Template-free electrochemical nanofabrication of polyaniline nanobrush and hybrid polyaniline with carbon nanohorns for supercapacitors.

Polyaniline (PANI) nanobrushes were synthesized by template-free electrochemical galvanostatic methods. When the same method was applied to the carbon nanohorn (CNH) solution containing aniline monomers, a hybrid nanostructure containing PANI and CNHs was enabled after electropolymerization. This is the first report on the template-free method to make PANI nanobrushes and homogeneous hybrid soft matter (PANI) with carbon nanoparticles. Raman spectroscopy was used to analyze the interaction between CNH and PANI. Electrochemical nanofabrication offers simplicity and good control when used to make electronic devices. Both of these materials were applied in supercapacitors and an improvement capacitive current by using the hybrid material was observed.

A novel hybrid phase-locked-loop frequency synthesizer using single-electron devices and CMOS transistors

This paper proposes a novel phase-locked loop (PLL) frequency synthesizer using single-electron devices (SEDs) and metal-oxide-semiconductor (MOS) field-effect transistors. The PLL frequency synthesizer mainly consists of a single-electron transistor (SET)/MOS hybrid voltage-controlled oscillator circuit, a single-electron (SE) turnstile/MOS hybrid phase-frequency detector (PFD) circuit and a SE turnstile/MOS hybrid frequency divider. The phase-frequency detection and frequency-division functions are realized by manipulating the single electrons. We propose a SPICE model to describe the behavior of the MOSFET-based SE turnstile. The authors simulate the performance of the PILL block circuits and the whole PLL synthesizer. Simulation results indicated that the circuit can well perform the operation of the PLL frequency synthesizer at room temperature. The PILL synthesizer is very compact. The total number of the transistors is less than 50. The power dissipation of the proposed PLL circuit is less than 3 uW. The authors discuss the effect of fabrication tolerance, the effect of background charge and the SE transfer accuracy on the performance of the PLL circuit. A technique to compensate parameter dispersions of SEDs is proposed.

Novel hybrid voltage controlled ring oscillators using single electron and MOS transistors

This paper proposes two kinds of novel hybrid voltage controlled ring oscillators (VCO) using a single electron transistor (SET) and metal-oxide-semiconductor (MOS) transistor. The novel SET/MOS hybrid VCO circuits possess the merits of both the SET circuit and the MOS circuit. The novel VCO circuits have several advantages: wide frequency tuning range, low power dissipation, and large load capability. We use the SPICE compact macro model to describe the SET and simulate the performances of the SET/MOS hybrid VCO circuits by HSPICE simulator. Simulation results demonstrate that the hybrid circuits can operate well as a VCO at room temperature. The oscillation frequency of the VCO circuits could be as high as 1 GHz, with a -71 dBc/Hz phase noise at 1 MHz offset frequency. The power dissipations are lower than 2 uW. We studied the effect of fabrication tolerance, background charge, and operating temperature on the performances of the circuits.

Growth and fabrication of high performance 980nm strained InGaAs quantum well lasers using novel hybrid material system of InGaAsP and AlGaAs

In this paper, we report on the design, growth and fabrication of 980nm strained InGaAs quantum well lasers employing novel material system of Al-free active region and AlGaAs cladding layers. The use of AlGaAs cladding instead of InGaP provides potential advantages in laser structure design, improvement of surface morphology and laser performance. We demonstrate an optimized broad-waveguide structure for obtaining high power 980nm quantum well lasers with low vertical beam divergence. The laser structure was grown by low-pressure metalorganic chemical vapor deposition, which exhibit a high internal quantum efficiency of similar to 90% and a low internal loss of 1.5-2.5 cm(-1). The broad-area and ridge-waveguide laser devices are both fabricated. For 100 mu m wide stripe lasers with cavity length of 800 mu m, a low threshold current of 170mA, a high slope efficiency of 1.0W/A and high output power of more than 3.5W are achieved. The temperature dependences of the threshold current and the emitting spectra demonstrate a very high characteristic temperature coefficient (T-o) of 200-250K and a wavelength shift coefficient of 0.34nm/degrees C. For 4 mu m-width ridge waveguide structure laser devices, a maximum output power of 340mW with GOD-free thermal roll-over characteristics is obtained.

