Lina Liu,Ruirui Sun,Yongsheng Zhang,Ruifei Qin,Dongmei Zhang,Chunjuan Tang,Linfeng Chen,Lishuang Liu
LaF 3 :Ce,Tb@SiO 2 core-shell nanostructures were synthesized using a new one-pot reverse microemulsion strategy. One-pot method facilitates the synthetic process of this kind of core-shell nanostructures. The crystalline phase, size, morphology, pore structure and luminescence properties were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen physisorption isotherm, photoluminescence (PL) excitation and emission spectra. The results revealed that the core-shell nanostructures have an average diameter of about 27 nm and cores of about 3 nm, and that these nanostructures contain micropores with an average pore diameter of 0.43 nm. The characteristic emissions of Tb 3+ were observed under the excitation of Ce 3+ 4f–5d transition due to the energy transfer from Ce 3+ to Tb 3+ . LaF 3 :Ce,Tb@SiO 2 nanostructures can disperse well in water and the colloid can emit bright green light under ultraviolet (UV) irradiation.
A novel core–shell–shell SiO2@CePO4:Tb@SiO2 submicro-sphere was controllably synthesized by a bridging ligand organosilane HOOCC6H4N(CONH(CH2)3Si(OCH2CH3)3)2 (MABA-Si) connecting the silica core and rare earth ions. The as-synthesized samples were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy (IR). It is found that SiO2@CePO4:Tb@SiO2 has a ∼25 nm outermost shell, a ∼4 nm intermediate shell, and a ∼200 nm core. SiO2@CePO4:Tb@SiO2 exhibits stable photoluminescence properties in aqueous solution: its photoluminescence intensity was unquenched even after 15 days. The core–shell–shell submicro-spheres were found to have better photoluminescence than the core–shell submicro-spheres because the SiO2 shell protected the phosphor materials and then improved its photoluminescence intensity and biocompatibility. A formation mechanism of the core–shell–shell SiO2@CePO4:Tb@SiO2 submicro-spheres was proposed. Thus, the low-cost preparation of the core–shell–shell SiO2@CePO4:Tb@SiO2 submicro-spheres could be rationally achieved using SiO2.
SiO2@GdPO4:Tb@SiO2 nanoparticles with core-shell-shell structure were successfully synthesized by a cheap silane coupling agent grafting method at room temperature. This method not only homogeneously coated rare-earth phosphate nanoparticles on the surface of silica spheres but also saved the use of rare-earth resources. The obtained nanoparticles consisted of SiO2 core with a diameter of approximately 210 nm, GdPO4:Tb intermediate shell with thickness of approximately 7 nm, and SiO2 outer shell with thickness of approximately 20 nm. This unique core-shell-shell structured nanoparticles exhibited strong luminescence properties compared with GdPO4:Tb nanoparticles. The core-shell-shell structured nanoparticles can effectively quench the intrinsic fluorescence of bovine serum albumin through a static quenching mode. The as-synthesized nanoparticles show great potential in biological cell imaging and cancer treatment.
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