A new langbeinite-type phosphate K2GdHf(PO4)3: synthesis, crystal structure, band structure and luminescence properties

2020 ◽  
Vol 76 (8) ◽  
pp. 771-778
Author(s):  
Hua Nan ◽  
Li Chen ◽  
Rui-Juan Zhang ◽  
Dan Zhao
Keyword(s):  
Optical Transition ◽  
Blue Emission ◽  
Large Family ◽  
Luminescence Properties ◽  
X Ray Diffraction ◽  
Blue Emission Band ◽  
Light Emitting ◽  
Direct Band ◽  
Cie Chromaticity ◽  
White Light Emitting Diodes

Langbeinite-type compounds are a large family that include phosphates, sulfates and arsenates, and which are accompanied by interesting physical properties. This work reports a new disordered langbeinite-type compound, K2GdHf(PO4)3 [dipotassium gadolinium hafnium tris(phosphate)], and its structure as determined by single-crystal X-ray diffraction. Theoretical studies reveal that K2GdHf(PO4)3 is an insulator with a direct band gap of 4.600 eV and that the optical transition originates from the O-2p→Hf-5d transition. A Ce3+-doped phosphor, K2Gd0.99Ce0.01Hf(PO4)3, was prepared and its luminescence properties studied. With 324 nm light excitation, a blue emission band was observed due to the 5d 1→4f 1 transition of Ce3+. The average luminescence lifetime was calculated to be 5.437 µs and the CIE chromaticity coordinates were (0.162, 0.035). One may expect that K2Gd0.99Ce0.01Hf(PO4)3 can be used as a good blue phosphor for three-colour white-light-emitting diodes (WLEDs).

Synthesis and Luminescence Properties of a Blue-Emitting Sr3NaLu(PO4)3F:Eu2+ Phosphor

2017 ◽  
Vol 727 ◽  
pp. 623-627 ◽  
Author(s):  
Zai Fa Yang ◽  
Deng Hui Xu ◽  
Xue Dong Gao ◽  
Jiang Nan Du ◽  
Jia Yue Sun
Keyword(s):  
Blue Emission ◽  
Fluorescence Decay ◽  
Ultraviolet Region ◽  
X Ray Diffraction ◽  
Blue Emission Band ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
Chromaticity Coordinates ◽  
Cie Chromaticity ◽  
White Light Emitting Diodes

A novel blue-emitting Sr3NaLu (PO4)3F:Eu2+ phosphor for white light-emitting diodes (w-LEDs) have been successfully prepared via the solid-state reaction. The crystal structure and phase of the prepared phosphors were investigated using X-ray diffraction (XRD). The band gap of Sr3NaLu (PO4)3F was estimated to be about 5.79 eV from the diffuse reflection spectrum. The Sr3NaLu (PO4)3F:0.05Eu2+ phosphor exhibits an intense and broad excitation band ranging from 200 to 450 nm in the near ultraviolet region and produces a bright blue emission band with the CIE chromaticity coordinates of x = 0.133 and y = 0.148 under the excitation of 365 nm, which were ascribed to the 4f-5d transitions of Eu2+. Moreover, the fluorescence decay curves were also investigated in detail. All the results suggest that Sr3NaLu (PO4)3F:Eu2+ might be a promising blue-emitting phosphor used in w-LEDs.

Luminescence Properties and Synthesis of SrMgAl10O17:Mn4+ Red Phosphor for White Light-Emitting Diodes

2016 ◽  
Vol 16 (4) ◽  
pp. 3489-3493 ◽  
Author(s):  
Renping Cao ◽  
Hongdong Xue ◽  
Xiaoguang Yu ◽  
Fen Xiao ◽  
Donglan Wu ◽  
...  
Keyword(s):  
Red Light ◽  
Solid State Reaction Method ◽  
Luminescence Properties ◽  
Conventional Solid State Reaction ◽  
Light Emitting ◽  
White Leds ◽  
Structure Morphology ◽  
Optimal Doping Concentration ◽  
Cie Chromaticity ◽  
White Light Emitting Diodes

