Eu3＋ doped borophosphate glasses with the chemical composition 20Li2O-30Al2O3-10B2O3-40P2O5-xEu2O3（where x=0.05 mol.%, 0.1 mol.%, 1.0 mol.%, 1.5 mol.% and 2.0 mol.%） were prepared by conventional melt quenching tec...Eu3＋ doped borophosphate glasses with the chemical composition 20Li2O-30Al2O3-10B2O3-40P2O5-xEu2O3（where x=0.05 mol.%, 0.1 mol.%, 1.0 mol.%, 1.5 mol.% and 2.0 mol.%） were prepared by conventional melt quenching technique. The structural and luminescence properties of the prepared Eu3＋ doped borophosphate glasses were studied and compared with reported results. The XRD pattern showed the amorphous nature of the prepared glasses. Whereas, the FTIR spectra revealed the vibrational modes in the prepared glasses. The bonding parameters（ β and ？） were calculated through the excitation spectra. Judd-Ofelt（J-O） intensity parameters were calculated from the emission spectra and were used to determine transition probability（A）, stimulated emission cross-section（σE P）, radiative lifetime（τR） and branching ratios（βexp） for the transition 5D0→7Fj（j=1, 2, 3 and 4） of Eu3＋ ions. Furthermore, the luminescence intensity ratio（R） of 5D0→7F2 to 5D0→7F1 transition was also calculated. Transition 5D0→7F2 had the highest value of stimulated emission cross-section and branching ratios and the results were comparable with the reported values. This indicated that the present glass is promising host material for Eu3＋ doped fiber amplifiers.展开更多
The transfer of trivalent europium ion in a liquid surfactant membrane system is investigated in order toclarify the characteristics of liquid membrane separation process and the availability of this technique forreco...The transfer of trivalent europium ion in a liquid surfactant membrane system is investigated in order toclarify the characteristics of liquid membrane separation process and the availability of this technique forrecovering trivalent lanthanides and actinides.A layered structure model for the emulsion globule is sug-gested.The equations describing the relationship among the effective membrane thickness,the time andother factors are derived and verified experimentally.Results show that under certain conditions the decreas-ing concentration of europium ion in the external phase is proportional to the square root of the time,the acidity of the internal phase and the carrier concentration in the membrane phase.The membrane phase consists of kerosene（solvent）,Span-80（surfactant）and di-（2-ethylhexyl） phosphoricacid（HDEHP,carrier）.The internal phase is dilute nitric acid and the external phase is aqueous solu-tion containing Eu（NO3）3.The mass transfer rate of europium in this system is high and the recovery ofeuropium may be more than 99%.展开更多
In crystals BaFX:Eu^(2+)(X=Cl,Br).there exists configuration interaction between 4f^65d and 4f^65s ex- cited state of Eu^(2+)ion.and it results in the change of relative intensities of d-f and f-f transition.The trans...In crystals BaFX:Eu^(2+)(X=Cl,Br).there exists configuration interaction between 4f^65d and 4f^65s ex- cited state of Eu^(2+)ion.and it results in the change of relative intensities of d-f and f-f transition.The transition ~S_-_2→4f^65d-6s is observed.The variation of F/X atomic ratio between 110/90 and 90/110 does not obvi- ously influence the luminescence of BaFX:Eu^(2-).There is energy transfer between Eu^(2+)(f-f)and Eu^(3+)which coexists in the matrices.展开更多
Thin nanocrystalline TiO2 films doped by europium ions (Eu3+) were obtained by the sol-gel method. The photoelectric properties of Eu3+-doped TiO2 film electrode sensitized by cis-RuL2(SCN)2·2H2O (L=cis-2,2′-bip...Thin nanocrystalline TiO2 films doped by europium ions (Eu3+) were obtained by the sol-gel method. The photoelectric properties of Eu3+-doped TiO2 film electrode sensitized by cis-RuL2(SCN)2·2H2O (L=cis-2,2′-bipyridine-4,4′-dicarboxlic acid) ruthenium complex were studied. The thin films were characterized by X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy. Effect of doping Eu3+ on microscopic structure and photoelectrical properties were discussed. The result shows that doping europium ions makes specific surface area of these films larger, which contributes to improving the photoelectric properties. It is found that an optimal composition doped with 0.2 mol.% Eu3+ exhibits the highest photoelectric properties. Isc is 0.37 mA·cm-2, which is 0.17 mA·cm-2 bigger than that of un-doped films; Voc is 405 mV, which is 50 mV bigger than that of un-doped films.展开更多
