High quality Tb^3＋/Eu^3＋ co-doped cubic NaYF 4 single crystal in the size of Φ1.0 cm×6.6 cm was grown by a modified Bridgman method using KF as assistant flux for NaF-YF 3 system under the condition of complet...High quality Tb^3＋/Eu^3＋ co-doped cubic NaYF 4 single crystal in the size of Φ1.0 cm×6.6 cm was grown by a modified Bridgman method using KF as assistant flux for NaF-YF 3 system under the condition of completely closed Pt crucible.A white light emission from the combination of the violet-blue,blue,green,orange,and red lights with chromaticity coordinates of x = 0.3107,y = 0.3274,correlated color temperature of T c = 6637 K,color rendering index of R a = 83,and color quality scale of Q a = 82 could be obtained from 1.51 mol%Tb^3＋ and 1.42 mol%Eu^3＋ co-doped cubic NaYF 4 single crystal when being excited by a 369 nm light.This indicates that Tb^3＋/Eu^3＋）co-doped cubic NaYF 4 single crystal has a potential application in white light emitting diode excited by ultraviolet light.展开更多
The generation of broadband white emission of theα-Y2Si2O7 nanocrystals was observed upon excitation by focused beam ofCW lasers operating in near infrared,visible and blue regions.The influence of excitation energy ...The generation of broadband white emission of theα-Y2Si2O7 nanocrystals was observed upon excitation by focused beam ofCW lasers operating in near infrared,visible and blue regions.The influence of excitation energy on order of process is presented.The temperature of sample emitting laser induced white emission(LIWE)was determined by luminescence nanothermometry technique.It is found that the temperature is much lower than that predicted by blackbody model characterized with the same energy.It is shown that the LIWE is accompanied by efficient photocurrent.An origin of white emission is discussed in terms of multiphoton ionization process leading to the inter valence charge transfer emission.展开更多
Carbon nitrides synthesized by thermal polycondensation of melamine at 700 ~C exhibit photoluminescence （PL） ranging from 400 to 650 nm. This broad PL is attributed to band to band transitions and bandtail transitio...Carbon nitrides synthesized by thermal polycondensation of melamine at 700 ~C exhibit photoluminescence （PL） ranging from 400 to 650 nm. This broad PL is attributed to band to band transitions and bandtail transitions of lone pair （LP） states of intra-tri-s-triazine and inter-tri-s-triazine nitrogens. The proposed PL mechanism is further confirmed by diffusion reflectance spectroscopy, as well as time-resolved and temperature-dependent PL. This intense fluorescence is stable at different pH and resistant to UV exposure, suggesting that this inexpensive broadband luminescent material could be significant for white- light-emitting （WLE） applications. Thus, quasi-WLE films and membranes with designed patterns are fabricated by embedding the carbon nitrides into polymethyl methacrylate. Moreover, even broader PL （400 to 740 nm） is acquired in com- posite films composed of carbon nitrides, further suggesting that the carbon nitrides are robust candidates for WLE.展开更多
The Eu^3＋/Ag co-doped rare earth disilicate Y2Si2O7 microcrystal was synthesized by sol-gel method. Through controlling the thermal treatment process of YzSi2OT：EU3＋/Ag precursor, various phases （amorphous, α, ...The Eu^3＋/Ag co-doped rare earth disilicate Y2Si2O7 microcrystal was synthesized by sol-gel method. Through controlling the thermal treatment process of YzSi2OT：EU3＋/Ag precursor, various phases （amorphous, α, β, γ, δ） were prepared. White light emis- sion was observed under UV light excitation in the samples heavily doped with Ag. The white light was realized by combining the intense red emission of Eu3＋, the green emission attributed to the very small molecule-like, non-plasmonic Ag particles （ML-Ag-particles）, and the blue emission due to Ag ions. Results demonstrated that Eu3＋/Ag co-doped Y2Si207 microcrystal could be potentially applied as white light emission phosphors for UV LED chips.展开更多
ZnS films were deposited on porous Si （PS） substrates using a pulsed laser deposition （PLD） technique. White light emission is observed in photoluminescence （PL） spectra, and the white light is the combination o...ZnS films were deposited on porous Si （PS） substrates using a pulsed laser deposition （PLD） technique. White light emission is observed in photoluminescence （PL） spectra, and the white light is the combination of blue and green emission from ZnS and red emission from PS. The white PL spectra are broad, intense in a visible band ranging from 450 to 700 nrn. The effects of the excitation wavelength, growth temperature of ZnS films, PS porosity and annealing temperature on the PL spectra of ZnS/PS were also investigated.展开更多
The intensities of the continuum emission and the Call K line of the white light flare with 3B importance on September 19, 1979 are measured and analyzed. Their variations with time are given. It is indicated that the...The intensities of the continuum emission and the Call K line of the white light flare with 3B importance on September 19, 1979 are measured and analyzed. Their variations with time are given. It is indicated that the continuum emission of this flare appeared in the early impulsive phase and lasted for about 5～6 min, with the time of maximum intensity 2～3 min earlier than that for the microwave radio burst. Based on the non-LTE theory, a semi-emplrical model at a time with the continuum emission being relatively intensive is presented. The resuhs show that the temperature in the flare photosphere is increased by 150～250 K, and that the continuum emission is produced mainly by the negative hydrogen ion. Finally, some discussions about the heating mechanism are also presented, implying that the heating energy may come from the lower atmosphere itself.展开更多
基金supported in part by the National Natural Science Foundation of China (Grant Nos.51472125 and 51272109)K.C.Wong Magna Fund in Ningbo University
文摘High quality Tb^3＋/Eu^3＋ co-doped cubic NaYF 4 single crystal in the size of Φ1.0 cm×6.6 cm was grown by a modified Bridgman method using KF as assistant flux for NaF-YF 3 system under the condition of completely closed Pt crucible.A white light emission from the combination of the violet-blue,blue,green,orange,and red lights with chromaticity coordinates of x = 0.3107,y = 0.3274,correlated color temperature of T c = 6637 K,color rendering index of R a = 83,and color quality scale of Q a = 82 could be obtained from 1.51 mol%Tb^3＋ and 1.42 mol%Eu^3＋ co-doped cubic NaYF 4 single crystal when being excited by a 369 nm light.This indicates that Tb^3＋/Eu^3＋）co-doped cubic NaYF 4 single crystal has a potential application in white light emitting diode excited by ultraviolet light.
