Er3+/Yb3+-codoped oxyfluoride crystallite glass was prepared with melting technique. The compositions and the melting temperature and the annealing temperature of the rare earth-doped crystallite glass were studied in...Er3+/Yb3+-codoped oxyfluoride crystallite glass was prepared with melting technique. The compositions and the melting temperature and the annealing temperature of the rare earth-doped crystallite glass were studied in detail. The emission spectra of samples were measured with the Hitachi F-4500 fluorescent photometer pumped by 980 nm wavelength laser. The up-conversion luminescence mechanism was illuminated on the view of the photophysics. By measuring the relationship between luminescent intensity and pump power, it is confirmed that the emission peaks at 550 nm belong to two-photon process, while that at 665 nm belongs to three-photon process. Moreover, the distributions of crystalline were determined by SEM.展开更多
The distribution characteristics of Er3+ ions doped in the oxyfluoride glass ceramics containing LaF3 nanocrystals heat-treated at 650 ℃ for different durations were investigated. The results of the integral absorpti...The distribution characteristics of Er3+ ions doped in the oxyfluoride glass ceramics containing LaF3 nanocrystals heat-treated at 650 ℃ for different durations were investigated. The results of the integral absorption cross-section analysis demonstrated that the partition fraction of Er3+ in LaF3 nanocrystals increases with prolonging of heating time. The anomalous phenomena of Er3+ emissions in the up-and the down-conversion fluorescence spectra are well explained based on the calculated results.展开更多
Er3+-doped heavy metal oxyfluoride silicate glass was fabricated and characterized, and the absorption spectrum and fluorescence spectrum of the glass were studied. The Judd-Ofelt intensity parameters Ωt （t =2, 4, 6...Er3+-doped heavy metal oxyfluoride silicate glass was fabricated and characterized, and the absorption spectrum and fluorescence spectrum of the glass were studied. The Judd-Ofelt intensity parameters Ωt （t =2, 4, 6）, spontaneous transition probability, fluorescence branching ratio and radiative lifetime of each energy levels for Er3+ were calculated by Judd-Ofelt theory, and stimulated emission cross-section of (（）4I13/2)→(（）4I15/2) transition was calculated by McCumber theory. The results show that fluorescence full width at half maximum and stimulated emission cross-section of Er3+-doped heavy metal oxyfluoride silicate glass are broad and large, respectively. Compared with other host glasses, the gain bandwidth property of Er3+-doped heavy metal oxyfluoride silicate glass is close to those of tellurite and bismuth glasses, and has advantage over those of silicate, phosphate and germante glasses.展开更多
Two isostructural inorganic-organic hybrid M(II)–Nb(V) oxyfluorides, namely, M(H2O)2(pyz)NbOF5 (M=Co 1, Cu 2; pyz=pyrazine) have been hydrothermally synthesized and structurally characterized. Both compounds possess ...Two isostructural inorganic-organic hybrid M(II)–Nb(V) oxyfluorides, namely, M(H2O)2(pyz)NbOF5 (M=Co 1, Cu 2; pyz=pyrazine) have been hydrothermally synthesized and structurally characterized. Both compounds possess two-dimensional layer structure constructed by neutral M(H2O)2NbOF5 chains inter-connected via bridging pyrazine ligands. The structure is further extended into three-dimensional supramolecular architecture through inter-layer H-bonding interactions between the coordinated water molecules and fluorine ions. The luminescent properties and thermal stability of both compounds have been investigated.展开更多
A series of oxyfluoride glasses with the compositions of 75 mol% TeO2, 10 mol% Nb2O5,(15 mol%-x) BaO, x BaF2(x = 0 mol%, 5 mol%, 10 mol%, 15 mol%) doped with Yb2O3 were prepared by the melt-quenching method. Their emi...A series of oxyfluoride glasses with the compositions of 75 mol% TeO2, 10 mol% Nb2O5,(15 mol%-x) BaO, x BaF2(x = 0 mol%, 5 mol%, 10 mol%, 15 mol%) doped with Yb2O3 were prepared by the melt-quenching method. Their emission cross-sections, fluorescence lifetimes, and gain properties were investigated by using the absorption spectra and the fluorescence decay curves. The results show that by substituting BaF2 for BaO, the emission cross-section decreases from 1.37 pm2 to 1.21 pm2, and the fluorescence lifetime increases from 0.71 ms to 0.96 ms. These properties indicate that this oxyfluoride tellurite glass may have potential uses as the Yb2O3-doped gain medium in a solid laser.展开更多
