The luminescent properties of Eu^3＋doped Ca2SiO4 red phosphors synthesized by the flux fusion reaction method were investigated. It was found that the excitation spectrum included two regions： the weak excitation ba...The luminescent properties of Eu^3＋doped Ca2SiO4 red phosphors synthesized by the flux fusion reaction method were investigated. It was found that the excitation spectrum included two regions： the weak excitation band below 325 nm and strong narrow peaks above 325 nm. The main peak of the excitation band was located at 400 nm. The peaks located at 290 nm were assigned to the combination of the charge transfer transition of O-Eu, peaks above 325 nm （325, 385, 400, 470, 511, and 539 nm） were assigned to the f-f transitions of Eu^3＋. The emission spectrum was dominated by the red peak located at 612 nm due to the electric dipole transition of ^5D0-^7F2. In addition, the effects of the Eu^3＋ content and charge compensators of Li^＋, Na^＋, K^＋, and Cl^- ions on the emission intensity were investigated. The experiment results suggested that the strongest emission was obtained when the concentration of the Eu^3＋ ions was 0.3 mol^-1, and Li^＋ ions gave the best improvement to enhance the emission intensity. Ca2SiO4：Eu^3＋, Li^＋ was thus suitable for low-cost trichromatic white light emitting diodes （WLED） based on UV InGaN chip.展开更多
YAl3 （BO3）4： Eu^3＋ phosphors were prepared by the conventional solid state reaction. The phase structure and morphology were investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. Dopi...YAl3 （BO3）4： Eu^3＋ phosphors were prepared by the conventional solid state reaction. The phase structure and morphology were investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. Doping YAl3（BO3）4： Eu^3＋ phosphors with concentration of Eu^3＋ ions of 0, 2, 5, 8 and 10 mol% were studied and their luminescent properties at room temperature were discussed. The excitation spectrum of Y0.95Eu0.05Al3（BO3）4 was composed of a broad band centered at about 252 nm and a group of lines in the longer wavelength region. In the emission spectra, the peak wavelength was about 614 nm under a 252 nm UV excitation. The optimal doping concentration of Eu^3＋ ions in YAl3（BO3）4： Eu^3＋ phosphors was 8 mol%.展开更多
Full-spectrum phosphor-converted white-light-emitting diodes(pc-WLED)are emerging as a mainstream technology in semiconductor lighting.Nevertheless,high-performance blue phosphor which can be excited efficiently by a ...Full-spectrum phosphor-converted white-light-emitting diodes(pc-WLED)are emerging as a mainstream technology in semiconductor lighting.Nevertheless,high-performance blue phosphor which can be excited efficiently by a 400 nm NUV diode chip is still lacking.Herein,we present a blue-emitting Na_(3)KMg_(7)(PO_(4))6:Eu^(2+)phosphor synthesized by the solid-reaction method.Particularly,we find that the using of Li_(2)CO_(3)as flux can significantly improve the crystal quality and thus the emission efficiency of the phosphor.Meanwhile,the excitation peak of the phosphor shifts from 365 to 400 nm,which is pivotal for efficient NUV(400 nm)diode chip excitation.The practical Eu^(2+)concentration is also enhanced by using Li_(2)CO_(3)as flux,and the absorption efficiency is greatly increased.This phosphor exhibits superior PL thermal stability,namely retains 94%integrated photoluminescence intensity at 150℃of that at 25℃.As a result,the optimized phosphor shows an emission band peaked at 437 nm with a bandwidth of 40 nm and a high external photoluminescence quantum yield of 51.7%.Finally,a pc-WLED was fabricated by using NKMPO:Eu^(2+)blue,Sr_(2)SiO_(4):Eu^(2+)green,CaAlSiN_(3):Eu^(2+)red phosphors,and a 400 nm NUV diode chip.It shows a high color rendering index of R_(a)=96.4 and a correlated color temperature of 4358 K.These results prove that NKMPO:Eu^(2+)is a promising blue phosphor for full-spectrum WLED based on NUV diode chips.展开更多
