Al-doped and B, Al-codoped silica xerogel was fabricated by sol-gel process. The influence of B ions and annealing temperature on luminescent properties of phosphors were studied by using fluorescence spectrum, X-ray ...Al-doped and B, Al-codoped silica xerogel was fabricated by sol-gel process. The influence of B ions and annealing temperature on luminescent properties of phosphors were studied by using fluorescence spectrum, X-ray diffraction, DSC, TG/DTG analysis and IR spectrum. The heat treatment has a large effect on the luminescent properties. Under 248 nm excitation, the emission spectrum of samples heated shows characteristic emission peaks of Eu^3＋ ions are, which are due to the transitions of ^5D0→^7FJ（J = 0, 1, 2, 3, 4） of Eu^3＋ , respectively. The transition of ^5D0→^7F1 is split into two peaks.展开更多
The Ce^3+ and Eu^2+ ions codoped calcium zinc chlorosilicate Ca_8Zn(SiO_4)_4Cl_2 phosphors have been synthesized for the first time. The diffuse reflection, excitation and emission spectra of Ca_8Zn(SiO_4)_4Cl_2∶Ce^3...The Ce^3+ and Eu^2+ ions codoped calcium zinc chlorosilicate Ca_8Zn(SiO_4)_4Cl_2 phosphors have been synthesized for the first time. The diffuse reflection, excitation and emission spectra of Ca_8Zn(SiO_4)_4Cl_2∶Ce^3+, Eu^2+ have been measured at room temperature. The luminescence sensitizaiton of Eu^2+ by Ce^3+ inCa_8Zn(SiO_4)_4Cl_2∶Ce^3+, Eu^2+ has been expounded under the excitation of ultraviolet light and the efficient nonradiative energy transfer from Ce^3+ to Eu^2+ in this system is confirmed.展开更多
The interaction sites between microperoxidase-8(MP-8) and Eu^3+ was determined using electrochemical techniques. It is found that two Eu^3+ ions would coordinate strongly with carboxylate oxygen of two propionic acid ...The interaction sites between microperoxidase-8(MP-8) and Eu^3+ was determined using electrochemical techniques. It is found that two Eu^3+ ions would coordinate strongly with carboxylate oxygen of two propionic acid groups of the heme group in an MP-8 molecule, leading to the increase in the reversibility of the electrochemical reaction of MP-8. The excessive Eu^3+ ions weakly interact with the oxygen containing groups in the peptide chain of MP-8.展开更多
Excitation and emission spectra of new borate La_2CaB_(10)O_(19) doped Eu^(3+) in VUV-VIS range, high resolution (emission) spectra at room temperature and lifetime of Eu^(3+) were investigated. The emission line at a...Excitation and emission spectra of new borate La_2CaB_(10)O_(19) doped Eu^(3+) in VUV-VIS range, high resolution (emission) spectra at room temperature and lifetime of Eu^(3+) were investigated. The emission line at about 616 nm attributed to the (()~5D_0)-(()~7F_2) transition of Eu^(3+) is the most intense emission of Eu^(3+). The broad band at about 244 nm is originated from charge transition band (CTB) of O^(2-)→Eu^(3+). According to the numbers of spectral lines (()~5D_0)-(()~7F_0) and (()~5D_0)-(()~7F_1) in high-resolution spectrum, Eu^(3+) ions occupy two crystallographic sites. The lifetimes of (()~5D_0)-(()~7F_0) transition of Eu^(3+) of two kinds of lattice sites are individually 2.1 and 2.6 ms, and both are exponential decay. In the VUV excitation spectrum, complicated band between 130 and 170 nm consists of host absorption and f-d transition of Eu^(3+).展开更多
Drought tolerance and toxicity variation of grass pea (Lathyrus Sativus L.) were studied in the presence and absence of earth element Eu 3+ under the pot-culture condition. The addition of exogenous Eu 3+ increases th...Drought tolerance and toxicity variation of grass pea (Lathyrus Sativus L.) were studied in the presence and absence of earth element Eu 3+ under the pot-culture condition. The addition of exogenous Eu 3+ increases the survival days (SD) and lowered the stomatal sensitivity of grass pea seedlings under the decreasing soil moisture from -0.2 MPa to -1 MPa, suggesting that Eu 3+ can improve the ability of grass pea seedlings to tolerate drought. But in this case, Eu 3+ is found to significantly inhibit the increase in contents of plant toxicity β-N-oxalyl-L-a, β-diaminopropionic acid (ODAP) level in leaves. Therefore, the results demonstrate that Eu 3+ application is a potential agronomic approach to improve drought tolerance while lowering the toxicity level in grass pea productivity.展开更多