Novel Hybrid Electrocatalyst with Enhanced Performance in Alkaline Media: Hollow Au/Pd Core/Shell Nanostructures with a Raspberry Surface

In this paper, a hollow Au/Pd core/shell nanostructure with a raspberry surface was developed for methanol, ethanol, and formic acid oxidation in alkaline media. The results showed that it possessed better electrocatalyst performance than hollow Au nanospheres or Pd nanoparticles. The nanostructure was fabricated via a two-step method. Hollow Au nanospheres were first synthesized by a galvanic replacement reaction, and then they were coated with a layer of Pd grains. Several characterizations such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS) were used to investigate the prepared nanostructures.

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.

A novel hybrid nanostructure based on SiO2@carbon nanotube coaxial nanocable

We present a simple, generally applicable procedure for obtaining diameter-controlled SiO2@ carbon nanotubes (CNTs) coaxial nanocables. These coaxial nanocables with high solubility in polar solvents, have been used as functional templates for assembling CNTs/Au nanorods heterogeneous nanostructures to form multifunctional assembly system. These hybrid nanostructures may find applications in nanoelectronics, photonics, and nanodevices.

A novel hybrid based on carbon nanotubes and heteropolyanions as effective catalyst for hydrogen evolution

Heteropolyanions of tungstophosphoric acid (PWA) have been successfully hybridized with carbon nanotubes (CNTs) by a severe mechanical milling. The obtained hybrid is electroactive for hydrogen evolution (HE) at potentials as positive as -0.16 V vs. Ag/AgCl in 0.2 M HClO4 aqueous solution and its electrocatalysis is up to the level of Pt/CNTs (20 wt% Pt) for HE, indicating a vigorous alternative to Pt group metals. The HE mechanism of the hybrid was also studied and it was found that the tungsten oxycarbides are the electroactive components for HE.

Non-affine structural evolution of soft colloidal crystalline latex films under stretching as observed via synchrotron X-ray scattering

A polymer dispersion consisting of soft latex spheres with a diameter of 135 nm was used to produce a crystalline film with face-centered cubic (fcc) packing of the spheres. Different from conventional small-molecule and hardsphere colloidal crystals, the crystalline latex film in the present case is soft (i.e., easily deformable). The structural evolution of this soft colloidal latex film under stretching was investigated by in-situ synchrotron ultra-small-angle X-ray scattering. The film exhibits polycrystalline scattering behavior corresponding to fcc structure. Stretching results not only in a large deformation of the crystallographic structure but also in considerable nonaffine deformation at high draw ratios. The unexpected nonaffine deformation was attributed to slippage between rows of particles and crystalline grain boundaries. The crystalline structure remains intact even at high deformation, suggesting that directional anisotropic colloidal crystallites can be easily produced.

Photochromic behavior and luminescent properties of novel hybrid organic-inorganic film doped with Preyssler's heteropoly acid H-12[EuP5W30O110] and polyvinylpyrrolidone

A novel hybrid photochromic composite film composed of Preyssler's heteropoly acid H-12[EuP5W30O110] (EuP5W30) and polyvinylpyrrolidone (PVP) was prepared by dip-coating method. Atomic force microscopy (AFM) was used to investigate the surface topography. The change of characteristic peak in the infrared spectra (IR) was investigated. The TG curve showed three steps of weight loss and approximately revealed the composition of the hybrid film. Ultraviolet-visible adsorption spectra (UV-VIS) and electron resonance spectrum (ESR) were used to investigate the photochromic behavior and mechanism of hybrid film. The photoluminescent behavior of the film at room temperature was investigated to show the characteristic Eu3+ emission pattern of D-5(o)-F-7(J). The occurrence of photoluminescent activity confirms the potential for creating luminescent thin film with polyoxometalates (POMs).

