Some new photostimulable F centers in the X-rayed BaFX: Eu2^+ were found. Their absorption bands are located in IR region. PSL process of X-rayed BaFX:Eu^(2+) consists of two subordinated process—e^--h^+ recombinatio...Some new photostimulable F centers in the X-rayed BaFX: Eu2^+ were found. Their absorption bands are located in IR region. PSL process of X-rayed BaFX:Eu^(2+) consists of two subordinated process—e^--h^+ recombination and radiative transition of Eu2^+ ions. The latter is a slow and rate-determining step. Dynamics and mechanism of that PSL have been investigated.展开更多
This paper reports the F-centers and photostimulated luminescence of Eu^(2+)-activated Sr_3Ca_2(PO_4)_3X crystals.The influence of various halide ions on the F-centers and their energy level is discussed.The mechanism...This paper reports the F-centers and photostimulated luminescence of Eu^(2+)-activated Sr_3Ca_2(PO_4)_3X crystals.The influence of various halide ions on the F-centers and their energy level is discussed.The mechanism for the photostimulated luminescence and valence change of Eu ion in that process have been investigated.展开更多
Photostimulated luminescence (PSL) phenomenon was observed in a fluoride-oxide glass ceramics doped with Eu 2+. When the UV light irradiated glass ceramic was stimulated by a longer wavelength light, PSL at 447 nm due...Photostimulated luminescence (PSL) phenomenon was observed in a fluoride-oxide glass ceramics doped with Eu 2+. When the UV light irradiated glass ceramic was stimulated by a longer wavelength light, PSL at 447 nm due to the 5d-4f transition of Eu 2+ was observed. The PSl excitation band peaking at 543 nm is due to the electron trap centers which are located either in the Eu 2+-doped crystallites or in the glass; where exactly they are located in is not yet known. The optical storage properties of this kind of glass ceramic were also studied. By comparing with the investigations on PSL phosphor Eu 2+ doped alkali halides, PSL mechanism in glass ceramics which is still an open question and has to be investigated in further experiments was explained.展开更多
In this paper, we have succesfully prepared the sample of BaFCl: Eu<sup>2+</sup>thin film using the vacuum thermal evaporation method and first studied photostimulated luminescence on BaFCl: Eu<sup>2...In this paper, we have succesfully prepared the sample of BaFCl: Eu<sup>2+</sup>thin film using the vacuum thermal evaporation method and first studied photostimulated luminescence on BaFCl: Eu<sup>2+</sup>thin film.展开更多
The polycrystalline Sr_9Ca(PO_4)_6Cl_2:Eu has been synthesized by solid state reaction.The reaction condition,the appropriate raw materials and their quantity used,which may affect the photostimulable luminescence (PS...The polycrystalline Sr_9Ca(PO_4)_6Cl_2:Eu has been synthesized by solid state reaction.The reaction condition,the appropriate raw materials and their quantity used,which may affect the photostimulable luminescence (PSL),have been systematically inves- tigated.The properties of this PSL phosphor as a material for storing and reproducing the X-ray image in computer-aided radiography have been reported briefly.展开更多
A series of Eu2+-doped fluorochlorozirconate glass-ceramics were prepared by solid state reaction method. X-ray diffraction, pho- toluminescence, photo-stimulated luminescence (PSL) and the turbidity of fluorozirco...A series of Eu2+-doped fluorochlorozirconate glass-ceramics were prepared by solid state reaction method. X-ray diffraction, pho- toluminescence, photo-stimulated luminescence (PSL) and the turbidity of fluorozirconate glass containing BaCl2 nano- and micro-crystals were measured for the samples annealed at 290℃ for 10 rain The PSL was attributed to the characteristic emission of Eu2+ in nano-crystallites of BaCI2, which formed in the glass upon annealing. The PSL efficiency of the glass ceramic was increased by increasing the concentration of BaCl2, which, however, resulted in the decreasing in the transparency of the sample. The sample turned to a semi-transparent glass ceramic or even an opaque and milky white one from a near-transparent glass. The trade-off between optical transparency and PSL intensity over different concentrations of BaCl2 for X-ray imaging plate applications was briefly discussed.展开更多
Europium doped MBrCl (M=Ca, Sr, and Ba) phosphors were prepared by solid state reaction in reductive atmosphere. Photolu- minescence (PL), photostimulated luminescence (PSL) after X-ray irradiation and optical a...Europium doped MBrCl (M=Ca, Sr, and Ba) phosphors were prepared by solid state reaction in reductive atmosphere. Photolu- minescence (PL), photostimulated luminescence (PSL) after X-ray irradiation and optical absorption studies of MBrCI:Eu2+ (M=Ca, Sr, and Ba) revealed that: (1) blue light emission, under the excitation of 300 nm, was observed in all these phosphors; (2) the shape of the emission spectra in CaBrCI:Eu2+ could be changed by varying the bromine/chlorine ratio during synthesis, while that in SrBrCI:Eu2+ and BaBrCI:Eu2+ showed no change; and (3) PSL was observed in SrBrCI:Eu2+ and BaBrCI:Eu2+ after X-ray irradiation. Difference absorption spectrum (DAS) in SrBrCl:Eu2+showed two broad bands centered at about 470 and 570 nm, and DAS in BaBrCl:Eu2+showed two bands at about 550 and 675 nm, respectively. This enabled the use of He-Ne laser (633 nm) or even semiconductor fight-emitting diodes (LED) instead of gas lasers for photostimulation.展开更多
