Papers by Keyword: Luminescent Properties

Abstract: Four types of titanium dioxide (TiO₂) materials doped with a single kind of rare earth ions Ln³⁺ (Eu³⁺, Tb³⁺, or Sm³⁺) and three rare earth ions (Eu³⁺, Tb³⁺, and Sm³⁺) were synthesized by the sol-gel method. The compositions, structures, and photophysical properties of these compounds were tested. The structure of the rare earth ion-doped TiO₂ samples was characterized by X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). Optical absorption and fluorescence information was obtained using UV-Vis spectroscopy and fluorescence spectroscopy. The surface morphology of rare earth ion-doped TiO₂ materials was observed using scanning electron microscopy (SEM). To further explore the photoluminescent properties of rare earth-doped TiO₂ materials for practical applications, small-scale LED light-emitting devices were fabricated.

Abstract: Tb (oct-phe)₃·H₂O and Eu (oct-phe)₃·H₂O were prepared by chemical reaction in solution. The molecular formula of the complex was determined by elemental analysis and FT-IR. The optical properties of rare earth complexes were further tested by ultraviolet-visible-infrared absorption measurements. The results show that the optical absorption performance is better in the wavelength range of 200-300 nm. The luminescent properties of the rare earth complexes in the wavelength range of 450-750 nm were tested. It was found that the rare earth (Eu, Tb) complexes of octylphenylalanine have good luminescent properties.

Abstract: 0.1% Ce³⁺:BaF₂ powders were prepared by coprecipitation method. Then the transparent ceramics were prepared by vacuum sintering. The effectts of sintering temperature and holding time on transparent ceramics were studied. The results show that the 0.1% Ce³⁺:BaF₂ powders prepared by coprecipitation are approximately spherical with the size ranging from 200~300nm and good dispersion. The maximum light transmittance of the 0.1% Ce³⁺:BaF₂ transparent ceramics reaches 69.2% when the sintering temperature is 1275°C. The fluorescence intensity of the transparent ceramics enhances with the increase of the sintering temperature. There are two characteristic f-f transition emission peaks at 610nm and 650nm when the excitation peak is at 290nm. The maximum transparency of 71.4% emerges when the holding time is 6h at 1275°C and the fluorescence intensity reaches the maximum. The 528nm (⁵D₁→²F_7/2) appears when excitated by the 524nm excitation light.

Abstract: The possibility of applying the spray drying method for the production of complex oxides powders with garnet structure is shown in paper. The processes occurring while heating of synthesized oxide-salt product, that lead to the formation of a material with a garnet structure were investigated by DTA, TGA, X-ray analysis. The possibility of producing single-phase structure of the garnet system (Y_xGd_(3-x))₃Al₅O₁₂ in wide range of compositions is demonstrated.

Abstract: Layered oxide coatings containing europium ferrite multiferroic have been synthesized on titanium plates through plasma electrolytic oxidation and extraction pyrolysis. The composites have weak ferromagnetic properties: the coercive force attains 45–78 Oe in the temperature range 3–340 K. Their luminescence properties are typical of inorganic materials with europium ions.

Abstract: Ce³⁺ doped cubic KLaF₄ system was synthesized by co-precipitation method. The sample was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis spectrophotometer and fluorescence spectrophotometer. The result indicated the nanoparticle diameter of KLaF₄:Ce³⁺ was 12.5 nm. The KLaF₄:Ce³⁺ had a stronger absorption at 250 nm, which could be explained by d elecronic transition of Ce³⁺ . The maximum emission peak of KLaF₄:Ce³⁺ was 355 nm in its luminescent spectrum, and emission band of Ce³⁺ also belonged to 5d→4f transition.

Abstract: The optical functionalized YVO₄: Eu³⁺/MCM-41 mesoporous composites were prepared by hydrothermal method. The structure, morphology, luminescence properties and fluorescence dynamics were studied systemically. The compared studies of the luminescence properties of YVO₄: Eu³⁺/MCM-41 with YVO₄: Eu³⁺ nanocrystal were performed. The results show that the YVO₄: Eu³⁺/MCM-41 retains high ordered mesoporous structure of MCM-41. In YVO₄: Eu³⁺/MCM-41, the intrinsic excitation bands of Eu³⁺ disappears and the lifetimes of Eu³⁺ become short. The luminescent efficiency of YVO₄: Eu³⁺/MCM-41 is higher than ones of the YVO₄: Eu³⁺ nanocrystal.

Abstract: The BaF₂: Ce³⁺, Yb³⁺ nanoparticles doped with different concentration were prepared by a hydrothermal method. The structure,morphology and photoluminescence properties were studied. In BaF₂: Ce³⁺, Yb³⁺ nanoparticles, a strong near infrared emissionat 900 – 1050 nm matching to energy of Si band gap of Si-based solar cells was observed under the excitation of 5d level of Ce³⁺. As a downconversion luminescent convertor, the kinds of materials have potential to be applied in front of Si-based solar cells to reduce thermalization loss and enhance conversion efficiency of solar cells.

Abstract: Using anion ligand phenoxyacetic acid (HPOA) and neutral ligand 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), a series of novel europium complexes EuxYy(TPTZ)2(POA)6·6H2O. The luminescence spectra, luminescence lifetimes and emission quantum efficiencies of the complexes were studied. The results show that doping appropriate amount of Y3+ can significantly increase the luminescence intensities, prolong the luminescent lifetime and improve the emission quantum efficiencies.

Abstract: Dy³⁺ doped blue-green Eu²⁺ doped strontium aluminate (Sr₄Al₁₄O₂₅:Eu²⁺) phosphor was prepared using a high temperature solid state method and the influence of the doped Dy³⁺ on the luminescent properties was studied using X-ray diffraction, scanning electron microscopy, fluorescence spectroscopy and a series of other characterization methods. It is found that Dy³⁺ doping can enhance the luminescent intensity and extend the afterglow time. The luminescent mechanism of rare earth ions doped strontium aluminate phosphor was also discussed deeply, the effects of the doping amount on the luminescent properties has been made detailed explanation and description. This work has important theoretical significance for the development of higher brightness and longer afterglow blue-green phosphors.