Deyan Kong

Multicolor Tuning of Manganese-Doped ZnS Colloidal Nanocrystals

In this paper, we report a facile route which is based on tuning doping concentration of Mn(2+) ions in ZnS nanocrystals, to achieve deliberate color modulation from blue to orange-yellow under single-wavelength excitation. X-ray diffraction (XRD), transmission electron microscopy (TEM), as well as photoluminescence (PL) spectra were employed to characterize the obtained samples. In this process, the relative emission intensities of both ZnS host (blue) and Mn(2+) dopant (orange-yellow) are sensitive to the Mn(2+) doping concentration, due to the energy transfer from ZnS host to Mn(2+) dopant. As a result of fine-tuning of these two emission components, white emission can be realized for Mn(2+)-doped ZnS nanocrystals. Furthermore, the as-synthesized doped nanocrystals possess extremely narrow size distribution and can be readily transferred into aqueous solution for the next potential applications.

Sol-gel Synthesis and Characterization of Zn2SiO4 : Mn@SiO2 Spherical Core-Shell Particles

The synthesis and characterization of Zn 2 SiO 4 :Mn phosphor layers on spherical silica spheres, i.e., core-shell particles of Zn 2 SiO 4 :Mn@SiO 2 are described in this paper. First, monodisperse silica spheres with an average size around 750 nm have been obtained via the Stober method by the hydrolysis and condensation of telraethoxysilane Si(OC 2 H 5 )4 under base condition (using NH 4 OH as the catalyst). Second, the silica spheres are coated with Zn 2 SiO 4 :Mn phosphor layers by a sol-gel process. The resulting core-shell particles are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscope, energy-dispersive X-ray spectroscopy, transmission electron microscopy, photoluminescence, low-voltage cathodoluminescence, as well as kinetic decay. The results confirm that the 1000°C-annealed sample consists of crystalline Zn 2 SiO 4 :Mn shells and amorphous SiO 2 cores with spherical morphology and narrow size distribution. The Zn 2 SiO 4 :Mn@SiO 2 particles show the green emission at 521 nm corresponding to 4 T 1 ( 4 G)- 6 A 1 ( 6 S) transition of Mn 2 + under the excitation of UV (250 nm), vacuum UV (172 nm), and electron-beams (1-6 kV). The luminescence intensity has been studied as a function of coating number, accelerating voltage, and filament current, respectively.

Mesoporous silica coated CeF3 : Tb3+ particles for drug release

CeF3:Tb3+ nanoparticles were successfully prepared by a polyol process using diethylene glycol ( DEG) as solvent. After being coated with dense silica, these CeF3:Tb3+ nanoparticles can be coated with mesoporous silica using nonionic triblock copolymer EO20PO70EO20 ( P 123) as structure-directing agent. The composite can load ibuprofen and release the drug in the PBS. The composite was characterized by X-ray diffraction ( XRD), transmission electron microscopy ( TEM), nitrogen absorption/desorption isotherms, fluorescence spectra, and UV/Vis absorption spectra, respectively.

Tunable photoluminescence in monodisperse silica spheres.

The nanometer-scale luminescent monodisperse silica spheres have been prepared by a water/oil (W/O) microemulsion method and the size of these spheres changed with the different concentrations of 3-aminopropyltriethoxysilane (APTES). The luminescent monodisperse silica spheres at the submicrometer scale have been prepared via Stöber method and the particles size increased with the increase of the amino concentrations. After calcination, all silica spheres do not change obviously in size. The annealed silica spheres contain C impurities and O defects, which resulted in the luminescence of silica spheres. The spheres showed variations in emission due to the different size and the concentration of organosiloxane precursors. Therefore, the emission can be tuned finely via the change of organosiloxane precursor and the size of samples.

Mesoporous silica coated CeF 3 : Tb 3+ particles for drug release

CeF3:Tb3+ nanoparticles were successfully prepared by a polyol process using diethylene glycol ( DEG) as solvent. After being coated with dense silica, these CeF3:Tb3+ nanoparticles can be coated with mesoporous silica using nonionic triblock copolymer EO20PO70EO20 ( P 123) as structure-directing agent. The composite can load ibuprofen and release the drug in the PBS. The composite was characterized by X-ray diffraction ( XRD), transmission electron microscopy ( TEM), nitrogen absorption/desorption isotherms, fluorescence spectra, and UV/Vis absorption spectra, respectively.

Mesoporous Silica Coated : Particles for Drug Release

CeF3:Tb3+ nanoparticles were successfully prepared by a polyol process using diethylene glycol ( DEG) as solvent. After being coated with dense silica, these CeF3:Tb3+ nanoparticles can be coated with mesoporous silica using nonionic triblock copolymer EO20PO70EO20 ( P 123) as structure-directing agent. The composite can load ibuprofen and release the drug in the PBS. The composite was characterized by X-ray diffraction ( XRD), transmission electron microscopy ( TEM), nitrogen absorption/desorption isotherms, fluorescence spectra, and UV/Vis absorption spectra, respectively.