A series of Mn4+ doped SrMgAl10O17 phosphors are synthesized by a conventional solid-state reaction method in air, and their crystal structure, morphology, and fluorescence properties are investigated. The luminescence properties show clearly that SrMgAl10O17:Mn4+ phosphor can be excited by UV (200–380 nm), near UV (380–420 nm), and blue (420–480 nm) bands of LEDs chip, and emits red light in the range of 600 nm to 750 nm with satisfying CIE chromaticity coordinates (0.7207, 0.2793). The optimal doping concentration of Mn4+ ion is ∼1 mol%, and its lifetime is ∼1.15 ms. The possible luminous mechanism of Mn4+ ion is discussed by Tanabe-Sugano diagram. These experiment results indicate that Mn4+ doped SrMgAl10O17 phosphors can be a potential application as a red-emitting phosphor candidate in white LEDs.

A New Salt-Inclusion Single-Phased White Phosphor Ba7B3SiO13Br:Dy3+ for White Light-Emitting Diodes

2019 ◽  
Vol 803 ◽  
pp. 93-97
Author(s):  
Hai Dong Ju ◽  
Bao Ling Wang ◽  
Qi Mei Yang
Keyword(s):  
White Light ◽  
Emission Band ◽  
Light Emitting Diodes ◽  
Hexagonal Phase ◽  
Blue Emission ◽  
Yellow Emission ◽  
Conventional Solid State Reaction ◽  
Blue Emission Band ◽  
Light Emitting ◽  
White Light Emitting Diodes

A series of Ba7B3SiO13Br:Dy3+ phosphors were synthesized by a conventional solid-state reaction method for the first time. The X-ray diffraction patterns confirmed that the samples were pure phase and crystallized in a hexagonal phase with a space group of the P63mc (186). The luminescence spectrum exhibited a strong blue emission band peaked at 478 nm, a strong yellow emission band at 575 nm and a weak emission band at 665 nm, corresponding to the transitions from 4F9/2 to 6H15/2, 6H13/2 and 6H13/2 of Dy3+, respectively. According to the emission spectrum of Ba6.92B3SiO13Br:0.08Dy3+ excited at 349 nm, the chromaticity coordinate was calculated to be (0.317, 0.358) located on the white light region. The concentration quenching mechanism of Dy3+ in Ba7B3SiO13Br was ascribed to the multipolar-multipolar interaction. The current researches suggested that the phosphor can be used as a white phosphor suitable for white light-emitting diodes.

Luminescence properties and first principles calculations of Dy3+ activated Sr3B2O6 phosphors

2015 ◽  
Vol 08 (02) ◽  
pp. 1550022 ◽  
Author(s):  
Lihan Cai ◽  
Xiaodan Li ◽  
Qijin Cheng ◽  
Jianghui Zheng ◽  
Baodian Fan ◽  
...  
Keyword(s):  
White Light ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Blue Emission ◽  
Concentration Quenching ◽  
Solid State Reactions ◽  
Luminescence Properties ◽  
Yellow Emission ◽  
Light Emitting ◽  
Cie Chromaticity

A novel white-light-emitting Sr 3 B 2 O 6: Dy 3+ phosphor was prepared by solid-state reactions and its luminescence properties were investigated. The excitation spectrum of obtained phosphor monitored at 479 nm covers a very broad spectral region from 320 nm to 460 nm with peaks at 323, 349, 363, 386, 427 and 456 nm. Under excitation at 349 nm, the phosphor exhibits a blue emission centered at 479 nm and a yellow emission centered at 574 nm. The optimal doping concentration of Dy 3+ is obtained to be 7 mol%, and the concentration quenching is observed when the concentration of Dy 3+ exceeds 7 mol%. This concentration quenching is due to the enhanced energy exchange among Dy 3+ ions. The CIE chromaticity coordinate (0.289, 0.302) of Sr 3-0.07 B 2 O 6:0.07 Dy 3+ located in the white-light region can be achieved. Theoretical calculations of electronic properties for Sr 3 B 2 O 6: Dy 3+ phosphor in the framework of the density functional theory (DFT) were carried out. Our results suggest that the Sr 3 B 2 O 6: Dy 3+ phosphor is a promising single-component white-light-emitting material.

