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ABSTRACT: Yb3+/Er3+ and Yb3+/Tm3+ co-doped LaF3 nanoparticles with upconversion luminescence properties were prepared via the co-precipitation method, followed by heat treatment at different temperatures in the range of 180°C to 600°C. We investigated the influence of heat treatment temperatures on the size, morphology, and upconversion luminescence intensity of the nanoparticles. Significant increases of the particle size and upconversion luminescence intensity of the nanoparticles were observed with increasing heat treatment temperature. The upconversion mechanism of the LaF3:Yb3+,Er3+ and LaF3:Yb3+,Tm3+ nanoparticles was also discussed.
Journal of Experimental Nanoscience 12/2007; 2(4):303-311. · 1.01 Impact Factor
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ABSTRACT: The lanthanide-doped GdF<sub>3</sub> nanoparticles have been produced by a simply hydrothermal synthesis procedure. The excitation and emission spectra of the Eu<sup>3+</sup>-doped GdF<sub>3</sub> nanoparticles showed that the excitation energy of Gd<sup>3+</sup> is efficiently transferred to Eu<sup>3+</sup> in the Eu<sup>3+</sup>-doped GdF<sub>3</sub> nanoparticles. Due to very low phonon energies of GdF <sub>3</sub> matrix, the <sup>5</sup>D<sub>1</sub> emission of Eu<sup>3+ </sup> ions in the Eu<sup>3+</sup>-doped GdF<sub>3</sub> nanoparticles can be observed at room temperature when the doping concentration of Eu <sup>3+</sup> ions is lower than 15 mol%. The luminescence intensity of the Eu<sup>3+</sup>-doped GdF<sub>3</sub> nanoparticles increased with increasing concentration of Eu<sup>3+</sup> ions and reached a maximum at approximately 15 mol%. The Er<sup>3+</sup>-doped GdF<sub>3</sub> nanoparticles exhibit the typical emission spectra of Er<sup>3+</sup> in the near-infrared region. The upconversion emission of the Er<sup>3+ </sup>/Yb<sup>3+</sup> codoped GdF<sub>3</sub> nanoparticles can also be observed. However, the upconversion emission intensity of the Er<sup>3+ </sup>/Yb<sup>3+</sup>-codoped GdF<sub>3</sub> nanoparticles was much weaker than that of the Er<sup>3+</sup>/Yb<sup>3+</sup>-codoped GdF<sub>3</sub> bulk crystal
IEEE Transactions on Nanotechnology 04/2006; · 2.29 Impact Factor
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ABSTRACT: Europium-doped LaF3 nanoparticles have been prepared by the ionic reaction in the ethanol at 60 degrees C. From the XRD pattern of nanoparticles and the emission spectra of Eu3+ ions, it has been concluded that the Eu3+ ions could easily substitute the La3+ sites and the solid solution La(1-x)Eu(x)F3 can be synthesized. Due to very low phonon energies of LaF3 matrix, the 5D1 emission of Eu3+ ions in La(1-x)Eu(x)F3 nanoparticles can be observed at room temperature when doping concentration of Eu3+ ions is lower than 30 mol%. The quenching process of 5D1 emission can be attributed to cross-relaxation. Since clusters of Eu3+ ions and resonance energy transfer only occurs within one particle due to the hindrance by the particle boundary, the concentration quenching resulted from resonance energy transfer between neighboring Eu3+ ions occurs at higher Eu3+ concentrations in the Eu3+ doped LaF3 nanoparticles.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 10/2005; 61(11-12):2455-9. · 2.10 Impact Factor
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ABSTRACT: Luminescent Ca1−xF2+x:Eux nanoparticles were synthesized by a chemical co-precipitation method in an ethanol solution. The Ca1−xF2+x:Eux nanoparticles exhibit a sphere-like morphology with particle diameter of about 15–20 nm. With increasing concentration of Eu3+ ion the intensity of XRD diffraction peaks decreased significantly and full width at half-maximum of the peaks increased gradually, which indicated that more Eu3+ ions resulted in the increase of structural defects. The emission spectrum of Ca1−xF2+x:Eux nanoparticles consisted of a few narrow, sharp lines corresponding to Eu3+ ions. The luminescence intensity of Ca1−xF2+x:Eux nanoparticles increased with increasing concentration of Eu3+ ion and reached a maximum at approximately 15 mol%.
Solid State Communications.