A series of long afterglow phosphors, Eu2+, Dy3+, with different iron content were prepared by nano-coating process. The resulted precursors were characterized by Transmission Electron Microscope (TEM), which suggeste...A series of long afterglow phosphors, Eu2+, Dy3+, with different iron content were prepared by nano-coating process. The resulted precursors were characterized by Transmission Electron Microscope (TEM), which suggested that the precursor particles had nanometer size distribution. The optical quenching of iron impurity on the phosphor powders were investigated by X-Ray powder Diffraction (XRD) and photoluminescence methods. The XRD indicates that a pure monoclinic SrAl2O4∶Eu2+, Dy3+ was formed at 1200 ℃ and iron impurity up to 296.36×10-4% had no effect on the SrAl2O4∶Eu2+, Dy3+ phase structure. However, the luminescence intensity were strongly dependent on the trace iron impurity, which might be explained that iron displace the aluminium and form Fe-O bond, which competed energy with Eu2+ and transfer red them to infrared sites.展开更多
A series of Dy^(3+)/Eu^(3+) single doped and co-doped SrLaAlO_(4) phosphors was synthesized by the traditional high-temperature solid-state method,and their structure,morphology and optical properties were characteriz...A series of Dy^(3+)/Eu^(3+) single doped and co-doped SrLaAlO_(4) phosphors was synthesized by the traditional high-temperature solid-state method,and their structure,morphology and optical properties were characterized.The X-ray diffraction(XRD) shows a small amount of doping with Dy^(3+) and Eu^(3+) does not change the crystal structure of the matrix SrLaAlO_(4) and the best synthesis temperature is 1450℃.The scanning electron microscopy(SEM) indicates the particle size directly ranges from 1 to 5μm roughly and the energy dispersive spectroscopy(EDS) patterns show that SrLaAlO_(4):Dy^(3+) phosphor and SrLaAlO_(4):Dy^(3+),Eu^(3+) phosphor were successfully synthesized.SrLaAlO_(4):Dy^(3+) phosphor can be effectively excited by near-ultraviolet light,producing two strong emission lights at 483 nm(blue light) and 579 nm(yellow light),presenting a cold white light;SrLaAlO_(4):Eu^(3+) phosphor can be effectively excited by nearultraviolet light,producing red lights at 622 nm;the characteristic emission peaks of Dy^(3+) and Eu^(3+)can be shown simultaneously under the same excitation wavelength in SrLaAlO_(4):Dy^(3+), Eu^(3+) phosphor.By changing the relative doping concentration ratio of Dy^(3+) and Eu^(3+),the modulation of SrLaAlO_(4):Dy^(3+),Eu3+phosphor from cold white to warm white light can be achieved.In addition,the study of the luminescent mechanism and lifetime shows that there is energy transfer between Dy^(3+) and Eu^(3+) in SrLaAlO_(4):Dy^(3+),Eu^(3+) phosphor.展开更多
White body-color （Y, Gd）BxV1-xO4-x ：Eu^3＋ phosphors were prepared by coprecipitation reaction. Under VUV excitation at 147 nm, the red emission colorimetric purity of （Y, Gd） BxV1-xO4-x： Eu^3＋ phosphor is much...White body-color （Y, Gd）BxV1-xO4-x ：Eu^3＋ phosphors were prepared by coprecipitation reaction. Under VUV excitation at 147 nm, the red emission colorimetric purity of （Y, Gd） BxV1-xO4-x： Eu^3＋ phosphor is much better than that of commercial PDP （plasma display panels） phosphor （Y, Gd）BO3：Eu^3＋ . But its relative emission intensity is only about 90% of the commercial phosphor.展开更多
A flower-like Eu^2＋ and Dy^3＋ co-doped SrAl2O4 long-lasting phosphorescent （LLP） phosphor was synthesized via the inorganic- salt-based sol-gel method. The crystal structure, morphology and optical properties of t...A flower-like Eu^2＋ and Dy^3＋ co-doped SrAl2O4 long-lasting phosphorescent （LLP） phosphor was synthesized via the inorganic- salt-based sol-gel method. The crystal structure, morphology and optical properties of the composite were characterized. X-ray diffraction diffusion （XRD） data and DSC-TG curves of the phosphor revealed that the SrAl2O4 crystallites have been formed after the precursor was calcined at 900 ℃ and to be single-phase SrA1204 at 1100 ℃. The SEM photographs indicated that the sample exhibited a universal flower-like morphology with crystallite size of about l-2μm. After being irradiated with ultraviolet （UV） light, the flower-like phosphor emitted long-lasting green phosphorescence with an excitation peak at 365 nm and emission peak at 500 nm which was ascribed to the characteristic 5d-4f transition of Eu^2＋. Both the PL spectra and the luminance decay curve revealed that this phosphor exhibited efficient luminescence and long lasting properties.展开更多