A method to fabricate europium ions doped-high silica glass for transparent fluorescence materials based on the fabrication and sintering technique of nano-porous silica glass was reported. Glasses impregnated with Eu...A method to fabricate europium ions doped-high silica glass for transparent fluorescence materials based on the fabrication and sintering technique of nano-porous silica glass was reported. Glasses impregnated with Eu ions and sintered at above 1150℃in a reduction atmosphere show a very strong blue light from an emission band at about 430 nm due to the 4f65d→4f7(8S7/2) transition of the Eu2+ ions. On the other hand, the Eu-doped glass obtained by co-impregnated with Y3+ and V5+ ions and sintering in oxidation atmosphere behaves a very strong red emission band at about 615 nm with a UV excitation. An appearance of vanadate band in the excitation spectrum of Eu3+ , Y3+ .and V5+ ions co-doped high silica glass implies an effective energy transferring from VO43- to Eu3+ and effective excitation of Eu3+ by about 500 nm strong broad emission of VO43- .展开更多
Nanoparticles and nanowires of LaPO 4: Eu phosphors were synthesized by hydrothermal method. Their luminescent properties including electronic transition, surface effect, and temperature-dependent luminescent charact...Nanoparticles and nanowires of LaPO 4: Eu phosphors were synthesized by hydrothermal method. Their luminescent properties including electronic transition, surface effect, and temperature-dependent luminescent characteristics were systemically studied and compared to the bulk powders. It can be concluded that in comparison with the bulk powders, the fluorescence intensity decreases in nanoparticles and nanowires, while the lifetime increases, indicating that the radiative transition rate decreases. The nonradiative transition rate in nanowires decreases than that in nanoparticles due to its decreased surface to volume ratio. The temperature-dependent experiments indicate that the thermal quenching in nanopowders becomes weaker than that in the bulk powders.展开更多
The fluorescent characteristic and emission spectra of Eu^(2+) in the cubic structure Ca_8Zn(SiO_4)_4Cl_2 with three kinds of cation sites is reported.The influence of temperature,Eu^(2+) concentra- tion and excitatio...The fluorescent characteristic and emission spectra of Eu^(2+) in the cubic structure Ca_8Zn(SiO_4)_4Cl_2 with three kinds of cation sites is reported.The influence of temperature,Eu^(2+) concentra- tion and excitation conditions on fluorescent properties of Eu^(2+) are studied at 77 and 298 K.The coordination number of Eu^(2+) at different sites is obtained.The green and red emission bands arise from Eu_(2+) ions locating on eight- and six- coordinated inequivalent sites respectively.展开更多
Novel soluble rare earth aromatic carboxylates were prepared. The triplet energy level of organic ligand was measured. The photoluminescence properties of the Tb 3+ and Eu 3+ aromatic carboxylates and lifetimes ...Novel soluble rare earth aromatic carboxylates were prepared. The triplet energy level of organic ligand was measured. The photoluminescence properties of the Tb 3+ and Eu 3+ aromatic carboxylates and lifetimes were investigated, which indicated that these rare earth complexes have high quantum efficiency. Because of their excellent solubility, polymer-doping rare earth carboxylates were fabricated as thin films by spin-coating method and their luminescence properties were studied. Some rare earth organic light-emitting diodes were successfully fabricated which performed high pure color. The maximum luminance of the device of ITO/PVK/PVK∶Tb(AS) 3Phen∶PBD/PBD/Al is 32 cd·m -2 at 28 V.展开更多
A series of Eu-doped ZnO films were prepared by a sol-gel method. Precursor and films were characterized by thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscope (SEM), UV-vis spectra, as we...A series of Eu-doped ZnO films were prepared by a sol-gel method. Precursor and films were characterized by thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscope (SEM), UV-vis spectra, as well as the magnetism measurement. The wurtzite structure of obtained films presents an extreme high c-orientation character. The film susceptibility resembles a Curie-Weiss behavior at high temperature, and presents an obvious enhancement at low temperature, indicating the presence of antiferromagnetic interactions in the Zn0.9Eu0.1O films.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
