scholarly journals Single Phase Cool White Light Emitting Novel Ca9Al(PO4)7: Dy3+ Nanophosphor under NUV excitation

2021 ◽  
Author(s):  
Manju Dahiya ◽  
Dinesh Kumar
Keyword(s):  
White Light ◽  
Single Phase ◽  
Emission Spectra ◽  
Critical Energy ◽  
Color Temperature ◽  
Solution Combustion ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
Crystallite Sizes ◽  
Cie Chromaticity

Abstract A series of novel single-phase white light-emitting Dy3+ doped Ca9Al(PO4)7 nanophosphors was successfully synthesized at 1100 ˚C via solution combustion route. X-ray diffraction (XRD) and Rietveld refinement analysis of Ca9Dy0.03Al0.97(PO4)7 sample confirmed that this phosphor had a trigonal crystal structure with space group R3c(161). Meanwhile, as-observed from the transmission electron microscopy (TEM) study; particles of Ca9DyxAl(1−x)(PO4)7 samples were found to have a quadrilateral shape with crystallite sizes around 40–60 nm which were also confirmed by the Debye Scherrer equation. Under near-ultraviolet (NUV) excitation at 350 nm, photoluminescence (PL) emission spectra of nanocrystalline Ca9Al(PO4)7: Dy3+ phosphors showed two peaks at 481 nm and 572 nm corresponding to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions, respectively. The optimum concentration was found to be x = 0.03 mol. The critical energy transfer distance was calculated to be 20 and further Huang analysis concluded the exact mechanism i.e. dipole-dipole interactions responsible for concentration quenching in Ca9DyxAl(1−x)(PO4)7 samples. Furthermore, the Commission Internationale de I’Eclairage (CIE) chromaticity coordinates of Ca9Dy0.03Al0.97(PO4)7 nanophosphor was calculated to be (0.260, 0.297) and this nanophosphor had correlated color temperature (CCT) of 11332 K which is located in a cool white area. Existing results indicate that Ca9Dy0.03Al0.97(PO4)7 nanophosphor may be considered as a favorable candidate in NUV based single-phase cool White light-emitting diodes (WLEDs).

Correlated color temperature tunability and energy transfer phenomenon in the NaBaBO3:Dy3+/Eu3+ phosphor for white light application

2015 ◽  
Vol 08 (06) ◽  
pp. 1550077 ◽  
Author(s):  
Jianghui Zheng ◽  
Qijin Cheng ◽  
Cheng Zheng ◽  
Guo Chen ◽  
Feng Shi ◽  
...  
Keyword(s):  
Energy Transfer ◽  
White Light ◽  
Single Phase ◽  
Color Temperature ◽  
Light Emitting ◽  
Transfer Phenomenon ◽  
Near Ultraviolet ◽  
Cie Chromaticity ◽  
Co Doped ◽  
The Eu

NaBa 0.97-x BO 3 0.03 Dy 3+, x Eu 3+(0 ≤ x ≤ 0.09) single-phase white phosphors with tunable correlated color temperature (CCT) were synthesized using a conventional solid state reaction method. The phase structure and luminescence properties of the as-prepared samples were investigated. The Dy 3+, Eu 3+ doped and Dy 3+/ Eu 3+ co-doped NaBaBO 3 phosphors excited by 361 nm show two blue and yellow emissions corresponding to the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions of Dy 3+ ions and two red emissions due to the 5 D 0 → 4 F J (J = 1, 2) transitions of Eu 3+ ions. Under 361-nm light excitation, the NaBa 0.97-x BO 3 0.03 Dy 3+, x Eu 3+(0 ≤ x ≤ 0.09) phosphors feature a white light emitting property. Through the Commission Internationale de L'Eclairage (CIE) chromaticity analysis and CCT calculation, the CIE chromaticity coordinates of the emission light are all located in the white region and can be tuned from bluish white light to reddish white light when the Eu 3+ concentration increases, and the CCT values of the obtained samples can vary from 5514.31 K to 8269.42 K. Furthermore, the energy transfer phenomenon from Dy 3+ ions to Eu 3+ ions in Dy 3+/ Eu 3+ co-doped samples was also investigated. The results indicated that, through tuning the Eu 3+ concentration of the NaBaBO 3: Dy 3+/ Eu 3+ phosphors, the NaBaBO 3-based phosphor can act as a potential single-phase white emitting phosphor for the application in the near-ultraviolet (NUV) white light emitting diodes.