Color-tunable phosphors Sr0.94MoO4：xEu^3＋, （0.06 - x）Tb^3＋ were synthesized rapidly by microwave ra- diation method with active carbon particle as microwave absorbent. The synthesized phosphors were investigated ...Color-tunable phosphors Sr0.94MoO4：xEu^3＋, （0.06 - x）Tb^3＋ were synthesized rapidly by microwave ra- diation method with active carbon particle as microwave absorbent. The synthesized phosphors were investigated by X-ray powder diffraction （XRD） and fluorescence spec- trophotometer. The effects of the ratio of Eu^3＋ and Tb^3＋ on the phase structure and luminescent properties of the phos- phors were discussed. The results show that Eu^3＋,Tb^3＋-doped samples can be well indexed to the pure tetragonal scheelite- type SrMoO4, indicating that Eu^3＋ and Tb^3＋ are effectively doped into the SrMoO4 host lattices. The as-synthesized Sro.94MoO4：xEu^3＋,（0.06 - x）Tb^3＋ phosphors have two luminescent centers （Eu^3＋ and Tb^3＋）, which can show red and green emissions under ultraviolet light excitation, respec- tively. Doping concentration of Eu^3＋ and Tb^3＋ has great effect on the intensity of emission peaks and the chromaticity of the samples, and the full color between green and red light can be achieved by adjusting the relative concentration of Eu^3＋ and Tb^3＋.展开更多
This study presents the photoluminescence characteristic analysis of a series of red phosphors of KAlSiO_(4):1.5 mol%Sm^(3+),x mol%Eu^(3+)(x=2,3,4,5,6,7)prepared via high-temperature solid-phase reaction.The results s...This study presents the photoluminescence characteristic analysis of a series of red phosphors of KAlSiO_(4):1.5 mol%Sm^(3+),x mol%Eu^(3+)(x=2,3,4,5,6,7)prepared via high-temperature solid-phase reaction.The results show that the X-ray diffraction(XRD)refinement results are reliable.The unit cell parameters and volume gradually decrease as the Eu^(3+) concentration increases,resulting in a grain size reduction of 10.22%.When x=6,the emission peaks of Sm^(3+) at 564,601,and 651 nm disappear completely,and the corresponding full width at half maximum becomes 0.At 610 nm,the emission peak intensity of Eu^(3+) is increased by a factor of 4.8.The resonant non-radiative energy transfer effect is greater than the co-excitation effect.A maximum energy transfer efficiency of 97.8%is achieved.The integral area at 610 nm is as high as 85%.The color purity of the phosphor is as high as 92.97%,and the internal quantum yield gradually changes from 32%to 51%.Ultimately,these results confirm that the silicate phosphor is suitable for the red component in the three primary color phosphors of white light-emitting diodes.展开更多
Sm^(3+), Eu^(3+)co-coped Ba_(3)Bi_(2)(PO_(4))_(4) phosphors,as potential phosphors for white light-emitting diode applications, were synthesized through the solid-state reaction method for the first time. The crystal ...Sm^(3+), Eu^(3+)co-coped Ba_(3)Bi_(2)(PO_(4))_(4) phosphors,as potential phosphors for white light-emitting diode applications, were synthesized through the solid-state reaction method for the first time. The crystal structure,absorption spectra, photoluminescence properties, decay time, energy transfer mechanism, temperature-dependent properties, and Commission International De L’Eclairage(CIE) chromaticity coordinates were investigated systematically. The pure eulytite-type Ba_(3)Bi_(2)(PO_(4))_(4) phase was obtained after heating at 980 ℃ for 5 h. A notably enhanced absorption efficiency at 393 nm was observed when Sm^(3+), as a sensitizer, was doped into Ba_(3)Bi_(1.82)(PO_(4))_(4): 0.18 Eu^(3+)and the band gap of the Ba_(3)Bi_(2)(PO_(4))_(4) host was estimated to be 4.19 eV. The emission intensity of Ba_(3)Bi_(1.82)(PO_(4))_(4): 0.18 Eu^(3+)was significantly enhanced when Sm^(3+)was co-doped. The existence and mechanism of energy transfer from Sm^(3+) to Eu^(3+)were evaluated by photoluminescence spectra and decay time measurements. The CIE chromaticity coordinate of Ba3 Bi1.75(PO4)4: 0.07 Sm^(3+), 0.18 Eu^(3+) phosphor was calculated to be(0.5746, 0.4197), respectively.展开更多