The Pr3+-Yb3+ co-doped oxyfluoride glass-ceramics containing CaF2 nanocrystals were obtained by thermal treatment on the as-made glasses. The structure of fluoride nanocrystals was investigated. The light-emitting mec...The Pr3+-Yb3+ co-doped oxyfluoride glass-ceramics containing CaF2 nanocrystals were obtained by thermal treatment on the as-made glasses. The structure of fluoride nanocrystals was investigated. The light-emitting mechanism of Pr3+-Yb3+ in the near infrared region was proposed and the fluorescence lifetime and quantum efficiency was calculated. The results indicate that the main phase in the oxyfluoride glass-ceramics is CaF2 nanocrystal sized at 30 nm. Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) have proved the incorporation of Pr3+ and Yb3+ into CaF2 nanocrystal lattice. Near-infrared quantum cutting involving Yb3+ 980 nm and 1 015 nm ( 2F5/2 → 2F7/2 ) emission has been achieved upon the excitation of the 3P0 energy level of Pr3+ at 482 nm. The fluorescence lifetime decreases sharply and quantum efficiency increases with increasing Yb3+ concentration, and the optimal quantum efficiency reaches 191%.展开更多
Rare earth ion-doped fluorescent glass has become a hotspot due to its characteristics.This work shows that the prepared Dy^3+and Dy^3+/Eu^3+doped glasses have white light emission under ultraviolet excitation.There i...Rare earth ion-doped fluorescent glass has become a hotspot due to its characteristics.This work shows that the prepared Dy^3+and Dy^3+/Eu^3+doped glasses have white light emission under ultraviolet excitation.There is a higher yellow light/blue light(Y/B)value,indicating an increase in the covalentity of Dy-O,and decrease in the symmetry with the increasing concentration of dopants(Dy^3+).The correlated color temperature(CCT)can be effectively reduced by the red light emission of Eu^3+,and the order of influence of excitation wavelength on CCT is 395 nm>382 nm>365 nm.The delay curve demonstrates the energy transfer from Dy^3+to Eu^3+.The glass has the characteristics of anti-blue light damage and wide tunable color temperature,which illustrates that it has potential application in the field of white LED.展开更多
Er3+/Yb3+-codoped transparent oxyfluoride borosilicate glass ceramics containing Ba2GdF7 nanocrystals were prepared and spectroscopic properties of rare earth ions were investigated. Fluoride nanocrystals Ba2GdF7 were...Er3+/Yb3+-codoped transparent oxyfluoride borosilicate glass ceramics containing Ba2GdF7 nanocrystals were prepared and spectroscopic properties of rare earth ions were investigated. Fluoride nanocrystals Ba2GdF7 were successfully precipitated in glass matrix, which was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) results. In comparison with the as-made precursor, significant enhancement of upconversion luminescence was observed in the Er3+/Yb3+ codoped oxyfluoride glass ceramics, which may be due to the variation of coordination environment around Er3+ and Yb3+ ions after crystallization. The transition mechanisms of the green and red upconversion luminescence were ascribed to a two-photon process, and that of the blue upconversion luminescence was a three-photon process.展开更多
The ultraviolet upconversion luminescence of Tm3+ ions sensitized by Yb3+ ions in oxyfluoride nanophase vitroceramics when excited by a 975 nm diode laser was studied. An ultraviolet upconversion luminescence line pos...The ultraviolet upconversion luminescence of Tm3+ ions sensitized by Yb3+ ions in oxyfluoride nanophase vitroceramics when excited by a 975 nm diode laser was studied. An ultraviolet upconversion luminescence line positioned at 363.6 nm was found. It was attributed to the fluorescence transition of 1D2→3H6 of Tm3+ ion. Sev- eral visible upconversion luminescence lines at 450.7 nm, (477.0 nm, 462.5 nm), 648.5 nm, (680.5 nm, 699.5 nm) and (777.2 nm, 800.7 nm) were also found, which result respectively from the fluorescence transitions of 1D2→3F4, 1G4→3H6, 1G4→3F4, 3F3→3H6 and 3H4→3H6 of Tm3+ ion. The careful measurement and analysis of the variation of upconversion luminescence intensity F as a function of the 975 nm pumping laser power P prove that the upconversion luminescence of 1D2 state is partly a five-photon upconversion luminescence, and the upconversion lumines- cence of 1G4 state and 3H4 state are respectively the three-photon and two-photon upconversion luminescence. The theoretical analysis suggested that the upcon- version mechanism of the 363.6 nm 1D2→3H6 upconversion luminescence is partly the cross energy transfer of {3H4(Tm3+)→3F4(Tm3+), 1G4(Tm3+)→1D2(Tm3+)} and {1G4(Tm3+)→3F4(Tm3+), 3H4(Tm3+)→1D2(Tm3+)} between Tm3+ ions. In addition, the upconversion luminescence of 1G4 and 3H4 state results respectively from the se- quential energy transfer {2F5/2(Yb3+)→2F7/2(Yb3+), 3H4(Tm3+)→1G4(Tm3+)} and {2F5/2(Yb3+) →2F7/2(Yb3+), 3F4(Tm3+)→3F2(Tm3+)} from Yb3+ ions to Tm3+ ions.展开更多