The Eu^(3+)-doped Na^(24)As_2W_(22)O_83 phosphor has been prepared by solidstare reaction from Na_3AsO_4.12H_2O, Na_2WO_4.2H_2O and WO_3, and characterized by elementalanalysis, infrared spectroscopy and powder X-ray ...The Eu^(3+)-doped Na^(24)As_2W_(22)O_83 phosphor has been prepared by solidstare reaction from Na_3AsO_4.12H_2O, Na_2WO_4.2H_2O and WO_3, and characterized by elementalanalysis, infrared spectroscopy and powder X-ray diffractometry. According to the measurements withX-ray diffraction, this material belongs to orthorhombic system with its lattice constants: avelence 1.4750 nm, b velence 1.1944 nm, c velence 1.1062 nm, it is consistent with space groupD_2~4-P2_12_12_1 (No.19). The emission and excitation spectra were measured. The luminescentproperties of Eu^(3+)-doped Na^(24)As_2W_(22)O_83 and mechanism of energy transfer were discussed.展开更多
Noncontact optical thermometers have attracted widespread attention,but existing problems such as single-mode and low-sensitivity thermometers still urgently need to be solved.Herein,a novel multiple-mode thermometer ...Noncontact optical thermometers have attracted widespread attention,but existing problems such as single-mode and low-sensitivity thermometers still urgently need to be solved.Herein,a novel multiple-mode thermometer was designed for the polymorphism LaSc_(3)(BO_(3))_(4):Eu^(2+/3+),Li^(+).X-ray diffraction(XRD)patterns revealed a slight transition betweenα-andβ-phases with the concentrations of the dopants,which is further proved by structure refinements and first-principles calculations.The coexistence of Eu^(2+)and Eu^(3+)in the phosphors and their relative percentages were confirmed by X-ray absorption near-edge structure(XANES)spectra.Benefiting from appropriate emissions from Eu^(2+)and Eu^(3+)without obvious energy transfer and their opposite changing trends with temperatures under 307 nm excitation,a triple-mode optical thermometer is obtained for this material within the temperature range of 150–450 K.The highest sensitivities of 27.65,14.05,and 7.68%·K^(−1)are achieved based on two fluorescence intensity ratio(FIR)modes of Eu^(2+)and Eu^(3+)(5d–4f/^(5)D_(0)–^(7)F_(2,4))and the fluorescence lifetime(FL)mode of Eu^(2+),respectively.To the best of our knowledge,the former is almost the highest in Eu^(2+)and Eu^(3+)co-doped thermometers.These results indicate that this material may be used as an excellent multiple-mode optical thermometer.展开更多
Europium-doped borosilicate glasses were prepared by melt-quenching procedure in the air.The mixed valence of Eu 2＋ and Eu 3＋ was identified by photoluminescence spectrum and electron paramagnetic resonance（EPR）.T...Europium-doped borosilicate glasses were prepared by melt-quenching procedure in the air.The mixed valence of Eu 2＋ and Eu 3＋ was identified by photoluminescence spectrum and electron paramagnetic resonance（EPR）.The existence of mixed valence was observed owing to the unequivalent substitution and de-polymerization network of the as-prepared borosilicate glasses.The variation of the glass composition in B 2 O 3 /BaO ratios changed the stability of the Eu 3＋ ions distinctly.In particular,as-prepared borosilicate glasses exhibited a tri-wavelength light excitable spectra centered at 397,466 and 534 nm to give the broadened orange-red emission at around 592 and 617 nm,due to supersensitive transitions of Eu 3＋ ions.This simultaneous tri-wavelength excitation happened to correspond with the emitting wavelength from near ultraviolet,blue AlInGaN chips and that from YAG：Ce 3＋.The total quantum yield（QY） of the Eu-doped glasses under 466 nm excitation was evaluated to be 10%,potentially providing a versatile combination with the europium-doped borosilicate glasses for red component addition to improve the quality of white light.展开更多
