29 resultados para PR3
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
The tertiary lanthanide complexes [Ln(hfth)(3)phen] (Ln=Er, Nd, Yb, Sm) and [Pr(tfnb)(3)phen] have been Successfully covalently attached in the ordered SBA-15 mesoporous materials via a functionalized 1,10-phenanthroline group 5-(N,N-bis-3-(triethoxysilyl)propyl)ureyl-1,10-phenanthroline (Phen-Si). The derivative materials [denoted as Ln(hfth)(3)phen-S15 and Pr(tfnb)(3)phen-S15; Ln=Er, Yb, Nd, Sm; hfth=4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)hexane-1,3-dionate; tfnb=4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedionate] were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and N-2 adsorption/desorption.
Resumo:
SrIn2O4:Dy3+/Pr3+/Tb3+ white/red/green phosphors were prepared by the Pechini sol-gel process. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), diffuse reflectance, photoluminescence, cathodoluminescence spectra, and lifetimes were utilized to characterize the samples. XRD reveal that the samples begin to crystallize at 800 degrees C and pure SrIn2O4 phase can be obtained at 900 degrees C. FE-SEM images indicate that the SrIn2O4:Dy3+, SrIn2O4:Pr3+, and SrIn2O4:Tb3+ samples consist of fine and spherical grains with size around 200-400 nm. Under the excitation of ultraviolet light and low-voltage electron beams (1 - 5 kV), the SrIn2O4:Dy3+, SrIn2O4: Pr3+, and SrIn2O4: Tb3+ phosphors show the characteristic emissions of Dy3+ (F-4(9/2) - H-6(15/2) at 492 nm and 4F(9/2) - 6H(13/2) at 581 nm, near white), Pr3+ (P-3(0) - H-3(4) at 493 nm, D-1(2) - H-3(4) at 606 nm, and P-3(0) - H-3(6) at 617 nm, red) and Tb3+ (D-5(4) - F-7(6,5,4,3) transitions dominated by D-5(4) - F-7(5) at 544 nm, green), respectively. All of the luminescence resulted from an efficient energy transfer from the SrIn2O4 host lattice to the doped Dy3+, Pr3+, and Tb3+ ions, and the luminescence mechanisms have been proposed.
Resumo:
Caln(2)O(4):Dy3+/Pr3+/Tb3+ blue-white/green/green phosphors were prepared by the Pechini sol-gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), diffuse reflectance, photoluminescence (PL) and cathodoluminescencc (CL) spectra as well as lifetimes were utilized to characterize the samples. The XRD results reveal that the samples begin to crystallize at 800 degrees C 3-1 and pure CaIn2O4 phase can be obtained after annealing at 900 degrees C. The FE-SEM images indicate that the CaIn2O4:Dy3+, CaIn2O4:Pr3+ and CaIn2O4:Tb3+ samples consist of spherical grains with size around 200-400nm. Under the excitation of ultraviolet light and low electron beams (1-5kV), the CaIn2O4:Dy3+, CaIn2O4:Pr3+ and CaIn2O4:Tb3+ phosphors show the characteristic emissions of Dy3+ ((F9/2-H15/2)-F-4-H-6 and (F9/2-H13/2)-F-4-H-6 transitions, blue-white), Pr3+ ((P0-H4)-P-3-H-3, (D2-H4)-D-1-H-3 and (P1-H5)-P-3-H-3 transitions, green) and Tb3+ ((D4-F6,5,4,3)-D-5-F-7 transitions, green), respectively. All the luminescence is resulted from an efficient energy transfer from the CaIn2O4 host lattice to the doped Dy3+ ,Pr3+ and Tb3+ ions, and the corresponding luminescence mechanisms have been proposed.