We report on the elemental redistribution behavior in oxyfluoride glasses with a high repetition rate nearinfrared femtosecond laser.Elemental analysis by an electro-probe microanalyzer demonstrates that the redistrib...We report on the elemental redistribution behavior in oxyfluoride glasses with a high repetition rate nearinfrared femtosecond laser.Elemental analysis by an electro-probe microanalyzer demonstrates that the redistributions of Ca^2+and Yb^3+ions change dramatically with pulse energy,which are quite different compared with previous reported results.Confocal fluorescence spectra of Yb^3+ions demonstrate that the luminescence intensity changes obviously with the elemental redistribution.The mechanism of the observed phenomenon is discussed.This observation may have potential applications in the fabrication of micro-optical devices.展开更多
Rare earths-doped oxyfluoride glasses based on germanium oxide and lead fluoride were prepared from commercial raw materials. The glasses with general composition of 50GeO2-(50-x-y)PbO-yPbF2-xLnF3 (Ln=Pr3+-Yb3+), cont...Rare earths-doped oxyfluoride glasses based on germanium oxide and lead fluoride were prepared from commercial raw materials. The glasses with general composition of 50GeO2-(50-x-y)PbO-yPbF2-xLnF3 (Ln=Pr3+-Yb3+), contained different concentrations of optically active dopants (x=0.2 mol.% and 2 mol.%) and PbF2 (y≤15 mol.%). The differential thermal analysis (DTA) was used to determine both thermal characteristic and thermal stability properties of the glasses in the function of the kind of dopant, its concentration, and a glass composition. Characteristic glass temperatures such as glass transition temperature (Tg), glass crystallization temperature (Tc) and temperature corresponding to the maximum of the crystallization rate (Tpc) were evaluated. On the basis of obtained results, the thermal stabilities of glasses under study were evaluated using various thermal stability criteria (Dietzel factor ?T, Saad-Poulain factors H' and S). It was found that the increase in rare earth fluoride contents influenced thermal characteristics when the characteristic temperatures of the individual glass was shifted towards higher values. The effect of the PbF2 content and the kind of rare earth impurity on the glass stability was observed. Absorption spectra of lanthanide-doped glasses were measured at room temperature and used to determine the phenomenological intensity parameters Ωt and next, to estimate radiative properties of lanthanide ions in this matrix. Radiative transition probabilities of luminescent states of Ln3+, branching ratios and radiative lifetimes were determined. The variation of the Ωt along the lanthanide series was presented and discussed.展开更多
The fluorine doping along with heavy metal oxides was remarkably raised the lifetime and the quantum efficiency of 3H4 in silicate glasses. The fluorine doping changed the local structure around Tm3+ ions, then low en...The fluorine doping along with heavy metal oxides was remarkably raised the lifetime and the quantum efficiency of 3H4 in silicate glasses. The fluorine doping changed the local structure around Tm3+ ions, then low energy vibrations related to fluorine are considered to largely reduce the multi-phonon relaxation rates in the oxyfluoride silicate glasses.展开更多
Ultrafine NdFeB waste is a relatively clean waste produced during NdFeB magnet processing.Fluorinecontaining wastewater is a common type of industrial wastewater,such as stainless steel pickling wastewater.In this wor...Ultrafine NdFeB waste is a relatively clean waste produced during NdFeB magnet processing.Fluorinecontaining wastewater is a common type of industrial wastewater,such as stainless steel pickling wastewater.In this work,rare earth element neodynium was recycled from ultrafine NdFeB waste by capturing fluorine ions in the fluorine-containing wastewater and prepared into neodynium oxyfluoride.The reaction process was investigated through UV-Vis-NIR,thermogravimetry/differential thermogravimetry(TG/DTG),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The neodymium hydroxide in the ultrafine NdFeB waste reacted with fluorine ions to form Nd(OH)_(2) F,and Nd(OH)_(2) F was then transformed into neodymium oxyfluoride after decomposition.The formed neodymium oxyfluoride is found to be particles with rhombohedral structure and a particle size of