The triplet state energies of para aminobenzoic acid and nicotinic acid were determined by means of low temperature phosphorescence spectrometry.The energy matches between them and the resonant emitting energy levels ...The triplet state energies of para aminobenzoic acid and nicotinic acid were determined by means of low temperature phosphorescence spectrometry.The energy matches between them and the resonant emitting energy levels of Eu^(3+),Tb^(3+),Sm^(3+),Dy^(3+)were studied.The intramolecular energy transfer processes from the two aromatic carboxylic acid ligands to rare earth ions were also discussed on the basis of the measurement results of luminescence intensities,lifetimes and quantum efficiencies.展开更多
Present paper reports on luminescence characteristics of individually doped Bi3+: PZL, Sm3+: PZL and co-doped (Bi3+/Sm3+): PZL (50P2O5-30ZnO-20LiF) glasses prepared by a melt quenching method. The results revealed tha...Present paper reports on luminescence characteristics of individually doped Bi3+: PZL, Sm3+: PZL and co-doped (Bi3+/Sm3+): PZL (50P2O5-30ZnO-20LiF) glasses prepared by a melt quenching method. The results revealed that Bi3+: PZL glass exhibited a broad emission peak at 440 nm (3P1→1S0) under excitation wavelength 300 nm (1S0→3P1). Sm3+: PZL doped glass has shown a prominent orange emission at 601 nm (4G5/2→6H7/2) with an excitation wavelength 403 nm (6H5/2→4F7/2). Later on Bi3+ is added to Sm3+: PZL glass by increasing its concentrations from 0.1 - 1.5 mol%. By co-doping Bi3+ to Sm3+: PZL glass, Sm3+ emission intensity has been considerably enhanced till 1.0 mol% due to energy transfer from Bi3+ to Sm3+ and when its concentration exceeds this critical value (1.0 mol%) there has been a drastic decrease in Sm3+ emission which is explained accordingly from photoluminescence spectra, energy level diagram and lifetime measurements.展开更多
The green phosphor for white LED, Ca 8Mg(SiO 4) 4Cl 2∶Eu 2+, Mn 2+, was synthesized by high temperature solid state reaction under reducing atmosphere. During the process of the phosphor prepared, the excess Ca...The green phosphor for white LED, Ca 8Mg(SiO 4) 4Cl 2∶Eu 2+, Mn 2+, was synthesized by high temperature solid state reaction under reducing atmosphere. During the process of the phosphor prepared, the excess CaCl 2 can improve the intensity of emission. The experimental results indicate that there is an effective energy transfer from Eu 2+ to Mn 2+in Ca 8Mg(SiO 4) 4Cl 2 host. This kind of energy transfer may be due to resonance transfer, and this energy transfer is limited.展开更多
Crystals of LiKGdF 5∶Er 3+, Tb 3+ grown by the hydrothermal synthesis technique with concentrations of 2% and 0.4% were analysed. By using site selective excitation measured at low temperature, luminescence and ex...Crystals of LiKGdF 5∶Er 3+, Tb 3+ grown by the hydrothermal synthesis technique with concentrations of 2% and 0.4% were analysed. By using site selective excitation measured at low temperature, luminescence and excitation spectra from Er 3+ and Tb 3+ ions embedded in LiKGdF 5 were clearly separated. The lifetimes of the emitting levels 4S 3/2 of Er 3+ and 5D 4 of Tb 3+ were also determined. Following the site selective spectroscopy study, the dominant energy transfer process from Tb 3+ to Er 3+ in the crystal was then investigated via transient experiments.展开更多
A series of CaMoO4:xTb3+ (x=0.01, 0.03, 0.05, 0.07, 0.09, 0.15 and 0.20) phosphors in pure phase were prepared via high temperature solid-state reaction approach. The crystal structure of the phosphors was investi...A series of CaMoO4:xTb3+ (x=0.01, 0.03, 0.05, 0.07, 0.09, 0.15 and 0.20) phosphors in pure phase were prepared via high temperature solid-state reaction approach. The crystal structure of the phosphors was investigated by X-ray diffraction (XRD), and the optical properties were investigated by Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis) and photoluminescence (PL) spectroscopy. The PL spectra illustrated that these phosphors could be efficiently excited by the charge transfer band of the host and the energy transfer efficiency from the host to the doped activator reached 60% when the doping con- centration of the activator Th3+ was 20 mol.%. The concentration quenching occurred at x= 10 mol.%, from which the critical distance of activator was calculated to be about 1.14 nm. The CIE coordinates were estimated to be close to the standard green value. The host sensitized samples had potential application as green phosphors.展开更多
