Co-reporter:Haoshuo Li, Lefu Mei, Haikun Liu, Yangai Liu, Libing Liao, and R. Vasant Kumar
Crystal Growth & Design May 3, 2017 Volume 17(Issue 5) pp:2809-2809
Publication Date(Web):March 20, 2017
DOI:10.1021/acs.cgd.7b00258
Herein, a facile surfactant-free hydrothermal method assisted with coprecipitation has been explored in order to prepare size-controlled HAP nanorods, and the growth mechanism of HAP nanostructures has also been proposed. In this article, the size of the HAP crystallites, ranging from 40 to 1500 nm, were controlled by varying the reaction conditions. Likewise, the experimental conditions can be changed to alter the shapes of the HAP nanostructures from nanorods to nanobelts. Additionally, interesting optically properties were induced in nano-HAP by doping with rare earth elements. The samples doped with terbium and europium generated green and red orange emissions, respectively, under irradiation by blue light, which is popularly used for wound healing and skin disease treatment. Thus, the doped HAP nanocrystals through the surfactant-free method have potential applications in blue phototherapy and photodynamic therapy.
Co-reporter:Haikun Liu, Libing Liao, Qingfeng Guo, Dan Yang, Lefu Mei
Journal of Luminescence 2017 Volume 181() pp:407-410
Publication Date(Web):January 2017
DOI:10.1016/j.jlumin.2016.09.060
The Ca9La(PO4)5(SiO4)Cl2:Dy3+ (CLPSCl:Dy3+) powder phosphor with apatite structure has been successfully synthesized via high-temperature solid state method. Single phase in such phosphor was verified through X-ray diffraction (XRD) technique. The Dy ions concentration dependent luminescence properties including emission, excitation and lifetimes of Dy ions were characterized using photoluminescence (PL) spectroscopy. The results showed that CLPSCl:Dy3+ phosphor could efficiently assimilate the n-UV light and emit blue (~486 nm) and yellow light (~578 nm), originating from the f-f transitions of Dy3+. The critical Dy3+ quenching concentration (QC) was determined to be about 12 mol%. The concentration quenching mechanism was also determined to be dipole–dipole interaction.
Co-reporter:Qingfeng Guo, Chenglong Zhao, Zhouqing Jiang, Libing Liao, Haikun Liu, Dan Yang, Lefu Mei
Dyes and Pigments 2017 Volume 139(Volume 139) pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.dyepig.2016.12.042
•Broad-band excited Ba10(PO4)6O:Eu2+,Tb3+/Li+ phosphors were prepared.•Efficient energy transfer from Eu2+ to Tb3+ in Ba10(PO4)6O were investigated.•Ba10(PO4)6O:Eu2+,Tb3+/Li+ have potential applications as blue-green emitting phosphors in w-LEDs.Developing color-tunable phosphors via the introduction of co-doping activators and sensitizers to the host with energy transfer processes has been a state-of-the-art topic for a long time. In this work, novel emission-tunable oxyapatites-type Ba10(PO4)6O:Eu2+,Tb3+/Li+ phosphors were prepared via a high temperature solid state reaction for the applications in white light emitting diodes (w-LEDs) with higher color rendering index. Tunable colors from blue to green can be realized in the Ba10(PO4)6O:Eu2+,Tb3+/Li+ by varying the relative ratios of Eu2+ to Tb3+, showing good absorption in the range of 230–400 nm. The energy transfer mechanism from Eu2+ to Tb3+ ions was demonstrated to be a quadrupole-quadrupole interaction by combining the Inokuti-Hirayama (IH) model and Reisfeld's approximation. Importantly, a prototype white lamp was packaged by mixing Ba9.83(PO4)6O: 0.03Eu2+, 0.07Tb3+, 0.07Li+ and commercial red phosphor CaAlSiN3: Eu2+, and the lamp exhibits a higher color rendering index (Ra = 92 and R9 = 56) and warm correlated color temperature of 4361 K for the actual application. Better luminescent properties compared to commercial Y3Al5O12:Ce3+-based w-LEDs, indicating that Ba10(PO4)6O: Eu2+, Tb3+/Li+ phosphors are emerging as potential phosphor-converted w-LEDs.