We reported on the high pressure luminescence spectra of polycrystalline Eu-doped GaN material synthesized in the reaction between alloys of gallium, bismuth and europium in ammonia atmosphere. The integrated luminesc...We reported on the high pressure luminescence spectra of polycrystalline Eu-doped GaN material synthesized in the reaction between alloys of gallium, bismuth and europium in ammonia atmosphere. The integrated luminescence intensity of the dominant Eu3＋ ion transition （5D0→^7F2） at 622 nm increased approximately one order of rnagnitude whereas its spectral position and line width did not change significantly between ambient and 6.8 GPa pressure, respectively. Moreover, material was characterized with photo- and cathodo-luminescence, and photoluminescence excitation spectra at different temperatures. It was found that the Eu3＋ ions occupying substitutional Ga site created different centers which could be effectively excited with above band gap excitation and from excitons resonantly photoexcited at the I2 bound exciton energy. Furthermore, the less efficient Eu3＋ ions excitation path existed through intrinsic impurities and defeels generating shallow energy levels in the forbidden gap. It was proposed that reduction of the thermal quenching and consequent enhancement of Eu3＋ ion emission intensity resulted from stronger localization of bound exciton on RESI trap induced by applied pressure.展开更多
Phosphor-in-glass(PiG)is a potential color convertor for high power WLEDs.A novel glass matrix with advanced performance is still a challenge.Recently,Eu^(3+)doped glass matrix has attracted much consideration mainly ...Phosphor-in-glass(PiG)is a potential color convertor for high power WLEDs.A novel glass matrix with advanced performance is still a challenge.Recently,Eu^(3+)doped glass matrix has attracted much consideration mainly due to its red compensation.A new borophosphate matrix to realize Eu^(3+)red light was designed in the Na_(2)O-ZnO-P_(2)O_(5)-B_(2)O_(3)-Eu_(2)O_(3)system.Meanwhile,a series of PiGs composed of different concentrations of Y3Al5O12:Ce phosphor and the matrix were also fabricated by re-sintering.The crystallization of Eu^(3+)based phosphate offers a novel red emission quenching apart from normal concentration quenching in the glass system.No direct energy transfer but only little reabso rption occurs between Eu^(3+)and Ce^(3+)ions.The Ce^(3+)concentration effect is obvious on the electroluminescent color.The optimized color rendering index of 79.7,the CIE coordinates near natural white and the range of CCT from 3943 to 6097 K were obtained for the packaged white light emitting diodes(WLEDs)together with the excellent CCT stability higher than about 97.5%and the quadruple thermal conductivity than that of silicon resin.The work implies borophosphate glass based PiGs with fine transparence and energy conversion efficiency are promising for excellent WLEDs,while the LED by using the PiG sample without any yellow phosphor doped is of high color purity and has a potential use as the 465 nm blue source.展开更多
The Eu^3＋/Ag co-doped rare earth disilicate Y2Si2O7 microcrystal was synthesized by sol-gel method. Through controlling the thermal treatment process of YzSi2OT：EU3＋/Ag precursor, various phases （amorphous, α, ...The Eu^3＋/Ag co-doped rare earth disilicate Y2Si2O7 microcrystal was synthesized by sol-gel method. Through controlling the thermal treatment process of YzSi2OT：EU3＋/Ag precursor, various phases （amorphous, α, β, γ, δ） were prepared. White light emis- sion was observed under UV light excitation in the samples heavily doped with Ag. The white light was realized by combining the intense red emission of Eu3＋, the green emission attributed to the very small molecule-like, non-plasmonic Ag particles （ML-Ag-particles）, and the blue emission due to Ag ions. Results demonstrated that Eu3＋/Ag co-doped Y2Si207 microcrystal could be potentially applied as white light emission phosphors for UV LED chips.展开更多