around 50 nm.The reaction kinetics of forming Nd(OH)_(2) F was investigated.The reaction kinetic equation was established and the reaction activation energy was calculated.The effect of fluorine ion concentration on the reaction rate and products was evaluated.The results show that the reaction rate increases with the increase of fluorine ion concentration in the range of 0.01-1.5 mol/L,but it has little effect.In addition,the fluorine ion concentration affects the crystallinity of formed neodymium oxyfluoride.The recycling process not only realizes the sustainable utilization of rare earths,but also reduces the concentration of fluorine ions in the fluorine-containing wastewater,achieving two goals with one stone.展开更多
Neodymium oxyfluoride has received much attention in the fields of anionic solid electrolytes.luminescent,catalytic and magnetic materials because of its structure combined advantages of rareearth cations with F^(-)an...Neodymium oxyfluoride has received much attention in the fields of anionic solid electrolytes.luminescent,catalytic and magnetic materials because of its structure combined advantages of rareearth cations with F^(-)and O_(2)^(-)anions.In this work,neodynium oxyfluoride was synthesized by the reaction between neodymium oxide and four fluoride media with different fluoride ion activities.The synthesis processes in molten LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),NaF-CaF_(2)-NdF_(3)and NaF-KF-NdF_(3)are observed in situ by a confocal scanning laser microscope.The expansion of neodymium oxide particle is observed in the LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),and NaF-KF-NdF_(3)melts,and the growth of needle crystals on neodymium oxide particle is clearly observed in molten NaF-CaF_(2)-NdF_(3).Based on scanning electron microscopy(SEM)-energy dispersive X-ray spectroscopy(EDS)and X-ray diffraction(XRD)analyses of products,neodynium oxyfluoride was successfully synthesized in the four fluoride media.The neodynium oxyfluoride generated in the LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),and NaF-KF-NdF_(3)melts is a tetragonal structure.However,in molten NaF-CaF_(2)-NdF_(3),neodynium oxyfluoride with a rhombohedral structure is formed.It is suggested that the substitution of Na(Ⅰ)and Ca(Ⅱ)for Nd(Ⅲ)can transform NdOF from tetragonal structure to rhombohedral structure.The growth rate of needle crystals generated in molten NaF-CaF_(2)-NdF_(3)was calculated based on the result of a confocal scanning laser microscope,and it is found that the reaction kinetics of crystal formation is zero-order reaction.The effect of fluoride media on the structure and morphology of formed NdOF were evaluated by XRD,X-ray photoelectron spectroscopy(XPS)and SEM.The neodymium oxyfluoride prepared in the fluoride media with high fluoride ion activity has low binding energy of F 1 s.The ratio of adsorbed oxygen to lattice oxygen for neodymium oxyfluoride prepared in molten LiF-NdF_(3)is larger than those in the other three fluoride media,so it can have better catalytic performance.展开更多
We numerically simulate a photonics phenomenon of what we call intensity inversion between red and green fluorescence in oxyfluoride nanophase vitroceramics Er(1%)Yb(8%):FOV through the integration of whole fluoresce...We numerically simulate a photonics phenomenon of what we call intensity inversion between red and green fluorescence in oxyfluoride nanophase vitroceramics Er(1%)Yb(8%):FOV through the integration of whole fluorescence’s theories.We found that it is essential to introduce a coefficient presenting the difference between the Stokes energy transfer and anti-Stokes energy transfer processes in nano-material when calculating the energy transfer rate.Under this consideration,and with the total crystallized volume ratio set to be 17.6%,the simulation results of the population probabilities values of all energy levels of Er^(3+) ion are coincident with the experimental result perfectly.展开更多
In order to investigate the influence of different heavy metal ions on the formation of the oxyfluoride glasses and glass ceramics, samples with different Pb F2/Cd F2 ratios have been prepared by the melting quenching...In order to investigate the influence of different heavy metal ions on the formation of the oxyfluoride glasses and glass ceramics, samples with different Pb F2/Cd F2 ratios have been prepared by the melting quenching and thermal treatment method. The different effects of Pb2 tand Cd2ton the glass network structure are investigated by FTIR and Raman spectra. During the formation of glass network structure, Pb2 tprefers to break the Sie Oe Si bond and subsequently bond to F for charge compensation, and Cd2 tprefers to break the SieO eA l bond and is surrounded by O2. Pb2 tand F gather together and form the fluoride nanocrystals,while Cd2 tremains in oxide matrix after thermal treatment. Introduction of proper Cd F2 is important to adjust and control the glass network structure and crystallization process in the fabrication of the transparent glass ceramics.展开更多