Co-reporter:Yuanyuan Zhang, Lefu Mei, Haikun Liu, Dan Yang, Libing Liao, Zhaohui Huang
Dyes and Pigments 2017 Volume 139(Volume 139) pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.dyepig.2016.11.011
•A novel apatite-type Ca9La(PO4)5(GeO4)F2:Dy3+ phosphor has been synthesized.•Ca9La(PO4)5(GeO4)F2:Dy3+ is a promising white-emitting phosphor for LED.•The Ca9La(PO4)5(GeO4)F2:Dy3+ phosphor shows excellent thermal stability.A novel apatite structure phosphor Ca9La(PO4)5(GeO4)F2:Dy3+ (CLPGF:Dy3+) with a hexagonal lattice in the P63/m space group was synthesized via a facile solid state technique. The crystal and fine local structure as well as their photoluminescence properties were investigated in detail. The CLPGF:Dy3+ phosphor can absorb in the UV-vis spectral region of 290–475 nm and exhibit two intense emission bands centered at 485 and 580 nm, which ascribes to 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+, respectively. The concentration quenching of Dy3+ emission occurs via the energy transfer among the nearest-neighbor ions and the corresponding quenching mechanism was verified to be the dipole-dipole interaction. The quantum efficiencies of the phosphors were examined to be 72.9% and its luminescence intensity at 150 °C decreases to 93.8% and 98.6% of the initial value at room temperature, which corresponds to 4F9/2 to 6H15/2 transition and 4F9/2 to 6H13/2 transition of Dy3+ ions, respectively. Their interesting photoluminescence properties indicate that the CLPGF:Dy3+ phosphor is a promising white-emitting candidate for w-LEDs applications.
Co-reporter:Yuanyuan Zhang, Lefu Mei, Haikun Liu, Zhaohui Huang
Journal of Luminescence 2017 Volume 192(Volume 192) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.jlumin.2017.07.013
Er3+ and/or Yb3+ doped Sr2ScF7 up-conversion (UC) phosphors were synthesized, and the optimum doping concentrations of Yb3+ and Er3+ in the Sr2ScF7 host were found to be 20% mol and 7% mol, respectively. Under excitation of 980 nm laser, the UC spectra of the samples is composed of three green emission bands from 510 to 570 nm centered at 525, 543 and 551 nm and two red emission band from 640 to 690 nm with two peaks at 657 and 671 nm, which is attributed to the 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+, respectively. The UC emission color of Er3+ can be tuned by adjusting the intensity ratio of red to green emission through manipulating the population of red and green emitting states.Download high-res image (165KB)Download full-size image
Co-reporter:Shusen Chen, Wenjiang Wang, Keli Wang, Ming Guan, Maxim S. Molokeev, Lefu Mei, Zhaohui Huang
Journal of Luminescence 2017 Volume 192(Volume 192) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.jlumin.2017.06.034
Er3+ / Yb3+ doped BaIn2O4 up-conversion (UC) phosphors are synthesized and their UC luminescent properties are characterized. BaIn2O4 has P21/c space group but Rietveld refinement suggests it has twice smaller cell parameter (a = 10.3975 Å, b = 5.8295 Å, c = 14.4457 Å) and volume than previous reported structure. Refinement also reveals Er3+/Yb3+ replaces In3+ ions in lattice because of the existence of InO6 octahedra. In these BaIn2O4 phosphors, co-doping with Yb3+ ions changes the predominant UC emission from green ( 2H11/2, 4S3/2 → 4I15/2 of Er3+) to red (about 665 nm, 4F9/2 → 4I15/2 of Er3+). By controlling of Er3+/Yb3+ concentrations, the BaIn2O4 phosphors have the potential of generating various UC spectra and color tunability. The pumping powers study shows two-photon process in these phosphors.