GaN thin films grown on sapphire were implanted by Eu^3＋ with three different fluences （5.0×10~14 , 2.5×10~15 and 5.0×10~15cm~–2 ）. The photoluminescence （PL） spectra show that, after annealing, t...GaN thin films grown on sapphire were implanted by Eu^3＋ with three different fluences （5.0×10~14 , 2.5×10~15 and 5.0×10~15cm~–2 ）. The photoluminescence （PL） spectra show that, after annealing, the samples exhibit strong emission at around 622.0 nm under 325 nm laser excitation. The intensity of this emission increases by one order of magnitude after annealing at from 600 ℃ to 900 ℃. Moreover, it increases less than 2 times when the fluence increases from 5×10~14 cm~–2 to 5×10~15 cm~–2 for the sample annealing at 900 ℃. The PL emission peaks around 622 nm of samples annealing at 900 ℃ can be well clarified by Gaussian fitting into 620.2, 622.0 and 625.0 nm, which are due to the Eu^3＋ related with defects, Eu^3＋ occupied at substitutional positions of Ga, and that located at interstitial sites, respectively. It shows that the different microenvironments and positions of Eu^3＋ are responsible for these peaks, and especially the defects introduced by implantation play an important role in the behavior of the PL because they set up an energy transmission bridge from exotic photons to Eu^3＋ .展开更多
In order to effectively improve the afterglow properties of CaAl_(2)O_(4):Eu^(2+),Nd^(3+) phosphors,a series of Ca_(0.982-x)Al_(2)O_(4):0.012 Eu^(2+),0.006 Nd^(3+),xGd^(3+)(x=0,0.012,0.024,0.036,0.048,0.060 mol) phosp...In order to effectively improve the afterglow properties of CaAl_(2)O_(4):Eu^(2+),Nd^(3+) phosphors,a series of Ca_(0.982-x)Al_(2)O_(4):0.012 Eu^(2+),0.006 Nd^(3+),xGd^(3+)(x=0,0.012,0.024,0.036,0.048,0.060 mol) phosphors were prepared by a high-temperature solid-phase approach.Crystalline composition and microstructure were characterized by XRD,TEM,HRTEM,and XPS,luminescence properties were systematically analyzed by fluorescence spectra,afterglow decay curves and TL glow curve.Results show that all of Ca_(0.982-x)Al_(2)O_(4):0.012 Eu^(2+),0.006 Nd^(3+),xGd^(3+)phosphors belong to monoclinic CaAl_(2)O_(4),without other cystalline phase.The blue emission at 442 nm is observed,which is assigned to the 4f^(6)5 d→4f^(7) transition of Eu^(2+) ions.Doping with appropriate amount of Gd^(3+) ions(x=0.036 mol) significantly improves the afterglow properties of phosphors,but the excessive doping of Gd^(3+) induces the fluorescent quenching.The doping of moderate Gd^(3+) changes the traps states,the trap depth varies from 0.598 to 0.644 eV and the trap concentration is also greatly improved,thus significantly improving afterglow performance.展开更多
High quality Tb^3＋/Eu^3＋ co-doped cubic NaYF 4 single crystal in the size of Φ1.0 cm×6.6 cm was grown by a modified Bridgman method using KF as assistant flux for NaF-YF 3 system under the condition of complet...High quality Tb^3＋/Eu^3＋ co-doped cubic NaYF 4 single crystal in the size of Φ1.0 cm×6.6 cm was grown by a modified Bridgman method using KF as assistant flux for NaF-YF 3 system under the condition of completely closed Pt crucible.A white light emission from the combination of the violet-blue,blue,green,orange,and red lights with chromaticity coordinates of x = 0.3107,y = 0.3274,correlated color temperature of T c = 6637 K,color rendering index of R a = 83,and color quality scale of Q a = 82 could be obtained from 1.51 mol%Tb^3＋ and 1.42 mol%Eu^3＋ co-doped cubic NaYF 4 single crystal when being excited by a 369 nm light.This indicates that Tb^3＋/Eu^3＋）co-doped cubic NaYF 4 single crystal has a potential application in white light emitting diode excited by ultraviolet light.展开更多