Silica glasses doped with Eu3＋ ions prepared by sol-gel methods were investigated. The X-ray diffraction （XRD） was used to verify the nature of the studied systems. Excitation and emission spectra of Eu3＋ ions in ...Silica glasses doped with Eu3＋ ions prepared by sol-gel methods were investigated. The X-ray diffraction （XRD） was used to verify the nature of the studied systems. Excitation and emission spectra of Eu3＋ ions in sol-gel glass materials were detected. Red-to-orange luminescence intensity ratios R/O related to integrated intensities of 5D0→TF2 to 5D0→7TF1 transitions and luminescence lifetimes for 5D0 state of Eu3＋ ions were determined. The results indicated that spectroscopic parameters for Eu3＋ ions strongly de- pended on reagents and their relative ratios used for sol-gel glass preparation.展开更多
Eu-doped ZnO nanoneedles with different doping concentrations were prepared via the facile hydrothermal method.The crystal structure,morphology and photoluminescence property of the ZnO nanoneedles were characterized ...Eu-doped ZnO nanoneedles with different doping concentrations were prepared via the facile hydrothermal method.The crystal structure,morphology and photoluminescence property of the ZnO nanoneedles were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）,photoluminescence spectroscopy（PL） and Raman spectroscopy.The results show that the europium ions are incorporated into the crystal lattice of ZnO matrix in trivalent ions.The nanoneedles are 2-3 μm in length and 100 nm in the tip diameter.PL and Raman measurements indicate that higher Eu^3＋ doping concentration may destroy the crystallization of the nanoneedles and decrease the ratio of IUV/IDLE,which is mainly due to the more defects in the doped ZnO nanoneedles.And the characteristic red emissions of Eu^3＋ ions are found by the PL spectroscopy with the Eu^3＋doping concentration increasing,which are attributed to the ^5D0→^7F0,^5D0→^7F1 and ^5D0→^7F2 transitions.展开更多
The abuse of antibiotics has become a global concern,thus it is significant to develop simple antibiotic assays.Herein,a novel type of lanthanide-doped bovine serum albumin(BSA)derived carbon dots(BCDs)dubbed Eu-BCDs ...The abuse of antibiotics has become a global concern,thus it is significant to develop simple antibiotic assays.Herein,a novel type of lanthanide-doped bovine serum albumin(BSA)derived carbon dots(BCDs)dubbed Eu-BCDs has been unveiled for ratiometric fluorescent detection of tetracycline(TC),which was formed from the one-step hydrothermal reaction of Eu^(3+)and BSA.Upon challenge with TC,the blue fluorescence of Eu-BCDs at 448 nm was gradually quenched due to the internal filtration effect,while the characteristic red fluorescence of Eu^(3+)at 618 nm was significantly enhanced owning to the antenna effect,leading to the ratiometric fluorescent detection of TC with fast response(2 min),a wide linear dynamic range(0-80μmol/L),and high selectivity and sensitivity(limit of detection(LOD)of 3 nmol/L).Moreover,Eu-BCDs can be successfully applied for the ratiometric fluorescent detection of TC in environmental and biological samples,such as river water,milk,honey and serum.The Eu-BCDs sensing platform would have great application potential in view of its simple preparation,rapid response,high sensitivity and good selectivity.展开更多
基金Project supported by the Ministry of Higher Education(MOHE),the Ministry of Science,Technology and Innovation(MOSTI)and Universiti Teknologi Malaysia via Research University Grant Project(R.J130000.7826.4F140)Nanofund Grant(J.130000.7926.4H007)
文摘Eu3＋ doped borophosphate glasses with the chemical composition 20Li2O-30Al2O3-10B2O3-40P2O5-xEu2O3（where x=0.05 mol.%, 0.1 mol.%, 1.0 mol.%, 1.5 mol.% and 2.0 mol.%） were prepared by conventional melt quenching technique. The structural and luminescence properties of the prepared Eu3＋ doped borophosphate glasses were studied and compared with reported results. The XRD pattern showed the amorphous nature of the prepared glasses. Whereas, the FTIR spectra revealed the vibrational modes in the prepared glasses. The bonding parameters（ β and ？） were calculated through the excitation spectra. Judd-Ofelt（J-O） intensity parameters were calculated from the emission spectra and were used to determine transition probability（A）, stimulated emission cross-section（σE P）, radiative lifetime（τR） and branching ratios（βexp） for the transition 5D0→7Fj（j=1, 2, 3 and 4） of Eu3＋ ions. Furthermore, the luminescence intensity ratio（R） of 5D0→7F2 to 5D0→7F1 transition was also calculated. Transition 5D0→7F2 had the highest value of stimulated emission cross-section and branching ratios and the results were comparable with the reported values. This indicated that the present glass is promising host material for Eu3＋ doped fiber amplifiers.
