As an Hg-free lamp using phosphor, the Bi^3＋ and EH^3＋ co-doped Y2O2S phosphors were prepared and their luminescence properties under vacuum ultraviolet（VUV） excitation were investigated. The VUV photoluminescent ...As an Hg-free lamp using phosphor, the Bi^3＋ and EH^3＋ co-doped Y2O2S phosphors were prepared and their luminescence properties under vacuum ultraviolet（VUV） excitation were investigated. The VUV photoluminescent intensity of Y2O2S：Eu^3＋ was weak, however, considerably stronger red emission at 626 nm with good color purity was observed in Y2O2S：Eu^3＋,Bi^3＋ systems. Investigation on the photoluminescence reveals that the strong VUV luminescence of Y2O2S：Eu^3＋,Bi^3＋ at 147 nm is mainly because the Bi^3＋ acts as a medium and effectively performs the energy transfer process： Y^3＋-O^2-→Bi^3＋→Eu^3＋, while the intense emission band at 172 nm is attributed to the absorption of the characteristic ^1So-^1P1 transition of Bi^3＋ and the direct energy transfer from Bi^3＋ to Eu^3＋. The Y2O2S：Eu^3＋,Bi^3＋ shows excellent VUV optical properties compared with the commercial （Y,Gd）BO3：Eu^3＋. Thus, the Y2O2S：Eu^3＋,Bi^3＋ can be a potential red VUV-excited candidate applied in Hg-free lamps for backlight of liquid crystal display.展开更多
Polycrystal of GdPO_(4):RE^(3+)(RE=Tb,Tm)phosphors were prepared by solid-state method.Vacuum ultraviolet excitation and emission spectrum and the energy transfer mechanism between the host and dopants of Tb^(3+)and T...Polycrystal of GdPO_(4):RE^(3+)(RE=Tb,Tm)phosphors were prepared by solid-state method.Vacuum ultraviolet excitation and emission spectrum and the energy transfer mechanism between the host and dopants of Tb^(3+)and Tm^(3+)were investigated respectively.The emission of Gd^(3+)at 313 nm was enhanced by the strong absorption of CTS of Tm^(3+)at 180 nm in GdPO_(4):Tm.It has also been concluded that the excitation of Gd^(3+)is transferred to Tb^(3+)and then emission peaks of^(5)D_(J)→^(7)F_(J)of Tb^(3+)were observed.展开更多
The phosphors that are able to convert vacuum ultraviolet（VUV） light into visible light are demanded for the development of novel displaying and lighting devices.NaYF4：Pr3＋,Dy3＋,NaGdF4：Pr3＋,NaGdF4：Dy3＋and NaG...The phosphors that are able to convert vacuum ultraviolet（VUV） light into visible light are demanded for the development of novel displaying and lighting devices.NaYF4：Pr3＋,Dy3＋,NaGdF4：Pr3＋,NaGdF4：Dy3＋and NaGdF4：Pr3＋,Dy3＋were prepared by hydrothermal synthesis method and their luminescent properties in VUV-vis spectral region were investigated at room temperature.For NaYF4：Pr3＋,Dy3＋,no energy transfer process from Pr3＋to Dy3＋was observed.However,the introduction of Gd3＋into the fluoride lattice led to intense Dy3＋emissions upon Pr3＋4f5d state excitation.Gd3＋acted as an intermediate,resulting in efficient energy transfer from Pr3＋to Dy3＋in NaGdF4.Pr3＋transferred most of its energy to Gd3＋,and then the energy was transferred from Gd3＋to Dy3＋.So NaGdF4：Pr3＋,Dy3＋not only took full advantage of the intense Pr3＋4f5d absorption,but converted the VUV excitation light into the near-white emission of Dy3＋.展开更多
SrGdGa3O7∶RE (RE=Ce3+, Pr3+, Tb3+) were prepared by traditional solid-state reaction and their luminescence properties in the range of VUV-Vis were investigated. The two broad bands situated at about 177 and 217 nm i...SrGdGa3O7∶RE (RE=Ce3+, Pr3+, Tb3+) were prepared by traditional solid-state reaction and their luminescence properties in the range of VUV-Vis were investigated. The two broad bands situated at about 177 and 217 nm in excitation spectra are attributed to the host lattices absorption, and they have no considerable change when doped different rare earth ions. The f-d transitions of Pr3+ and Tb3+ calculated by the formula gathered by Dorenbos were compared to the experimental results. The excitation spectra also show the sharp Gd3+ excitation line at about 274 nm pointing to an efficient energy transfer from Gd3+ to Pr3+ and Tb3+. All of the emission spectra present the characteristic emissions of rare earth ions when excited by VUV and UV.展开更多
Volatile organic compounds(VOCs) have attracted much attention for decades as they are the precursors of photochemical smog and are harmful to the environment and human health. Vacuum ultraviolet(VUV) photodegradation...Volatile organic compounds(VOCs) have attracted much attention for decades as they are the precursors of photochemical smog and are harmful to the environment and human health. Vacuum ultraviolet(VUV) photodegradation is a simple and effective method to decompose VOCs (ranging from tens to hundreds of ppmV) without additional oxidants or catalysts in the air at atmospheric pressure. In this paper, we review the research progress of VOCs removal via VUV photodegradation. The fundamentals are outlined and the key operation factors for VOCs degradation, such as humidity, oxygen content, VOCs initial concentration, light intensity, and flow rate, are discussed. VUV photodegradation of VOCs mixture is elucidated. The application of VUV photodegradation in combination with ozoneassisted catalytic oxidation(OZCO) and photocatalytic oxidation(PCO) systems, and as the pre-treatment technique for biological purification are illustrated. Based on the summary,we propose the challenges of VUV photodegradation and perspectives for its future development.展开更多