The design and fabrication of rare earth ions incorporated into the inorganic/organic hybrid materials have attracted growing attention for seeking improved optical properties and photofunctional performances.In this ...The design and fabrication of rare earth ions incorporated into the inorganic/organic hybrid materials have attracted growing attention for seeking improved optical properties and photofunctional performances.In this paper,a novel hybrid composite based on the layered rare earth hydroxides was successfully prepared by the ion-exchange and intercalation chemical process.The rare earth elements in the composite contain gadolinium(Gd)and europium(Eu)and the molar ratio of Gd to Eu is kept constant at 1.9:0.1.Organic sodium dodecyl sulfonate and dye coumarin-3-carboxyllc acid are simultaneously incorporated into the layered rare earth hydroxides as supporting agent and light-harvesting antenna,respectively.The resulting hybrid layered rare earth hydroxides exhibit the enlarged interlayer distance with about 2.60 nm,and the chemical composition was confirmed through X-ray diffraction,carbon,hydrogen and nitrogen(CHN)elemental analysis,infrared spectroscopy,and thermogravimetric analysis.The layered solid compound shows the characteristic red emission corresponding to the^(5)D_(0)→^(7)F_(2)transition of Eu^(3+)ion,and the luminescence intensity of the optimized compound is greatly enhanced as compared to its corresponding nitrate and the hybrid composite without the introduction of dye molecule.The hybrid layered rare earth hydroxides can be exfoliated into bright colloidal solution,which show superior recognition capability to Cu^(2+)ion with the distinct luminescence quenching.The large quenching constant(1.4×10^(4)L/mol)and low detection limit(0.35μmol/L)are achieved for Cu^(2+)ion,implying a"turn-off"fluorescent sensor for Cu^(2+)detection.Moreover,a transparent film was prepared based on the colloidal solution and displays the typical red emission in folded shape.The new hybrid compound with enhanced luminescence and excellent photofunctional performances is expected to be applied in the fields of fluorescent sensing and flexible optical devices.展开更多
Cyan-emitting Ca_(9)NaGd_(2/3)(PO_(4))_(7):Eu^(2+)phosphors were synthesized via high temperature solid-state route.X-ray powder diffraction(XRD)and scanning electron microscopy(SEM)were used to verify the phase and m...Cyan-emitting Ca_(9)NaGd_(2/3)(PO_(4))_(7):Eu^(2+)phosphors were synthesized via high temperature solid-state route.X-ray powder diffraction(XRD)and scanning electron microscopy(SEM)were used to verify the phase and morphology of the Ca_(9)NaGd_(2/3)(PO_(4))_(7):Eu^(2+)(CNGP:Eu^(2+))phosphors.The as-obtained phosphor exhibits a broad excitation band of 250-420 nm,which is near the ultraviolet region.An intense asymmetric cyan emission at 496 nm corresponds to the 5 d-4 f transition of Eu^(2+).The multiplesite luminescent properties of Eu^(2+)ions in CNGP benefit from versatile structure ofβ-Ca3(PO4)2 compounds.The effective energy transfer distance is 5.46 nm(through the spectral overlap calculation),validating that the resonant energy migration type is via dipole-dipole interaction mechanism.Compared to the initial one at room temperature,the luminescent intensity of CNGP:Eu^(2+)phosphor can maintain 77%as it is heated up to 420 K.A white light-emitting diode(WLED)with excellent luminesce nt properties was successfully fabricated.Moreover,the CIE chromaticity coordinates of fabricated WLED driven by changing current just change slightly.展开更多
文摘Al-doped and B, Al-codoped silica xerogel was fabricated by sol-gel process. The influence of B ions and annealing temperature on luminescent properties of phosphors were studied by using fluorescence spectrum, X-ray diffraction, DSC, TG/DTG analysis and IR spectrum. The heat treatment has a large effect on the luminescent properties. Under 248 nm excitation, the emission spectrum of samples heated shows characteristic emission peaks of Eu^3＋ ions are, which are due to the transitions of ^5D0→^7FJ（J = 0, 1, 2, 3, 4） of Eu^3＋ , respectively. The transition of ^5D0→^7F1 is split into two peaks.
文摘The Ce^3+ and Eu^2+ ions codoped calcium zinc chlorosilicate Ca_8Zn(SiO_4)_4Cl_2 phosphors have been synthesized for the first time. The diffuse reflection, excitation and emission spectra of Ca_8Zn(SiO_4)_4Cl_2∶Ce^3+, Eu^2+ have been measured at room temperature. The luminescence sensitizaiton of Eu^2+ by Ce^3+ inCa_8Zn(SiO_4)_4Cl_2∶Ce^3+, Eu^2+ has been expounded under the excitation of ultraviolet light and the efficient nonradiative energy transfer from Ce^3+ to Eu^2+ in this system is confirmed.