CaMoO_(4):Eu^(3+)and CaMoO_(4):Eu^(3+),A+(A=Li,Na,K)phosphors for light-emitting diode(LED)applications have been prepared by microwave sintering method(MSM),and their structure and luminescence properties are investi...CaMoO_(4):Eu^(3+)and CaMoO_(4):Eu^(3+),A+(A=Li,Na,K)phosphors for light-emitting diode(LED)applications have been prepared by microwave sintering method(MSM),and their structure and luminescence properties are investigated.The influences of microwave reaction time and concentration of different kinds of charge compensation A+and Eu^(3+)on luminescence have also been discussed.The samples emit a red luminescence at 615 nm attributed to the^(5)D0→^(7)F2 transition of Eu^(3+)under 464 nm excitation.It is observed that adding charge compensation A+in the sample synthesis increases luminescence intensity.The optimized sample made with 32 mol%Li+and 32 mol%Eu^(3+)has an enhancement factor of 4 in photoluminescence compared to the sample made without charge compensation.The CIE(Commission Internationale de l'Eclairage)coordinates of Ca0.36MoO_(4):0.32Eu^(3+),0.32Li+are x=0.661 and y=0.339,which indicate that the obtained phosphor can be a promising red color candidate for white LED fabrications.展开更多
CaWO_(4):xEu^(3+),yTm^(3+)crystals were obtained by facile synthesis at low temperature by the microwaveassisted hydrothermal method(MAH).The phase formation,morphology,luminescent properties and ene rgy transfer were...CaWO_(4):xEu^(3+),yTm^(3+)crystals were obtained by facile synthesis at low temperature by the microwaveassisted hydrothermal method(MAH).The phase formation,morphology,luminescent properties and ene rgy transfer were investigated.The X-ray diffraction(XRD)re sults show the formation of a scheelitelike tetragonal structure without the presence of secondary phases.The growth mechanism of hierarchical micro structures based on self-assembly and Ostwald-ripening processes was evaluated,obtaining different types of morphologies.The luminescence spectra of CaWO_(4):Eu^(3+),Tm^(3+)at 325 nm excitation show the predominance of red emission at the 5 D0→7 F2(Eu^(3+))transition at 624 nm.This feature signals dominant behavior of the electric dipole type.The presence of Tm^(3+)is notably evident in the absorption spectra by the related excitation transitions:3 H6→1 G4,3 H6→3 F3 and 3 H6→3 H4.Color parameters are discussed to characterize CaWO_(4):Eu^(3+),Tm^(3+)emission.The study of the emission spectrum as a function of the concentration of Eu^(3+)(x mol%)and Tm^(3+)(y mol%)indicates that the CaWO_(4):Eu^(3+),Tm^(3+)phosphors show stronger red emission intensity and exhibit the CIE value of x=0.63 and y=0.35.The photoluminescence results show 97%high color purity for CaWO_(4):4 mol%Eu^(3+),a high CRI(92%)and a low CCT of 1085 K.These results demonstrate that the CaWO_(4):Eu^(3+),Tm^(3+)red phosphors are promising as color converters for application in white light-emitting diodes and display devices.展开更多