文摘The transfer of trivalent europium ion in a liquid surfactant membrane system is investigated in order toclarify the characteristics of liquid membrane separation process and the availability of this technique forrecovering trivalent lanthanides and actinides.A layered structure model for the emulsion globule is sug-gested.The equations describing the relationship among the effective membrane thickness,the time andother factors are derived and verified experimentally.Results show that under certain conditions the decreas-ing concentration of europium ion in the external phase is proportional to the square root of the time,the acidity of the internal phase and the carrier concentration in the membrane phase.The membrane phase consists of kerosene（solvent）,Span-80（surfactant）and di-（2-ethylhexyl） phosphoricacid（HDEHP,carrier）.The internal phase is dilute nitric acid and the external phase is aqueous solu-tion containing Eu（NO3）3.The mass transfer rate of europium in this system is high and the recovery ofeuropium may be more than 99%.
基金Project supported by the National Natural Science Foundation of China
文摘In crystals BaFX:Eu^(2+)(X=Cl,Br).there exists configuration interaction between 4f^65d and 4f^65s ex- cited state of Eu^(2+)ion.and it results in the change of relative intensities of d-f and f-f transition.The transition ~S_-_2→4f^65d-6s is observed.The variation of F/X atomic ratio between 110/90 and 90/110 does not obvi- ously influence the luminescence of BaFX:Eu^(2-).There is energy transfer between Eu^(2+)(f-f)and Eu^(3+)which coexists in the matrices.
文摘Thin nanocrystalline TiO2 films doped by europium ions (Eu3+) were obtained by the sol-gel method. The photoelectric properties of Eu3+-doped TiO2 film electrode sensitized by cis-RuL2(SCN)2·2H2O (L=cis-2,2′-bipyridine-4,4′-dicarboxlic acid) ruthenium complex were studied. The thin films were characterized by X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy. Effect of doping Eu3+ on microscopic structure and photoelectrical properties were discussed. The result shows that doping europium ions makes specific surface area of these films larger, which contributes to improving the photoelectric properties. It is found that an optimal composition doped with 0.2 mol.% Eu3+ exhibits the highest photoelectric properties. Isc is 0.37 mA·cm-2, which is 0.17 mA·cm-2 bigger than that of un-doped films; Voc is 405 mV, which is 50 mV bigger than that of un-doped films.
基金Project supported by Shanghai Nanotechnology Promotion Center (0352nm042)
文摘A method to fabricate europium ions doped-high silica glass for transparent fluorescence materials based on the fabrication and sintering technique of nano-porous silica glass was reported. Glasses impregnated with Eu ions and sintered at above 1150℃in a reduction atmosphere show a very strong blue light from an emission band at about 430 nm due to the 4f65d→4f7(8S7/2) transition of the Eu2+ ions. On the other hand, the Eu-doped glass obtained by co-impregnated with Y3+ and V5+ ions and sintering in oxidation atmosphere behaves a very strong red emission band at about 615 nm with a UV excitation. An appearance of vanadate band in the excitation spectrum of Eu3+ , Y3+ .and V5+ ions co-doped high silica glass implies an effective energy transferring from VO43- to Eu3+ and effective excitation of Eu3+ by about 500 nm strong broad emission of VO43- .
文摘Nanoparticles and nanowires of LaPO 4: Eu phosphors were synthesized by hydrothermal method. Their luminescent properties including electronic transition, surface effect, and temperature-dependent luminescent characteristics were systemically studied and compared to the bulk powders. It can be concluded that in comparison with the bulk powders, the fluorescence intensity decreases in nanoparticles and nanowires, while the lifetime increases, indicating that the radiative transition rate decreases. The nonradiative transition rate in nanowires decreases than that in nanoparticles due to its decreased surface to volume ratio. The temperature-dependent experiments indicate that the thermal quenching in nanopowders becomes weaker than that in the bulk powders.
