Long afterglow phosphors MAl2O4：Eu^2＋ , Dy^3＋ （M = Ca, Sr, Ba） were synthesized by microemulsion method, and their crystal structure and luminescent properties were compared and investigated. XRD patterns of samp...Long afterglow phosphors MAl2O4：Eu^2＋ , Dy^3＋ （M = Ca, Sr, Ba） were synthesized by microemulsion method, and their crystal structure and luminescent properties were compared and investigated. XRD patterns of samples indicate that phosphors CaAl2O4：Eu^2＋, Dy^3＋ and SrAl2O4 ： Eu^2＋, Dy^3＋ are with monoelinie crystal structure and phosphor BaAl2O4：Eu^2＋ , Dy^3＋ is with hexagonal crystal structure. The wide range of excitation spectrum of phosphors MAl2O4： Eu^2 ＋ , Dy^3＋ （M = Ca,Sr, Ba） indicates that the luminescent materials can he excited by light from ultraviolet ray to visible light and the maximum emission wavelength of phosphors MAl2O4：Eu^2＋ , Dy^3＋ （M = Ca, Sr, Ba） is found mainly at λem of 440 nm （M = Ca）, 520 nm （M = Sr） and 496 nm （M = Ba） respectively, the corresponding colors of emission light are blue, green and eyna-green respectively. The afterglow decay tendency of phosphors can he summarized as three processes： initial rapid decay, intermediate transitional decay and very long slow decay. Afterglow decay curves coincide with formula I = At^ - n, and the sequence of afterglow intensity and time is Sr 〉 Ca 〉 Ba.展开更多
CaO-SiO2-B2O3 ：Sm2O3 glasses were synthesized in air atmosphere with conventional high temperature process. The optimal temperature of synthesis, the absorption spectrum and the luminescent properties of the glasses ...CaO-SiO2-B2O3 ：Sm2O3 glasses were synthesized in air atmosphere with conventional high temperature process. The optimal temperature of synthesis, the absorption spectrum and the luminescent properties of the glasses were studied. The fluorescence spectrum of Sm^3＋ was observed in CaO-SiO2-B2O3 ： Sm2O3 glasses. The fluorescence spectrum of the sample has three major emission bands peaking at 568, 605 and 650 nm respectively. The strongest emission band peak at 605 nm. It is concluded that the emissions were caused by the f-f transition of the 4f electrons of Sm^3＋. The emission bands peaking at 568, 604 and 650 nm correspond to the ^4G5/2→^6H5/2 transition, ^4G5/2→^6H7/2 transition and ^4G5/2→^6H9/2 trasition respectively. The luminescent properties of CaO-SiO2-B2O3 glasses indicate that the glass can convert the ultraviolet in the sunlight into red light, thus increasing the intensity of red light. The luminescent properties of these glasses may be used to make kinds of light-conversion glass for agriculture.展开更多
The roles of different point defects in persistent luminescence of SrAl2O4：Eu,Dy phosphors were investigated. The research results showed that Dyer plays an important role in the persistent luminescence of SrA1EO4：E...The roles of different point defects in persistent luminescence of SrAl2O4：Eu,Dy phosphors were investigated. The research results showed that Dyer plays an important role in the persistent luminescence of SrA1EO4：Eu, Dy phosphors. It can serve as the electron trap of suitable depth for persistent luminescence. V~ does not serve as the electron trap of suitable depth, but its existence can increase the depth of electron traps. There is interaction between the Dy^3＋（ DySr ） and the Eu^2＋（Eu^x Sr ）, and only if the distance between the Dy^3＋（DySr） and the Eu^2＋ （Eu^x Sr） is close enough, the Dyer can work as an effective electron trap. The point defect of V＂ Sr can be hole trap, but the change of its density in crystal matrix does not arouse the obvious change of persistent luminescence.展开更多