YVO_(4):Eu^(3+) phosphors have been widely used in optoelectronic integration fields of its chemical and thermal stability.However,the excitation spectrum band of VO_(4)^(3-) is too narrow for high-efficiency luminesc...YVO_(4):Eu^(3+) phosphors have been widely used in optoelectronic integration fields of its chemical and thermal stability.However,the excitation spectrum band of VO_(4)^(3-) is too narrow for high-efficiency luminescence,restricting its further development.Herein,flower-like and linear-like YVO_(4):Eu^(3+) hollow mesoporous spheres were synthesized and connected with Eu organic ligand,to obtain a new hybrid luminescent material.The characterization shows that the pores of microspheres are in size of about 2-50 nm,sticked with regular morphology,well crystallized,and in uniform distribution.The emission intensity of hybrid luminescent material is higher than that of single YVO_(4):Eu^(3+) and single Eu co mplexes realizing the purpose of mutually reinforcing luminesce nce.This paper provides a new idea to connect rare earth complexes for a new non-silicon-based mesoporous spherical matrix.展开更多
基金supported by Jiangxi Provincial Department of Education (GJJ08344)
文摘The luminescent properties of Eu^3＋doped Ca2SiO4 red phosphors synthesized by the flux fusion reaction method were investigated. It was found that the excitation spectrum included two regions： the weak excitation band below 325 nm and strong narrow peaks above 325 nm. The main peak of the excitation band was located at 400 nm. The peaks located at 290 nm were assigned to the combination of the charge transfer transition of O-Eu, peaks above 325 nm （325, 385, 400, 470, 511, and 539 nm） were assigned to the f-f transitions of Eu^3＋. The emission spectrum was dominated by the red peak located at 612 nm due to the electric dipole transition of ^5D0-^7F2. In addition, the effects of the Eu^3＋ content and charge compensators of Li^＋, Na^＋, K^＋, and Cl^- ions on the emission intensity were investigated. The experiment results suggested that the strongest emission was obtained when the concentration of the Eu^3＋ ions was 0.3 mol^-1, and Li^＋ ions gave the best improvement to enhance the emission intensity. Ca2SiO4：Eu^3＋, Li^＋ was thus suitable for low-cost trichromatic white light emitting diodes （WLED） based on UV InGaN chip.
文摘YAl3 （BO3）4： Eu^3＋ phosphors were prepared by the conventional solid state reaction. The phase structure and morphology were investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. Doping YAl3（BO3）4： Eu^3＋ phosphors with concentration of Eu^3＋ ions of 0, 2, 5, 8 and 10 mol% were studied and their luminescent properties at room temperature were discussed. The excitation spectrum of Y0.95Eu0.05Al3（BO3）4 was composed of a broad band centered at about 252 nm and a group of lines in the longer wavelength region. In the emission spectra, the peak wavelength was about 614 nm under a 252 nm UV excitation. The optimal doping concentration of Eu^3＋ ions in YAl3（BO3）4： Eu^3＋ phosphors was 8 mol%.
基金Project supported by the National Natural Science Foundation of China(11974351)。
文摘Full-spectrum phosphor-converted white-light-emitting diodes(pc-WLED)are emerging as a mainstream technology in semiconductor lighting.Nevertheless,high-performance blue phosphor which can be excited efficiently by a 400 nm NUV diode chip is still lacking.Herein,we present a blue-emitting Na_(3)KMg_(7)(PO_(4))6:Eu^(2+)phosphor synthesized by the solid-reaction method.Particularly,we find that the using of Li_(2)CO_(3)as flux can significantly improve the crystal quality and thus the emission efficiency of the phosphor.Meanwhile,the excitation peak of the phosphor shifts from 365 to 400 nm,which is pivotal for efficient NUV(400 nm)diode chip excitation.The practical Eu^(2+)concentration is also enhanced by using Li_(2)CO_(3)as flux,and the absorption efficiency is greatly increased.This phosphor exhibits superior PL thermal stability,namely retains 94%integrated photoluminescence intensity at 150℃of that at 25℃.As a result,the optimized phosphor shows an emission band peaked at 437 nm with a bandwidth of 40 nm and a high external photoluminescence quantum yield of 51.7%.Finally,a pc-WLED was fabricated by using NKMPO:Eu^(2+)blue,Sr_(2)SiO_(4):Eu^(2+)green,CaAlSiN_(3):Eu^(2+)red phosphors,and a 400 nm NUV diode chip.It shows a high color rendering index of R_(a)=96.4 and a correlated color temperature of 4358 K.These results prove that NKMPO:Eu^(2+)is a promising blue phosphor for full-spectrum WLED based on NUV diode chips.