文摘The fluorescent characteristic and emission spectra of Eu^(2+) in the cubic structure Ca_8Zn(SiO_4)_4Cl_2 with three kinds of cation sites is reported.The influence of temperature,Eu^(2+) concentra- tion and excitation conditions on fluorescent properties of Eu^(2+) are studied at 77 and 298 K.The coordination number of Eu^(2+) at different sites is obtained.The green and red emission bands arise from Eu_(2+) ions locating on eight- and six- coordinated inequivalent sites respectively.
文摘Novel soluble rare earth aromatic carboxylates were prepared. The triplet energy level of organic ligand was measured. The photoluminescence properties of the Tb 3+ and Eu 3+ aromatic carboxylates and lifetimes were investigated, which indicated that these rare earth complexes have high quantum efficiency. Because of their excellent solubility, polymer-doping rare earth carboxylates were fabricated as thin films by spin-coating method and their luminescence properties were studied. Some rare earth organic light-emitting diodes were successfully fabricated which performed high pure color. The maximum luminance of the device of ITO/PVK/PVK∶Tb(AS) 3Phen∶PBD/PBD/Al is 32 cd·m -2 at 28 V.
基金Project supported by the National Natural Science Foundation of China (20331030, 20373004) the Program for New Century Excellent Talents in University (NCET-04-0164) Engineering Research Institute, Peking University ( ERIPKU-204030)
文摘A series of Eu-doped ZnO films were prepared by a sol-gel method. Precursor and films were characterized by thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscope (SEM), UV-vis spectra, as well as the magnetism measurement. The wurtzite structure of obtained films presents an extreme high c-orientation character. The film susceptibility resembles a Curie-Weiss behavior at high temperature, and presents an obvious enhancement at low temperature, indicating the presence of antiferromagnetic interactions in the Zn0.9Eu0.1O films.
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This project is financially supported by the National Natural Science Foundation of China (No. 29971024) the Natural Science Foundation of Hubei Education Committee (No. 2002A00008)
文摘The Eu^(3+)-doped Na^(24)As_2W_(22)O_83 phosphor has been prepared by solidstare reaction from Na_3AsO_4.12H_2O, Na_2WO_4.2H_2O and WO_3, and characterized by elementalanalysis, infrared spectroscopy and powder X-ray diffractometry. According to the measurements withX-ray diffraction, this material belongs to orthorhombic system with its lattice constants: avelence 1.4750 nm, b velence 1.1944 nm, c velence 1.1062 nm, it is consistent with space groupD_2~4-P2_12_12_1 (No.19). The emission and excitation spectra were measured. The luminescentproperties of Eu^(3+)-doped Na^(24)As_2W_(22)O_83 and mechanism of energy transfer were discussed.
基金financially supported by the National Natural Science Foundation of China(Nos.51972347 and 21771195).
文摘Noncontact optical thermometers have attracted widespread attention,but existing problems such as single-mode and low-sensitivity thermometers still urgently need to be solved.Herein,a novel multiple-mode thermometer was designed for the polymorphism LaSc_(3)(BO_(3))_(4):Eu^(2+/3+),Li^(+).X-ray diffraction(XRD)patterns revealed a slight transition betweenα-andβ-phases with the concentrations of the dopants,which is further proved by structure refinements and first-principles calculations.The coexistence of Eu^(2+)and Eu^(3+)in the phosphors and their relative percentages were confirmed by X-ray absorption near-edge structure(XANES)spectra.Benefiting from appropriate emissions from Eu^(2+)and Eu^(3+)without obvious energy transfer and their opposite changing trends with temperatures under 307 nm excitation,a triple-mode optical thermometer is obtained for this material within the temperature range of 150–450 K.The highest sensitivities of 27.65,14.05,and 7.68%·K^(−1)are achieved based on two fluorescence intensity ratio(FIR)modes of Eu^(2+)and Eu^(3+)(5d–4f/^(5)D_(0)–^(7)F_(2,4))and the fluorescence lifetime(FL)mode of Eu^(2+),respectively.To the best of our knowledge,the former is almost the highest in Eu^(2+)and Eu^(3+)co-doped thermometers.These results indicate that this material may be used as an excellent multiple-mode optical thermometer.
