Effects of Sintering Route and Flux on the Luminescence and Morphology of YAG: Ce Phosphors for White Emitting-Light Diodes (LEDs)

2012 ◽  
Vol 236-237 ◽  
pp. 9-15
Author(s):  
Tao Han ◽  
Shi Xiu Cao ◽  
Ming Xing Ma ◽  
Da Chuan Zhu ◽  
Cong Zhao ◽  
...  
Keyword(s):  
White Light ◽  
Potential Application ◽  
Color Temperature ◽  
Precipitation Method ◽  
Photoluminescence Intensity ◽  
White Led ◽  
White Leds ◽  
Chromaticity Coordinates ◽  
Co Precipitation ◽  
Surface Morphologies

YAG:Ce phosphors were synthesized by co-precipitation method. The photoluminescence intensity of samples sintered by the two-step route increases by about 10%, and with 0.5 wt.% NH4Cl added as flux, surface morphologies and size distribution are improved. The white LEDs were fabricated using as-obtained phosphors. It shows natural white light with chromaticity coordinates of (0.3083, 0.3163), color temperature (Tc) of 6886 K, the average CRI of 75, and the luminous efficacy of 85 ml/W. Therefore, The as-obtained YAG:Ce phosphors could be regard to have potential application in white LED devices.

scholarly journals Luminescence and energy transfer of warm white-emitting phosphor Mg2Y2Al2Si2O12:Dy3+,Eu3+ for white LEDs

RSC Advances ◽  
2021 ◽  
Vol 11 (52) ◽  
pp. 32707-32716
Author(s):  
Zizhong Zhu ◽  
Chunjing Tao ◽  
Zhijun Wang ◽  
Zhiping Yang ◽  
Panlai Li
Keyword(s):  
Energy Transfer ◽  
White Light ◽  
Color Temperature ◽  
White Leds ◽  
Warm White Light ◽  
Chromaticity Coordinates ◽  
Cie Chromaticity

MYAS:xDy3+,yEu3+ can produce warm white light with CIE chromaticity coordinates of (0.4071, 0.3944) and relative color temperature of 3500 K.

Co-Precipitation Synthesis and Photoluminescence Properties of K2SiF6:Mn4+ Red Phosphor for White Light Emitting Diodes

2019 ◽  
Vol 807 ◽  
pp. 101-109
Author(s):  
Di Wu ◽  
Xin Yu Ye ◽  
Lin Sheng Wang ◽  
Qing Hua Zeng
Keyword(s):  
White Light ◽  
Luminescent Properties ◽  
Color Temperature ◽  
Precipitation Method ◽  
Light Emitting ◽  
Warm White Light ◽  
Co Precipitation ◽  
White Light Emitting Diodes ◽  
Color Rendering ◽  
Fluorescence Spectrometer

A novel red-emitting K2SiF6:Mn4+ phosphors with different Mn4+ doping mole fraction were synthesized by co-precipitation method. X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and fluorescence spectrometer were used to characterize the properties of K2SiF6:Mn4+ phosphors. As-prepared K2SiF6:Mn4+ phosphors have cubic crystal structure. Under excitation at 450 nm, an intense red emission peak around 632 nm corresponding to the 2Eg-4A2 transition of Mn4+ was observed for 8.37 mol% K2SiF6:Mn4+ phosphors and was used as the optimum doping concentration. The excellent luminescent properties make the phosphor K2SiF6:Mn4+ a candidate for applications in InGaN-YAG:Ce3+ type LEDs for high color rendering. “A warm” white light LED with an efficiency of 147 lm/w and a color rendering index of 87.4 at a color temperature of 2864K has been obtained by fabricating YAG:Ce3+ with K2SiF6:Mn4+ on an InGaN chip.

Novel Fe3O4/HNT@rGO composite via a facile co-precipitation method for the removal of contaminants from aqueous system

RSC Advances ◽  
2016 ◽  
Vol 6 (54) ◽  
pp. 49228-49235 ◽  
Author(s):  
Chengwei Gao ◽  
Baojun Li ◽  
Ning Chen ◽  
Jie Ding ◽  
Qiang Cai ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Water Treatment ◽  
Potential Application ◽  
High Performance ◽  
Aqueous System ◽  
Precipitation Method ◽  
Precipitation Process ◽  
System P ◽  
Removal Of Contaminants ◽  
Co Precipitation

Fe3O4/HNT@rGO composite (FHGC) was fabricated via a facile co-precipitation process, followed by heat treatment. For RhB and As5+removal, the high performance and easy separation of FHGC highlight its potential application in water treatment.