GdF3:Eu^3+ and GdF3:Eu^3+ nanoparticles were prepared by a co-precipitation method in the presence of the chelating agent, citric acid. The structural properties of the products were characterized by X-ray diffrac...GdF3:Eu^3+ and GdF3:Eu^3+ nanoparticles were prepared by a co-precipitation method in the presence of the chelating agent, citric acid. The structural properties of the products were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The average crystallite size was estimated from the full-width at half-maximum (FWHM) of the diffraction peaks by the Scherrer equation. The sizes of the nanoparticles were 12 nm for LaF3:Eu3+ and 17 nm for GdF3:Eu^3+. The luminescent properties of the nanoparticles were investigated by excitation and emission spectra. Energy transfer from Gd3+ to Eu3+ was observed.展开更多
A series of CaMoO_4:Tb^(3+),Eu^(3+) phosphors were prepared by the method of precipitation. The structure and morphology of the phosphors were characterized by the X-ray diffraction(XRD) and field emission sc...A series of CaMoO_4:Tb^(3+),Eu^(3+) phosphors were prepared by the method of precipitation. The structure and morphology of the phosphors were characterized by the X-ray diffraction(XRD) and field emission scanning electron microscopy(FE-SEM). The photoluminescence properties of the prepared products were researched, and the energy transfer from Tb^(3+) to Eu^(3+) in CaMoO_4 phosphors was studied. By adjusting the doping concentration of Eu^(3+) ions in CaMoO_4:Tb^(3+),Eu^(3+) phosphors, the emitting color of the phosphors could be easily tuned from green to red. With Tb^(3+) doped in the phosphors, the red luminescence of Eu^(3+) by near UV excitation was significantly enhanced. The energy transfer efficiency, rate and average distance between Tb^(3+) and Eu^(3+) in CaMoO_4:5%Tb^(3+),x%Eu^(3+)(mole percent) phosphors(x=0.3-10) were calculated. It was found that the interaction type between Tb^(3+) and Eu^(3+) was electric dipole-dipole interaction in the phosphors.展开更多
By controlling the concentration of Tb3+, a series of GdF3 samples were synthesized by a hydrothermal method without any surfactant. The samples were characterized by X-ray diffraction (XRD) patterns, field emissio...By controlling the concentration of Tb3+, a series of GdF3 samples were synthesized by a hydrothermal method without any surfactant. The samples were characterized by X-ray diffraction (XRD) patterns, field emission scanning electron microscopy (FE-SEM) images, photoluminescence (PL) excitation and emission spectra as well as luminescent dynamic decay curves. The opti-cal properties of Tb3+, the concentration quenching phenomenon of Tb3+, and the energy transfer from host Gd3+to Tb3+were inves-tigated and discussed based on the concentration of Tb3+in the GdF3 samples. The experimental results suggested that the optical properties of Tb3+and the energy transfer from host Gd3+to Tb3+could be adjusted by the concentration of Tb3+in the samples.展开更多
Ce^3+, Tb^3+ doped orthorhombic phases of KLu2F7 microcrystals with hexagonal disk morphology were synthesized by a hydrothermal method. Enhanced emissions of Tb^3+ were observed in the Ce^3+,Tb^3+ co-doped KLu2F...Ce^3+, Tb^3+ doped orthorhombic phases of KLu2F7 microcrystals with hexagonal disk morphology were synthesized by a hydrothermal method. Enhanced emissions of Tb^3+ were observed in the Ce^3+,Tb^3+ co-doped KLu2F7 sample compared to the Tb^3+ single-doped KLu2F7. The energy transfer efficiency from Ce^3+ to Tb^3+ was calculated by the photoluminescence intensity in the Ce^3+,Tb^3+ co-doped KLu2F7 samples. The average separations between Ce^3+ and Tb^3+ were calculated and the critical distance was 0.922 nm estimated by method of concentration quenching. The theoretical calculation proved the results. The theoretical analysis also suggested that the energy transfer from Ce^3+ to Tb^3+ in the KLu2F7 occurred predominantly via the dipole-quadrupole interaction. The KLu2F7 should be good host materials for emitters.展开更多
Phosphors with controlled emission spectra are of great interest due to their application for white light emitting diodes.Herein, a new class of Sr3Y2(SiO3)6:Ce3+,Tb3+ phosphors were synthesized by a facile sol-g...Phosphors with controlled emission spectra are of great interest due to their application for white light emitting diodes.Herein, a new class of Sr3Y2(SiO3)6:Ce3+,Tb3+ phosphors were synthesized by a facile sol-gel combustion method. The phase structure,morphology, and luminescence properties of the phosphors were characterized by using powder X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), and photoluminescence excitation and emission spectra,respectively. The results on luminescence properties indicated that co-doped Ce3+ ions served as UV-light sensitizers with excitation energy partially transferred to Tb3+ ions, leading to green emission from Tb3+. Particularly, the corresponding emitting colors of the phosphors could be well-tuned from deep blue(0.16, 0.05) to green region(0.25, 0.45) by adjusting the molar ratio of Ce3+/Tb3+.展开更多
