The remarkable narrow-band emission of trivalent lanthanide-doped phosphors excited by the vacuum ultraviolet(VUV)radiation lines of Xe atoms/Xe_(2) molecules at 147/172 nm are extensively investigated in the developm...The remarkable narrow-band emission of trivalent lanthanide-doped phosphors excited by the vacuum ultraviolet(VUV)radiation lines of Xe atoms/Xe_(2) molecules at 147/172 nm are extensively investigated in the development of plasma display panels and Hg-free fluorescent lamps,which are frequently used in our daily lives.Numerous solid materials,particularly Tb^(3+)-doped oxides,such as silicates,phosphates and borates,are efficient green/blue sources with color-tunable properties.The excitation wavelength and rare earth concentration are usually varied to optimize efficiency and the luminescent properties.However,some underlying mechanisms for the shift in the emission colors remain unclear.The present study shows that a UV/VUV switch systematically controls the change in the phosphor(Ba_(3)Si_(6)O_(12)N_(2):Tb)photoluminescence from green to blue,resulting in a green emission when the system is excited with UV radiation.However,a blue color is observed when the radiation wavelength shifts to the VUV region.Thus,a configurational coordinate model is proposed for the color-reversal effect.In this model,the dominant radiative decay results in a green emission under low-energy UV excitation from the ^(5)D_(4) state of the f–f inner-shell transition in the Tb system.However,under high-energy VUV excitation,the state switches into the ^(5)D_(3) state,which exhibits a blue emission.This mechanism is expected to be generally applicable to Tb-doped phosphors and useful in adjusting the optical properties against well-known cross-relaxation processes by varying the ratio of the green/blue contributions.展开更多
The photoluminescence spectra and excitation spectra in the vacuum ultraviolet (VUV) and ultraviolet (UV) spectra region of GdVO 4∶Eu 3+ were reported. The excitation and emission spectra indicate that GdVO 4...The photoluminescence spectra and excitation spectra in the vacuum ultraviolet (VUV) and ultraviolet (UV) spectra region of GdVO 4∶Eu 3+ were reported. The excitation and emission spectra indicate that GdVO 4∶Eu 3+ is a highly efficient phosphor for the excitation in the VUV and UV spectrum region. The excitation band in the VUV and UV spectrum region of 60～350 nm consists mainly of the absorption of host, which has obvious absorption of 4f n-1 5d of Eu 3+ and Gd 3+ . In GdVO 4∶Eu 3+ , there is the energy transfer: VO 4 3- →Eu 3+ , Gd 3+ →Eu 3+ and Gd 3+ →VO 4 3- →Eu 3+ . Through the last two procedures, maybe the quantum cutting of Gd 3+ -Eu 3+ occurs.展开更多
基金the Science and Technology of Taiwan(Contract No.MOST 104-2113-M-002-012-MY3,MOST 104-2119-M-002-027-MY3,MOST 104-2923-M-002-007-MY3 and MOST 104-2917-I-564-060).
文摘The remarkable narrow-band emission of trivalent lanthanide-doped phosphors excited by the vacuum ultraviolet(VUV)radiation lines of Xe atoms/Xe_(2) molecules at 147/172 nm are extensively investigated in the development of plasma display panels and Hg-free fluorescent lamps,which are frequently used in our daily lives.Numerous solid materials,particularly Tb^(3+)-doped oxides,such as silicates,phosphates and borates,are efficient green/blue sources with color-tunable properties.The excitation wavelength and rare earth concentration are usually varied to optimize efficiency and the luminescent properties.However,some underlying mechanisms for the shift in the emission colors remain unclear.The present study shows that a UV/VUV switch systematically controls the change in the phosphor(Ba_(3)Si_(6)O_(12)N_(2):Tb)photoluminescence from green to blue,resulting in a green emission when the system is excited with UV radiation.However,a blue color is observed when the radiation wavelength shifts to the VUV region.Thus,a configurational coordinate model is proposed for the color-reversal effect.In this model,the dominant radiative decay results in a green emission under low-energy UV excitation from the ^(5)D_(4) state of the f–f inner-shell transition in the Tb system.However,under high-energy VUV excitation,the state switches into the ^(5)D_(3) state,which exhibits a blue emission.This mechanism is expected to be generally applicable to Tb-doped phosphors and useful in adjusting the optical properties against well-known cross-relaxation processes by varying the ratio of the green/blue contributions.
文摘The photoluminescence spectra and excitation spectra in the vacuum ultraviolet (VUV) and ultraviolet (UV) spectra region of GdVO 4∶Eu 3+ were reported. The excitation and emission spectra indicate that GdVO 4∶Eu 3+ is a highly efficient phosphor for the excitation in the VUV and UV spectrum region. The excitation band in the VUV and UV spectrum region of 60～350 nm consists mainly of the absorption of host, which has obvious absorption of 4f n-1 5d of Eu 3+ and Gd 3+ . In GdVO 4∶Eu 3+ , there is the energy transfer: VO 4 3- →Eu 3+ , Gd 3+ →Eu 3+ and Gd 3+ →VO 4 3- →Eu 3+ . Through the last two procedures, maybe the quantum cutting of Gd 3+ -Eu 3+ occurs.
