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The yellow SrSi2O2N2:Eu2+ phosphor has been synthesized by using a simple solid-state reaction method with Sr2SiO4:Eu2+ as the precursor. It shows a broad excitation band extending from 250 to 520 nm and an asymmetric emission band with a main peak at about 550 nm. The emission intensity of the SrSi2O2N2:Eu2+ is about 1.2 times higher than the commercial yellow phosphor YAG:Ce3+ (P46-Y3). The temperature-dependent luminescence characteristic of SrSi2O2N2:Eu2+ has been investigated in this paper. With increasing temperature, the emission band of SrSi2O2N2:Eu2+ shows anomalous blue-shift along with decreasing emission intensity and the broadening full width at half maximum (FWHM). Particularly, compared with YAG:Ce3+ (P46-Y3), the yellow SrSi2O2N2:Eu2+ phosphors exhibit higher thermal stability due to their weaker electron-phonon coupling strength (1.1), lower stokes shift (0.0576 eV) and larger activation energy (0.288 eV). All these results indicate that SrSi2O2N2:Eu2+ yellow phosphors have potential application for white light-emitting diodes (LEDs). What's more, an energy level scheme is constructed to explain the anomalous blue-shift phenomenon. [Copyright &y& Elsevier]

Reduced graphene oxide (RGO) and silver nanoparticle (AgNP) hybrids (RGO-AgNP) were prepared by a facile one-pot method using Poly (N-vinyl-2-pyrrolidone) as reductant and stabilizer. Folic acid (FA) molecules were attached to the RGO-AgNP by physisorption for targeting specific cancer cells with folate receptors (FRs) and using as Raman reporter molecules. The internalization of the FA loaded RGO-AgNP (RGO-AgNP-FA) inside the FRs-positive cancer cell was confirmed by confocal laser scanning and transmission electron microscopy. The Raman signals of the FA in live cancer cells were detected by confocal Raman spectroscope at 514 nm excitation, indicating that the RGO-AgNP-FA material has great potential as a Raman probe for cancer diagnosis in vitro.

Yellow-light-emitting phosphor SrSi2O2N2:Eu2+ was synthesized by using a simple solid-state reaction method with Sr2SiO4:Eu2+ as the precursor. This phosphor was found to be well-crystallized by utilizing XRD. Luminescence and afterglow properties of it have been systematically investigated. After 15 minutes excitation with an unfiltered xenon arc lamp at 1000 lux, its afterglow can be seen for more than 2.5 h in the limit of light perception of dark-adapted human eyes (0.32 mcd/m2). Furthermore, its temperature-dependent long-lasting phosphorescence (LLP) characteristic was investigated for the first time, combining information from thermoluminescence (TL) spectrum, a possible mechanism for the LLP of SrSi2O2N2:Eu2+ phosphor was discussed in this paper.

Using cheaper CaH2 as calcium sources and an efficient reductant, red emitting phosphors (Ca1-xEux)2Si5N8 (x = 0.002, 0.005, 0.008, 0.01, 0.02 [?] 0.09) were prepared under 1540degC via the traditional solid-state reaction method. The photoluminescence characteristics with various Eu2+-doping concentrations were investigated. A broad excitation spectrum is full with a range of 200[?]600 nm. Broad band emissions and a high absorption were achieved and the emission peaks shifted from 603 to 617 nm with increased Eu2+ concentration. A large emission tunability and a high solubility of activators (a 14 nm red-shift at x = 0.09) make the obtained phosphors excellent candidates for LED conversion phosphors. With increasing Li3N concentration, the small particles gradually grow into well-crystallized and well-dispersed particles with a mean size of 5 um. The additive of Li3N is helpful to improve the uniformity and coarsening of Ca2Si5N8: Eu2+ particle.

Using cheaper CaH2as calcium sources and an efficient reductant, red emitting phosphors (Ca1-xEux)2Si5N8(x = 0.002, 0.005, 0.008, 0.01, 0.02 ∼ 0.09) were prepared under 1540°C via the traditional solid-state reaction method. The photoluminescence characteristics with various Eu2+-doping concentrations were investigated. A broad excitation spectrum is full with a range of 200∼600 nm. Broad band emissions and a high absorption were achieved and the emission peaks shifted from 603 to 617 nm with increased Eu2+concentration. A large emission tunability and a high solubility of activators (a 14 nm red-shift at x = 0.09) make the obtained phosphors excellent candidates for LED conversion phosphors. With increasing Li3N concentration, the small particles gradually grow into well-crystallized and well-dispersed particles with a mean size of 5 μm. The additive of Li3N is helpful to improve the uniformity and coarsening of Ca2Si5N8: Eu2+particle.

Yellow-light-emitting phosphor SrSi2O2N2:Eu2+was synthesized by using a simple solid-state reaction method with Sr2SiO4:Eu2+as the precursor. This phosphor was found to be well-crystallized by utilizing XRD. Luminescence and afterglow properties of it have been systematically investigated. After 15 minutes excitation with an unfiltered xenon arc lamp at 1000 lux, its afterglow can be seen for more than 2.5 h in the limit of light perception of dark-adapted human eyes (0.32 mcd/m2). Furthermore, its temperature-dependent long-lasting phosphorescence (LLP) characteristic was investigated for the first time, combining information from thermoluminescence (TL) spectrum, a possible mechanism for the LLP of SrSi2O2N2:Eu2+phosphor was discussed in this paper.