A series of chalcohalide glasses based on the composition of 0.9(Ge30Ga5Se65)-0.1CsI with different Tm3+/Dy3+-codoped ions concentrations were synthesized by melt-quenching technique.The absorption spectra and 2.9...A series of chalcohalide glasses based on the composition of 0.9(Ge30Ga5Se65)-0.1CsI with different Tm3+/Dy3+-codoped ions concentrations were synthesized by melt-quenching technique.The absorption spectra and 2.9 μm mid-infrared fluorescence spectra of glass samples under 800 nm laser excitation were measured.The results showed that Tm3+ was an efficient sensitizer,which could enhance the Dy3+: 2.9 μm fluorescence intensity significantly.The effective energy transfer between the two rare-earth ions were mainly attributed to the resonance energy transfer from Tm3+:3F4 to Dy3+:6H11/2 level.Emission cross section of 2.9 μm mid-infrared luminescence was also investigated according to Judd-Ofelt theory,σe=2.51×10–20 cm2.展开更多
A series of single-phase and color-tunable phosphors Sr_(2)La_(3)(SiO_(4))_(3)F:0.15Tb^(3+),xSm^(3+)(SLSOF:0.15Tb^(3+),xSm^(3+)) was prepared using solid-state route.The X-ray diffraction(XRD) was used to characterize...A series of single-phase and color-tunable phosphors Sr_(2)La_(3)(SiO_(4))_(3)F:0.15Tb^(3+),xSm^(3+)(SLSOF:0.15Tb^(3+),xSm^(3+)) was prepared using solid-state route.The X-ray diffraction(XRD) was used to characterize the phase of the as-prepared samples.The synthesized phosphors have apatite-type structure without other impurities.Sm^(3+) and Tb^(3+) ions substitute La^(3+) into the lattice and form a single-phase solid solution.The elements are evenly distributed in the sample according to the scanning electron microscopy(SEM) results.The crystal structure of the host phosphor was refined by the Rietveld method.The optical properties were studied in detail by investigation of the luminescence and diffuse spectra,fluorescence decay curves and energy transfer efficiency.The phosphor color can be changed from green(0.29,0.48) to yellow/orange and red(0.57,0.42) via adjusting the doping ratio of Sm^(3+).The SLSOF:0.15Tb^(3+),xSm^(3+)phosphors can emit typical multicolor light such as green,yellow,orange and red with gradually increasing Sm^(3+)doping concentration.All results indicate the occurrence of the energy transfer which results in the color-tunable properties of the phosphors.展开更多
A new kind of apatite-type red-emitting Ba_(2)La_(8)(GeO_(4))_(6)O_(2):Eu^(3+)phosphor was prepared by high temperature solid-state method.The Rietveld analysis based on the powder diffraction data shows that Ba_(2)La...A new kind of apatite-type red-emitting Ba_(2)La_(8)(GeO_(4))_(6)O_(2):Eu^(3+)phosphor was prepared by high temperature solid-state method.The Rietveld analysis based on the powder diffraction data shows that Ba_(2)La_(8)(GeO_(4))_(6)O_(2):Eu^(3+)phosphors possess a pure apatite phase without any impurity.The emission spectrum of Ba_(2)La_(8)(GeO_(4))_(6)O_(2):Eu^(3+)phosphor consists of two bands,an orange emission band from 500 to 600 nm and a red emission band from 600 to 680 nm.By varying the amount of the doped europium ions from 0.02 to 0.14 mol,it is found that the luminescent properties of this rare earth phosphor are the best when the concentration of europium ion is 0.08 mol.The optimum concentration is eventually proved to be 0.08 mol.The Eu^(3+)doping dependent luminescence quenching can be further ascribed to dipole-quadrupole interactions.The quantum yield of Ba_(2)La_(7.92)(GeO_(4))_(6)O_(2):0.08 Eu^(3+)is 37.23%.The CIE analysis confirms a reddish emission in the near ultraviolet(n-UV)excitation.All these above properties of the phosphor can help in contribution of promoting white light-emitting diode.展开更多
Herein,melt-quenching and Er^(3+) doping were used to synthesize fluoride glass specimens with low phonon energies(582 cm^(-1)).These glass specimens exhibit intense 3.1 μm mid-infrared band emission when they are ex...Herein,melt-quenching and Er^(3+) doping were used to synthesize fluoride glass specimens with low phonon energies(582 cm^(-1)).These glass specimens exhibit intense 3.1 μm mid-infrared band emission when they are excited by a 980 nm laser diode,achieving a full width at half maximum(FWHM) of about166 nm.This 3.1 μm emission intensity is enhanced by the introduction of ZnF_(2) to the AlF_(3)-based fluoride glass.Up-conversion emission,strong near-infrared emission,and fluorescence lifetime are enhanced to different degrees by increasing the ZnF_(2) content.Moreover,the spectroscopic characteristics of the glass specimens and the highly efficient Er^(3+):~4S_(3/2)→~4F_(9/2) transition's energy transfer mechanism were investigated.The absorption spectra and emission spectra of these aluminum fluoride glass specimens were used to calculate their gain coefficients and maximum cross sections at 1.5 and 3.1 μm.Overall,the spectral properties of these prepared aluminum fluoride glass specimens demonstrate their high potential for use as infrared laser host materials.展开更多