High color rendering index single phase white light emitting phosphors based on Tb3+/Sm3+ co-doped CePO4 nanocrystals: the role of Tb3+ as a bridge between Ce3+ and Sm3+

2019 ◽  
Vol 43 (44) ◽  
pp. 17367-17382 ◽  
Author(s):  
Sisira S. ◽  
Linju Ann Jacob ◽  
Kamal P. Mani ◽  
Biju P. R. ◽  
N. V. Unnikrishnan ◽  
...  
Keyword(s):  
White Light ◽  
Single Phase ◽  
Color Temperature ◽  
Light Emitting ◽  
Chromaticity Coordinates ◽  
Color Rendering Index ◽  
Cie Chromaticity ◽  
Color Rendering

Single phase white light emitting CePO4 nanocrystals doped with Tb3+ and Sm3+ were synthesized. The quality of white light is characterized by CIE chromaticity coordinates, color temperature, color rendering index and quantum yield.

scholarly journals Preparation of Bismuth Oxide Photocatalyst and Its Application in White-light LEDs

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Yen-Chang Chu ◽  
Gang-Juan Lee ◽  
Chin-Yi Chen ◽  
Shih-Hsin Ma ◽  
Jerry J. Wu ◽  
...  
Keyword(s):  
Bismuth Oxide ◽  
White Light ◽  
Front Surface ◽  
Color Temperature ◽  
Spray Pyrolysis Method ◽  
Light Emitting ◽  
White Leds ◽  
Air Purifier ◽  
Cie Chromaticity ◽  
White Light Emitting Diodes

Bismuth oxide photocatalysts were synthesized and coated on the front surface of phosphor-converted white light-emitting diodes to produce a safe and environmentally benign lighting source. Bismuth oxide photocatalyst powders were synthesized with a spray pyrolysis method at 500°C, 600°C, 700°C, and 800°C. Using the absorption spectrum in the blue and UV regions of the bismuth oxide photocatalysts, the blue light and UV leakage problems of phosphor-converted white LEDs can be significantly reduced. The experimental results showed that bismuth oxide photocatalyst synthesized at 700°C exhibited the most superior spectrum inhibiting ability. The suppressed ratio reached 52.33% in the blue and UV regions from 360 to 420 nm. Related colorimetric parameters and the photocatalyst decomposition ability of fabricated white-light LEDs were tested. The CIE chromaticity coordinates(x,y)were (0.349, 0.393), and the correlated color temperature was 4991 K. In addition, the coating layer of photocatalyst can act as an air purifier and diffuser to reduce glare. A value of66.2±0.60 ppmv of molecular formaldehyde gas can be decomposed in 120 mins.

scholarly journals Crystal Structure and Luminescence Properties of a Thermally Stable Single-Phase White Emitting Phosphor CaSr2(PO4)2: Dy3+, Li+

2021 ◽  
Author(s):  
Qingfeng Guo ◽  
Yuying Chen ◽  
Qiang Hao ◽  
Stefan Lis ◽  
Haikun Liu ◽  
...  
Keyword(s):  
White Light ◽  
Single Phase ◽  
Emission Spectra ◽  
Luminescence Properties ◽  
Solid State Method ◽  
Excellent Thermal Stability ◽  
Light Emitting ◽  
Diffraction Patterns ◽  
White Light Emitting Diodes ◽  
White Luminescence

Abstract Single-phase CaSr2(PO4)2:Dy3+,Li+ phosphors were prepared using the high-temperature solid-state method in the air. To characterize the luminescence properties of the synthesized phosphors, Powder X-ray diffraction patterns (XRD), scanning electron microscopy images (SEM), photoluminescence spectra, and concentration-dependent emission spectra were measured to characterize the luminescence properties of the synthesized phosphors. The results showed that the CaSr2(PO4)2:Dy3+,Li+ phosphors exhibited white luminescence, and the emission spectra of the phosphors consisted of two sharp peaks at ≈486 and ≈578 nm (the most intense one). The optimum concentration of Dy3+ doping was determined to 0.06 mol.%. On the basis of the Dexter's theory, the mechanism of energy transfer between the Dy3+ ions was determined to dipole–dipole interactions. The results of the temperature-dependent luminescence confirmed that the as-prepared phosphors are proved to be promising UV-convertible material capable of white light emitting in UV-LEDs due to its excellent thermal stability and luminescence properties. Luminescence intensity and decay time of the CaSr2(PO4)2:Dy3+,Li+ phosphors were improved remarkably with the addition of charge compensators (Li+ ions), which would promote their applications in white light-emitting diodes based on the near-UV chip.