文摘Er3+/Yb3+-codoped oxyfluoride crystallite glass was prepared with melting technique. The compositions and the melting temperature and the annealing temperature of the rare earth-doped crystallite glass were studied in detail. The emission spectra of samples were measured with the Hitachi F-4500 fluorescent photometer pumped by 980 nm wavelength laser. The up-conversion luminescence mechanism was illuminated on the view of the photophysics. By measuring the relationship between luminescent intensity and pump power, it is confirmed that the emission peaks at 550 nm belong to two-photon process, while that at 665 nm belongs to three-photon process. Moreover, the distributions of crystalline were determined by SEM.
基金Project supported by the Shanghai ＂Post-Qi-Ming-Xing plan＂ for Young Scientists, China （Grant No 04QMX1448） and the National Natural Science Foundation of China （Grant No 60207006）.The author would like to thank Wen L,Shen Y H and Zhao Y for their help in machining and measuring.
基金the National Natural Science Foundation of China (No. 50672098)the Project of Nano-molecular Functional Materials of Fujian Province (2005HZ01-1)
文摘The distribution characteristics of Er3+ ions doped in the oxyfluoride glass ceramics containing LaF3 nanocrystals heat-treated at 650 ℃ for different durations were investigated. The results of the integral absorption cross-section analysis demonstrated that the partition fraction of Er3+ in LaF3 nanocrystals increases with prolonging of heating time. The anomalous phenomena of Er3+ emissions in the up-and the down-conversion fluorescence spectra are well explained based on the calculated results.
文摘Er3+-doped heavy metal oxyfluoride silicate glass was fabricated and characterized, and the absorption spectrum and fluorescence spectrum of the glass were studied. The Judd-Ofelt intensity parameters Ωt （t =2, 4, 6）, spontaneous transition probability, fluorescence branching ratio and radiative lifetime of each energy levels for Er3+ were calculated by Judd-Ofelt theory, and stimulated emission cross-section of (（）4I13/2)→(（）4I15/2) transition was calculated by McCumber theory. The results show that fluorescence full width at half maximum and stimulated emission cross-section of Er3+-doped heavy metal oxyfluoride silicate glass are broad and large, respectively. Compared with other host glasses, the gain bandwidth property of Er3+-doped heavy metal oxyfluoride silicate glass is close to those of tellurite and bismuth glasses, and has advantage over those of silicate, phosphate and germante glasses.
基金supported by the NNSFC (Nos. 20771102 and 20873149)NSF of Fujian Province (No. 2008J0174 )973 Program (No. 2006CB932904)
文摘Two isostructural inorganic-organic hybrid M(II)–Nb(V) oxyfluorides, namely, M(H2O)2(pyz)NbOF5 (M=Co 1, Cu 2; pyz=pyrazine) have been hydrothermally synthesized and structurally characterized. Both compounds possess two-dimensional layer structure constructed by neutral M(H2O)2NbOF5 chains inter-connected via bridging pyrazine ligands. The structure is further extended into three-dimensional supramolecular architecture through inter-layer H-bonding interactions between the coordinated water molecules and fluorine ions. The luminescent properties and thermal stability of both compounds have been investigated.
基金supported by the National Natural Science Foundation of China(Grant Nos.61177086,61307046,and 61308086)the West Light Foundation of the Chinese Academy of Sciences(Grant No.Y129261213)
文摘A series of oxyfluoride glasses with the compositions of 75 mol% TeO2, 10 mol% Nb2O5,(15 mol%-x) BaO, x BaF2(x = 0 mol%, 5 mol%, 10 mol%, 15 mol%) doped with Yb2O3 were prepared by the melt-quenching method. Their emission cross-sections, fluorescence lifetimes, and gain properties were investigated by using the absorption spectra and the fluorescence decay curves. The results show that by substituting BaF2 for BaO, the emission cross-section decreases from 1.37 pm2 to 1.21 pm2, and the fluorescence lifetime increases from 0.71 ms to 0.96 ms. These properties indicate that this oxyfluoride tellurite glass may have potential uses as the Yb2O3-doped gain medium in a solid laser.