基金Supported by the Project of the Combination of Industry and Research by the Ministry of Education of China and Guang-dong Province, China(No.0712226100023)
文摘As an Hg-free lamp using phosphor, the Bi^3＋ and EH^3＋ co-doped Y2O2S phosphors were prepared and their luminescence properties under vacuum ultraviolet（VUV） excitation were investigated. The VUV photoluminescent intensity of Y2O2S：Eu^3＋ was weak, however, considerably stronger red emission at 626 nm with good color purity was observed in Y2O2S：Eu^3＋,Bi^3＋ systems. Investigation on the photoluminescence reveals that the strong VUV luminescence of Y2O2S：Eu^3＋,Bi^3＋ at 147 nm is mainly because the Bi^3＋ acts as a medium and effectively performs the energy transfer process： Y^3＋-O^2-→Bi^3＋→Eu^3＋, while the intense emission band at 172 nm is attributed to the absorption of the characteristic ^1So-^1P1 transition of Bi^3＋ and the direct energy transfer from Bi^3＋ to Eu^3＋. The Y2O2S：Eu^3＋,Bi^3＋ shows excellent VUV optical properties compared with the commercial （Y,Gd）BO3：Eu^3＋. Thus, the Y2O2S：Eu^3＋,Bi^3＋ can be a potential red VUV-excited candidate applied in Hg-free lamps for backlight of liquid crystal display.
基金supported by the Natural Science Foundation of Tianjin City(Grant No.033601111).
文摘Polycrystal of GdPO_(4):RE^(3+)(RE=Tb,Tm)phosphors were prepared by solid-state method.Vacuum ultraviolet excitation and emission spectrum and the energy transfer mechanism between the host and dopants of Tb^(3+)and Tm^(3+)were investigated respectively.The emission of Gd^(3+)at 313 nm was enhanced by the strong absorption of CTS of Tm^(3+)at 180 nm in GdPO_(4):Tm.It has also been concluded that the excitation of Gd^(3+)is transferred to Tb^(3+)and then emission peaks of^(5)D_(J)→^(7)F_(J)of Tb^(3+)were observed.
基金supported by National Natural Science Foundation of China(11274038,10979009,61078069)Fundamental Research Funds for the Central Universities(2011JBM296)
文摘The phosphors that are able to convert vacuum ultraviolet（VUV） light into visible light are demanded for the development of novel displaying and lighting devices.NaYF4：Pr3＋,Dy3＋,NaGdF4：Pr3＋,NaGdF4：Dy3＋and NaGdF4：Pr3＋,Dy3＋were prepared by hydrothermal synthesis method and their luminescent properties in VUV-vis spectral region were investigated at room temperature.For NaYF4：Pr3＋,Dy3＋,no energy transfer process from Pr3＋to Dy3＋was observed.However,the introduction of Gd3＋into the fluoride lattice led to intense Dy3＋emissions upon Pr3＋4f5d state excitation.Gd3＋acted as an intermediate,resulting in efficient energy transfer from Pr3＋to Dy3＋in NaGdF4.Pr3＋transferred most of its energy to Gd3＋,and then the energy was transferred from Gd3＋to Dy3＋.So NaGdF4：Pr3＋,Dy3＋not only took full advantage of the intense Pr3＋4f5d absorption,but converted the VUV excitation light into the near-white emission of Dy3＋.
文摘SrGdGa3O7∶RE (RE=Ce3+, Pr3+, Tb3+) were prepared by traditional solid-state reaction and their luminescence properties in the range of VUV-Vis were investigated. The two broad bands situated at about 177 and 217 nm in excitation spectra are attributed to the host lattices absorption, and they have no considerable change when doped different rare earth ions. The f-d transitions of Pr3+ and Tb3+ calculated by the formula gathered by Dorenbos were compared to the experimental results. The excitation spectra also show the sharp Gd3+ excitation line at about 274 nm pointing to an efficient energy transfer from Gd3+ to Pr3+ and Tb3+. All of the emission spectra present the characteristic emissions of rare earth ions when excited by VUV and UV.
文摘Volatile organic compounds(VOCs) have attracted much attention for decades as they are the precursors of photochemical smog and are harmful to the environment and human health. Vacuum ultraviolet(VUV) photodegradation is a simple and effective method to decompose VOCs (ranging from tens to hundreds of ppmV) without additional oxidants or catalysts in the air at atmospheric pressure. In this paper, we review the research progress of VOCs removal via VUV photodegradation. The fundamentals are outlined and the key operation factors for VOCs degradation, such as humidity, oxygen content, VOCs initial concentration, light intensity, and flow rate, are discussed. VUV photodegradation of VOCs mixture is elucidated. The application of VUV photodegradation in combination with ozoneassisted catalytic oxidation(OZCO) and photocatalytic oxidation(PCO) systems, and as the pre-treatment technique for biological purification are illustrated. Based on the summary,we propose the challenges of VUV photodegradation and perspectives for its future development.