Co-reporter:Haikun Liu, Libing Liao, Yuanyuan Zhang, Tianshuai Zhou, Qingfeng Guo, Li Li, Lefu Mei
Dyes and Pigments 2017 Volume 140(Volume 140) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.dyepig.2017.01.033
•Novel apatite-type compound Mn2Gd8(SiO4)6O2 was successfully synthesized.•The spectroscopic data and fluorescence decay indicated that the Mn2+ only occupy 4f sites with C3 point symmetry.•This work offered an idea to design novel manganese compounds.The structural and luminescence properties of apatite-type compound Mn2Gd8(SiO4)6O2 have been investigated. The crystal structure of Mn2Gd8(SiO4)6O2 has been obtained from the X-ray diffraction data by Rietveld method in the hexagonal system, space group P63/m, a = 9.3851 Å, c = 6.7904 Å, V = 517.97 Å3, Z = 1. The Mn2Gd8(SiO4)6O2 phase contains two cationic sites, one site (4f site with point symmetry C3) is a distorted tricapped trigonal prismatic polyhedron formed by nine oxygen atoms, and other site (6h sites with point symmetry Cs) is an irregular polyhedron of pentagonal bipyramidal geometry with the coordination by seven oxygen atoms. It is found that the Mn2+ ions occupy only 4f sites with C3 point symmetry, that has been verified by photoluminescence spectrum and decay curves. This work provides an insight to the novel inorganic compound design and gives an impetus to discover new functional materials and develop new applications.
Co-reporter:Haikun Liu, Yuanyuan Zhang, Lefu Mei, Qingfeng Guo, Haoshuo Li, Libing Liao
Dyes and Pigments 2017 Volume 145(Volume 145) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.dyepig.2017.06.045
•The solid solution phosphors Ca9La(PO4)5[(Si1-xGex)O4]F2:Ce3+ have been prepared.•A red-shift phenomenon occurs with the introduction of [GeO4]4- into the solid solution phosphors.•An insight to design color-tunable phosphors based on the tetrahedral substitution.A series of solid solution phosphors Ca9La(PO4)5[(Si1-xGex)O4]F2:Ce3+ with apatite structure in the P63/m space group have been prepared. The novel solid solution phosphors show continuously controlled violet-blue emission. It is found that both substantial spectra broadening (45 → 100 nm) and red-shift (404 → 422 nm) can be realized with the continuous introduction of [GeO4]4- into the crystal lattice which has been simulated by a crystal-field model. The above results indicate that the tetrahedral substitution is interesting to induce spectral tuning properties based on the chemical composition control of the iso-structural solid solutions.
Co-reporter:Yuanyuan Zhang, Haikun Liu, Lefu Mei, Maxim S. Molokeev, Yongjie Wang, Zhaohui Huang
Journal of Solid State Chemistry 2017 Volume 255(Volume 255) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.jssc.2017.07.026
A series of novel luminescent emission-tunable phosphors Mg2La8(SiO4)6O2:Ce3+,Tb3+ (MLS:Ce3+,Tb3+) have been prepared by a solid-state reaction. The phase formation was firstly confirmed through X-ray diffraction technique and refined by the Rietveld method. The MLS:Ce3+,Tb3+ phosphors, which crystallized in apatite-type hexagonal phase, exhibited a broad excitation band ranging from 200 to 400 nm and several emission bands centered at 426 nm and 551 nm. Energy transfer from Ce3+ to Tb3+ ions via a dipole-dipole mechanism occurred in the as-synthesized phosphors upon ultraviolet (UV) excitation. The energy transfer efficiency increases with increasing doping content of Tb3+ ions, which was confirmed by the luminescence spectra and fluorescence decay curves of corresponding ions simultaneously. The energy transfer critical distance was calculated and evaluated by both the concentration quenching and spectral overlap methods. The chromaticity of emission-tunable phosphors was also characterized by the Commission International de l'éclairage (CIE) chromaticity indexes, and the color tone can be tuned from blue (0.179, 0.122) to green (0.267, 0.408) by controlling the ratio of Ce3+/Tb3+.Download high-res image (365KB)Download full-size image