Study of Growth and Characterization of Fe-Catalyzed β-Ga2O3 Nanowires

2015 ◽  
Vol 1751 ◽  
Author(s):  
Sudheer Kumar ◽  
C. Tessarek ◽  
A. Hähnel ◽  
S. Christiansen ◽  
R. Singh
Keyword(s):  
Emission Band ◽  
Blue Emission ◽  
Chemical Vapor ◽  
Luminescence Properties ◽  
Chemical Vapor Deposition Method ◽  
X Ray Diffraction ◽  
Blue Emission Band ◽  
Single Crystalline ◽  
Transmission Electron ◽  
High Resolution Tem

ABSTRACTIn the present study, Fe as a catalyst was used to grow single crystalline monoclinic gallium oxide (β-Ga2O3) nanowires using chemical-vapor-deposition method. The morphology, structure and luminescence properties of the as-grown β-Ga2O3 nanowires were investigated using various characterization techniques. The diameter of the as-grown nanowires was in the range of 50 to 100 nm, and the lengths up to tens of micrometers. The structural investigation of the nanowires was carried out using X-ray diffraction that showed monoclinic phase of Ga2O3. Further, the transmission electron microscope (TEM) investigations along with selected area diffraction pattern revealing single crystalline nature of the nanowires. The as-grown β-Ga2O3 nanowires had preferred orientation along [1-1-1] direction. The high resolution TEM image showed regular arrangement of atoms and the lattice spacing between (1-1-1) planes was around 0.266 nm. The luminescence properties of the as-grown nanowires were measured using cathodoluminescence (CL) spectroscopy. The CL measurements of β-Ga2O3 nanowires revealed a strong broad UV-blue emission band and a weak red emission band.

Synthesis of Sr2Si5N8:Eu2+ Phosphor for Enhanced Red Emission

2011 ◽  
Vol 233-235 ◽  
pp. 2705-2709 ◽  
Author(s):  
Van Duong Luong ◽  
Wen Tao Zhang ◽  
Hong Ro Lee
Keyword(s):  
Single Phase ◽  
Luminescence Properties ◽  
Heating Process ◽  
X Ray Diffraction ◽  
Red Phosphor ◽  
Red Emission ◽  
Light Emitting ◽  
White Leds ◽  
Xrd Patterns ◽  
White Light Emitting Diodes

For removing impurities to improve luminescence properties, Eu2+- activated Sr2Si5N8 red phosphor for white light-emitting diodes (LEDs) was prepared by multiple heat-treatment synthesis which includes carbothermal reduction and nitridation. The X-ray diffraction (XRD) patterns were showed the standard single phase of Sr2Si5N8. With an optimized amount of Eu2+ (2 at. %) dopant, the broad excitation band of Sr2Si5N8:Eu2+ indicated that the phosphor was suitable for application of white LEDs with UV or blue chip, and red emission peak at 628 nm in spectra originating from the 4f65d1→4f7 transition of Eu2+ ion. After third heating process, luminescence properties of the obtained phosphor were improved obviously and higher than commercial YAG:Ce3+ phosphor.

scholarly journals LUMINESCENCE BEHAVIOUR OF DY3+ ION DOPED MAGNESIUM SULFOBORATE PHOSPHOR FOR WHITE LIGHT EMITTING DIODES