基金supported by National Natural Science Foundation of China (50872091,51102265)Key Discipline of Materials Physics and Chemis-try (Tianjin,China) (10SYSYJC28100)
文摘Europium-doped borosilicate glasses were prepared by melt-quenching procedure in the air.The mixed valence of Eu 2＋ and Eu 3＋ was identified by photoluminescence spectrum and electron paramagnetic resonance（EPR）.The existence of mixed valence was observed owing to the unequivalent substitution and de-polymerization network of the as-prepared borosilicate glasses.The variation of the glass composition in B 2 O 3 /BaO ratios changed the stability of the Eu 3＋ ions distinctly.In particular,as-prepared borosilicate glasses exhibited a tri-wavelength light excitable spectra centered at 397,466 and 534 nm to give the broadened orange-red emission at around 592 and 617 nm,due to supersensitive transitions of Eu 3＋ ions.This simultaneous tri-wavelength excitation happened to correspond with the emitting wavelength from near ultraviolet,blue AlInGaN chips and that from YAG：Ce 3＋.The total quantum yield（QY） of the Eu-doped glasses under 466 nm excitation was evaluated to be 10%,potentially providing a versatile combination with the europium-doped borosilicate glasses for red component addition to improve the quality of white light.
文摘Silica glasses doped with Eu3＋ ions prepared by sol-gel methods were investigated. The X-ray diffraction （XRD） was used to verify the nature of the studied systems. Excitation and emission spectra of Eu3＋ ions in sol-gel glass materials were detected. Red-to-orange luminescence intensity ratios R/O related to integrated intensities of 5D0→TF2 to 5D0→7TF1 transitions and luminescence lifetimes for 5D0 state of Eu3＋ ions were determined. The results indicated that spectroscopic parameters for Eu3＋ ions strongly de- pended on reagents and their relative ratios used for sol-gel glass preparation.
基金Supported by the National Natural Science Foundation of China（Nos.61178074, 61008051）, the Program for the Development of Science and Technology of Jilin Province, China（Nos.20100113, 20140101205 JC） and the Natural Science Foundation of Jiangsu Province, China（No.BK2011513）.
文摘Eu-doped ZnO nanoneedles with different doping concentrations were prepared via the facile hydrothermal method.The crystal structure,morphology and photoluminescence property of the ZnO nanoneedles were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）,photoluminescence spectroscopy（PL） and Raman spectroscopy.The results show that the europium ions are incorporated into the crystal lattice of ZnO matrix in trivalent ions.The nanoneedles are 2-3 μm in length and 100 nm in the tip diameter.PL and Raman measurements indicate that higher Eu^3＋ doping concentration may destroy the crystallization of the nanoneedles and decrease the ratio of IUV/IDLE,which is mainly due to the more defects in the doped ZnO nanoneedles.And the characteristic red emissions of Eu^3＋ ions are found by the PL spectroscopy with the Eu^3＋doping concentration increasing,which are attributed to the ^5D0→^7F0,^5D0→^7F1 and ^5D0→^7F2 transitions.
基金supported by the fund of the Shanghai Science and Technology Committee (19ZR1473300)the director fund of Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration (SHUES2022C03)the Fundamental Research Funds for the Central Universities
文摘The abuse of antibiotics has become a global concern,thus it is significant to develop simple antibiotic assays.Herein,a novel type of lanthanide-doped bovine serum albumin(BSA)derived carbon dots(BCDs)dubbed Eu-BCDs has been unveiled for ratiometric fluorescent detection of tetracycline(TC),which was formed from the one-step hydrothermal reaction of Eu^(3+)and BSA.Upon challenge with TC,the blue fluorescence of Eu-BCDs at 448 nm was gradually quenched due to the internal filtration effect,while the characteristic red fluorescence of Eu^(3+)at 618 nm was significantly enhanced owning to the antenna effect,leading to the ratiometric fluorescent detection of TC with fast response(2 min),a wide linear dynamic range(0-80μmol/L),and high selectivity and sensitivity(limit of detection(LOD)of 3 nmol/L).Moreover,Eu-BCDs can be successfully applied for the ratiometric fluorescent detection of TC in environmental and biological samples,such as river water,milk,honey and serum.The Eu-BCDs sensing platform would have great application potential in view of its simple preparation,rapid response,high sensitivity and good selectivity.