The spectroscopic properties of a series of Dy^(3+)single-doped and Dy^(3+)/Nd^(3+),Dy^(3+)/Tb^(3+),and Dy^(3+)/Tm^(3+)co-doped YAlO_(3)(yttrium aluminum perovskite,YAP)phosphors were investigated and compared through...The spectroscopic properties of a series of Dy^(3+)single-doped and Dy^(3+)/Nd^(3+),Dy^(3+)/Tb^(3+),and Dy^(3+)/Tm^(3+)co-doped YAlO_(3)(yttrium aluminum perovskite,YAP)phosphors were investigated and compared through the measurements of optical absorption,emission spectra,and fluorescence decay curves.For the Dy^(3+)ion single-doped samples,the intensity of each absorption band increases with an increment in Dy^(3+)ion doping concentration,and the identified strong absorption peak at 447 nm indicates that Dy^(3+):YAP phosphors are suitable to be pumped by a blue laser diode(LD).For all co-doped samples,absorption peaks of Dy^(3+)ion along with some of the absorption bands of Nd^(3+),Tb^(3+),and Tm^(3+)ions are observed.Under 351 and 447 nm excitation,a prominent emission peak at 572 nm was obtained in all the samples,corresponding to Dy^(3+):^(4)F_(9/2)→^(6)H_(13/2)transition.Here,2 at%Dy^(3+):YAP phosphor exhibits the highest yellow emission intensity under 447 nm pumping.Among the three kinds of Dy^(3+)co-doped phosphors,Dy^(3+)/Tb^(3+):YAP phosphor possesses the dominant yellow emission.The fluorescence decay curves show exponential behaviour and are fitted well.The Commission International de L’Eclairage(CIE)chromaticity coordinates were calculated following the respective emission spectra,and it is found that all the coordinates locate in the yellow region.The energy transfer(ET)processes were investigated and the concentration quenching mechanism was discussed.The obtained results suggest that Dy^(3+)-activated YAP phosphors are good candidates for yellow LED applications.展开更多
A series of Na3Bi2–x(PO4)3:xEu3+ and Na3Bi1–x(PO4)2:xEu3+phosphors were successfully synthesized by solid-state method. The structure and luminescence properties were carefully investigated. The excitation s...A series of Na3Bi2–x(PO4)3:xEu3+ and Na3Bi1–x(PO4)2:xEu3+phosphors were successfully synthesized by solid-state method. The structure and luminescence properties were carefully investigated. The excitation spectra presented an obvious excitation band, and the peak was located at 396 nm, which matched well with the popular emissions from near-UV light-emitting diode chips. With the phase of Na3Bi2–x(PO4)3:xEu3+ changing to that of Na3Bi1–x(PO4)2:xEu3+, the intensity of magnetic dipole transition (5D0→F1) at 598 nm became stronger than that of electric dipole transition (5D0→7F2) at 621 nm. Under 396 nm excitation, the chromaticity coor-dinates and the decay curves of the entitled phosphors were also investigated. Based on all experiments without concentration quenching, we could control the luminescence intensity of the material by adjusting the doping amount of the active ions. All results indicated thatNa3Bi2–x(PO4)3:xEu3+ and Na3Bi1–x(PO4)2:xEu3+ phosphors have potential application as red phosphors in near UV chip-based white light emitting diodes.展开更多
A single-phase full-color emitting phosphor Sr_(2)Ca_(2)La(PO_(4))_(3)O:Eu^(2+),Tb^(3+),Mn^(2+) was synthesized by the high temperature solid-state method.The phase formation,luminescence properties,thermal stability,...A single-phase full-color emitting phosphor Sr_(2)Ca_(2)La(PO_(4))_(3)O:Eu^(2+),Tb^(3+),Mn^(2+) was synthesized by the high temperature solid-state method.The phase formation,luminescence properties,thermal stability,and energy transfer from Eu^(2+)to Tb^(3+) and Eu^(2+)to Mn^(2+) in Sr_(2)Ca_(2)La(PO_(4))_(3)O were investigated in details.Tunable emission color from blue to blueish green or orange can be observed under 365 nm near-ultraviolet excitation based on the energy transfer from Eu^(2+) to Tb^(3+)or Mn^(2+) ions by varying the ratio of Eu^(2+)/Tb^(3+)or Eu^(2+)/Mn^(2+) ions.White light was obtained with chromaticity coordinates of(0.3558,0.3500)in the Sr_(2)Ca_(2)La(PO_(4))_(3)O:0.04Eu^(2+),0.08Tb^(3+),0.40Mn^(2+) phosphor,suggesting their potential applications in white light emitting diodes.展开更多
文摘The triplet state energies of para aminobenzoic acid and nicotinic acid were determined by means of low temperature phosphorescence spectrometry.The energy matches between them and the resonant emitting energy levels of Eu^(3+),Tb^(3+),Sm^(3+),Dy^(3+)were studied.The intramolecular energy transfer processes from the two aromatic carboxylic acid ligands to rare earth ions were also discussed on the basis of the measurement results of luminescence intensities,lifetimes and quantum efficiencies.