2020 ◽  
Vol 1 (1) ◽  
pp. 11-15
Author(s):  
A. S. Dalhatu ◽  
R. Hussin ◽  
B. Ibrahim ◽  
Y. A. Yamusa ◽  
A. Baballe
Keyword(s):  
Solid State Reaction Method ◽  
Lanthanide Ions ◽  
Luminescence Properties ◽  
State University ◽  
X Ray Diffraction ◽  
Light Emitting ◽  
White Leds ◽  
Trivalent Lanthanide ◽  
Yellow Region ◽  
White Light Emitting Diodes

Several studies showed the interesting properties of trivalent lanthanide ions when doped in various types of phosphor. Magnesium sulfoborate phosphor doped with different concentrations of Dy3+ were synthesized using solid-state reaction method at 850 °C for 4 hours. The samples were characterized by X-ray Diffraction (XRD). The excitation and luminescence properties of MgO-SO4-B2O3:Dy3+ were determined. The emission spectrum of Dy3+ ion doped MgO-SO4-B2O3 phosphor exhibit three bands at 480 nm, 573 nm and 660 nm with excitation of 386 nm due to 4F9/2 →6H15/2, 6H13/2 and 6H11/2 of Dy3+ transitions, respectively. The excitation spectrum of Dy3+ ion doped MgO-SO4-B2O3 phosphor display several bands at 347 nm, 362 nm, 386 nm, 426 nm, 449 nm and 469 nm with emission of 573 nm, which is in agreement with the ultraviolet LED (349.9–410 nm) and blue LED (450–470 nm). An intense in the emission peak at 573 nm in the yellow region was observed with the 0.5 Dy2O3. The luminescence properties of phosphor show that MgO-SO4-B2O3:Dy3+ phosphor could be potentially used as white LEDs. Dalhatu, A. S. | Department of Physics, Bauchi State University Nigeria, 65 Gadau, Bauchi, Nigeria

Synthesis and luminescence properties of Sr2−xY x Si5−xAl x N8:Eu2+ red phosphor for white light-emitting diodes

2018 ◽  
Vol 53 (14) ◽  
pp. 10240-10248 ◽  
Author(s):  
Dongsheng Zhou ◽  
Wentao Zhang ◽  
Guilin Yan ◽  
Yiyao Wang ◽  
Qi Xu ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Luminescence Properties ◽  
Red Phosphor ◽  
Light Emitting ◽  
White Light Emitting Diodes

Photoluminescence studies on LiNa5(PO4)2:Dy3+, Sm3+ phosphor

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Miyapuram Ravi ◽  
Ghanta Pushpa Chakrapani ◽  
Mandava Balachandrika ◽  
Pavuluri Vasudevarao ◽  
Chendela Nageswararao ◽  
...  
Keyword(s):  
White Light ◽  
X Ray Diffraction ◽  
Light Emitting ◽  
New Class ◽  
Light Region ◽  
Crystalline Nature ◽  
Photoluminescence Studies ◽  
White Light Emitting Diodes ◽  
Good Agreement ◽  
Pure White

Abstract This paper describes the preparation, structure and photoluminescence properties of a new class LiNa5(PO4)2:Dy3+, Sm3+-phosphor. Crystalline nature confirmed by X-ray diffraction. The phases obtained are in good agreement with the standard phase. Excitation dependence and concentration effect on luminescence features are investigated. Color purity and optical bandgap are also estimated for the LiNa5(PO4)2:Dy3+, Sm3+ phosphors. The result shows LiNa5(PO4)2:Dy3+, Sm3+-phosphor excited by 374 nm nUV light produces pure white light than others. Admixing of 4f configurations and energy transfer between dopants are identified while varying the concentration of Sm3+. The CIE coordinates for LiNa5(PO4)2:0.05Dy3+, 0.05Sm3+ (x = 0.309, y = 0.332) are positioned well in white light region and very close to pure white light. The present study on LiNa5(PO4)2:Dy3+, Sm3+-phosphor suggests that it is useful for the fabrication of white light emitting diodes.

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