Phosphor-Conversion White Light Emitting Diode Using InGaN Near-Ultraviolet Chip

2007 ◽  
Vol 124-126 ◽  
pp. 499-502 ◽  
Author(s):  
Kyoung Jae Choi ◽  
Joung Kyu Park ◽  
Kyung Nam Kim ◽  
Chang Hae Kim ◽  
Ho Kun Kim
Keyword(s):  
White Light ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Forward Bias ◽  
Color Temperature ◽  
Operating Voltage ◽  
Current Increase ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
Yellow Region

We have synthesized a Eu2+-activated Sr3MgSi2O8 blue phosphor and (Sr,Ba)2SiO4 yellow phosphor. We fabricated a phosphor-conversion white light emitting diode(LED) using an InGaN chip that emits 400 nm near-ultraviolet(n-UV) light and phosphors that emit in the blue and yellow region. When the white LED was operated at a forward-bias current of 20 mA at room temperature(RT), the color temperature(Tcp), average color rendering(Ra), operating voltage(Vf) and luminous efficacy(ηL) were estimated to be 5800K, 72.08, 3.4V, and 7.61 lm/W, respectively. The commission International de I’Eclarirage(CIE) chromaticity coordinates obtained from the measured spectra remained almost constant during the forward-baias current increase from 0.5 mA to 60 mA.

scholarly journals A broadband cyan-emitting Ca2LuZr2(AlO4)3:Ce3+ garnet phosphor for near-ultraviolet-pumped warm-white light-emitting diodes with an improved color rendering index

2020 ◽  
Vol 8 (3) ◽  
pp. 1095-1103 ◽  
Author(s):  
Liangling Sun ◽  
Balaji Devakumar ◽  
Jia Liang ◽  
Shaoying Wang ◽  
Qi Sun ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Emission Spectra ◽  
Light Emitting ◽  
White Leds ◽  
Near Ultraviolet ◽  
Warm White Light ◽  
Color Rendering Index ◽  
White Light Emitting Diodes ◽  
Color Rendering

Broadband cyan-emitting Ca2LuZr2(AlO4)3:Ce3+ garnet phosphors enabled to fill the cyan gap in the emission spectra of near-ultraviolet-pumped warm-white LEDs, thus resulting in improved color rendering index.

Luminescence properties of single-phase color-tunable Li4SrCa(Si2O4N8/3):Eu2+ phosphor for white light-emitting diodes

RSC Advances ◽  
2016 ◽  
Vol 6 (45) ◽  
pp. 38731-38740 ◽  
Author(s):  
Chenxia Li ◽  
Jian Dai ◽  
Hua Yu ◽  
Degang Deng ◽  
Jun Huang ◽  
...  
Keyword(s):  
White Light ◽  
Single Phase ◽  
Light Emitting Diodes ◽  
Color Temperature ◽  
White Led ◽  
Light Emitting ◽  
Color Coordinates ◽  
Uv Led ◽  
Color Tunable ◽  
White Light Emitting Diodes

A white LED consisting of a LSCSN:0.03Eu2+ phosphor and a 375 nm UV LED chip had CIE color coordinates of (0.3568, 0.3111) and achieved a Ra of 82.5 around the correlated color temperature of 3318 K.

scholarly journals Luminescence properties of novel red-emitting phosphor InNb1-xPxO4:Eu3+ for white light emitting-diodes

2015 ◽  
Vol 33 (2) ◽  
pp. 331-334 ◽  
Author(s):  
An Tang ◽  
Tao Ma ◽  
Liduo Gu ◽  
Yongtao Zhao ◽  
Junhui Zhang ◽  
...  
Keyword(s):  
White Light ◽  
Luminescence Intensity ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Emission Spectra ◽  
Luminescence Properties ◽  
Potential Candidate ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
White Light Emitting Diodes

AbstractInNb1-xPxO4:Eu3+ red phosphors were synthesized by solid-state reaction and their luminescence properties were also studied through photoluminescence spectra. The excitation and emission spectra make it clear that the as-prepared phosphors can be effectively excited by near-ultraviolet (UV) 394 nm light and blue 466 nm light to emit strong red light located at 612 nm, due to the Eu3+ transition of 5D0 → 7F2. The luminescence intensity is dependent on phosphorus content, and it achieves the maximum at x = 0.4. Excessive phosphorus in the phosphors can result in reduction of luminescence intensity owing to concentration quenching.With the increasing content of phosphorus, the phosphors are prone to emit pure red light. This shows that the InNb1.6P0.4O4:0.04Eu3+ phosphor may be a potential candidate as a red component for white light emitting-diodes.

Ba1.3Ca0.7SiO4:Eu2+,Mn2+: A Promising Single-Phase, Color-Tunable Phosphor for Near-Ultraviolet White-Light-Emitting Diodes

2014 ◽  
Vol 53 (20) ◽  
pp. 11007-11014 ◽  
Author(s):  
Wenzhen Lv ◽  
Mengmeng Jiao ◽  
Qi Zhao ◽  
Baiqi Shao ◽  
Wei Lü ◽  
...  
Keyword(s):  
White Light ◽  
Single Phase ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
Color Tunable ◽  
White Light Emitting Diodes
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