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Hydrophilic BaYF5 nanocrystals have been prepared via a facile and fast microwave-assisted method at low temperature without the assistance of template reagents. The Yb3+/Er3+, Ce3+/Tb3+ doped BaYF5 nanocrystals could be dispersed well in water and alcohol. BaYF5:Ce3+/Tb3+ nanocrystals show bright green luminescence. The existence of the Ce3+ ions can dramatically enhance the luminescence intensity of the Tb3+ ions, due to the efficient energy transfer from Ce3+ to Tb3+ ions. More importantly, when doped with Yb3+/Er3+ ions, the BaYF5 nanocrystals show bright red upconversion luminescence. [ABSTRACT FROM AUTHOR]

In this paper, uniform rice-shaped lanthanide doped BiPO4 upconversion submicron particles have been successfully synthesized via a facile room-temperature co-precipitation reaction and subsequent calcination route. The morphology, phase transformation and upconversion luminescent properties of synthesized submicron particles (SMPs) were characterized by using different analytical techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TG-DSC) and upconversion luminescence (UCL) spectra. The transformation from hexagonal phase to monoclinic phase is crucial for upconversion luminescent properties due to the loss of water molecules in the lattice of hexagonal phase. With different variety and concentration of the dopant Ln3+ (Ln = Yb, Er, Tm and Ho) ions, the obtained samples present bright green, blue, and red upconversion emissions under a 980 nm continual wave laser diode excitation. Multicolor and bright white upconversion emissions have also been obtained by precisely adjusting the dopants concentration in the host lattice. [ABSTRACT FROM AUTHOR]

A facile method is proposed for the synthesis of three-dimensional (3D) flower-like Co3-xFexO4 ferrite (CF) hollow spheres, using SiO2@FeOOH as precursor. The CF hollow spheres are efficient for the catalytic degradation of methylene blue (MB) in the presence of H2O2 at 80 °C. The obtained CF hollow spheres were characterized using transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, X-ray photo-electron spectroscopy, and N2 adsorption-desorption isotherm measurements. The formation of 3D hierarchical flower-like superstructure was influenced by the relative amount of urea used. As the mole ratio of CoCl2 and urea decreased, the structure of the products was tailored from yolk-like spheres to hollow spheres with different sized void interiors. Moreover, N2 adsorption-desorption isotherm analysis showed that the CF hollow spheres have a large specific surface area (163 m(2) g(-1)) which provided more activity sites. The CF hollow spheres can catalyze the oxidation of MB efficiently. These results indicate that the designed CF hollow spheres exhibit promising capability for the degradation of dyes.