties

88%

Sun X. , Li N. , Hang J. , Jin L. , Shi L. , Cheng Z. , Shang D.

Optica Applicata

2015

tom Vol. 45, nr 3

393--404

Ultraviolet-curable hybrid light-diffusing films with good optical, mechanical and thermal properties were prepared by involving vinyl-silane-modified nano-silica into light-diffusing films. The light-diffusing films were two-phase materials consisting of UV-curable matrix and light-diffusing agent. The effect of three different light-diffusing agents, viz. inorganic layered particle (CaCO3), spherical acrylic resin (MR-7HG) and organosilicone resin (KMP-590) and their contents, on the optical properties of light-diffusing films was studied. The results showed the light-diffusing film exhibited good optical properties (the transmittance was 90.7% and the haze was 95.5%) when KMP-590 was a light-diffusing agent and its content was 25%. It was because that KMP-590 showed good transparency, good dispersion in the UV-curable matrix and the greater difference in refractive index with UV-curable matrix and polycarbonate substrate. Furthermore, the effect of nano-silica on the optical, mechanical and thermal properties of the hybrid light-diffusing films was investigated. Compared to that of the light-diffusing films without nano-silica, the haze of the hybrid light-diffusing films containing nano-silica was lightly enhanced to above 98%, while their transmittance basically remained unchanged at a high value (above 89%). Additionally, scratch and abrasion resistance of the hybrid films were obviously improved by nano-silica especially with the particle size of 10–15 nm. Furthermore, the mechanical property and thermal stability of the hybrid films were improved as the content of nano-silica with the particle size of 10–15 nm increased. The enhanced mechanical property and thermal stability of the films could be attributed to the dense structure induced by the increase in network density with the addition of vinyl-silane-modified nano-silica.