The valence changes of doped samarium and the creation as well as the annihilation of F-centers in the processes of thermostimulated luminescence (TSL) and photostimulated luminescence (PSL) of BaFCl∶Sm crystal have ...The valence changes of doped samarium and the creation as well as the annihilation of F-centers in the processes of thermostimulated luminescence (TSL) and photostimulated luminescence (PSL) of BaFCl∶Sm crystal have been studied. As being irradiated by X-ray,a large number of electron-hole pairs are created in the crystal.Most of the electrons may be trapped at the anion vacancies,producing F-centers.The doped samarium ions,which existed mostly in trivalent state (Sm^(3+)),may capture the holes and convert themselves to tetravalent state.So that part of the incident X-ray energy are stored in this nonequilibrium system.On optical and thermal stimulation the stored energy can be liberated as a characteristic emission of trivalent samarium ion.This emission originates from the recombination of the F-center electrons with tetravalent samarium ions,i.e.the F-center electrons may be excited to the conduction band by optical or thermal stirnulation and then recombine with tetravalent samarium ions.This recombination makes the samarium ions to be in situ reduced to the excited state of Sm^(3+),and gives rise to the characteristic emission of Sm^(3+). On the other hand,during X-irradiation a few electrons can be trapped at the sites of trivalent samarium ions and reduce them to divalent state.But the formation of divalent samarium On X-irradiation is very small as compared with that of F-centers and so their influence on the PSL and TSL can be neglected.展开更多
A series of Sr2A12SiO7 phosphors with fixed Eu2+ concentration and various Tm3+ concentrations were synthesized via a high temperature solid state reaction. The structure and luminescence properties of the samples w...A series of Sr2A12SiO7 phosphors with fixed Eu2+ concentration and various Tm3+ concentrations were synthesized via a high temperature solid state reaction. The structure and luminescence properties of the samples were characterized by X-ray powder diffraction (XRD), photoluminescence (PL) spectra, decay curves, thermoluminescence (TL) glow curves as well as the photostimu- lated luminescence (PSL) spectra. Sr2A12SiO7:Eu2+,Tm3+ phosphors exhibited strong green phosphorescence and photostimulated lu- minescence originating from 4f65d1-4f7 transition of Eu2+ after ultraviolet light stimulation. Deep traps were found by analyses on the phosphorescence decays and thermoluminescence spectra. It was also found that with increasing the time interval between UV excita- tion turn-off and stimulation turn-on, the photostimulated luminescence became stronger. This phenomenon resulted from the fact that the captured electron was retrapped by the deep traps. Compared with the Tm3+-free sample, it was found that the PSL intensity was strongly enhanced in Tm3+ eodoping samples.展开更多
In Ref.[1] we reported the V centers and hole-photostimulated luminescence(HPSL) of BaFCl crystal. The result shows that the V centers play an equal role asthe F centers in the X-ray storage and photostimulated lumine...In Ref.[1] we reported the V centers and hole-photostimulated luminescence(HPSL) of BaFCl crystal. The result shows that the V centers play an equal role asthe F centers in the X-ray storage and photostimulated luminescence (PSL) processes.Previous research work paid much attention to the F centers but neglected the Vcenters. So the X-ray storage and PSL processes have not been revealed completelyyet. Our research work is significant as a complement to the previous documents.展开更多
Thermal stimulated luminescence (TSL) and photostimulated luminescence (PSL) were used to investigate the luminescent performance of Al 3+ doped BaFBr∶Eu 2+ in different synthetic conditions. Theory analys...Thermal stimulated luminescence (TSL) and photostimulated luminescence (PSL) were used to investigate the luminescent performance of Al 3+ doped BaFBr∶Eu 2+ in different synthetic conditions. Theory analysis shows that the decay of TSL spectra is different from that of PSL spectra. Theoretical calculation was used to investigate the effects of energy state in Al 3+ doped BaFBr∶Eu 2+ by different synthetic conditions. The relationship of color center’s energy and different synthetic conditions is discussed.展开更多
V centers (hole centers) and hole-photostimulated luminescence of BaFCl crystal are reported for the first time. The absorption bands of V1, V2 and V3 centers are peaking at 205, 238 and 355 nm respectively. V2 center...V centers (hole centers) and hole-photostimulated luminescence of BaFCl crystal are reported for the first time. The absorption bands of V1, V2 and V3 centers are peaking at 205, 238 and 355 nm respectively. V2 center creation by X-irradiation and decay during photostimulated luminescence process are synchronousl with that of F center. This indicates that V centers play the same roles as F centers in X-ray storage and photostimulated luminescence processes.展开更多
基金The project supported by the Natioal Natural Science Foundation of China
文摘Some new photostimulable F centers in the X-rayed BaFX: Eu2^+ were found. Their absorption bands are located in IR region. PSL process of X-rayed BaFX:Eu^(2+) consists of two subordinated process—e^--h^+ recombination and radiative transition of Eu2^+ ions. The latter is a slow and rate-determining step. Dynamics and mechanism of that PSL have been investigated.
