Preparation of SrAl2O4:Eu2+, Dy3+ fibers by electrospinning combined with sol-gel process

One-dimensional SrAl2O4:Eu2+, Dy3+ fibers were fabricated by a simple electrospinning combined with sol-gel process. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and photoluminescence were used to characterize the fibers. The results show that the phase structure of SrAl2O4:Eu2+, Dy3+ belongs to a monoclinic one, the composite fibers and fibers calcined at high temperature remain the original one-dimensional texture, and the SrAl2O4:Eu2+, Dy3+ was a green emission. (C) 2010 Elsevier Inc. All rights reserved.

A facile synthesis and characterization of monodisperse spherical pigment particles with a core/shell structnre

In this paper, a facile sol-gel process for producing monodisperse, spherical, and nonaggregated pigment particles with a core/shell structure is reported. Spherical silica particles (245 and 385 nm in diameter) and Cr2O3, alpha-Fe2O3, ZnCo2O4, CuFeCrO4, MgFe2O4, and CoAl2O4 pigments are selected as cores and shells, respectively. The obtained core/shell-structured pigment samples, denoted as SiO2@Cr2O3 (green), SiO2@alpha-Fe2O3 (red), SiO2@MgFe2O4 (brown), SiO2@ZnCo2O4 (dark green), SiO2@CoAl2O4 (blue), and SiO2@CuFeCrO4 (black), are well characterized by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and UV-vis diffuse reflection, as well as by investigating the magnetic properties. The results of XRD and high-resolution TEM (HRTEM) demonstrate that the pigment shells crystallize well on the surface Of SiO2 Particles. The thickness of the pigment shell can be tuned by the number of coatings, to some extent. These pigment particles can be well dispersed in some solvents (such as glycol) to form relatively more stable suspensions than the commercial products.

Growth of highly crystalline CaMoO4 : Tb3+ phosphor layers on spherical SiO2 particles via sol-gel process: Structural characterization and luminescent properties

Highly crystalline CaMoO4:Tb3+ phosphor layers were grown on monodisperse SiO2 particles through a simple sol-gel method, resulting in formation of core-shell structured SiO2@CaMoO4:Tb3+ submicrospheres. The resulting SiO2@CaMoO4: Tb3+ core-shell particles were fully characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), photoluminescence (PL), low-voltage cathodoluminescence (CL), and kinetic decays. The XRD results demonstrate that the CaMoO4:Tb3+ layers begin to crystallize on the SiO2 spheres after annealing at 400 degrees C and the crystallinity increases with raising the annealing temperature. SEM and TEM analysis indicates that the obtained submicrospheres have a uniform size distribution and obvious core-shell structure. SiO2@CaMoO4:Tb3+ submicrospheres show strong green emission under short ultraviolet (260 nm) and low-voltage electron beam (1-3 kV) excitation, and the emission spectra are dominated by a D-5(4) -F-7(5) transition of Tb3+(544 nm, green) from the CaMoO4:Tb3+ shells.

Monodisperse and core-shell-structured SiO2@YBO3 : Eu3+ spherical particles: Synthesis and characterization

Y0.9Eu0.1BO3 phosphor layers were deposited on monodisperse SiO2 particles of different sizes (300, 570, 900, and 1200 nm) via a sol-gel process, resulting in the formation of core-shell-structured SiO2@Y0.9Eu0.1BO3 particles. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL), and cathodoluminescence (CL) spectra as well as lifetimes were employed to characterize the resulting composite particles. The results of XRD, FE-SEM, and TEM indicate that the 800 degrees C annealed sample consists of crystalline YBO3 shells and amorphous SiO2 cores, in spherical shape with a narrow size distribution. Under UV (240 nm) and VUV (172 nm) light or electron beam (1-6 kV) excitation, these particles show the characteristic D-5(0)-F-7(1-4) orange-red emission lines of Eu3+ with a quantum yield ranging from 36% (one-layer Y0.9Eu0.1BO3 on SiO2) to 54% (four-layer Y0.9Eu0.1BO3 on SiO2).

Synthesis and luminescent properties of europium (III) schiff base complexes covalently bonded to silica xerogels

A new kind of luminescent organic-inorganic hydrid material consisting of Eu(III)-schiff base complex covalently bonded to silica xerogel was synthesized via the sol-gel method using a Eu (N-propylene salicylimine ligand) complex modified with pendant triethoxysilane groups (Eu(III)(salenHSi)). The Eu(III)(salenHSi) complex is characterized by Fourier transform infrared (FT-IR) spectroscopy. Luminescent properties of the complex and the resulted hybrid silica xerogels have been investigated at room temperature.