Co-reporter:Haikun Liu, Libing Liao, Jian Chen, Qingfeng Guo, Yuanyuan Zhang, Lefu Mei
Journal of Luminescence 2016 Volume 169(Part B) pp:739-743
Publication Date(Web):January 2016
DOI:10.1016/j.jlumin.2015.09.022
•Tb3+,Sm3+-codoped Ba3NaLa(PO4)3F phosphors have been synthesized.•The emission color of the obtained phosphors can be modulated from green to red.•This phosphor has a good thermal stability.Tb3+–Sm3+ co-doped Ba3NaLa(PO4)3F phosphors with apatite structure have been prepared by a high temperature solid-state reaction, and their luminescence properties have been investigated in detail. The energy transfer (ET) mechanism was verified as the dipole–quadrupole mechanism, and the ET efficiency as well as the critical distance is also estimated. As a result of fine-tuning of the emission composition of the Tb3+ and Sm3+ ions, tunable luminescence properties can be realized by combining the emission of Tb3+ and Sm3+ in a single host lattice under UV light excitation. The emission color of the obtained phosphors can be modulated from green to yellow by controlling the doping content of the Sm3+ ions with the fixed Tb3+ content. Additional, as the temperature increases from RT to 150 °C, the PL intensities of Ba3NaLa0.7(PO4)3F:0.10Tb3+,0.20Sm3+ decreased to 80.4% and 78.6% of the initial PL intensity, corresponding to the intensity of transition of Sm3+ and transition of Tb3+ in the Ba3NaLa0.7(PO4)3F:0.10Tb3+,0.20Sm3+ phosphor, respectively. These results indicate the series of Ba3NaLa1−x−y(PO4)3F:xTb3+,ySm3+ phosphors can be acted as a good candidate for the application in white light-emitting diodes.
Co-reporter:Haikun Liu, Libing Liao, Dan Yang, Qingfeng Guo, Lefu Mei
Ceramics International 2016 Volume 42(Issue 15) pp:16579-16583
Publication Date(Web):15 November 2016
DOI:10.1016/j.ceramint.2016.07.078
Abstract
Tb3+-Sm3+ co-doped Sr9Gd(PO4)5(SiO4)F2 (SGPSF) phosphors were prepared through a solid-state reaction, and their luminescence properties as well as energy transfer mechanism have been investigated in detail. The SGPSF:Tb3+, Sm3+ phosphors system could be efficiently excited at wavelengths ranging from 200 to 500 nm, which is well matched with the spectra of near ultraviolet chips. The emission of SGPSF:Tb3+, Sm3+ phosphor covers the entire visible region with sharp peaks in the blue, green, and red regions. The emission color of SGPSF:Tb3+, Sm3+ could be adjusted from green (0.275, 0.378) to red (0.519, 0.295) by controlling the doping content of Sm3+/Tb3+.
Co-reporter:Qingfeng Guo, Bin Ma, Libing Liao, Maxim S. Molokeev, Lefu Mei, Haikun Liu
Ceramics International 2016 Volume 42(Issue 10) pp:11687-11691
Publication Date(Web):1 August 2016
DOI:10.1016/j.ceramint.2016.04.086
Abstract
In this paper, a series of novel luminescent Sr10−x(SiO4)3(SO4)3O:xEu2+ phosphors with apatite structure were synthesized by a high temperature solid-state reaction. The phase structure, photoluminescence (PL) properties, as well as the PL thermal stability were investigated. Sr9.92(SiO4)3(SO4)3O:0.08Eu2+ phosphor exhibits better thermal quenching resistance, retaining the luminance of 66.55% at 150 °C compared with that at 25 °C. The quenching concentration of Eu2+ in Sr10(SiO4)3(SO4)3O was about 0.08 (mol) with the dipole–quadrupole interaction. The Sr10−x(SiO4)3(SO4)3O:xEu2+ phosphors exhibited a broad-band green emission at 538 nm upon excitation at 396 nm. The results indicate that Sr10−x(SiO4)3(SO4)3O:xEu2+ phosphors have potential applications as near UV-convertible phosphors for white-light UV LEDs.