Resumo:
Nanocrystalline CaTiO3:Pr3+ phosphor layers were coated on nonaggregated, monodisperse, and spherical SiO2 particles by the sol-gel method, resulting in the formation of core-shell structured SiO2-CaTiO3:Pr3+ particles. X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence, cathodoluminescence spectra, as well as lifetimes were utilized to characterize the core-shell structured SiO2-CaTiO3:Pr3+ phosphor particles. The obtained core-shell structured phosphors consist of well dispersed submicron spherical particles with a narrow size distribution. The thickness of the CaTiO3:Pr3+ shell could be easily controlled by changing the number of deposition cycles (about 70 nm for four deposition cycles). The core-shell SiO2-CaTiO3:Pr3+ particles show a strong red emission corresponding to D-1(2)-H-3(4) (612 nm) of Pr3+ under the excitation of ultraviolet (326 nm) and low voltage electron beams (1-5 kV). These particles may be used in field emission displays.
Resumo:
Bulk and nanoscale powders of YAG:Re (Re = Ce, Pr, Tb) were synthesized by solid-state and sol-gel method. The changes of spectra and energy level were studied. Compared with the bulk YAG:Re (Re = Ce, Pr, Tb) crystals, the lattice parameter of YAG:Re (Re = Ce, Pr, Tb) nanocrystals decreases. It is also found that the excitation peaks of 5d energy levels shift in nanocrystals. The physical reason for spectral and energy level changes is a comprehensive result from the shift of energy centroid of the 5d orbit, the Coulomb interaction between 4f and 5d electrons and the crystal field splitting of the 5d energy level.
Resumo:
The density matrix resonant two-photon absorption (TPA) theory is applied to a rare-earth ion-doped laser crystal. TPA cross sections for transitions from the ground state to the first 4f5d state in Pr3+:YAG are calculated. The results indicate the density matrix TPA theory is attractive in studying TPA in laser crystals. (C) 2000 Elsevier Science B.V. All rights reserved.
Resumo:
The density matrix resonant two-photon absorption (TPA) theory applicable to laser crystals doped with rare earth ions is described. Using this theory, resonant TPA cross sections for transitions from the ground state to the second excited state of the 4f5d configuration in cm(4)s Pr3+:Y3Al5O12 are calculated. The peak value of TPA cross section calculated is 2.75 x 10(-50) cm(4)s which is very close to the previous experimental value 4 x 10(-50) cm(4) s. The good agreement of calculated data with measured values demonstrates that the density matrix resonant TPA theory can predict resonant TPA intensity much better than the standard second-order perturbation TPA theory.
Resumo:
Near-infrared to ultraviolet upconversion luminescence was observed in the Pr3+ :Y2SiO5 crystal with 120 fs, 800 mn infrared laser irradiation. The observed emissions at around 270 nm and 305 nm could be assigned to 5d -> 4f transitions of Pr3+ ions. The relationship between the upconversion luminescence intensity and the pump power of the femtosecond laser reveals that the UV emission belongs to simultaneous three-photon absorption induced upconversion luminescence. (c) 2007 Elsevier B.V. All rights reserved.