基金Project supported by the Natonal Research Centre,Poland(UMO-2015/19/N/ST5/02680)
文摘The generation of broadband white emission of theα-Y2Si2O7 nanocrystals was observed upon excitation by focused beam ofCW lasers operating in near infrared,visible and blue regions.The influence of excitation energy on order of process is presented.The temperature of sample emitting laser induced white emission(LIWE)was determined by luminescence nanothermometry technique.It is found that the temperature is much lower than that predicted by blackbody model characterized with the same energy.It is shown that the LIWE is accompanied by efficient photocurrent.An origin of white emission is discussed in terms of multiphoton ionization process leading to the inter valence charge transfer emission.
文摘Carbon nitrides synthesized by thermal polycondensation of melamine at 700 ~C exhibit photoluminescence （PL） ranging from 400 to 650 nm. This broad PL is attributed to band to band transitions and bandtail transitions of lone pair （LP） states of intra-tri-s-triazine and inter-tri-s-triazine nitrogens. The proposed PL mechanism is further confirmed by diffusion reflectance spectroscopy, as well as time-resolved and temperature-dependent PL. This intense fluorescence is stable at different pH and resistant to UV exposure, suggesting that this inexpensive broadband luminescent material could be significant for white- light-emitting （WLE） applications. Thus, quasi-WLE films and membranes with designed patterns are fabricated by embedding the carbon nitrides into polymethyl methacrylate. Moreover, even broader PL （400 to 740 nm） is acquired in com- posite films composed of carbon nitrides, further suggesting that the carbon nitrides are robust candidates for WLE.
基金Project supported by the National Natural Science Foundation of China(11074232,11274288,21002097,11304300)the National Basic Research Program of China(2011CB932801,2012CB933702)Ministry of Education of China(20123402110034)
文摘The Eu^3＋/Ag co-doped rare earth disilicate Y2Si2O7 microcrystal was synthesized by sol-gel method. Through controlling the thermal treatment process of YzSi2OT：EU3＋/Ag precursor, various phases （amorphous, α, β, γ, δ） were prepared. White light emis- sion was observed under UV light excitation in the samples heavily doped with Ag. The white light was realized by combining the intense red emission of Eu3＋, the green emission attributed to the very small molecule-like, non-plasmonic Ag particles （ML-Ag-particles）, and the blue emission due to Ag ions. Results demonstrated that Eu3＋/Ag co-doped Y2Si207 microcrystal could be potentially applied as white light emission phosphors for UV LED chips.
基金supported by the Natural Science Foundation of Shandong Province of China(No.Y2002A09)the Research Foundation for Young Scientists in Innovation Engineering of Binzhou University,China(No.BZXYQNLG200703).
文摘ZnS films were deposited on porous Si （PS） substrates using a pulsed laser deposition （PLD） technique. White light emission is observed in photoluminescence （PL） spectra, and the white light is the combination of blue and green emission from ZnS and red emission from PS. The white PL spectra are broad, intense in a visible band ranging from 450 to 700 nrn. The effects of the excitation wavelength, growth temperature of ZnS films, PS porosity and annealing temperature on the PL spectra of ZnS/PS were also investigated.
基金the National Natural Science Foundation of Chinathe Doctoral Foundation of the State Education Committee of China.
文摘The intensities of the continuum emission and the Call K line of the white light flare with 3B importance on September 19, 1979 are measured and analyzed. Their variations with time are given. It is indicated that the continuum emission of this flare appeared in the early impulsive phase and lasted for about 5～6 min, with the time of maximum intensity 2～3 min earlier than that for the microwave radio burst. Based on the non-LTE theory, a semi-emplrical model at a time with the continuum emission being relatively intensive is presented. The resuhs show that the temperature in the flare photosphere is increased by 150～250 K, and that the continuum emission is produced mainly by the negative hydrogen ion. Finally, some discussions about the heating mechanism are also presented, implying that the heating energy may come from the lower atmosphere itself.