文摘Present paper reports on luminescence characteristics of individually doped Bi3+: PZL, Sm3+: PZL and co-doped (Bi3+/Sm3+): PZL (50P2O5-30ZnO-20LiF) glasses prepared by a melt quenching method. The results revealed that Bi3+: PZL glass exhibited a broad emission peak at 440 nm (3P1→1S0) under excitation wavelength 300 nm (1S0→3P1). Sm3+: PZL doped glass has shown a prominent orange emission at 601 nm (4G5/2→6H7/2) with an excitation wavelength 403 nm (6H5/2→4F7/2). Later on Bi3+ is added to Sm3+: PZL glass by increasing its concentrations from 0.1 - 1.5 mol%. By co-doping Bi3+ to Sm3+: PZL glass, Sm3+ emission intensity has been considerably enhanced till 1.0 mol% due to energy transfer from Bi3+ to Sm3+ and when its concentration exceeds this critical value (1.0 mol%) there has been a drastic decrease in Sm3+ emission which is explained accordingly from photoluminescence spectra, energy level diagram and lifetime measurements.
文摘The green phosphor for white LED, Ca 8Mg(SiO 4) 4Cl 2∶Eu 2+, Mn 2+, was synthesized by high temperature solid state reaction under reducing atmosphere. During the process of the phosphor prepared, the excess CaCl 2 can improve the intensity of emission. The experimental results indicate that there is an effective energy transfer from Eu 2+ to Mn 2+in Ca 8Mg(SiO 4) 4Cl 2 host. This kind of energy transfer may be due to resonance transfer, and this energy transfer is limited.
文摘Crystals of LiKGdF 5∶Er 3+, Tb 3+ grown by the hydrothermal synthesis technique with concentrations of 2% and 0.4% were analysed. By using site selective excitation measured at low temperature, luminescence and excitation spectra from Er 3+ and Tb 3+ ions embedded in LiKGdF 5 were clearly separated. The lifetimes of the emitting levels 4S 3/2 of Er 3+ and 5D 4 of Tb 3+ were also determined. Following the site selective spectroscopy study, the dominant energy transfer process from Tb 3+ to Er 3+ in the crystal was then investigated via transient experiments.
基金Project supported by National Natural Science Foundation of China(20903123)Key Project of Chinese Ministry of Education(211154)Natural Science Foundation Project of Chongqing(KJ110532,CSTCjjA1425)
文摘A series of CaMoO4:xTb3+ (x=0.01, 0.03, 0.05, 0.07, 0.09, 0.15 and 0.20) phosphors in pure phase were prepared via high temperature solid-state reaction approach. The crystal structure of the phosphors was investigated by X-ray diffraction (XRD), and the optical properties were investigated by Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis) and photoluminescence (PL) spectroscopy. The PL spectra illustrated that these phosphors could be efficiently excited by the charge transfer band of the host and the energy transfer efficiency from the host to the doped activator reached 60% when the doping con- centration of the activator Th3+ was 20 mol.%. The concentration quenching occurred at x= 10 mol.%, from which the critical distance of activator was calculated to be about 1.14 nm. The CIE coordinates were estimated to be close to the standard green value. The host sensitized samples had potential application as green phosphors.
基金support from the Polish Ministry of Science and Higher EducationGrant N N204 329736
文摘GdF3:Eu^3+ and GdF3:Eu^3+ nanoparticles were prepared by a co-precipitation method in the presence of the chelating agent, citric acid. The structural properties of the products were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The average crystallite size was estimated from the full-width at half-maximum (FWHM) of the diffraction peaks by the Scherrer equation. The sizes of the nanoparticles were 12 nm for LaF3:Eu3+ and 17 nm for GdF3:Eu^3+. The luminescent properties of the nanoparticles were investigated by excitation and emission spectra. Energy transfer from Gd3+ to Eu3+ was observed.