Growth and Light Properties of Fluorescent SiC for White LEDs

2012 ◽  
Vol 717-720 ◽  
pp. 87-92
Author(s):  
Mikael Syväjärvi ◽  
Rositza Yakimova ◽  
Motoaki Iwaya ◽  
Tetsuya Takeuchi ◽  
Isamu Akasaki ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
White Light ◽  
Energy Savings ◽  
Red Light ◽  
Visible Range ◽  
White Led ◽  
Light Emitting ◽  
Blue Led ◽  
White Leds ◽  
New Type

The LED technology started to developed many years ago with red light emitting diodes. To achieve the blue LED, novel growth technologies and process steps were explored, and made it possible to demonstrate efficient blue LED performance from nitrides. The efficiency was further developed and blue LEDs were commercially introduced in the 1990’s. The white LED became possible by the use of the blue LED and a phosphor that converts a part of the blue light to other colors in the visible range to combine into white light. However, even today there are limitations in the phosphor-based white LED technology, in particular for general lighting, and new solutions should be explored to speed the pace when white LEDs will be able to make substantial energy savings. In this paper we overview gallium nitride materials evolution and growth concepts for LEDs. We describe the fluorescent silicon carbide material prepared by a novel growth technology for a new type of white LED in general lighting with pure white light. This paper introduces an interesting research in fundamental growth and optical properties of light emitting silicon carbide.

Fabrication and Luminescence Properties of CaMoO4:Eu3+ Red Phosphors for White LED

2010 ◽  
Vol 663-665 ◽  
pp. 441-444
Author(s):  
Zhen Hua Liang ◽  
Yu Zhi Feng ◽  
Xiao Xia Liu ◽  
Gui Hua Peng
Keyword(s):  
Luminescent Properties ◽  
Luminescence Properties ◽  
Precipitation Method ◽  
White Led ◽  
Doping Amount ◽  
Red Phosphors ◽  
Co Precipitation ◽  
The Relationship

CaMoO4: Eu3+ red phosphors were synthesized by co-precipitation method with H3BO3 as an additive and the relationship between H3BO3 doping amount and luminescent properties were studied. The brightness increased with increasing H3BO3 amount, the brightness of the CaMoO4: Eu3+ powder with 10 mol％ H3BO3 was 3.2 times higher than that of the phosphor without H3BO3.

Moisture-resistant Nb-based fluoride K2NbF7:Mn4+ and oxyfluoride phosphor K3(NbOF5)(HF2):Mn4+: synthesis, improved luminescence performance and application in warm white LED

2021 ◽  
Author(s):  
Ge Pang ◽  
Feng Hong ◽  
Xiaoyi Liu ◽  
Yunxiao Zhang ◽  
Chunyan Zhang ◽  
...  
Keyword(s):  
Acid Solution ◽  
High Efficiency ◽  
Precipitation Method ◽  
White Led ◽  
Co Precipitation ◽  
Moisture Resistant ◽  
Luminescence Performance

Herein, high-efficiency Nb-based oxyfluoride K3(NbOF5)(HF2):Mn4+ and fluoride K2NbF7:Mn4+ phosphors were successfully synthesized using different amounts of HF acid solution by simple co-precipitation method. XRD, SEM and EDS were used to...

scholarly journals Chromaticity Study of Curcumin Dye Extracted from Curcuma longa L. Using for UV Light down Conversion for White Light Emitting Diode

2019 ◽  
Vol 290 ◽  
pp. 183-189
Author(s):  
Mahmood Al Shafouri ◽  
Naser Mahmoud Ahmed ◽  
Zainuriah Hassan ◽  
Munirah Abdullah Almessiere
Keyword(s):  
White Light ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Curcuma Longa ◽  
Color Temperature ◽  
Light Emitting ◽  
Chromaticity Coordinates ◽  
Major Factors ◽  
Color Rendering ◽  
Down Conversion