SnO2 nanocrystal and rare-earth Eu^3＋ ion co-doped SiO2 thin films are prepared by sol-gel and spin coating methods. The formation of tetragonal rutile structure SnO2 nanocrystals with a uniform distribution is confi...SnO2 nanocrystal and rare-earth Eu^3＋ ion co-doped SiO2 thin films are prepared by sol-gel and spin coating methods. The formation of tetragonal rutile structure SnO2 nanocrystals with a uniform distribution is confirmed by X-ray diffraction and transmission electron microscopy. Fourier transform infrared spectroscopy is used to investigate the densities of the hydroxyl groups, and it is found that the emission intensity from the 5Do-TF2 transitions of the Eu^3＋ ions is enhanced by two orders of magnitude due to energy transfer from the oxygen-vacancy-related defects of the SnO2 nanocrystals to nearby Eu^3＋ ions. The influences of the amounts of Sn and the post-annealing temperatures are systematically evaluated to further understand the mechanism of energy transfer. The luminescence intensity ratio of Eu^3＋ ions from electric dipole transition and magnetic dipole transition indicate the different probable locations of Eu^3＋ ions in the sol-gel thin film, which are further discussed based on temperature-dependent photoluminescence measurements.展开更多
The influences of the flux KCl or KF on the XRD spectra, cell parameters and crystal appearance, and spectral properties of the phosphor LaMgB_5O_(10)∶Ce^(3+), Mn^(2+) were studied. The results indicate that when 4.2...The influences of the flux KCl or KF on the XRD spectra, cell parameters and crystal appearance, and spectral properties of the phosphor LaMgB_5O_(10)∶Ce^(3+), Mn^(2+) were studied. The results indicate that when 4.2%, 8.6%, 12.8% KCl and 5.3%, 10.5%KF are respectively added into phosphor (La_(0.85)Ce_(0.15)) (Mg_(0.9)Mn_(0.1))B_5O_(10), compared with the normal card of JCPDS (No 35-120), the intensity of XRD spectra is enhanced, the values corresponded to 17/28, 18/28, 16/28, 18/28 and 2/28 and the cell parameters diminish because of the flux KCl and KF. The use of 5% KCl a fraction of Cu monocrystals are observed in the phosphor. There are six hexagonal crystal-faces and eight triangular crystal-faces representing crystal-face index {100} and {111}. When 15% KCl is added to the phosphor, law of crystal plane and self-regulaton are formed, the emission intensity of Ce^(3+) 5d-4f ((()~2F_(5/2),) (()~2F_(7/2))) and Mn^(2+) ((()~4G) and (()~6S)) increases by 3.41 times and 2.36 times respectively.展开更多
Three new 1,10-phenanthroline derivatives, dipyrido (3,2-f: 2,3-h) quinoxaline (DPQN), imidazo (5,6-f)-(1,10)-phenanthroline (IP) and 3-phenyl-imidazo (5,6-f)-(1,10)-phenanthroline (PIP) were designed and synthesized ...Three new 1,10-phenanthroline derivatives, dipyrido (3,2-f: 2,3-h) quinoxaline (DPQN), imidazo (5,6-f)-(1,10)-phenanthroline (IP) and 3-phenyl-imidazo (5,6-f)-(1,10)-phenanthroline (PIP) were designed and synthesized as a secondary ligand to coordinate with europium (Ⅲ) ion while dibenzoylmethane (DBM) was used as the first ligand. The compositions of the ligands and the europium (Ⅲ) ternary complexes were confirmed by elementary analysis, IR and (()~1H-NMR) spectroscopy. The UV-visible absorption spectra, thermal stability, photoluminescence spectra, quantum yield and fluorescence life time of the Eu(Ⅲ) complexes were investigated. The effect of the structure of the secondary ligand on the photoluminescence of the complexes was discussed. The results show that the synthesized Eu(Ⅲ) complexes are good red-emitiing materials for potential application in fabrication of organic electroluminescence devices.展开更多
文摘Long afterglow phosphors MAl2O4：Eu^2＋ , Dy^3＋ （M = Ca, Sr, Ba） were synthesized by microemulsion method, and their crystal structure and luminescent properties were compared and investigated. XRD patterns of samples indicate that phosphors CaAl2O4：Eu^2＋, Dy^3＋ and SrAl2O4 ： Eu^2＋, Dy^3＋ are with monoelinie crystal structure and phosphor BaAl2O4：Eu^2＋ , Dy^3＋ is with hexagonal crystal structure. The wide range of excitation spectrum of phosphors MAl2O4： Eu^2 ＋ , Dy^3＋ （M = Ca,Sr, Ba） indicates that the luminescent materials can he excited by light from ultraviolet ray to visible light and the maximum emission wavelength of phosphors MAl2O4：Eu^2＋ , Dy^3＋ （M = Ca, Sr, Ba） is found mainly at λem of 440 nm （M = Ca）, 520 nm （M = Sr） and 496 nm （M = Ba） respectively, the corresponding colors of emission light are blue, green and eyna-green respectively. The afterglow decay tendency of phosphors can he summarized as three processes： initial rapid decay, intermediate transitional decay and very long slow decay. Afterglow decay curves coincide with formula I = At^ - n, and the sequence of afterglow intensity and time is Sr 〉 Ca 〉 Ba.