基金Funded by Key Laboratory for Ultrafine Materials of Ministry of Education(No.08DZ2230500),School of Materials Science and Engineering,East China University of Science and Technology
文摘The Pr3+-Yb3+ co-doped oxyfluoride glass-ceramics containing CaF2 nanocrystals were obtained by thermal treatment on the as-made glasses. The structure of fluoride nanocrystals was investigated. The light-emitting mechanism of Pr3+-Yb3+ in the near infrared region was proposed and the fluorescence lifetime and quantum efficiency was calculated. The results indicate that the main phase in the oxyfluoride glass-ceramics is CaF2 nanocrystal sized at 30 nm. Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) have proved the incorporation of Pr3+ and Yb3+ into CaF2 nanocrystal lattice. Near-infrared quantum cutting involving Yb3+ 980 nm and 1 015 nm ( 2F5/2 → 2F7/2 ) emission has been achieved upon the excitation of the 3P0 energy level of Pr3+ at 482 nm. The fluorescence lifetime decreases sharply and quantum efficiency increases with increasing Yb3+ concentration, and the optimal quantum efficiency reaches 191%.
基金Project supported by Science and Technology Department of Jilin Province of China(20190302006GX)Technology Innovation Fund of Changchun University of Science and Technology(XJJLG-2017-06,XJJLG-2018-10)。
文摘Rare earth ion-doped fluorescent glass has become a hotspot due to its characteristics.This work shows that the prepared Dy^3+and Dy^3+/Eu^3+doped glasses have white light emission under ultraviolet excitation.There is a higher yellow light/blue light(Y/B)value,indicating an increase in the covalentity of Dy-O,and decrease in the symmetry with the increasing concentration of dopants(Dy^3+).The correlated color temperature(CCT)can be effectively reduced by the red light emission of Eu^3+,and the order of influence of excitation wavelength on CCT is 395 nm>382 nm>365 nm.The delay curve demonstrates the energy transfer from Dy^3+to Eu^3+.The glass has the characteristics of anti-blue light damage and wide tunable color temperature,which illustrates that it has potential application in the field of white LED.
基金Project supported by China Postdoctoral Science Foundation funded project (20080430216)National Natural Science Foundation of China (60508014)+1 种基金Program for New Century Excellent Talents in University (NCET-07-0786)Zhejiang Provincial Natural Science Foundation of China (Z4100030)
文摘Er3+/Yb3+-codoped transparent oxyfluoride borosilicate glass ceramics containing Ba2GdF7 nanocrystals were prepared and spectroscopic properties of rare earth ions were investigated. Fluoride nanocrystals Ba2GdF7 were successfully precipitated in glass matrix, which was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) results. In comparison with the as-made precursor, significant enhancement of upconversion luminescence was observed in the Er3+/Yb3+ codoped oxyfluoride glass ceramics, which may be due to the variation of coordination environment around Er3+ and Yb3+ ions after crystallization. The transition mechanisms of the green and red upconversion luminescence were ascribed to a two-photon process, and that of the blue upconversion luminescence was a three-photon process.