Sol-gel deposition and luminescence properties of LiYF4 : Tb3+ thin films

Tb3+-doped LiYF4 films were deposited on quartz glass by a simple sol-gel method. X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), photoluminescence spectra, and lifetimes were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 300 degrees C and fully crystallized at 400 degrees C. AFM and FESEM images of singly coated LiY0.95Tb0.05F4 annealed at 400 degrees C indicated that the film is uniform and crack-free films with average grain size of 90 nm, root mean square roughness of 11 nm and thickness of 120 nm. The doped Tb3+ ions showed its characteristic emission in crystalline LiYF4 films, i.e., D-5(3), F--7(4)J (J = 6, 5, 4, 3) emissions. The optimum doping concentration of the Tb3+ was determined to be 5.0 mol% of Y3+ in LiYF4 films.

Pechini sol-gel deposition and luminescent properties of SrLa1-xRExGa3O7 (RE = Eu, Tb) phosphor films

SrLa1-xRExGa3O7 (RE = EU3+, Tb3+) phosphor films were deposited on quartz glass substrates by a simple Pechim sol-gel method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy, field-emission scanning electron microscopy, photoluminescence spectra, and lifetimes were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 700 degrees C and crystallized fully at 900 degrees C. The results of FNR spectra were in agreement with those of XRD. Uniform and crack-free films annealed at 900 degrees C were obtained with average grain size of 80 nm, root mean square roughness of 46 nm and thickness of 130 nm The RE ions showed their characteristic emission in crystalline SrLa1-xRExGa3O7 films, i.e., Eu3+ D-0-F-7(J) (J = 0, 1, 2, 3, 4), Tb3+5D4 -(7) F-J (J = 6, 5, 4, 3) emissions, respectively. The optimum concentrations (x) of Eu3+ and Tb3+ were determined to be 50, and 80 mol% in SrLa(1-x)RE(x)GGa(3)O(7) films, respectively.

Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized in sol-gel-derived ceramic-carbon nanotube nanocomposite film

The sol-gel-derived ceramic-carbon nanotube (SGCCN) nanocomposite film fabricated by doping multiwall carbon nanotubes (MWNTs) into a silicate get matrix was used to immobilize protein. The SGCCN film can provide a favorable microenvironment for horseradish peroxidase (HRP) to perform direct electron transfer (DET) at glassy carbon electrode. The HRP immobilized in the SGCCN film shows a pair of well-defined redox waves and retains its bioelectrocatalytic activity to the reduction of O-2 and H2O2, which is superior to that immobilized in silica sol-gel film.

The preparation of sol-gel materials doped with ionic liquids and trialkyl phosphine oxides for Yttrium(III) uptake

A new material (IL923SGs) composed of ionic liquids and trialkyl phosphine oxides (Cyanex 923) for Y(III) uptake was prepared via a sol-gel method. The hydrophobic ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate (C(8)mim(+)PF(6)-) was used as solvent medium and pore templating material. The extraction of Y(III) by IL923SGs was mainly due to the complexation of metal ions with Cyanex 923 doped in the solid silica. Ionic liquid was stably doped into the silica gel matrix providing a diffusion medium for Cyanex 923, and this will result in higher removal efficiencies and excellent stability for metal ions separation. IL923SGs were also easily regenerated and reused in the subsequent removal of Y(III) in four cycles.

Deposition of GdVO4 : Eu3+ nanoparticles on silica nanospheres by a simple sol-gel method

The deposition and coating of GdVO4: Eu3+ nanoparticles on spherical silica was carried out using a simple sol - gel method at low temperature. The GdVO4: Eu3+-coated silica composites obtained were characterized by differential thermal analysis (DTA), thermogravimetric (TG) analysis, x-ray diffraction (XRD), Fourier-transform IR spectroscopy (FT-IR), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), photoluminescence spectra, and kinetic decay. It is found that the similar to 5 nm GdVO4: Eu3+ nanoparticles coating the silica spheres are crystal in the as-prepared samples and the crystallinity increases with increasing annealing temperature. The composites obtained are spherical in shape with an average size of 100 nm. The GdVO4: Eu3+ nanoparticles are linked with silica cores by a chemical bond. The photoluminescence spectra of the obtained GdVO4: Eu3+-coated silica composites are similar to those of the bulk GdVO4: Eu3+ phosphors. The strongest peak is near 617 nm, which indicates that Eu3+ is located in the low symmetry site with non-inversion centre.

Extending electrochemical activity of polyaniline to alkaline media via electrostatic interaction and sol-gel route

The electroactivity of polyaniline was extended to pH = 14 alkaline media by preparation of a novel electrostatic interaction conductive hybrid from water-borne conductive polyaniline and silica network containing carboxyl groups via sol-gel process. In addition, the obtained conductive polyaniline hybrid film displayed very low conductivity threshold percolation and demonstrated excellent stability upon cycling.