基金supported by the National Natural Science Foundation of China(51002041)Natural Science Foundation of Heilongjiang Province(F201202)
文摘A series of CaMoO_4:Tb^(3+),Eu^(3+) phosphors were prepared by the method of precipitation. The structure and morphology of the phosphors were characterized by the X-ray diffraction(XRD) and field emission scanning electron microscopy(FE-SEM). The photoluminescence properties of the prepared products were researched, and the energy transfer from Tb^(3+) to Eu^(3+) in CaMoO_4 phosphors was studied. By adjusting the doping concentration of Eu^(3+) ions in CaMoO_4:Tb^(3+),Eu^(3+) phosphors, the emitting color of the phosphors could be easily tuned from green to red. With Tb^(3+) doped in the phosphors, the red luminescence of Eu^(3+) by near UV excitation was significantly enhanced. The energy transfer efficiency, rate and average distance between Tb^(3+) and Eu^(3+) in CaMoO_4:5%Tb^(3+),x%Eu^(3+)(mole percent) phosphors(x=0.3-10) were calculated. It was found that the interaction type between Tb^(3+) and Eu^(3+) was electric dipole-dipole interaction in the phosphors.
基金supported by National Natural Science Foundation of China(61205217)the Project of the Key Subject of Atomic and Molecular Physics of Jiangxi Province(2011-1015)
文摘By controlling the concentration of Tb3+, a series of GdF3 samples were synthesized by a hydrothermal method without any surfactant. The samples were characterized by X-ray diffraction (XRD) patterns, field emission scanning electron microscopy (FE-SEM) images, photoluminescence (PL) excitation and emission spectra as well as luminescent dynamic decay curves. The opti-cal properties of Tb3+, the concentration quenching phenomenon of Tb3+, and the energy transfer from host Gd3+to Tb3+were inves-tigated and discussed based on the concentration of Tb3+in the GdF3 samples. The experimental results suggested that the optical properties of Tb3+and the energy transfer from host Gd3+to Tb3+could be adjusted by the concentration of Tb3+in the samples.
基金Project supported by the National Natural Science Foundation of China(61205217,11204258)Program for New Century Excellent Talents in University of Fujian Province for 2015 and 2014(ZA14228)+1 种基金Project of Science and Technology Plan of Fujian Province(2016H0037)Science and Technology Plan of Xiamen City(3502Z20151236,3502Z20153018)
文摘Ce^3+, Tb^3+ doped orthorhombic phases of KLu2F7 microcrystals with hexagonal disk morphology were synthesized by a hydrothermal method. Enhanced emissions of Tb^3+ were observed in the Ce^3+,Tb^3+ co-doped KLu2F7 sample compared to the Tb^3+ single-doped KLu2F7. The energy transfer efficiency from Ce^3+ to Tb^3+ was calculated by the photoluminescence intensity in the Ce^3+,Tb^3+ co-doped KLu2F7 samples. The average separations between Ce^3+ and Tb^3+ were calculated and the critical distance was 0.922 nm estimated by method of concentration quenching. The theoretical calculation proved the results. The theoretical analysis also suggested that the energy transfer from Ce^3+ to Tb^3+ in the KLu2F7 occurred predominantly via the dipole-quadrupole interaction. The KLu2F7 should be good host materials for emitters.
基金supported by National Natural Science Foundation of China(31070517,21173042)the National Basic Research Program of China(2013CB932902)
文摘Phosphors with controlled emission spectra are of great interest due to their application for white light emitting diodes.Herein, a new class of Sr3Y2(SiO3)6:Ce3+,Tb3+ phosphors were synthesized by a facile sol-gel combustion method. The phase structure,morphology, and luminescence properties of the phosphors were characterized by using powder X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), and photoluminescence excitation and emission spectra,respectively. The results on luminescence properties indicated that co-doped Ce3+ ions served as UV-light sensitizers with excitation energy partially transferred to Tb3+ ions, leading to green emission from Tb3+. Particularly, the corresponding emitting colors of the phosphors could be well-tuned from deep blue(0.16, 0.05) to green region(0.25, 0.45) by adjusting the molar ratio of Ce3+/Tb3+.
基金Project supported by the National Natural Science Foundation of China (60878042, 60978058)Natural Science Foundation of Zhejiang Province (Y407253, Y1090996)K.C. Wong Magna Fund in Ningbo University
文摘A series of chalcohalide glasses based on the composition of 0.9(Ge30Ga5Se65)-0.1CsI with different Tm3+/Dy3+-codoped ions concentrations were synthesized by melt-quenching technique.The absorption spectra and 2.9 μm mid-infrared fluorescence spectra of glass samples under 800 nm laser excitation were measured.The results showed that Tm3+ was an efficient sensitizer,which could enhance the Dy3+: 2.9 μm fluorescence intensity significantly.The effective energy transfer between the two rare-earth ions were mainly attributed to the resonance energy transfer from Tm3+:3F4 to Dy3+:6H11/2 level.Emission cross section of 2.9 μm mid-infrared luminescence was also investigated according to Judd-Ofelt theory,σe=2.51×10–20 cm2.