基金the National Natural Science Foundation of China (20376009)
文摘A series of long afterglow phosphors, Eu2+, Dy3+, with different iron content were prepared by nano-coating process. The resulted precursors were characterized by Transmission Electron Microscope (TEM), which suggested that the precursor particles had nanometer size distribution. The optical quenching of iron impurity on the phosphor powders were investigated by X-Ray powder Diffraction (XRD) and photoluminescence methods. The XRD indicates that a pure monoclinic SrAl2O4∶Eu2+, Dy3+ was formed at 1200 ℃ and iron impurity up to 296.36×10-4% had no effect on the SrAl2O4∶Eu2+, Dy3+ phase structure. However, the luminescence intensity were strongly dependent on the trace iron impurity, which might be explained that iron displace the aluminium and form Fe-O bond, which competed energy with Eu2+ and transfer red them to infrared sites.
基金Project supported by Outstanding Young and Middle-aged Scientific Innovation Team of Colleges and Universities of Hubei Province(T2020008)。
文摘A series of Dy^(3+)/Eu^(3+) single doped and co-doped SrLaAlO_(4) phosphors was synthesized by the traditional high-temperature solid-state method,and their structure,morphology and optical properties were characterized.The X-ray diffraction(XRD) shows a small amount of doping with Dy^(3+) and Eu^(3+) does not change the crystal structure of the matrix SrLaAlO_(4) and the best synthesis temperature is 1450℃.The scanning electron microscopy(SEM) indicates the particle size directly ranges from 1 to 5μm roughly and the energy dispersive spectroscopy(EDS) patterns show that SrLaAlO_(4):Dy^(3+) phosphor and SrLaAlO_(4):Dy^(3+),Eu^(3+) phosphor were successfully synthesized.SrLaAlO_(4):Dy^(3+) phosphor can be effectively excited by near-ultraviolet light,producing two strong emission lights at 483 nm(blue light) and 579 nm(yellow light),presenting a cold white light;SrLaAlO_(4):Eu^(3+) phosphor can be effectively excited by nearultraviolet light,producing red lights at 622 nm;the characteristic emission peaks of Dy^(3+) and Eu^(3+)can be shown simultaneously under the same excitation wavelength in SrLaAlO_(4):Dy^(3+), Eu^(3+) phosphor.By changing the relative doping concentration ratio of Dy^(3+) and Eu^(3+),the modulation of SrLaAlO_(4):Dy^(3+),Eu3+phosphor from cold white to warm white light can be achieved.In addition,the study of the luminescent mechanism and lifetime shows that there is energy transfer between Dy^(3+) and Eu^(3+) in SrLaAlO_(4):Dy^(3+),Eu^(3+) phosphor.
文摘White body-color （Y, Gd）BxV1-xO4-x ：Eu^3＋ phosphors were prepared by coprecipitation reaction. Under VUV excitation at 147 nm, the red emission colorimetric purity of （Y, Gd） BxV1-xO4-x： Eu^3＋ phosphor is much better than that of commercial PDP （plasma display panels） phosphor （Y, Gd）BO3：Eu^3＋ . But its relative emission intensity is only about 90% of the commercial phosphor.
基金Project supported by the National Natural Science Foundation of China (20671042,50872045)Natural Science Foundation of Guangdong Province (05200555,7005918)
文摘A flower-like Eu^2＋ and Dy^3＋ co-doped SrAl2O4 long-lasting phosphorescent （LLP） phosphor was synthesized via the inorganic- salt-based sol-gel method. The crystal structure, morphology and optical properties of the composite were characterized. X-ray diffraction diffusion （XRD） data and DSC-TG curves of the phosphor revealed that the SrAl2O4 crystallites have been formed after the precursor was calcined at 900 ℃ and to be single-phase SrA1204 at 1100 ℃. The SEM photographs indicated that the sample exhibited a universal flower-like morphology with crystallite size of about l-2μm. After being irradiated with ultraviolet （UV） light, the flower-like phosphor emitted long-lasting green phosphorescence with an excitation peak at 365 nm and emission peak at 500 nm which was ascribed to the characteristic 5d-4f transition of Eu^2＋. Both the PL spectra and the luminance decay curve revealed that this phosphor exhibited efficient luminescence and long lasting properties.
