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In this work, a Cs2ZrF6:Mn4+ red phosphor, a novel and efficient supplement for commercial Y3Al5O12:Ce3+ type white light-emitting diodes (WLEDs), is successfully fabricated on a large scale through a cation exchange method using K2MnF6 as the Mn4+ source at ambient temperature. The crystal structure and morphology were characterized using powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), in detail. The complex is well crystallized in a single-phase with particulate morphology and presents sharp red emissions under blue light illumination. From the aspects of Ra and Tc, the optical performance of a WLED made with the Cs2ZrF6:Mn4+ red phosphor supplement is significantly improved and it can be used for indoor lighting applications. [ABSTRACT FROM AUTHOR]

A single-phased Mn4+ doped fluorozirconate red phosphor, K3ZrF7:Mn4+, has been successfully synthesized. Its structure, morphology, composition and optical properties were investigated by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic absorption spectroscopy, diffuse reflectance spectroscopy, photoluminescence spectroscopy and by using luminescence decay curves. It was found that Mn4+ ions only coordinating with seven F− anions in a K3ZrF7 crystal field can possess intense red emission under blue light illumination. Mixing the obtained K3ZrF7:Mn4+ red phosphor with commercial Y3Al5O12:Ce3+ and coating the mixture on a blue-GaN chip, obvious warm white light with a low correlated color temperature (2970 K) and a high color rendering index (Ra = 91.4 and R9 = 72) were achieved from white light-emitting diode devices. [ABSTRACT FROM AUTHOR]

Ca3SiO4Cl2 co-doped with Ce3+,Eu2+ was prepared by high temperature reaction. The structure, luminescent properties and the energy transfer process of Ca3SiO4Cl2: Ce3+,Eu2+ were investigated. Eu2+ ions can give enhanced green emission through Ce3+,Eu2+ energy transfer in these phosphors. The green phosphor Ca2.9775SiO4Cl2:0.0045Ce3+,0.018Eu2+ showed intense green emission with broader excitation in the near-ultraviolet light range. A green light-emitting diode (LED) based on this phosphor was made, and bright green light from this green LED could be observed by the naked eye under 20mA current excitation. Hence it is considered to be a good candidate for the green component of a three-band white LED. [ABSTRACT FROM AUTHOR]

Red phosphors K 2 XF 6 :Mn 4+ (X = Ti, Si and Ge) have been successfully synthesized by one-pot chemical co-precipitation method in low HF concentration with the addition of acetic acid glacial. The crystal structure and morphology of these phosphors were characterized by powder X-ray diffraction (XRD), scanning-electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) in detail. Their optical properties were investigated by excitation and emission spectra, diffuse reflectance spectra, and decay curves. These phosphors exhibit intense red emission with high color-purity under blue light excitation. Finally, the applications on the white-light-emitting diodes (WLEDs) of the as-prepared sample were investigated. The WLEDs fabricated with K 2 XF 6 :Mn 4+ display warm white light with lower color temperature ( T c < 4000 K) and higher color rendering index ( Ra > 80). [ABSTRACT FROM AUTHOR]

Cs2TiF6:Mn4+ powder as a novel red phosphor has been successfully fabricated on a large scale through the cation exchange method using K2MnF6 as a Mn4+ source at ambient temperature. The Cs2TiF6:Mn4+ product is well crystallized into a single-phase with a hexagonal micro-rod morphology and presents sharp red emissions under blue light illumination. It can significantly improve Ra and CCT levels of the YAG type white LED used for indoor lighting. [ABSTRACT FROM AUTHOR]

LaBSiO5 phosphors doped with Ce3+ and Tb3+ were synthesized using the conventional solid-state method at 1100 °C. The phase purity and luminescent properties of these phosphors are investigated. LaBSiO5:Tb3+ phosphors show intense green emission, and LaBSiO5 phosphors doped with Ce3+ show blue-violet emission under UV light excitation. LaBSiO5 phosphors co-doped with Ce3+ and Tb3+ exhibit blue-violet and green emission under excitation by UV light. The blue-violet emission is due to the 5 d-4 f transition of Ce3+ and the green emission is ascribed to the 5 D4 → 7 F5 transition of Tb3+. The spectral overlap between the excitation band of Tb3+ and the emission band of Ce3+ supports the occurrence of energy transfer from Ce3+ to Tb3+, and the energy transfer process was investigated. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this work, we report a new and efficient red phosphor BaGeF6:Mn4+ (denoted as BGFM) by hydrothermally etching BaCO3 and GeO2 in HF solution with an optimized KMnO4 concentration. The crystal structure and morphology were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) in detail. The influence of synthesis conditions on its photo-luminescent (PL) properties has been investigated comprehensively. It can present broad adsorption and sharp emissions in blue and red ranges respectively. The white LED device made of a blue GaN chip merged with a YAG:Ce–BGFM mixture presents warmer white light than that merged with only one YAG:Ce component. [ABSTRACT FROM AUTHOR]