基金the National Natural Science Foundation of China (Grant No. 10674019)
文摘The ultraviolet upconversion luminescence of Tm3+ ions sensitized by Yb3+ ions in oxyfluoride nanophase vitroceramics when excited by a 975 nm diode laser was studied. An ultraviolet upconversion luminescence line positioned at 363.6 nm was found. It was attributed to the fluorescence transition of 1D2→3H6 of Tm3+ ion. Sev- eral visible upconversion luminescence lines at 450.7 nm, (477.0 nm, 462.5 nm), 648.5 nm, (680.5 nm, 699.5 nm) and (777.2 nm, 800.7 nm) were also found, which result respectively from the fluorescence transitions of 1D2→3F4, 1G4→3H6, 1G4→3F4, 3F3→3H6 and 3H4→3H6 of Tm3+ ion. The careful measurement and analysis of the variation of upconversion luminescence intensity F as a function of the 975 nm pumping laser power P prove that the upconversion luminescence of 1D2 state is partly a five-photon upconversion luminescence, and the upconversion lumines- cence of 1G4 state and 3H4 state are respectively the three-photon and two-photon upconversion luminescence. The theoretical analysis suggested that the upcon- version mechanism of the 363.6 nm 1D2→3H6 upconversion luminescence is partly the cross energy transfer of {3H4(Tm3+)→3F4(Tm3+), 1G4(Tm3+)→1D2(Tm3+)} and {1G4(Tm3+)→3F4(Tm3+), 3H4(Tm3+)→1D2(Tm3+)} between Tm3+ ions. In addition, the upconversion luminescence of 1G4 and 3H4 state results respectively from the se- quential energy transfer {2F5/2(Yb3+)→2F7/2(Yb3+), 3H4(Tm3+)→1G4(Tm3+)} and {2F5/2(Yb3+) →2F7/2(Yb3+), 3F4(Tm3+)→3F2(Tm3+)} from Yb3+ ions to Tm3+ ions.
文摘We report on the elemental redistribution behavior in oxyfluoride glasses with a high repetition rate nearinfrared femtosecond laser.Elemental analysis by an electro-probe microanalyzer demonstrates that the redistributions of Ca^2+and Yb^3+ions change dramatically with pulse energy,which are quite different compared with previous reported results.Confocal fluorescence spectra of Yb^3+ions demonstrate that the luminescence intensity changes obviously with the elemental redistribution.The mechanism of the observed phenomenon is discussed.This observation may have potential applications in the fabrication of micro-optical devices.
文摘Rare earths-doped oxyfluoride glasses based on germanium oxide and lead fluoride were prepared from commercial raw materials. The glasses with general composition of 50GeO2-(50-x-y)PbO-yPbF2-xLnF3 (Ln=Pr3+-Yb3+), contained different concentrations of optically active dopants (x=0.2 mol.% and 2 mol.%) and PbF2 (y≤15 mol.%). The differential thermal analysis (DTA) was used to determine both thermal characteristic and thermal stability properties of the glasses in the function of the kind of dopant, its concentration, and a glass composition. Characteristic glass temperatures such as glass transition temperature (Tg), glass crystallization temperature (Tc) and temperature corresponding to the maximum of the crystallization rate (Tpc) were evaluated. On the basis of obtained results, the thermal stabilities of glasses under study were evaluated using various thermal stability criteria (Dietzel factor ?T, Saad-Poulain factors H' and S). It was found that the increase in rare earth fluoride contents influenced thermal characteristics when the characteristic temperatures of the individual glass was shifted towards higher values. The effect of the PbF2 content and the kind of rare earth impurity on the glass stability was observed. Absorption spectra of lanthanide-doped glasses were measured at room temperature and used to determine the phenomenological intensity parameters Ωt and next, to estimate radiative properties of lanthanide ions in this matrix. Radiative transition probabilities of luminescent states of Ln3+, branching ratios and radiative lifetimes were determined. The variation of the Ωt along the lanthanide series was presented and discussed.
文摘The fluorine doping along with heavy metal oxides was remarkably raised the lifetime and the quantum efficiency of 3H4 in silicate glasses. The fluorine doping changed the local structure around Tm3+ ions, then low energy vibrations related to fluorine are considered to largely reduce the multi-phonon relaxation rates in the oxyfluoride silicate glasses.
基金Project supported by the Natural Science Foundation of Inner Mongolia(2020BS05033,2020MS05012)Inner Mongolia Major Basic Research Open Project(0406091701)。
文摘Ultrafine NdFeB waste is a relatively clean waste produced during NdFeB magnet processing.Fluorinecontaining wastewater is a common type of industrial wastewater,such as stainless steel pickling wastewater.In this work,rare earth element neodynium was recycled from ultrafine NdFeB waste by capturing fluorine ions in the fluorine-containing wastewater and prepared into neodynium oxyfluoride.The reaction process was investigated through UV-Vis-NIR,thermogravimetry/differential thermogravimetry(TG/DTG),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The neodymium hydroxide in the ultrafine NdFeB waste reacted with fluorine ions to form Nd(OH)_(2) F,and Nd(OH)_(2) F was then transformed into neodymium oxyfluoride after decomposition.The formed neodymium oxyfluoride is found to be particles with rhombohedral structure and a particle size of around 50 nm.The reaction kinetics of forming Nd(OH)_(2) F was investigated.The reaction kinetic equation was established and the reaction activation energy was calculated.The effect of fluorine ion concentration on the reaction rate and products was evaluated.The results show that the reaction rate increases with the increase of fluorine ion concentration in the range of 0.01-1.5 mol/L,but it has little effect.In addition,the fluorine ion concentration affects the crystallinity of formed neodymium oxyfluoride.The recycling process not only realizes the sustainable utilization of rare earths,but also reduces the concentration of fluorine ions in the fluorine-containing wastewater,achieving two goals with one stone.