基金financially supported by the National Natural Science Foundation of China (No.21301046)
文摘Color-tunable phosphors Sr0.94MoO4：xEu^3＋, （0.06 - x）Tb^3＋ were synthesized rapidly by microwave ra- diation method with active carbon particle as microwave absorbent. The synthesized phosphors were investigated by X-ray powder diffraction （XRD） and fluorescence spec- trophotometer. The effects of the ratio of Eu^3＋ and Tb^3＋ on the phase structure and luminescent properties of the phos- phors were discussed. The results show that Eu^3＋,Tb^3＋-doped samples can be well indexed to the pure tetragonal scheelite- type SrMoO4, indicating that Eu^3＋ and Tb^3＋ are effectively doped into the SrMoO4 host lattices. The as-synthesized Sro.94MoO4：xEu^3＋,（0.06 - x）Tb^3＋ phosphors have two luminescent centers （Eu^3＋ and Tb^3＋）, which can show red and green emissions under ultraviolet light excitation, respec- tively. Doping concentration of Eu^3＋ and Tb^3＋ has great effect on the intensity of emission peaks and the chromaticity of the samples, and the full color between green and red light can be achieved by adjusting the relative concentration of Eu^3＋ and Tb^3＋.
基金Project supported by the Scientific Research Projects of Universities in Xinjiang Autonomous Region(XJEDU2017I009)the Scientific Research and Innovation Project of Postgraduates in Xinjiang Autonomous Region(XJ2020G233)。
文摘This study presents the photoluminescence characteristic analysis of a series of red phosphors of KAlSiO_(4):1.5 mol%Sm^(3+),x mol%Eu^(3+)(x=2,3,4,5,6,7)prepared via high-temperature solid-phase reaction.The results show that the X-ray diffraction(XRD)refinement results are reliable.The unit cell parameters and volume gradually decrease as the Eu^(3+) concentration increases,resulting in a grain size reduction of 10.22%.When x=6,the emission peaks of Sm^(3+) at 564,601,and 651 nm disappear completely,and the corresponding full width at half maximum becomes 0.At 610 nm,the emission peak intensity of Eu^(3+) is increased by a factor of 4.8.The resonant non-radiative energy transfer effect is greater than the co-excitation effect.A maximum energy transfer efficiency of 97.8%is achieved.The integral area at 610 nm is as high as 85%.The color purity of the phosphor is as high as 92.97%,and the internal quantum yield gradually changes from 32%to 51%.Ultimately,these results confirm that the silicate phosphor is suitable for the red component in the three primary color phosphors of white light-emitting diodes.
基金financially supported by the National Natural Science Foundation of China(No.51762010)Guizhou Provincial Science and Technology Planning Project(No.2018-5781)Guizhou Provincial High-level Innovative Talents(No.2015-4006)。
文摘Sm^(3+), Eu^(3+)co-coped Ba_(3)Bi_(2)(PO_(4))_(4) phosphors,as potential phosphors for white light-emitting diode applications, were synthesized through the solid-state reaction method for the first time. The crystal structure,absorption spectra, photoluminescence properties, decay time, energy transfer mechanism, temperature-dependent properties, and Commission International De L’Eclairage(CIE) chromaticity coordinates were investigated systematically. The pure eulytite-type Ba_(3)Bi_(2)(PO_(4))_(4) phase was obtained after heating at 980 ℃ for 5 h. A notably enhanced absorption efficiency at 393 nm was observed when Sm^(3+), as a sensitizer, was doped into Ba_(3)Bi_(1.82)(PO_(4))_(4): 0.18 Eu^(3+)and the band gap of the Ba_(3)Bi_(2)(PO_(4))_(4) host was estimated to be 4.19 eV. The emission intensity of Ba_(3)Bi_(1.82)(PO_(4))_(4): 0.18 Eu^(3+)was significantly enhanced when Sm^(3+)was co-doped. The existence and mechanism of energy transfer from Sm^(3+) to Eu^(3+)were evaluated by photoluminescence spectra and decay time measurements. The CIE chromaticity coordinate of Ba3 Bi1.75(PO4)4: 0.07 Sm^(3+), 0.18 Eu^(3+) phosphor was calculated to be(0.5746, 0.4197), respectively.
基金supported by the National Natural Science Foundation of China(No.21271074)teamwork projects funded by Guangdong Natural Science Foundation(No.S2013030012842)CAS-Foshan Cooperation Funding Program(No.2012HY100685).