文摘The interaction sites between microperoxidase-8(MP-8) and Eu^3+ was determined using electrochemical techniques. It is found that two Eu^3+ ions would coordinate strongly with carboxylate oxygen of two propionic acid groups of the heme group in an MP-8 molecule, leading to the increase in the reversibility of the electrochemical reaction of MP-8. The excessive Eu^3+ ions weakly interact with the oxygen containing groups in the peptide chain of MP-8.
文摘Excitation and emission spectra of new borate La_2CaB_(10)O_(19) doped Eu^(3+) in VUV-VIS range, high resolution (emission) spectra at room temperature and lifetime of Eu^(3+) were investigated. The emission line at about 616 nm attributed to the (()~5D_0)-(()~7F_2) transition of Eu^(3+) is the most intense emission of Eu^(3+). The broad band at about 244 nm is originated from charge transition band (CTB) of O^(2-)→Eu^(3+). According to the numbers of spectral lines (()~5D_0)-(()~7F_0) and (()~5D_0)-(()~7F_1) in high-resolution spectrum, Eu^(3+) ions occupy two crystallographic sites. The lifetimes of (()~5D_0)-(()~7F_0) transition of Eu^(3+) of two kinds of lattice sites are individually 2.1 and 2.6 ms, and both are exponential decay. In the VUV excitation spectrum, complicated band between 130 and 170 nm consists of host absorption and f-d transition of Eu^(3+).
文摘Drought tolerance and toxicity variation of grass pea (Lathyrus Sativus L.) were studied in the presence and absence of earth element Eu 3+ under the pot-culture condition. The addition of exogenous Eu 3+ increases the survival days (SD) and lowered the stomatal sensitivity of grass pea seedlings under the decreasing soil moisture from -0.2 MPa to -1 MPa, suggesting that Eu 3+ can improve the ability of grass pea seedlings to tolerate drought. But in this case, Eu 3+ is found to significantly inhibit the increase in contents of plant toxicity β-N-oxalyl-L-a, β-diaminopropionic acid (ODAP) level in leaves. Therefore, the results demonstrate that Eu 3+ application is a potential agronomic approach to improve drought tolerance while lowering the toxicity level in grass pea productivity.
基金supported by the Polish Committee for Scientific Research (PBZ/MEiN/01/2006/39)
文摘We reported on the high pressure luminescence spectra of polycrystalline Eu-doped GaN material synthesized in the reaction between alloys of gallium, bismuth and europium in ammonia atmosphere. The integrated luminescence intensity of the dominant Eu3＋ ion transition （5D0→^7F2） at 622 nm increased approximately one order of rnagnitude whereas its spectral position and line width did not change significantly between ambient and 6.8 GPa pressure, respectively. Moreover, material was characterized with photo- and cathodo-luminescence, and photoluminescence excitation spectra at different temperatures. It was found that the Eu3＋ ions occupying substitutional Ga site created different centers which could be effectively excited with above band gap excitation and from excitons resonantly photoexcited at the I2 bound exciton energy. Furthermore, the less efficient Eu3＋ ions excitation path existed through intrinsic impurities and defeels generating shallow energy levels in the forbidden gap. It was proposed that reduction of the thermal quenching and consequent enhancement of Eu3＋ ion emission intensity resulted from stronger localization of bound exciton on RESI trap induced by applied pressure.
基金Project supported by the Joint Funds of the National Natural Science Foundation of China(U1932160)the National Natural Science Foundation of China(51605272)。
文摘Phosphor-in-glass(PiG)is a potential color convertor for high power WLEDs.A novel glass matrix with advanced performance is still a challenge.Recently,Eu^(3+)doped glass matrix has attracted much consideration mainly due to its red compensation.A new borophosphate matrix to realize Eu^(3+)red light was designed in the Na_(2)O-ZnO-P_(2)O_(5)-B_(2)O_(3)-Eu_(2)O_(3)system.Meanwhile,a series of PiGs composed of different concentrations of Y3Al5O12:Ce phosphor and the matrix were also fabricated by re-sintering.The crystallization of Eu^(3+)based phosphate offers a novel red emission quenching apart from normal concentration quenching in the glass system.No direct energy transfer but only little reabso rption occurs between Eu^(3+)and Ce^(3+)ions.The Ce^(3+)concentration effect is obvious on the electroluminescent color.The optimized color rendering index of 79.7,the CIE coordinates near natural white and the range of CCT from 3943 to 6097 K were obtained for the packaged white light emitting diodes(WLEDs)together with the excellent CCT stability higher than about 97.5%and the quadruple thermal conductivity than that of silicon resin.The work implies borophosphate glass based PiGs with fine transparence and energy conversion efficiency are promising for excellent WLEDs,while the LED by using the PiG sample without any yellow phosphor doped is of high color purity and has a potential use as the 465 nm blue source.