基金Project supported by National Key Research and Development Program of China(2020YFC1909102)Natural Science Foundation of Inner Mongolia(2020BS05033)+1 种基金Inner Mongolia Major Basic Research Open Project(0406091701)Major Projects of Natural Science Foundation of Inner Mongolia of China(2018ZD07)。
文摘Neodymium oxyfluoride has received much attention in the fields of anionic solid electrolytes.luminescent,catalytic and magnetic materials because of its structure combined advantages of rareearth cations with F^(-)and O_(2)^(-)anions.In this work,neodynium oxyfluoride was synthesized by the reaction between neodymium oxide and four fluoride media with different fluoride ion activities.The synthesis processes in molten LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),NaF-CaF_(2)-NdF_(3)and NaF-KF-NdF_(3)are observed in situ by a confocal scanning laser microscope.The expansion of neodymium oxide particle is observed in the LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),and NaF-KF-NdF_(3)melts,and the growth of needle crystals on neodymium oxide particle is clearly observed in molten NaF-CaF_(2)-NdF_(3).Based on scanning electron microscopy(SEM)-energy dispersive X-ray spectroscopy(EDS)and X-ray diffraction(XRD)analyses of products,neodynium oxyfluoride was successfully synthesized in the four fluoride media.The neodynium oxyfluoride generated in the LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),and NaF-KF-NdF_(3)melts is a tetragonal structure.However,in molten NaF-CaF_(2)-NdF_(3),neodynium oxyfluoride with a rhombohedral structure is formed.It is suggested that the substitution of Na(Ⅰ)and Ca(Ⅱ)for Nd(Ⅲ)can transform NdOF from tetragonal structure to rhombohedral structure.The growth rate of needle crystals generated in molten NaF-CaF_(2)-NdF_(3)was calculated based on the result of a confocal scanning laser microscope,and it is found that the reaction kinetics of crystal formation is zero-order reaction.The effect of fluoride media on the structure and morphology of formed NdOF were evaluated by XRD,X-ray photoelectron spectroscopy(XPS)and SEM.The neodymium oxyfluoride prepared in the fluoride media with high fluoride ion activity has low binding energy of F 1 s.The ratio of adsorbed oxygen to lattice oxygen for neodymium oxyfluoride prepared in molten LiF-NdF_(3)is larger than those in the other three fluoride media,so it can have better catalytic performance.
基金The research was supported by the National Natural Science Foundation of China(10674019).
文摘We numerically simulate a photonics phenomenon of what we call intensity inversion between red and green fluorescence in oxyfluoride nanophase vitroceramics Er(1%)Yb(8%):FOV through the integration of whole fluorescence’s theories.We found that it is essential to introduce a coefficient presenting the difference between the Stokes energy transfer and anti-Stokes energy transfer processes in nano-material when calculating the energy transfer rate.Under this consideration,and with the total crystallized volume ratio set to be 17.6%,the simulation results of the population probabilities values of all energy levels of Er^(3+) ion are coincident with the experimental result perfectly.
基金supported by the National Science Fund for Talent Training in Basic Sciences (No. J1103208)
文摘In order to investigate the influence of different heavy metal ions on the formation of the oxyfluoride glasses and glass ceramics, samples with different Pb F2/Cd F2 ratios have been prepared by the melting quenching and thermal treatment method. The different effects of Pb2 tand Cd2ton the glass network structure are investigated by FTIR and Raman spectra. During the formation of glass network structure, Pb2 tprefers to break the Sie Oe Si bond and subsequently bond to F for charge compensation, and Cd2 tprefers to break the SieO eA l bond and is surrounded by O2. Pb2 tand F gather together and form the fluoride nanocrystals,while Cd2 tremains in oxide matrix after thermal treatment. Introduction of proper Cd F2 is important to adjust and control the glass network structure and crystallization process in the fabrication of the transparent glass ceramics.