In thus study, Turmeric phosphor dye was extracted from Curcuma Longa L. via a simple technique using silica gel. The phosphor was used for light down-conversion of UV light for the manufacture white light emitting diode (WLED). The UV-LED was analyzed over 395nm wavelengths. The characteristics of the white light chromaticity were controlled by tuning the current and phosphor concentration. An optimum color rendering index (CRI) value of 63.4 was obtained. The chromaticity coordinates (CIE) and correlated color temperature (CCT) were measured for various currents and phosphor concentrations. The white phosphor exhibited CIE value of 0.355,0.338 and CCT of 4567 K. The concentration of phosphor and amount of applied current were confirmed to be major factors that control the intensity of white light emitted from the sample, where CIE and CRI of the emitted light steadily increased with the concentration of phosphor and current. Thus, phosphor concentration has a critical effect on conversion efficiency. Key words: Turmeric, phosphor, WLED, curcumin

scholarly journals Simultaneously Improve White LED Omni-Directional Package Efficacy and Spatial Color Uniformity on Scattered Photon Extraction Technology

Crystals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 21 ◽  
Author(s):  
Tsung-Xian Lee ◽  
Yun-Chieh Huang
Keyword(s):  
Extraction Efficiency ◽  
Critical Index ◽  
Light Extraction Efficiency ◽  
Color Temperature ◽  
Scattered Photon ◽  
Lens Design ◽  
White Led ◽  
Extraction Technology ◽  
White Leds ◽  
Color Uniformity

The Scattered Photon Extraction (SPE™) based on the concept of TIR lens combined with remote phosphor is proven to be one of the effective solutions for improving white LED efficiency, and it provides the omnidirectional light distribution for luminaire design. Not only the light extraction efficiency (LEE) is important, but also the angular uniformity of correlated color temperature (CCT) is a critical index in the evaluation of high-quality white LEDs. A non-optimized SPE™ will cause an increase in the angular CCT deviation (ACCTD) and ultimately affect lighting quality. Two possible ways using lens design are proposed to reduce the ACCTD and even improve its efficiency. Among them, using the concept of light guiding to design the lens can minimum the deviation of forward and backward CCT from 2720 K to 657 K, and the overall efficiency can be further enhanced by 12% compared to typical SPE™ lens.

Synthesis and warm-white LED applications of an efficient narrow-band red emitting phosphor, Rb2ZrF6:Mn4+

2017 ◽  
Vol 5 (29) ◽  
pp. 7253-7261 ◽  
Author(s):  
L. Y. Wang ◽  
E. H. Song ◽  
Y. Y. Zhou ◽  
T. T. Deng ◽  
S. Ye ◽  
...  
Keyword(s):  
Narrow Band ◽  
Precipitation Method ◽  
White Led ◽  
Red Phosphor ◽  
Yellow Phosphor ◽  
Co Precipitation ◽  
Red Emitting Phosphor

Phosphor Rb2ZrF6:Mn4+has been synthesizedviaa co-precipitation method. Series of WLEDs were fabricated by combining YAG:Ce3+yellow phosphor and different amount of Rb2ZrF6:Mn4+red phosphor with InGaN blue chips.

Enhancement of white-light-emission from single-phase Sr5(PO4)3F:Eu2+,Mn2+ phosphors for near-UV white LEDs

2015 ◽  
Vol 44 (33) ◽  
pp. 15006-15013 ◽  
Author(s):  
Yaomiao Feng ◽  
Jinping Huang ◽  
Lili Liu ◽  
Jie Liu ◽  
Xibin Yu
Keyword(s):  
White Light ◽  
Electronic Structures ◽  
Single Phase ◽  
Light Emission ◽  
White Light Emission ◽  
Photoluminescence Intensity ◽  
White Leds ◽  
The Relationship ◽  
Uv Excitation

Single-phase Sr5(PO4)3F:Eu2+,Mn2+ phosphors are prepared, showing white-light emission under near UV excitation. The photoluminescence intensity is enhanced by 85% by using KCl as flux. The relationship between photoluminescence and the crystal and electronic structures is studied.

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