Papers by Keyword: Vacuum Ultraviolet

Abstract: K₂Gd_0.97Zr (PO₄)₃:3mol% Eu³⁺ were prepared by the solid-state diffusion method and under a vacuum ultra-violet (VUV) region, photoluminescence properties of the phosphor were examined. The phenomenon of visible quantum harvesting via DC was observed in synthesized phosphor for the Gd³⁺–Eu³⁺ pair. In the process of quantum harvesting, the two visible light photons are emitted per absorbed VUV photon. This phenomenon occurred upon the 190 nm excitation of Gd³⁺ at the ⁶G_J level through a two-step energy transfer from Gd³⁺ to Eu³⁺ by cross-relaxation and sequential transfer of the remaining excitation energy. The consequences are that the quantum efficiency of the K₂Gd_0.97Zr (PO₄)₃:3mol% Eu³⁺ phosphor in the energy transfer process from Gd³⁺ to Eu³⁺ could reach 233%. The quantum efficiency goes to more than 200% (i.e., 233%) at just low concentration Eu³⁺ ions (i.e. 3% only). This novelty was found in the prepared phosphor. Therefore, the phosphor K₂Gd_0.97Zr (PO₄)₃:3mol% Eu³⁺ was a potential quantum harvester and potential candidate for mercury free fluorescent lamp and plasma display panel.

Abstract: Phosphors Zn₂Si_1+xO_4+2x: Mn²⁺(0x0.5) were synthesized through sol-gel process and their photoluminescence in UV and VUV region were investigated. At 254 nm excitation, the phosphor gives intense green emission (527 nm) and the luminescence intensity was enhanced with the increasing of x. At 147 nm excitation, the optimum luminescence intensity occurred at x = 0.1 and the absorption of host became blue shift slightly, which could be related with the absorption of excess SiO₂. The sample Zn₂Si_1.1O_4.2 had the highest emission intensity and it is 40% higher than that of Zn₂SiO₄:Mn²⁺.

Abstract: A series of phosphor of MBPO7:Tm3+, and MBPO7:Tm3+, Gd3+ (M= Mg, Sr, Ca) were prepared and studied. The XRD data showed Tm3+, Gd3+ didn’t affects the lattice parameters. Excitation spectra exhibited high absorption in vacuum ultraviolet (VUV) region. There existed strong emission peaking at 453nm and 363nm correspond to the 1D2 →3HJ (J=4, 6) emission transition of Tm 3+ when excited under VUV. With the changes of cation in the samples, the excitation spectra changed greatly, and lead a great change in its emission spectra. The crystal lattice parameters affect the ratio of intensity of the peak at 454nm and 312nm.

Abstract: The phosphors of MO-Re2O3-B2O3:Eu3+ (M = Mg, Sr; Re = Y, Gd) were prepared by conventional solid-state reaction. Red-emitting MO-Re2O3-B2O3:Eu3+ (M=Mg, Sr; Re=Y, Gd) phosphors had the highest luminescence intensity under vacuum ultraviolet (VUV) excitation. They had sharp emission peak lines at 591 and 613nm, which were assigned to the transitions of 5D0→7F1 and 5D0→7F2. By the introduction of Sr into MgO-Re2O3-B2O3:Eu3+ (M=Mg, Sr; Re=Y, Gd), the intensity of absorption peaked at 172nm and the emission peak intensity were enhanced.