Co-reporter:Qingfeng Guo, Libing Liao, Lefu Mei, Haikun Liu
Journal of Luminescence 2016 Volume 172() pp:191-196
Publication Date(Web):April 2016
DOI:10.1016/j.jlumin.2015.12.013
A series of blue-emitting La5.90−xBa4+x(SiO4)6−x(PO4)xF2:0.10Ce3+ (x= 0, 1, 2, and 3) phosphors with apatite structure were synthesized by a solid-state reaction. The crystal structure and the photoluminescence properties were investigated in detail. The crystallographic occupancy of Ce3+ in La2.90Ce0.10Ba7(SiO4)3(PO4)3F2 and La5.90Ce0.10Ba4(SiO4)6F2 were studied based on Rietveld refinements results and the crystal chemistry rules. La5.90−xBa4+x(SiO4)6−x(PO4)xF2:0.10Ce3+ exhibited strong blue light emission in the range of 407–414 nm with high thermal stability upon excitation at 276 nm. Besides, the activation energy E of La5.90Ce0.10Ba4(SiO4)6F2 and La2.90Ce0.10Ba7(SiO4)3(PO4)3F2 phosphors were calculated to be 0.152 and 0.177 eV. These results suggest that La5.90−xBa4+x(SiO4)6−x(PO4)xF2:0.10Ce3+ is a potential blue phosphor candidate for near-UV-pumped w-LEDs.
Co-reporter:Haikun Liu, Libing Liao, Maxim S. Molokeev, Qingfeng Guo, Yuanyuan Zhang and Lefu Mei
RSC Advances 2016 vol. 6(Issue 29) pp:24577-24583
Publication Date(Web):26 Feb 2016
DOI:10.1039/C5RA23348H
A novel single-phase white light emitting phosphor Ca9La(PO4)5(SiO4)F2:Dy3+ was prepared through traditional high-temperature solid state technology. The crystal structures of Ca9La(PO4)5(SiO4)F2 with or without Dy3+ ions were refined by the Rietveld method. The diffuse reflection spectra, excitation spectra, emission spectra, and decay times were characterized to investigate the photoluminescence properties for application in white light-emitting diodes. The results showed that the Ca9La(PO4)5(SiO4)F2:Dy3+ phosphor could efficiently assimilate n-UV light and emit blue (∼485 nm) and yellow light (∼580 nm), originating from the f–f transitions of Dy3+. The critical Dy3+ quenching concentration (QC) was determined to be about 15 mol%, and the corresponding QC mechanism was verified to be the dipole–dipole interaction. Additionally, the emission colors of all samples were located close to the ideal white light region, and the optimal chromaticity coordinates and correlated color temperature (CCT) were determined to be (x = 0.338, y = 0.336) and 5262 K. All the above results indicate that the as-prepared Ca9La(PO4)5(SiO4)F2:Dy3+ phosphor could serve as a promising candidate for white-light n-UV-LEDs.
Co-reporter:Xiaoxue Ma, Lefu Mei, Haikun Liu, Libing Liao, Yuqin Liu, Kun Nie, Zhaohui Li
Chemical Physics Letters 2016 Volume 653() pp:212-215
Publication Date(Web):1 June 2016
DOI:10.1016/j.cplett.2016.04.092
Highlights
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A new inorganic framework of Ba3Sc(PO4)3:Sm3+ phosphors with eulytite structure has been synthesized.