基金supported by the National Natural Science Foundation of China (51872269)the Science and Technology Research Project of Hubei Provincial Department of Education (B2021091)+2 种基金Hubei Key Laboratory for New Textile Materials and Applications,Wuhan Textile University (FZXCL202107)the Open Project Program of High-Tech Organic Fibers Key Laboratory of Sichuan Province,China,Guangdong Basic and Applied Basic Research Foundation(2021A1515110283,2021A1515110702)China Postdoctoral Science Foundation(2021M702562)。
文摘A series of single-phase and color-tunable phosphors Sr_(2)La_(3)(SiO_(4))_(3)F:0.15Tb^(3+),xSm^(3+)(SLSOF:0.15Tb^(3+),xSm^(3+)) was prepared using solid-state route.The X-ray diffraction(XRD) was used to characterize the phase of the as-prepared samples.The synthesized phosphors have apatite-type structure without other impurities.Sm^(3+) and Tb^(3+) ions substitute La^(3+) into the lattice and form a single-phase solid solution.The elements are evenly distributed in the sample according to the scanning electron microscopy(SEM) results.The crystal structure of the host phosphor was refined by the Rietveld method.The optical properties were studied in detail by investigation of the luminescence and diffuse spectra,fluorescence decay curves and energy transfer efficiency.The phosphor color can be changed from green(0.29,0.48) to yellow/orange and red(0.57,0.42) via adjusting the doping ratio of Sm^(3+).The SLSOF:0.15Tb^(3+),xSm^(3+)phosphors can emit typical multicolor light such as green,yellow,orange and red with gradually increasing Sm^(3+)doping concentration.All results indicate the occurrence of the energy transfer which results in the color-tunable properties of the phosphors.
基金Project supported by the National Natural Science Foundation of China(51672257,51872269)。
文摘A new kind of apatite-type red-emitting Ba_(2)La_(8)(GeO_(4))_(6)O_(2):Eu^(3+)phosphor was prepared by high temperature solid-state method.The Rietveld analysis based on the powder diffraction data shows that Ba_(2)La_(8)(GeO_(4))_(6)O_(2):Eu^(3+)phosphors possess a pure apatite phase without any impurity.The emission spectrum of Ba_(2)La_(8)(GeO_(4))_(6)O_(2):Eu^(3+)phosphor consists of two bands,an orange emission band from 500 to 600 nm and a red emission band from 600 to 680 nm.By varying the amount of the doped europium ions from 0.02 to 0.14 mol,it is found that the luminescent properties of this rare earth phosphor are the best when the concentration of europium ion is 0.08 mol.The optimum concentration is eventually proved to be 0.08 mol.The Eu^(3+)doping dependent luminescence quenching can be further ascribed to dipole-quadrupole interactions.The quantum yield of Ba_(2)La_(7.92)(GeO_(4))_(6)O_(2):0.08 Eu^(3+)is 37.23%.The CIE analysis confirms a reddish emission in the near ultraviolet(n-UV)excitation.All these above properties of the phosphor can help in contribution of promoting white light-emitting diode.
基金Project supported by Shanghai Sailing Program from Science and Technology Committee of Shanghai (21YF1416200)。
文摘Herein,melt-quenching and Er^(3+) doping were used to synthesize fluoride glass specimens with low phonon energies(582 cm^(-1)).These glass specimens exhibit intense 3.1 μm mid-infrared band emission when they are excited by a 980 nm laser diode,achieving a full width at half maximum(FWHM) of about166 nm.This 3.1 μm emission intensity is enhanced by the introduction of ZnF_(2) to the AlF_(3)-based fluoride glass.Up-conversion emission,strong near-infrared emission,and fluorescence lifetime are enhanced to different degrees by increasing the ZnF_(2) content.Moreover,the spectroscopic characteristics of the glass specimens and the highly efficient Er^(3+):~4S_(3/2)→~4F_(9/2) transition's energy transfer mechanism were investigated.The absorption spectra and emission spectra of these aluminum fluoride glass specimens were used to calculate their gain coefficients and maximum cross sections at 1.5 and 3.1 μm.Overall,the spectral properties of these prepared aluminum fluoride glass specimens demonstrate their high potential for use as infrared laser host materials.