基金Project supported by the National Natural Science Foundation of China(11074232,11274288,21002097,11304300)the National Basic Research Program of China(2011CB932801,2012CB933702)Ministry of Education of China(20123402110034)
文摘The Eu^3＋/Ag co-doped rare earth disilicate Y2Si2O7 microcrystal was synthesized by sol-gel method. Through controlling the thermal treatment process of YzSi2OT：EU3＋/Ag precursor, various phases （amorphous, α, β, γ, δ） were prepared. White light emis- sion was observed under UV light excitation in the samples heavily doped with Ag. The white light was realized by combining the intense red emission of Eu3＋, the green emission attributed to the very small molecule-like, non-plasmonic Ag particles （ML-Ag-particles）, and the blue emission due to Ag ions. Results demonstrated that Eu3＋/Ag co-doped Y2Si207 microcrystal could be potentially applied as white light emission phosphors for UV LED chips.
基金Supported by the National Natural Science Foundation of China (10775106)
文摘GaN thin films grown on sapphire were implanted by Eu^3＋ with three different fluences （5.0×10~14 , 2.5×10~15 and 5.0×10~15cm~–2 ）. The photoluminescence （PL） spectra show that, after annealing, the samples exhibit strong emission at around 622.0 nm under 325 nm laser excitation. The intensity of this emission increases by one order of magnitude after annealing at from 600 ℃ to 900 ℃. Moreover, it increases less than 2 times when the fluence increases from 5×10~14 cm~–2 to 5×10~15 cm~–2 for the sample annealing at 900 ℃. The PL emission peaks around 622 nm of samples annealing at 900 ℃ can be well clarified by Gaussian fitting into 620.2, 622.0 and 625.0 nm, which are due to the Eu^3＋ related with defects, Eu^3＋ occupied at substitutional positions of Ga, and that located at interstitial sites, respectively. It shows that the different microenvironments and positions of Eu^3＋ are responsible for these peaks, and especially the defects introduced by implantation play an important role in the behavior of the PL because they set up an energy transmission bridge from exotic photons to Eu^3＋ .
基金the National Natural Science Fund of China(51772099,51572069,51872091)Scientific and Technological Research Projects of Colleges and Universities in Hebei Province(QN2019049)the Doctoral Initiation Fund(BS2017025)。
文摘In order to effectively improve the afterglow properties of CaAl_(2)O_(4):Eu^(2+),Nd^(3+) phosphors,a series of Ca_(0.982-x)Al_(2)O_(4):0.012 Eu^(2+),0.006 Nd^(3+),xGd^(3+)(x=0,0.012,0.024,0.036,0.048,0.060 mol) phosphors were prepared by a high-temperature solid-phase approach.Crystalline composition and microstructure were characterized by XRD,TEM,HRTEM,and XPS,luminescence properties were systematically analyzed by fluorescence spectra,afterglow decay curves and TL glow curve.Results show that all of Ca_(0.982-x)Al_(2)O_(4):0.012 Eu^(2+),0.006 Nd^(3+),xGd^(3+)phosphors belong to monoclinic CaAl_(2)O_(4),without other cystalline phase.The blue emission at 442 nm is observed,which is assigned to the 4f^(6)5 d→4f^(7) transition of Eu^(2+) ions.Doping with appropriate amount of Gd^(3+) ions(x=0.036 mol) significantly improves the afterglow properties of phosphors,but the excessive doping of Gd^(3+) induces the fluorescent quenching.The doping of moderate Gd^(3+) changes the traps states,the trap depth varies from 0.598 to 0.644 eV and the trap concentration is also greatly improved,thus significantly improving afterglow performance.