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Ba3Sc(PO4)3:Sm3+ phosphors can be accurately excited by 406 nm which locates at the near ultraviolet region.
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The synthesis technique of Ba3Sc(PO4)3:Sm3+ phosphors was simple.
Co-reporter:Mengyan Yin, Yangai Liu, Lefu Mei, Maxim S. Molokeev, Zhaohui Huang and Minghao Fang
RSC Advances 2015 vol. 5(Issue 89) pp:73077-73082
Publication Date(Web):17 Aug 2015
DOI:10.1039/C5RA12959A
Up-conversion (UC) phosphors Gd2(WO4)3:Er3+/Yb3+ were synthesized by a high temperature solid-state reaction method. The crystal structure of Gd2(WO4)3:3% Er3+/10% Yb3+ was refined by Rietveld method and it was showed that Er3+/Yb3+ were successfully doped into the host lattice replacing Gd3+. Under 980 nm laser excitation, intense green and weak red emissions centered at around 532 nm, 553 nm, and 669 nm were observed, which were assigned to the Er3+ ion transitions of 4H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2, respectively. The optimum Er3+ doping concentration was determined as 3 mol% when the Yb3+ concentration was fixed at 10 mol%. The pump power study indicated that the energy transfer from Yb3+ to Er3+ in Er3+, Yb3+ co-doped Gd2(WO4)3 was a two-photon process, and the related UC mechanism of energy transfer was discussed in detail.
Co-reporter:Ming Guan, Hong Zheng, Zhaohui Huang, Bin Ma, Maxim S. Molokeev, Saifang Huang and Lefu Mei
RSC Advances 2015 vol. 5(Issue 73) pp:59403-59407
Publication Date(Web):08 Jul 2015
DOI:10.1039/C5RA08467A
Up-conversion (UC) phosphors of (Ca1−xSrx)In2O4:Yb3+/Ho3+ (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0) were prepared. Based on the crystal structure evolution of these series solid solution samples, which were characterized by Rietveld refinement, the variation of UC luminescent properties was discussed in detail. Sr and Ca occupied one position and Yb/Ho dissolved in the In ion site in the (Ca1−xSrx)In2O4 lattice. With increasing Sr substituting Ca atoms, the cell parameters and cell volumes of these samples increased linearly, and distortions of (Ca/Sr)O8 polyhedron were formed. The distortions on crystal structures showed a negative relation with UC luminescent intensities in these series phosphors.
Co-reporter:Jing Xie, Lefu Mei, Libing Liao, Ming Guan, Haikun Liu
Journal of Physics and Chemistry of Solids 2015 Volume 83() pp:152-156
Publication Date(Web):August 2015
DOI:10.1016/j.jpcs.2015.04.006
•Up-conversion phosphors BaLa2ZnO5 co-doped with Ho3+/Yb3+ were synthesized.•The crystal structure of BaLa2ZnO5 and the changes of cell parameters and volume of BaLa2ZnO5 after doping Ho3+ and Yb3+ have been discussed.•The luminescence properties of BaLa2ZnO5 co-doped with Ho3+/Yb3+ were excellent.•Energy transfer between Yb3+ and Ho3+ in BaLa2ZnO5 has been discussed.Up-conversion phosphors BaLa2ZnO5 co-doped with Ho3+/Yb3+ were synthesized by high temperature solid-state reaction method. The phase composition of the phosphors was characterized by X-ray diffraction (XRD). The structure of BaLa2ZnO5: 0.75% Ho/15% Yb phosphor was refined by the Rietveld method and results showed the decreased unit cell parameters and cell volume after doping Ho3+ and Yb3+, indicating Ho3+ and Yb3+ have successfully replaced La3+. Under the excitation of 980 nm diode laser, the strong green and weak red up-conversion emissions centered at 548 nm, 664 nm and 758 nm were observed, which originating from 5S2, 5F2→5I8, 5F4→5I8 and 5S2, 5F2→5I7 transitions of Ho3+ ions, respectively. The optimum doping concentrations of Ho3+ and Yb3+ were determined to be 0.75% and 15%, and the corresponding Commission International de L'Eclairage (CIE) coordinates are calculated to be x=0.298 and y=0.692. The related UC mechanism of Ho3+/Yb3+ co-doped BaLa2ZnO5 depending on pump power was studied in detail. The results indicate that BaLa2ZnO5: Ho3+/Yb3+ can be an effective candidate for up-conversion yellowish-green light emitter.