基金The project supported by the National Natural Science Foundation of China
文摘This paper reports the F-centers and photostimulated luminescence of Eu^(2+)-activated Sr_3Ca_2(PO_4)_3X crystals.The influence of various halide ions on the F-centers and their energy level is discussed.The mechanism for the photostimulated luminescence and valence change of Eu ion in that process have been investigated.
文摘Photostimulated luminescence (PSL) phenomenon was observed in a fluoride-oxide glass ceramics doped with Eu 2+. When the UV light irradiated glass ceramic was stimulated by a longer wavelength light, PSL at 447 nm due to the 5d-4f transition of Eu 2+ was observed. The PSl excitation band peaking at 543 nm is due to the electron trap centers which are located either in the Eu 2+-doped crystallites or in the glass; where exactly they are located in is not yet known. The optical storage properties of this kind of glass ceramic were also studied. By comparing with the investigations on PSL phosphor Eu 2+ doped alkali halides, PSL mechanism in glass ceramics which is still an open question and has to be investigated in further experiments was explained.
基金Project Supported by the National Science Foundation of China.
文摘In this paper, we have succesfully prepared the sample of BaFCl: Eu<sup>2+</sup>thin film using the vacuum thermal evaporation method and first studied photostimulated luminescence on BaFCl: Eu<sup>2+</sup>thin film.
文摘The polycrystalline Sr_9Ca(PO_4)_6Cl_2:Eu has been synthesized by solid state reaction.The reaction condition,the appropriate raw materials and their quantity used,which may affect the photostimulable luminescence (PSL),have been systematically inves- tigated.The properties of this PSL phosphor as a material for storing and reproducing the X-ray image in computer-aided radiography have been reported briefly.
基金supported by the National Natural Science Foundation of China (10644002)Beijing Municipal Science & Technology Commission Foundation (Y0406001040711)the Foundation of Beijing Jiaotong University (2006XM051)
文摘A series of Eu2+-doped fluorochlorozirconate glass-ceramics were prepared by solid state reaction method. X-ray diffraction, pho- toluminescence, photo-stimulated luminescence (PSL) and the turbidity of fluorozirconate glass containing BaCl2 nano- and micro-crystals were measured for the samples annealed at 290℃ for 10 rain The PSL was attributed to the characteristic emission of Eu2+ in nano-crystallites of BaCI2, which formed in the glass upon annealing. The PSL efficiency of the glass ceramic was increased by increasing the concentration of BaCl2, which, however, resulted in the decreasing in the transparency of the sample. The sample turned to a semi-transparent glass ceramic or even an opaque and milky white one from a near-transparent glass. The trade-off between optical transparency and PSL intensity over different concentrations of BaCl2 for X-ray imaging plate applications was briefly discussed.
