Electrospinning Preparation, Structure, and Properties of Fe3O4/Tb(acac)3phen/Polystyrene Bifunctional Microfibers.

Compared to single functional materials, multifunctional materials with magnetism and luminescence are more attractive and promising; Thus, it has become an important subject. In our work, bifunctional Fe3O4/Tb(acac)3phen/polystyrene) microfibers with magnetic and luminescent properties (acac: acetylacetone, phen: 1,10-phenanthroline) were synthesized by simple electrospinning process. The doping of Fe3O4 and Tb(acac)3phen made the fiber diameter larger. The surface of pure polystyrene microfibers and microfibers doped only with Fe3O4 nanoparticles were chapped similar to bark, whereas the surface of the microfibers was smoother after doping with Tb(acac)3phen complexes. The luminescent properties of the composite microfibers were systematically studied in contrast to pure Tb(acac)3phen complexes, including excitation and emission spectra, fluorescence dynamics, and the temperature dependence of intensity. Compared with the pure complexes, the thermal activation energy and thermal stability of composite microfiber was significantly improved, and the luminescence of the unit mass of Tb(acac)3phen complexes in composite microfibers was stronger than that in pure Tb(acac)3phen complexes. The magnetic properties of the composite microfibers were also investigated using hysteresis loops, and an interesting experimental phenomenon was found that the saturation magnetization of the composite microfibers gradually increased with the increase in the doping proportion of terbium complexes.

Synthesis and characterization of new bifunctional nanocomposites possessing upconversion and oxygen-sensing properties.

A new type of bifunctional nanocomposites for biomedical applications, upconversion NaY F(4):Y b(3+), Tm(3+) nanoparticles coated with Ru(II) complex chemically doped SiO(2), has been developed by combining the useful functions of upconversion and oxygen-sensing properties into one nanoparticle. NaY F(4):Y b(3+), Tm(3+) nanoparticles were successfully coated with an Ru(II) complex doped SiO(2) shell with a thickness of approximately 30 nm, and the surface of the SiO(2) was functionalized with amines. The obtained nanocomposites exhibited bright blue upconversion emission, and the luminescent emission intensity of the Ru(II) complex in the nanocomposites was sensitive to oxygen. Compared with the simple mixture of Ru(II) complex and SiO(2), the core-shell nanocomposites showed better linearity between emission intensity of Ru(II) complex and oxygen concentrations. These bifunctional nanocomposites may find applications in biochemical and biomedical fields, such as biolabels and optical oxygen sensors, which can measure the oxygen concentrations in biological fluids.

Preparation and photoluminescence properties of three-dimensionally ordered macroporous ZrO2:Eu3+.

Three-dimensionally ordered macroporous (3DOM) ZrO2:Eu3+ (0.5%, 1%, 2% and 5%) were successfully prepared using a polystyrene (PS) colloidal crystal template in combination with a sol-gel method. The structure, morphology, porosity, and optical properties of the materials were well characterized by X-ray diffraction (XRD), Field emission scanning electron micrograph (FESEM), N2 adsorption, and photoluminescence (PL) spectra. The results indicated that the closely packed material exhibited three-dimensional ordering of pores and a strong red (5)D0-->(7)F2 transitions under charge transfer excitation. Strong PL and abundant porosity are of particular interest and give this multifunctional material future potential.

Electrospinning preparation of uniaxially aligned ternary terbium complex/polymer composite fibers and considerably improved photostability.

In order to improve photoluminescence properties, terbium complex Tb(acac)3phen (acacacetylacetone, phen-1,10-phenanthroline) was incorporated into polystyrene (PS), polyvinylpyrrolidone (PVP), and polymethylmethacrylate (PMMA) matrixes and electrospun into various aligned composite fibers. Their morphology, structure and photoluminescence properties were systematically characterized and studied. The results demonstrated that under the ultraviolet (UV) light exposure, the emission intensity for 5D4 --> 7F(J) of Tb3+ in the composite fibers considerably increased, while it was greatly quenched in the pure complex, implying remarkably improved photostability in the composites. The composite fibers also demonstrated much better temperature stability of photoluminescence over the pure complex.

Preparation and upconversion luminescence of three-dimensionally ordered macroporous ZrO2: Er3+, Yb3+.

The three-dimensionally ordered macroporous (3DOM) ZrO2: Er(3+), Yb(3+) materials were successfully synthesized by the sol-gel method combined with a polystyrene latex sphere templating technique, and their morphologies, surface physicochemical properties, and upconversion photoluminescence (UC-PL) properties were studied. The results indicate that the materials exhibited both porosity and strong UC-PL under the excitation of a 978 nm diode laser. In comparison with the nonporous samples, the relative intensity of the red ((4)F(9/2)-(4)I(15/2)) to the green ((4)S(3/2)/(2)H(11/2)-(4)I(15/2)) emission decreased visibly because of the decreased nonradiative relaxation in the 3DOM materials. It was also observed that the relative intensity of the green emission to the red emission increased significantly with the increasing excitation power. An indirect three-photon populating process occurred for the green emission as the excitation power and Yb(3+) concentration was high enough.

CdS/Cyclohexylamine inorganic-organic hybrid semiconductor nanofibers with strong quantum confinement effect.