文摘CaO-SiO2-B2O3 ：Sm2O3 glasses were synthesized in air atmosphere with conventional high temperature process. The optimal temperature of synthesis, the absorption spectrum and the luminescent properties of the glasses were studied. The fluorescence spectrum of Sm^3＋ was observed in CaO-SiO2-B2O3 ： Sm2O3 glasses. The fluorescence spectrum of the sample has three major emission bands peaking at 568, 605 and 650 nm respectively. The strongest emission band peak at 605 nm. It is concluded that the emissions were caused by the f-f transition of the 4f electrons of Sm^3＋. The emission bands peaking at 568, 604 and 650 nm correspond to the ^4G5/2→^6H5/2 transition, ^4G5/2→^6H7/2 transition and ^4G5/2→^6H9/2 trasition respectively. The luminescent properties of CaO-SiO2-B2O3 glasses indicate that the glass can convert the ultraviolet in the sunlight into red light, thus increasing the intensity of red light. The luminescent properties of these glasses may be used to make kinds of light-conversion glass for agriculture.
基金This study is financially supported by the Jiangxi University of Finance and Economy (Project No. 0421205) Jiangxi Provincial Department of Education (Project No. (2007) 260)
文摘The roles of different point defects in persistent luminescence of SrAl2O4：Eu,Dy phosphors were investigated. The research results showed that Dyer plays an important role in the persistent luminescence of SrA1EO4：Eu, Dy phosphors. It can serve as the electron trap of suitable depth for persistent luminescence. V~ does not serve as the electron trap of suitable depth, but its existence can increase the depth of electron traps. There is interaction between the Dy^3＋（ DySr ） and the Eu^2＋（Eu^x Sr ）, and only if the distance between the Dy^3＋（DySr） and the Eu^2＋ （Eu^x Sr） is close enough, the Dyer can work as an effective electron trap. The point defect of V＂ Sr can be hole trap, but the change of its density in crystal matrix does not arouse the obvious change of persistent luminescence.
基金Project supported by the National Natural Science Foundation of China(Grant No.61036001)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK2010010)the Fundamental Research Funds for the Central Universities of China(Grant Nos.1112021001 and 1116021003)
文摘SnO2 nanocrystal and rare-earth Eu^3＋ ion co-doped SiO2 thin films are prepared by sol-gel and spin coating methods. The formation of tetragonal rutile structure SnO2 nanocrystals with a uniform distribution is confirmed by X-ray diffraction and transmission electron microscopy. Fourier transform infrared spectroscopy is used to investigate the densities of the hydroxyl groups, and it is found that the emission intensity from the 5Do-TF2 transitions of the Eu^3＋ ions is enhanced by two orders of magnitude due to energy transfer from the oxygen-vacancy-related defects of the SnO2 nanocrystals to nearby Eu^3＋ ions. The influences of the amounts of Sn and the post-annealing temperatures are systematically evaluated to further understand the mechanism of energy transfer. The luminescence intensity ratio of Eu^3＋ ions from electric dipole transition and magnetic dipole transition indicate the different probable locations of Eu^3＋ ions in the sol-gel thin film, which are further discussed based on temperature-dependent photoluminescence measurements.
文摘The influences of the flux KCl or KF on the XRD spectra, cell parameters and crystal appearance, and spectral properties of the phosphor LaMgB_5O_(10)∶Ce^(3+), Mn^(2+) were studied. The results indicate that when 4.2%, 8.6%, 12.8% KCl and 5.3%, 10.5%KF are respectively added into phosphor (La_(0.85)Ce_(0.15)) (Mg_(0.9)Mn_(0.1))B_5O_(10), compared with the normal card of JCPDS (No 35-120), the intensity of XRD spectra is enhanced, the values corresponded to 17/28, 18/28, 16/28, 18/28 and 2/28 and the cell parameters diminish because of the flux KCl and KF. The use of 5% KCl a fraction of Cu monocrystals are observed in the phosphor. There are six hexagonal crystal-faces and eight triangular crystal-faces representing crystal-face index {100} and {111}. When 15% KCl is added to the phosphor, law of crystal plane and self-regulaton are formed, the emission intensity of Ce^(3+) 5d-4f ((()~2F_(5/2),) (()~2F_(7/2))) and Mn^(2+) ((()~4G) and (()~6S)) increases by 3.41 times and 2.36 times respectively.
文摘Three new 1,10-phenanthroline derivatives, dipyrido (3,2-f: 2,3-h) quinoxaline (DPQN), imidazo (5,6-f)-(1,10)-phenanthroline (IP) and 3-phenyl-imidazo (5,6-f)-(1,10)-phenanthroline (PIP) were designed and synthesized as a secondary ligand to coordinate with europium (Ⅲ) ion while dibenzoylmethane (DBM) was used as the first ligand. The compositions of the ligands and the europium (Ⅲ) ternary complexes were confirmed by elementary analysis, IR and (()~1H-NMR) spectroscopy. The UV-visible absorption spectra, thermal stability, photoluminescence spectra, quantum yield and fluorescence life time of the Eu(Ⅲ) complexes were investigated. The effect of the structure of the secondary ligand on the photoluminescence of the complexes was discussed. The results show that the synthesized Eu(Ⅲ) complexes are good red-emitiing materials for potential application in fabrication of organic electroluminescence devices.