Red-emitting phosphors LaBSiO 5 :Eu 3+ and LaBSiO 5 :Eu 3+ , Al 3+ were synthesized by the conventional solid state method at 1100 °C. The structure and luminescent properties of these phosphors are investigated. LaBSiO 5 :Eu 3+ and LaBSiO 5 :Eu 3+ , Al 3+ could be efficiently excited by near ultraviolet light with the strongest excitation peak at 395 nm. The main emission peak is located at around 616 nm, which corresponds to the transition of 5 D 0 → 7 F 2 of Eu 3+ ions. The emission intensity of LaBSiO 5 :Eu 3+ was enhanced by introducing Al 3+ ions. Compared with Y 2 O 2 S:0.05Eu 3+ , the sample La 0.70 B 0.75 SiO 5 :0.30Eu 3+ , 0.25Al 3+ shares the intense red emission, and its emission intensity is about 3.8 times as strong as that of Y 2 O 2 S:0.05Eu 3+ under 395 nm light excitation. Bright red light can be observed from the red LED based on La 0.70 B 0.75 SiO 5 :0.30Eu 3+ , 0.25Al 3+ , hence La 0.70 B 0.75 SiO 5 :0.30Eu 3+ , 0.25Al 3+ maybe find application on near-UV InGaN-based white LEDs. [ABSTRACT FROM AUTHOR]

Abstract: New red tungstates phosphors, Na5La1−x Ln x (WO4)4 (Ln=Eu, Sm) and Na5Eu1−x Sm x (WO4)4, were prepared by solid-state reaction technique. And their structure and photo-luminescent properties were investigated. The introduction of Sm3+ broadened the excitation band around 400nm of the phosphors, and strengthened the red emission. And the possible energy transfer process from Sm3+ to Eu3+ is discussed. The single red LED was fabricated by combining InGaN chip with Na5Eu0.94Sm0.06(WO4)4 as red phosphor, intense red light can be observed by naked eyes. Then the phosphor Na5Eu0.94Sm0.06(WO4)4 may be a good candidate for red component of near-UV InGaN-based W-LEDs, because of efficient red-emitting with broadened absorption around 400nm and appropriate CIE chromaticity coordinates (x =0.65, y =0.34). [Copyright &y& Elsevier]

Abstract: The phosphors, NaLa1−x Tb x (MoO4)2 and NaLa1−x Tbx(WO4)2, were prepared by the solid-state reaction. The structures and photoluminescent properties of the phosphors were studied. The result of XRD patterns indicates that these phosphors are of the similar scheelite-like (CaWO4) isostructure. The absence of concentration quenching of Tb3+ was observed in NaLa1−x Tb x (WO4)2 by investigating their photoluminescent properties. This phenomenon has not been reported before, as we known. The phosphor NaTb(WO4)2 shows stronger green emission under 378nm excitation with broader excitation band, compared with NaLa1−x Tb x (MoO4)2. [Copyright &y& Elsevier]

Abstract: A series of new red phosphors, NaEu(MoO4)2−2x (SO4)2x , were prepared by the conventional solid state reaction. Their excitation spectra, emission spectra and decay curves were measured at room temperature. When the SO4 2− content is in excess of 20%, other phases appear. With the introduction of SO4 2−, the Mo–O charge transfer band of NaEu(MoO4)2−2x (SO4)2x shows red shift, and the excitation intensities of the 4f – 4f transitions of Eu3+ are strengthened, compared with that of NaEu(MoO4)2. The single red light-emitting diodes-based these phosphors were fabricated. The light-emitting diode fabricated with the phosphor NaEu(MoO4)1.80(SO4)0.20 exhibited higher red emission relative to that with NaEu(MoO4)2. Bright red light can be observed by naked eyes from the light-emitting diode-based NaEu(MoO4)1.80(SO4)0.20. [Copyright &y& Elsevier]

The article presents a study which examines the feasibility of using Dendrocalamus barbatus as a substitute for wood fiber. The researchers have collected the samples of D. barbatus culms of different ages from the acquaculture ponds in Yunnan, China. The samples of chipped specimens were taken in Petri dishes and observed under the microscope for measurement of fiber length, width, and wall thickness. The study shows that D. barbatus has good potential as a raw material for pulp.

Abstract: The red phosphor NaEu(MoO4)2 was prepared by the combustion method, and its morphology and structure were measured by the X-ray diffraction (XRD) and scanning electronic microscopy (SEM). Its photo-luminescent properties were investigated and compared with that prepared by the high temperature solid state reaction method. The sample prepared by the combustion method with the firing temperature at 800 °C is of uniform particles size (about 500 nm), and it shows the intense red light emission under 395 nm excitation with the appropriate CIE chromaticity coordinates (x =0.66, y =0.34), therefore it may find application on near UV InGaN chip-based white light-emitting diodes. [Copyright &y& Elsevier]

Abstract: NaEu0.96Sm0.04(MoO4)2 was prepared by the Pechini method (P phosphor) and as a comparison, also by solid-state reaction technique (S phosphor). The photo-luminescent properties, the morphology and the grain size were investigated. The phosphors show broadened excitation band around 400nm, high intensity of Eu3+ 5 D 0→7 F 2 emission upon excitation around 400nm, and appropriate CIE chromaticity coordinates. Intensive red light-emitting diodes (LEDs) were fabricated by combining the phosphor and a 400nm InGaN chip for the first time, which confirm that the phosphor is a good candidate for near UV LED. The luminescent intensity of P phosphor prepared at 700°C is near that of S phosphor prepared at 800°C. In addition, P phosphor shows advantages of lower calcining temperature, shorter heating time, and smaller grain size. Considering all these factors, the suitable method for preparing the promising near UV LED phosphor NaEu0.96Sm0.04(MoO4)2 is recommended to be the Pechini process at 700°C. [Copyright &y& Elsevier]