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Hydrothermal synthesis of mixed rare earth-alkali metal or ammonium fluorides

Journal of rare earths 2010年第5期28卷 676-679页

作者：由芳田黄世华时秋峰 Key Laboratory of Luminescence and Optical Information Ministry of Education Institute of Optoelectronic Technology Beijing Jiaotong University

The recent results on hydrothermal synthesis of mixed rare earth-alkali or ammonium fluorides were presented. The initial ratios of the starting materials, pH value and reaction temperature were the critical factors for obtaining the single-phase product. Four main types of complex rare earth fluorides, AREF4, A2REF5, ARE2F7 and ARE3F10 (A=Na+, K+, Rb+, NH4+), appeared in the primary hydrothermal reactions. The correlation between cation sizes and the formation of mixed rare earth fluorides under mild hydro...

关键词： hydrothermal synthesis rare earth fluorides alkali metals ammonium cation size

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Ultrasonic synthesis, characterization and formation mechanism of aggregated nanorings of EuF_3

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Journal of rare earths 2008年第5期26卷 684-687页

作者：武大鹏王新军白正宇蒋凯 Chemistry and Environmental College Henan Normal University

The aggregated nanorings of EuF3 were synthesized via ultrasonic irritation in aqueous solution. The products were characterized by X-ray powder diffraction （XRD）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. XRD pattern proved that the crystalline phase of the EuF3 rings was hexagonal. The SEM and TEM images indicated that the as-prepared EuF3 nanocrystals had ring-like morphology and were aggregated by numerous small crystallites （about 10-15 nm in diameter）; the outer diameter of the rings was in the range of 200--300 nm, while the inner diameter was in the range of 50-80 nm with a thickness of 30-40 nm. Moreover, the time-depend experiments were carried out to disclose the formation mechanism of the as-prepared ring-like nanostructures.

关键词： nanostructttres rare earth fluorides nanorings ultrasonic irritation rare earths

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Fabrication of Ordered Magnetite-Doped rare earth Fluoride Nanotube Arrays by Nanocrystal Self-Assembly

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Nano Research 2009年第4期2卷 292-305页

作者： Fan Zhang Dongyuan Zhao Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Department of Chemistryand Laboratory of Advanced MaterialsFudan UniversityShanghai 200433China

We describe a nanocrystal self-assembly method for the preparation of rare earth fluoride nanotube(ReF-NT)arrays and magnetite-doped rare earth fluoride nanotubes(Fe_(3)O_(4)ReF-NTs)by using porous anodic aluminum oxide(AAO)as a hard *** ReF-NTs can be simply prepared by the impregnation of-NaYF_(4)nanocrystals doped with Yb and Er into the channels of the porous AAO and show a highly ordered nanotube array and excellent upconversion(UC)fluorescence ***,the Fe_(3)O_(4)ReF-NTs are obtained by the self-assembly of a mixture of Fe_(3)O_(4)and Yb/Er doped-NaYF4 nanocrystals in the AAO pore channels and have a uniform dispersion of magnetite nanocrystals on the rare earth fluoride tube matrix and possess multifunctional magnetic/UC *** diameter of these nanotubes can be varied from 60 nm to several micrometers depending on the pore size of the AAO *** wall thickness can be increased from 10 to 35 nm by increasing the concentration of nanocrystals from 0.02 to 0.4 mmol/L,while the morphology of the nanotubes can be varied from small isolated domain structures to percolating domains and eventually to compact domains.A template-directed formation mechanism is proposed and the quantitative predictions of the model for such self-assembled nanocrystal spreading processes are *** UC fluorescent emissions are realized for the nanotube arrays and multifunctional nanotubes with UC excitation in the near-infrared(NIR)region.A strong magnetic response of the multifunctional nanotubes is observed,which facilitates their easy separation from solution by magnetic decantation using a permanent magnet.

关键词： Nanotubes synthesis nanocrystals self-assembly upconversion luminescence magnetic rare earth fluorides

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