基金supported in part by the National Natural Science Foundation of China (Grant Nos.51472125 and 51272109)K.C.Wong Magna Fund in Ningbo University
文摘High quality Tb^3＋/Eu^3＋ co-doped cubic NaYF 4 single crystal in the size of Φ1.0 cm×6.6 cm was grown by a modified Bridgman method using KF as assistant flux for NaF-YF 3 system under the condition of completely closed Pt crucible.A white light emission from the combination of the violet-blue,blue,green,orange,and red lights with chromaticity coordinates of x = 0.3107,y = 0.3274,correlated color temperature of T c = 6637 K,color rendering index of R a = 83,and color quality scale of Q a = 82 could be obtained from 1.51 mol%Tb^3＋ and 1.42 mol%Eu^3＋ co-doped cubic NaYF 4 single crystal when being excited by a 369 nm light.This indicates that Tb^3＋/Eu^3＋）co-doped cubic NaYF 4 single crystal has a potential application in white light emitting diode excited by ultraviolet light.
基金Project supported by the National Natural Science Foundation of China(51972097)。
文摘The design and fabrication of rare earth ions incorporated into the inorganic/organic hybrid materials have attracted growing attention for seeking improved optical properties and photofunctional performances.In this paper,a novel hybrid composite based on the layered rare earth hydroxides was successfully prepared by the ion-exchange and intercalation chemical process.The rare earth elements in the composite contain gadolinium(Gd)and europium(Eu)and the molar ratio of Gd to Eu is kept constant at 1.9:0.1.Organic sodium dodecyl sulfonate and dye coumarin-3-carboxyllc acid are simultaneously incorporated into the layered rare earth hydroxides as supporting agent and light-harvesting antenna,respectively.The resulting hybrid layered rare earth hydroxides exhibit the enlarged interlayer distance with about 2.60 nm,and the chemical composition was confirmed through X-ray diffraction,carbon,hydrogen and nitrogen(CHN)elemental analysis,infrared spectroscopy,and thermogravimetric analysis.The layered solid compound shows the characteristic red emission corresponding to the^(5)D_(0)→^(7)F_(2)transition of Eu^(3+)ion,and the luminescence intensity of the optimized compound is greatly enhanced as compared to its corresponding nitrate and the hybrid composite without the introduction of dye molecule.The hybrid layered rare earth hydroxides can be exfoliated into bright colloidal solution,which show superior recognition capability to Cu^(2+)ion with the distinct luminescence quenching.The large quenching constant(1.4×10^(4)L/mol)and low detection limit(0.35μmol/L)are achieved for Cu^(2+)ion,implying a"turn-off"fluorescent sensor for Cu^(2+)detection.Moreover,a transparent film was prepared based on the colloidal solution and displays the typical red emission in folded shape.The new hybrid compound with enhanced luminescence and excellent photofunctional performances is expected to be applied in the fields of fluorescent sensing and flexible optical devices.
基金Project supported by Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications(2019XGJSKFJJ01)the Construction Program of the key discipline in Hunan Province+4 种基金the Projects of the Education Department of Hunan Province(18A465)Science and Technology Plan Project of Chenzhou City(jsyf2017014)Natural Science Foundation of Shandong Province(ZR2018LB002)Key Research and Development Project of Shandong Province(2019GGX102081)Key Research and Development Project of Jining(2019ZDGH026)。
文摘Cyan-emitting Ca_(9)NaGd_(2/3)(PO_(4))_(7):Eu^(2+)phosphors were synthesized via high temperature solid-state route.X-ray powder diffraction(XRD)and scanning electron microscopy(SEM)were used to verify the phase and morphology of the Ca_(9)NaGd_(2/3)(PO_(4))_(7):Eu^(2+)(CNGP:Eu^(2+))phosphors.The as-obtained phosphor exhibits a broad excitation band of 250-420 nm,which is near the ultraviolet region.An intense asymmetric cyan emission at 496 nm corresponds to the 5 d-4 f transition of Eu^(2+).The multiplesite luminescent properties of Eu^(2+)ions in CNGP benefit from versatile structure ofβ-Ca3(PO4)2 compounds.The effective energy transfer distance is 5.46 nm(through the spectral overlap calculation),validating that the resonant energy migration type is via dipole-dipole interaction mechanism.Compared to the initial one at room temperature,the luminescent intensity of CNGP:Eu^(2+)phosphor can maintain 77%as it is heated up to 420 K.A white light-emitting diode(WLED)with excellent luminesce nt properties was successfully fabricated.Moreover,the CIE chromaticity coordinates of fabricated WLED driven by changing current just change slightly.