基金Projects supported by the National Natural Science Foundation of China(51872286,51832007,51472240,61675204)Science and Technology Plan Leading Project of Fujian Province(2018H0046)+3 种基金State Key Laboratory of Rare Earth Resource Utilization(RERU2018004,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences)the National Key Research and Development Program of China(2016YFB0701002)the fund of the State Key Laboratory of Solidification Processing(SKLSP201908,Northwestern Polytechnical University)Natural Science Foundation of Jiangxi Province(20181BAB211009)。
文摘The spectroscopic properties of a series of Dy^(3+)single-doped and Dy^(3+)/Nd^(3+),Dy^(3+)/Tb^(3+),and Dy^(3+)/Tm^(3+)co-doped YAlO_(3)(yttrium aluminum perovskite,YAP)phosphors were investigated and compared through the measurements of optical absorption,emission spectra,and fluorescence decay curves.For the Dy^(3+)ion single-doped samples,the intensity of each absorption band increases with an increment in Dy^(3+)ion doping concentration,and the identified strong absorption peak at 447 nm indicates that Dy^(3+):YAP phosphors are suitable to be pumped by a blue laser diode(LD).For all co-doped samples,absorption peaks of Dy^(3+)ion along with some of the absorption bands of Nd^(3+),Tb^(3+),and Tm^(3+)ions are observed.Under 351 and 447 nm excitation,a prominent emission peak at 572 nm was obtained in all the samples,corresponding to Dy^(3+):^(4)F_(9/2)→^(6)H_(13/2)transition.Here,2 at%Dy^(3+):YAP phosphor exhibits the highest yellow emission intensity under 447 nm pumping.Among the three kinds of Dy^(3+)co-doped phosphors,Dy^(3+)/Tb^(3+):YAP phosphor possesses the dominant yellow emission.The fluorescence decay curves show exponential behaviour and are fitted well.The Commission International de L’Eclairage(CIE)chromaticity coordinates were calculated following the respective emission spectra,and it is found that all the coordinates locate in the yellow region.The energy transfer(ET)processes were investigated and the concentration quenching mechanism was discussed.The obtained results suggest that Dy^(3+)-activated YAP phosphors are good candidates for yellow LED applications.
基金Project supported by the National Natural Science Foundation of China(50902042)the Midwest Universities Comprehensive Strength Promotion Project,the Funds for Distinguished Young Scientists of Hebei Province,China(A2015201129)+2 种基金the Natural Science Foundation of Hebei Province,China(A2014201035,E2014201037)the Education Office Research Foundation of Hebei Province,China(ZD2014036,QN2014085)China Postdoctoral Science Foundation(2015M581311)
文摘A series of Na3Bi2–x(PO4)3:xEu3+ and Na3Bi1–x(PO4)2:xEu3+phosphors were successfully synthesized by solid-state method. The structure and luminescence properties were carefully investigated. The excitation spectra presented an obvious excitation band, and the peak was located at 396 nm, which matched well with the popular emissions from near-UV light-emitting diode chips. With the phase of Na3Bi2–x(PO4)3:xEu3+ changing to that of Na3Bi1–x(PO4)2:xEu3+, the intensity of magnetic dipole transition (5D0→F1) at 598 nm became stronger than that of electric dipole transition (5D0→7F2) at 621 nm. Under 396 nm excitation, the chromaticity coor-dinates and the decay curves of the entitled phosphors were also investigated. Based on all experiments without concentration quenching, we could control the luminescence intensity of the material by adjusting the doping amount of the active ions. All results indicated thatNa3Bi2–x(PO4)3:xEu3+ and Na3Bi1–x(PO4)2:xEu3+ phosphors have potential application as red phosphors in near UV chip-based white light emitting diodes.
基金Project supported by the Natural Science Research of Jiangsu Higher Education Institutions of China (19KJA150011,18KJB140002,17KJA460004)。
文摘A single-phase full-color emitting phosphor Sr_(2)Ca_(2)La(PO_(4))_(3)O:Eu^(2+),Tb^(3+),Mn^(2+) was synthesized by the high temperature solid-state method.The phase formation,luminescence properties,thermal stability,and energy transfer from Eu^(2+)to Tb^(3+) and Eu^(2+)to Mn^(2+) in Sr_(2)Ca_(2)La(PO_(4))_(3)O were investigated in details.Tunable emission color from blue to blueish green or orange can be observed under 365 nm near-ultraviolet excitation based on the energy transfer from Eu^(2+) to Tb^(3+)or Mn^(2+) ions by varying the ratio of Eu^(2+)/Tb^(3+)or Eu^(2+)/Mn^(2+) ions.White light was obtained with chromaticity coordinates of(0.3558,0.3500)in the Sr_(2)Ca_(2)La(PO_(4))_(3)O:0.04Eu^(2+),0.08Tb^(3+),0.40Mn^(2+) phosphor,suggesting their potential applications in white light emitting diodes.