基金supported by the National Natural Science Foundation of China (10644002)Beijing Municipal Science & Technology Commission Foundation (Y0406001040711)+1 种基金Foundation of Beijing Jiaotong UniversityInnovation Project of Beijing Jiaotong University (48002)
文摘Europium doped MBrCl (M=Ca, Sr, and Ba) phosphors were prepared by solid state reaction in reductive atmosphere. Photolu- minescence (PL), photostimulated luminescence (PSL) after X-ray irradiation and optical absorption studies of MBrCI:Eu2+ (M=Ca, Sr, and Ba) revealed that: (1) blue light emission, under the excitation of 300 nm, was observed in all these phosphors; (2) the shape of the emission spectra in CaBrCI:Eu2+ could be changed by varying the bromine/chlorine ratio during synthesis, while that in SrBrCI:Eu2+ and BaBrCI:Eu2+ showed no change; and (3) PSL was observed in SrBrCI:Eu2+ and BaBrCI:Eu2+ after X-ray irradiation. Difference absorption spectrum (DAS) in SrBrCl:Eu2+showed two broad bands centered at about 470 and 570 nm, and DAS in BaBrCl:Eu2+showed two bands at about 550 and 675 nm, respectively. This enabled the use of He-Ne laser (633 nm) or even semiconductor fight-emitting diodes (LED) instead of gas lasers for photostimulation.
文摘The valence changes of doped samarium and the creation as well as the annihilation of F-centers in the processes of thermostimulated luminescence (TSL) and photostimulated luminescence (PSL) of BaFCl∶Sm crystal have been studied. As being irradiated by X-ray,a large number of electron-hole pairs are created in the crystal.Most of the electrons may be trapped at the anion vacancies,producing F-centers.The doped samarium ions,which existed mostly in trivalent state (Sm^(3+)),may capture the holes and convert themselves to tetravalent state.So that part of the incident X-ray energy are stored in this nonequilibrium system.On optical and thermal stimulation the stored energy can be liberated as a characteristic emission of trivalent samarium ion.This emission originates from the recombination of the F-center electrons with tetravalent samarium ions,i.e.the F-center electrons may be excited to the conduction band by optical or thermal stirnulation and then recombine with tetravalent samarium ions.This recombination makes the samarium ions to be in situ reduced to the excited state of Sm^(3+),and gives rise to the characteristic emission of Sm^(3+). On the other hand,during X-irradiation a few electrons can be trapped at the sites of trivalent samarium ions and reduce them to divalent state.But the formation of divalent samarium On X-irradiation is very small as compared with that of F-centers and so their influence on the PSL and TSL can be neglected.
基金supported by the National Natural Science Foundation of China(1137404411104024)+2 种基金Natural Science Foundation of Liaoning Province(2014025010)Fundamental Research Funds for the Central Universities(31320143273132015143)
文摘A series of Sr2A12SiO7 phosphors with fixed Eu2+ concentration and various Tm3+ concentrations were synthesized via a high temperature solid state reaction. The structure and luminescence properties of the samples were characterized by X-ray powder diffraction (XRD), photoluminescence (PL) spectra, decay curves, thermoluminescence (TL) glow curves as well as the photostimu- lated luminescence (PSL) spectra. Sr2A12SiO7:Eu2+,Tm3+ phosphors exhibited strong green phosphorescence and photostimulated lu- minescence originating from 4f65d1-4f7 transition of Eu2+ after ultraviolet light stimulation. Deep traps were found by analyses on the phosphorescence decays and thermoluminescence spectra. It was also found that with increasing the time interval between UV excita- tion turn-off and stimulation turn-on, the photostimulated luminescence became stronger. This phenomenon resulted from the fact that the captured electron was retrapped by the deep traps. Compared with the Tm3+-free sample, it was found that the PSL intensity was strongly enhanced in Tm3+ eodoping samples.
基金Project supported by the National Natural Science Foundation of China.
文摘In Ref.[1] we reported the V centers and hole-photostimulated luminescence(HPSL) of BaFCl crystal. The result shows that the V centers play an equal role asthe F centers in the X-ray storage and photostimulated luminescence (PSL) processes.Previous research work paid much attention to the F centers but neglected the Vcenters. So the X-ray storage and PSL processes have not been revealed completelyyet. Our research work is significant as a complement to the previous documents.
文摘Thermal stimulated luminescence (TSL) and photostimulated luminescence (PSL) were used to investigate the luminescent performance of Al 3+ doped BaFBr∶Eu 2+ in different synthetic conditions. Theory analysis shows that the decay of TSL spectra is different from that of PSL spectra. Theoretical calculation was used to investigate the effects of energy state in Al 3+ doped BaFBr∶Eu 2+ by different synthetic conditions. The relationship of color center’s energy and different synthetic conditions is discussed.
基金Project supported by the National Natural Science Foundation of China.
文摘V centers (hole centers) and hole-photostimulated luminescence of BaFCl crystal are reported for the first time. The absorption bands of V1, V2 and V3 centers are peaking at 205, 238 and 355 nm respectively. V2 center creation by X-irradiation and decay during photostimulated luminescence process are synchronousl with that of F center. This indicates that V centers play the same roles as F centers in X-ray storage and photostimulated luminescence processes.