Co-reporter:Haikun Liu, Wenlong Gu, Yun Hai, Lixin Zhang, Libing Liao, Lefu Mei
Optical Materials 2015 Volume 42() pp:553-555
Publication Date(Web):April 2015
DOI:10.1016/j.optmat.2014.12.042
•Ce3+ doped Sr2La8(SiO4)6O2 phosphors have been synthesized by facile sol-combustion method.•The concentration quenching mechanism was estimated to be dipole–dipole interaction.•This phosphor can generate apparent violent-blue emission.The Sr2La8(SiO4)6O2:Ce3+ powder phosphor with apatite structure has been successfully synthesized via a facile route of sol-combustion technique. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and photoluminescence (PL) spectroscopy were used to characterize the as-prepared samples. Sr2La8(SiO4)6O2:Ce3+ phosphor was composed of particles with average sizes range about 300 nm. The phosphor exhibited an absorption ranging from 220 to 390 nm in ultraviolet range and a broad blue-violet emission band peaked at 403 nm with a CIE coordinates of (0.167, 0.028). The concentration quenching mechanism was also determined to be dipole–dipole interaction.
Co-reporter:Chao Zeng, Haikun Liu, Yingmo Hu, Libing Liao, Lefu Mei
Optics & Laser Technology 2015 Volume 74() pp:6-10
Publication Date(Web):November 2015
DOI:10.1016/j.optlastec.2015.05.003
•The Ba3GdNa(PO4)3F:Eu2+, Tb3+ phosphor exhibits a broad excitation band.•The energy transfer between Eu2+ and Tb3+ takes place in Ba3GdNa(PO4)3F:Eu2+, Tb3+.•The Ba3GdNa(PO4)3F:Eu2+, Tb3+ emission color adjusts from blue to green.A series of Eu2+ and Eu2+/Tb3+ co-doped Ba3GdNa(PO4)3F phosphors have been synthesized via a high temperature solid-state reaction. The relative intensity of PL spectra of Ba3GdNa(PO4)3F:xEu2+ increases with increasing x value, and reaches a maximum at x=0.04. Ba3GdNa(PO4)3F:Eu2+, Tb3+ phosphors exhibit a broad excitation band ranging from 220 to 450 nm, which matches perfectly with the characteristic emission of n-UV light-emitting diode (LED) chips. Upon 365 nm excitation, the Ba3GdNa(PO4)3F:Eu2+, Tb3+ phosphors show two dominating bands peaked at 466 and 543 nm, which are assigned to the 4f7→4f65d1 transition of the Eu2+ ions and the 5D4→7F5 transition of the Tb3+ ions, respectively. In view of the energy transfer mechanism between Eu2+ and Tb3+, the Ba3GdNa(PO4)3F:Eu2+, Tb3+ emission color can adjust from blue to green, and their chromatic coordinates (x, y) vary from (0.16, 0.135) to (0.254, 0.398). The critical distance was also calculated to be 16.90 Å. The above results indicate that the Ba3GdNa(PO4)3F: Eu2+, Tb3+ phosphors are a candidate for blue–green components in the application of n-UV w-LEDs.
Co-reporter:Xiaoxue Ma, Lefu Mei, Haikun Liu, Libing Liao, Kun Nie, Yuqin Liu, Zhaohui Li
Polyhedron (24 November 2016) Volume 119() pp:223-226
Publication Date(Web):24 November 2016
DOI:10.1016/j.poly.2016.09.001
