A simple co-precipitation approach taking place between Ln3＋, Sr2＋ cations and F anions, led to the formation of nanocrystalline Eu3＋ doped Sr2LnF7 （Ln-La and Gd） complex fluorides. The reaction was carried out i...A simple co-precipitation approach taking place between Ln3＋, Sr2＋ cations and F anions, led to the formation of nanocrystalline Eu3＋ doped Sr2LnF7 （Ln-La and Gd） complex fluorides. The reaction was carried out in the presence of polyeth- ylene glycol, PEG 6000 as a surfactant/surface modifier, providing small size and homogeneity of the products. The synthesized compounds were composed of small nanoparticles with an average size of 15 nm. All obtained Eu3＋ doped compounds exhibited an intensive red luminescence. In the case of gadolinium based compounds, the energy transfer phenomena could be observed from Gd3＋ ions to Eu3＋ ions. In order to study the structure and morphology of the synthesized fluorides, powder X-ray diffraction （XRD） and transmission electron microscopy （TEM） measurements were performed. Also FT-IR spectra of the products were re- corded, revealing the presence of PEG molecules on the nanoparticles suN＇ace. A spectrofluorometry technique was applied to examine optical properties of the synthesized nanoparticles. Excitation and emission spectra as well as luminescence decay curves were measured and analysed. The performed analysis revealed a red luminescence, typical for the Eu3＋ ion situated in the inorganic, highly symmetric matrix. Concentration quenching phenomena and lifetimes shortening, together with an increasing of the Eu3＋ doping level, were observed and discussed. Judd-Ofelt analysis was also performed for all doped samples, in order to support the registered spectroscopic data and examine in details structural and optoelectronic properties of the synthesized nanomaterials.展开更多
A facile co-precipitation and microemulsion methods were applied to obtain core/shell type nanoparticles. Cerium fluoride doped with terbittrn（Ⅲ） ions supplied intensive green luminescence of the system. Due to the...A facile co-precipitation and microemulsion methods were applied to obtain core/shell type nanoparticles. Cerium fluoride doped with terbittrn（Ⅲ） ions supplied intensive green luminescence of the system. Due to the presence of magnetite nanoparticles as cores, the prod- uct was highly sensitive to external magnetic field. Both sorts of nanostructures were encapsulated by silica shell. Such external layer of inert oxide can potentially increase the resistance of prepared nanostructttres to thermal oxidation, aggressive agents, changing ofpH or destructive radiation. Morphology of the product was examined using transmission electron microscopy （TEM）. Formations of the core/shell type nanostructures were clearly seen in the TEM pictures. Powder X-ray diffraction （XRD） confirmed the structure of the products, their nanocrystallinity and amorphous nature of silica shell. Optical properties were investigated by measuring excitation and emission spectra. Such multifunctional luminescent and magnetic nanoparticles coated with easily functionalized silica shell could be applied in many field of science.展开更多
基金Project supported by Polish Ministry of Science and Higher Education(Diamond Grant"Nr DI2011 011441)
文摘A simple co-precipitation approach taking place between Ln3＋, Sr2＋ cations and F anions, led to the formation of nanocrystalline Eu3＋ doped Sr2LnF7 （Ln-La and Gd） complex fluorides. The reaction was carried out in the presence of polyeth- ylene glycol, PEG 6000 as a surfactant/surface modifier, providing small size and homogeneity of the products. The synthesized compounds were composed of small nanoparticles with an average size of 15 nm. All obtained Eu3＋ doped compounds exhibited an intensive red luminescence. In the case of gadolinium based compounds, the energy transfer phenomena could be observed from Gd3＋ ions to Eu3＋ ions. In order to study the structure and morphology of the synthesized fluorides, powder X-ray diffraction （XRD） and transmission electron microscopy （TEM） measurements were performed. Also FT-IR spectra of the products were re- corded, revealing the presence of PEG molecules on the nanoparticles suN＇ace. A spectrofluorometry technique was applied to examine optical properties of the synthesized nanoparticles. Excitation and emission spectra as well as luminescence decay curves were measured and analysed. The performed analysis revealed a red luminescence, typical for the Eu3＋ ion situated in the inorganic, highly symmetric matrix. Concentration quenching phenomena and lifetimes shortening, together with an increasing of the Eu3＋ doping level, were observed and discussed. Judd-Ofelt analysis was also performed for all doped samples, in order to support the registered spectroscopic data and examine in details structural and optoelectronic properties of the synthesized nanomaterials.
基金Project supported by the Polish Ministry of Science and Higher Education (N N204 329736)
文摘A facile co-precipitation and microemulsion methods were applied to obtain core/shell type nanoparticles. Cerium fluoride doped with terbittrn（Ⅲ） ions supplied intensive green luminescence of the system. Due to the presence of magnetite nanoparticles as cores, the prod- uct was highly sensitive to external magnetic field. Both sorts of nanostructures were encapsulated by silica shell. Such external layer of inert oxide can potentially increase the resistance of prepared nanostructttres to thermal oxidation, aggressive agents, changing ofpH or destructive radiation. Morphology of the product was examined using transmission electron microscopy （TEM）. Formations of the core/shell type nanostructures were clearly seen in the TEM pictures. Powder X-ray diffraction （XRD） confirmed the structure of the products, their nanocrystallinity and amorphous nature of silica shell. Optical properties were investigated by measuring excitation and emission spectra. Such multifunctional luminescent and magnetic nanoparticles coated with easily functionalized silica shell could be applied in many field of science.