Inorganic-organic hybrid semiconductor nanofibers of CdS/CHA (CHA = cyclohexylamine) were successfully synthesized by a simple solvothermal method. The fibers obtained had average diameter of 20 nm and length of several micrometers. In these fibers, periodic layer-like sub-nanometer structures with thickness of approximately 3 nm were identified by high-resolution transmission electron microscope (HR-TEM). The absorption of the hybrids exhibited a large blue-shift in contrast to the bulk, which was attributed to strong quantum confinement effect (QCE) induced by internal sub-nanometer structures. Pure hexagonal wurtzite CdS (H-CdS) nanorods were also obtained by extracting the CdS/CHA hybrids with dimethyl formamide (DMF). The rods obtained had average diameter of 20 nm and length of 200 nm. A CdS/CHA/polyvinyl alcohol (PVA) composite film emitting white light was prepared by spin coating.

Upconversion white light devices: Ln(3+)-tridoped NaYF4 nanoparticles and PVP modified films.

Upconversion (UC) white light hybrid thin films containing Ln(3+)-tridoped (Yb3+, Er3+ and Tm3+) NaYF4 nanoparticles and poly(vinyl pyrrolidone) (PVP, M(w) approximately 1300000) were prepared by a spin-coating method and characterized by X-ray diffraction (XRD), field emission scanning electron micrograph (FE-SEM) and Fourier transform infrared spectra (FT-IR). White light was generated by two different lanthanide ions, Er3+ (red and green) and Tm3+ (blue) under excitation by a 980-nm laser diode. Due to the modification of PVP to the UC populating processes, the color stability of the white light in the hybrid films was remarkably improved.

Preparation, characterization and photoluminescence properties of ternary europium complexes Eu(DBM)3bath encapsulated into aluminosilicate zeolites.

To modify the photoluminescence properties the Eu(DBM)3bath complexes were encapsulated into the sub-nanometer pores of aluminosilicates zeolites L and Y and characterized by X-ray diffraction (XRD), transmission electron micrographs (TEM), Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-vis) absorption spectra. The luminescent properties of the encapsulated composites (Eu-L and Eu-Y) were systematically studied. The results indicate that in both the two composites the crystal-field symmetry becomes lower, as a consequence, the 5D0-7F2 electronic-dipole transition relative to the 5D0-7F1 magnetic-dipole transition of Eu3+ increases in contrast to the pure complexes. The outer quantum efficiency of the Eu3+ emission and the photostability of Eu3+ are both improved considerably. The adsorption of water in the composites has influence on the thermostability and decay dynamics of the Eu3+ emission. In the composite Eu-L, which contains less water the thermostability of luminescence is improved considerably and the lifetime becomes longer in comparison to the pure complexes. Overall, zeolite L is a more ideal host material for modification of lanthanide complexes.

White luminescence by up-conversion from thin film made with Ln(3+)-doped NaYF4 nanoparticles.

White light-emitting thin films containing Ln(3+)-doped NaYF4 nanoparticles were prepared by a simple spin-coating method. White light was generated by two different lanthanide ions, Er3+ (red and green) and Tm3+ (blue), by upconversion process under the excitation of a 980-nm laser diode. The ratio of the intensity of the three main emissions was tuned by controlling the concentration of the nanoparticles in the thin film and the concentration of the lanthanide ions in the nanoparticles. The color coordinates corresponding to emissions of different nanoparticle concentrations and with the different pump powers were investigated. When the pump power was fixed at 900 mW, the thin film with a concentration ratio of 2.5:1 emitted pure white light with coordinates of (0.333, 0.339).

Improved photoluminescence properties of ternary terbium complexes in mesoporous molecule sieves.

Ternary terbium complexes were fully encapsulated and uniformly distributed into the channels of unmodified and modified mesoporous molecule sieves of SBA-15 and characterized by transmission electron micrographs (TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-vis) absorption spectra, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and elemental analysis. The luminescent properties for the encapsulated complexes were systematically studied in contrast to the pure complexes, including excitation and emission spectra, fluorescence dynamics, photostability under UV exposure, and the temperature dependence of intensity and lifetime. The results indicate that the excitation bands assigned to the pi-pi* electron transition of the ligands for Tb complexes encapsulated in SBA-15 were split into different components due to decreased symmetry and disappeared at long wavelengths. Owing to suppressed vibration transitions, the outer quantum efficiency of the 5D4-7FJ (J = 0-5) emissions was enhanced largely in comparison to the pure complexes. In addition, the photostability and thermostability of the emissions were also improved considerably.

Solvothermal synthesis and photoluminescent properties of ZnS/cyclohexylamine: inorganic-organic hybrid semiconductor nanowires.

An inorganic-organic hybrid semiconductor, ZnS/CHA (CHA = cyclohexylamine) nanocomposites was successfully synthesized via a solvothermal method using CHA as solvent, which yielded uniform and ultralong nanowires with widths of 100-1000 nm and lengths of 5-20 microm. Changing the reaction conditions could alter the morphology and optical properties of the nanocomposites. The periodic layer subnanometer structures were identified by high-resolution transmission electron microscopy (HR-TEM) images, with thickness of approximately 2 nm. The composites exhibited a very large blue-shift in their optical absorption edge as well as an exciton excitation band due to a strong quantum confinement effect caused by the internal subnanometer-scale structures. The pure hexagonal wurtzite ZnS nanowires were also obtained by extracting the ZnS/CHA nanocomposites with dimethyl formamide (DMF). In addition, the luminescent properties of exciton and defect-related transitions in different samples of ZnS/CHA were discussed in detail.