Synthesis and photoluminescence of Ca1-xTiO3 ：xEu^3＋ nanoparticles

Ca1-xTiO3 ：xEu^3＋ nanoparticles （NPs） with the size ranging from 27 nm to 135 nm were prepared by means of a chemical co-precipitation method. The structural and optical properties of the NPs were investigated, and the influence of Eu doping content and sintering temperature on the photoluminescence of the Ca1-xTiO3 ：xEu^3＋ NPs were examined. An obvious red emission band centered at 615 nm were observed under the excitation with 395 nm for the Ca1-xTiO3 ：xEu^3＋ NPs. X-ray photoelectron spectroscopy analyses suggest that Eu^3＋ is incorporated into not only the Ca-site, but also Ti-site of CaTiO3 crystal lattice. Our study shows the promise of the Ca1-xTiO3 ：xEu^3＋ NPs as a red nanophosphor.

Functionalized TiO_2@ZrO_2@Y_2O_3:Eu^(3+) core-multishell microspheres and their photoluminescence properties

TiO2@ZrO2@Y2O3 ：Eu3＋ composite particles with a core-multishell structure were synthesized through the combination of a layer-by-layer （LBL） self-assembly method and a sol-gel process. The obtained sam- ples were characterized with scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray photoelectron spectroscopy （XPS）, X-ray diffraction （XRD）, and fluorescence spectropho- tometry. The results showed that the composite particles had a core-multishell structure, spherical morphology, and a narrow size distribution. The presence of a ZrO2 layer on the TiO2 core can effec- tively prevent the reaction between the TiO2 core and a Y203 shell; the temperature for the reaction between the TiO2 core and the Y203 shell in the TiO2@ZrO2@Y2O3 ：Eu core-multishell phosphor can be elevated by 300 ℃ compared to that for TiO2@ZrO2：Eu. Upon excitation of the core-multishell particles in the ultraviolet （254 nm）, the Eu3＋ ion in the Y2O3 ：Eu3＋ shell shows its characteristic red emission （611 nm, 5D0→7F2）, and the photoluminescence （PL） intensity of the phosphor with the core-multishell structure was obviously greater than that of the core-shell TiO2@Y2O3 ：Eu phosphor.

Synthesis of high quality Ce：YAG nanopowders by graphene oxide nanosheet-assisted co-precipitation method

（Ce_（0.04）Y_（2.96））Al_5O_（12） phosphor nanoparticles were prepared by a modified co-precipitation method with graphene oxide（GO） nanosheets used as dispersing agent. The GO concentration is controlled at 0.0.005,0.01, 0.02, and 0.03 g/L. The addition of lamellar GO nanosheets in the precipitant solution possibly enhances both the dispersity of precursor particles and the crystallinity of phosphor nanoparticles. Pure Ce-doped YAG phase is obtained by calcining the precipitate at 1000 ℃ for 3 h. The（Ce_（0.04）Y_（2.96））Al_5 O_（12）phosphor nanoparticles have an average size of 64 nm and there is no significant change on particle size with increase of the GO concentration in precipitant solution. The luminescence property of（Ce_（0.04）Y_（2.96））Al_5O_（12） phosphor nanoparticles varies with different concentrations of GO. The photoluminescence emission intensity of the optimum sample with 0.02 g/L GO is about 1.6 times higher than the sample without using GO.