Resumo:
We report on cooperative downconversion in Yb3+-RE3+ (RE = Tm or Pr) codoped lanthanum borogermanate glasses (LBG), which are capable of splitting a visible photon absorbed by Tm3+ or Pr3+ ions into two near-infrared photons. The results indicate that Pr3+-Yb3+ is a more efficient ion couple than Tm3+-Yb3+ in terms of cooperative downconversion. We have obtained a highest quantum yield of 165% and 138% for Pr3+-Yb3+ and Tm3+-Yb3+ codoped LBG glasses under 468 nm excitation, respectively. However, ultraviolet light excitation to the charge transfer band of Yb3+ does not result in quantum splitting as rapid relaxation from the charge transfer band to 4f(13) levels of Yb3+ dominates. (C) 2008 Optical Society of America
Resumo:
Field Emission Displays, FEDFEDFED (FED)(FED)-(FED) [(LaGaO3: Re3+ (Re = Eu, Tb, Dy, Tm, Sm)][(CaIn2O4: Re3+ (Re = Eu, Pr, Tb, Dy,)][(SrIn2O4: Re3+ (Re = Pr, Tb, Dy)][Lu3Ga5O12:Re3+ (Re = Eu, TbPr)]Pr, Sm, Eu, Tb, Dy, TmSr2CeO4SiO2CaTiO3:Pr3+, Y3Al5O12:Ce3+/Tb3+/Ga2O3:Dy3+XRDFTIRSEMTEM(PL)(CL) (LaGaO3)(Eu3+, Tb3+, Dy3+, Tm3+, Sm3+)(Eu3+, Tb3+, Dy3+, Tm3+, Sm3+)LaGaO3: Eu3+LaGaO3: Dy3+LaGaO3: Tm3+LaGaO3: Sm3+LaGaO3: Sm3+,Tb3+LaGaO3: Tb3+Tb3+LaGaO3: Tb3+LaGaO3: Tm3+FED(Y2SiO5: Ce3+NP-1047)LaGaO3: Sm3+((Zn,Cd)S: AgNP-1020)(LaGaO3: Sm3+,Tb3+), [(LaGaO3: Re3+ (Re = Eu, Tb, Dy, Tm, Sm )] Sr/CaIn2O4Sr/CaIn2O4Pr3+/Tb3+/Dy3+Sr/CaIn2O4Pr3+/ Tb3+/Dy3+Pr3+/Tb3+/Dy3+Sr/CaIn2O4: Pr3+/Tb3+/Dy3+(CL)(PL)CL CaIn2O4:Eu3+CaIn2O4:Eu3+Eu3+ Lu3Ga5O12:Re3+ (Re = Eu, TbPr)UVLu3Ga5O12: Eu3+, Lu3Ga5O12: Pr3+Eu3+, Pr3+Lu3Ga5O12:Tb3+Tb3+ Sr2CeO4UV(Ce4+-O2-) SiO2@CaTiO3:Pr3+SiO2@Y3Al5O12: Ce3+/Tb3+, FESEMTEMSiO2UVSiO2@CaTiO3:Pr3+Pr3+ 1D23H4 (612 nm)SiO2@Y3Al5O12:Ce3+SiO2@Y3Al5O12:Tb3+ Ce3+5d-4fTb3+5D4-7FJ (J = 6, 5, 4, 3)PLCL Ga2O3:Dy3+-Ga2O3:Dy3+--Ga2O3Dy3+--Ga2O3:Dy3+
Resumo:
MAIF5MCaSrBaLIMAIFaMCaSrCaAIFSrAIFBaAICaAIF6LrAISrAlF5LiSrAlF6llCoAIF6BaAlF5LiCaAlF6KMgF3:EuKMgFa:EU6P7/28S7/2420nml6P7/2-8S7/2Eu3+GdEuKMgFaBaLiF3BaY2F8Gd2+Eu2+Gd3+Eu2+Gd3+Eu2+Pr+ KMgF2LiYF4BaY2F8KMgFa:Pr3+352nmPr3+KMg1-xCaxF3Pr3+Ca2MgSi2O2EuEu3+Eu2+Ca2Eu8Si6O26X-ray
Resumo:
-Ce0.87Sm0.13-xPrxO2-(x=0.00,0.01,0.02),X,,PrCe0.87Sm0.13O2-.,Pr3+,,,.
Resumo:
Lu3Ga5O12:Eu3+, Lu3Ga5O12:Tb3+, and Lu3Ga5O12:Pr3+ phosphors were prepared through a Pechini-type sol-gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence, and cathodoluminescence spectra were utilized to characterize the synthesized phosphors. The XRD results reveal that the sample begins to crystallize at 800 degrees C and fully crystallined pure Lu3Ga5O12 phase can be obtained at 1000 degrees C. The FESEM image indicates that the phosphor sample is composed of aggregated rice grainlike particles with sizes around 80-120 nm.