文摘CaMoO_(4):Eu^(3+)and CaMoO_(4):Eu^(3+),A+(A=Li,Na,K)phosphors for light-emitting diode(LED)applications have been prepared by microwave sintering method(MSM),and their structure and luminescence properties are investigated.The influences of microwave reaction time and concentration of different kinds of charge compensation A+and Eu^(3+)on luminescence have also been discussed.The samples emit a red luminescence at 615 nm attributed to the^(5)D0→^(7)F2 transition of Eu^(3+)under 464 nm excitation.It is observed that adding charge compensation A+in the sample synthesis increases luminescence intensity.The optimized sample made with 32 mol%Li+and 32 mol%Eu^(3+)has an enhancement factor of 4 in photoluminescence compared to the sample made without charge compensation.The CIE(Commission Internationale de l'Eclairage)coordinates of Ca0.36MoO_(4):0.32Eu^(3+),0.32Li+are x=0.661 and y=0.339,which indicate that the obtained phosphor can be a promising red color candidate for white LED fabrications.
基金Project supported by National Council for Scientific and Technological Development-CNPq(303,604/2018-2)the Coordination for the Improvement of Higher Education Personnel(CAPES)-Brazil。
文摘CaWO_(4):xEu^(3+),yTm^(3+)crystals were obtained by facile synthesis at low temperature by the microwaveassisted hydrothermal method(MAH).The phase formation,morphology,luminescent properties and ene rgy transfer were investigated.The X-ray diffraction(XRD)re sults show the formation of a scheelitelike tetragonal structure without the presence of secondary phases.The growth mechanism of hierarchical micro structures based on self-assembly and Ostwald-ripening processes was evaluated,obtaining different types of morphologies.The luminescence spectra of CaWO_(4):Eu^(3+),Tm^(3+)at 325 nm excitation show the predominance of red emission at the 5 D0→7 F2(Eu^(3+))transition at 624 nm.This feature signals dominant behavior of the electric dipole type.The presence of Tm^(3+)is notably evident in the absorption spectra by the related excitation transitions:3 H6→1 G4,3 H6→3 F3 and 3 H6→3 H4.Color parameters are discussed to characterize CaWO_(4):Eu^(3+),Tm^(3+)emission.The study of the emission spectrum as a function of the concentration of Eu^(3+)(x mol%)and Tm^(3+)(y mol%)indicates that the CaWO_(4):Eu^(3+),Tm^(3+)phosphors show stronger red emission intensity and exhibit the CIE value of x=0.63 and y=0.35.The photoluminescence results show 97%high color purity for CaWO_(4):4 mol%Eu^(3+),a high CRI(92%)and a low CCT of 1085 K.These results demonstrate that the CaWO_(4):Eu^(3+),Tm^(3+)red phosphors are promising as color converters for application in white light-emitting diodes and display devices.
基金Project supported by the Shaanxi Provincial Department of Science and Technology Key Industry Innovation Chain Project (2019TSLGY07-04)the Shaanxi Provincial Science and Technology Plan Project Cooperation Unit Project (2019TD-019-01)+2 种基金Xi’an Key Laboratory of Clean Energy(2019219914SYS014CG036)the Natural Science Foundation of Xi’an (XA2020-CXRCFW-0247)the Yulin Industry-University-Research Cooperation Project(2019-173)。
文摘YVO_(4):Eu^(3+) phosphors have been widely used in optoelectronic integration fields of its chemical and thermal stability.However,the excitation spectrum band of VO_(4)^(3-) is too narrow for high-efficiency luminescence,restricting its further development.Herein,flower-like and linear-like YVO_(4):Eu^(3+) hollow mesoporous spheres were synthesized and connected with Eu organic ligand,to obtain a new hybrid luminescent material.The characterization shows that the pores of microspheres are in size of about 2-50 nm,sticked with regular morphology,well crystallized,and in uniform distribution.The emission intensity of hybrid luminescent material is higher than that of single YVO_(4):Eu^(3+) and single Eu co mplexes realizing the purpose of mutually reinforcing luminesce nce.This paper provides a new idea to connect rare earth complexes for a new non-silicon-based mesoporous spherical matrix.