Synthesis and thermotropic liquid crystalline behaviour of novel poly(aryl ether ketone)s with a lateral methoxy group

Novel poly(aryl ether ketone)s containing a lateral methoxy group were synthesized by nucleophilic substitution reactions of 4,4'-biphenol and methoxyhydroquinone with 1,4-bis(4-fluorobenzoyl)benzene in a sulfolane solvent in the presence of anhydrous potassium carbonate. Their thermotropic liquid crystalline properties were characterized by a variety of experimental techniques, e.g. differential scanning calorimetry (DSC), polarized light microscopy and temperature-dependent FTIR. Thermotropic liquid crystalline behaviour was observed in the copolymers containing 30-80 mol-% mexthoxyhydroquinone. Both melting (T-m) and isotropization (T-i) transitions appeared in the DSC curves. The polarized light microscopy study of the liquid crystalline copolymers suggested their ordered smectic structures. As expected, the copolymers had lower melting transitions than the biphenol-based homopoly(aryl ether ketone)s because of the copolymerization effect of the crystal-disrupting monomer methoxyhydroquinone.

Synthesis and characterization of a novel hybrid single crystal [Ga-3(PO4)(3)F-2]H3O center dot (H3NCH2CH2)(2)NH2

A novel three-dimensional fluorinated gallium phosphate has been hydrothermally,synthesized by using diethylenetriamine as an organic structure-directing agent. X-ray single crystal structure analysis indicates this compound crystallizes in the orthorhombic space group P-bca, a = 1. 605 6 (7) nm, b = 1.011 4 (4) nm, c=1. 854 6(5) nm, V=3. 011 6(19) nm(3), Z=4. The three-dimensional framework based on linkage of corner-sharing polyhedron PO4, GaO4F and GaO4F2 delimit ten-ring channels along b axis in which the triply protonated amines are located serving as charge compensating guests and supporters.

Preparation and characterization of doped polyaniline films

Stable monolayer of the polyaniline doped with camphor sulfonic acid at the air-water interface has been obtained, of which multilayers have been successfully deposited by Langmuir-Blodgett technique onto CaF2 substrate. The limiting mean molecular area and collapse pressure are found to be 0.294 nm(2) and 41 mN/m, respectively. The multilayers were characterized by IR and W-Vis-NIR spectroscopies. X-ray small-angle diffraction data show that the multilayer was periodic layer structure with the layer spacing of 1.60 nm. The comparisons are also made with characterization of the casting film. (C) 1999 Elsevier Science S.A. All rights reserved.

The synthesis and thermotropic liquid crystalline behaviour of novel main chain poly(aryl ether ketone)s containing a lateral phenyl group

Novel main chain poly(aryl ether ketone)s containing a lateral phenyl group were synthesized by nucleophilic substitution reactions of 4,4'-biphenol and phenylhydroquinone with either 4,4'-difluorobenzophenone or 1,4-bis(4-fluorobenzoyl)benzene and their thermotropic liquid crystalline properties were characterized by a variety of experimental techniques. Thermotropic liquid crystalline behaviour was observed in the copolymers containing 50 and 70mol% biphenol. Melting (T-m) and isotropization (T-i) transitions both appeared on the DSC thermograms. A banded texture was formed after shearing the sample in the liquid crystalline nematic state. As expected, each of the copolymers had a relatively lower melting transition than the biphenol-based homopoly(aryl ether ketone)s because of the copolymerization effect of the crystal-disrupting monomer phenylhydroquinone.

Studies On The Electrical Properties Of Some Crystalline Organic Compounds And Conducting Polymers

Solid electrolytes for applications like chemical sensing, energy storage, and conversion have been actively investigated and developed since the early sixties. Although of immense potential, solid state protonic conductors have been ignored in comparison with the great interest that has been shown to other ionic conductors like lithium and silver ion conductors. The non-availability of good, stable protonic conductors could be partly the reason for this situation. Although organic solids are better known for their electrical insulating character, ionic conductors of organic origin constitute a recent addition to the class of ionic conductors. However, detailed studies (N1 such conductors are scarce. Also the last decade has witnessed an unprecedented boom in research on organic "conducting polymers". These newly devised materials show conductivity spanning from insulator to metallic regimes, which can be manipulated by appropriate chemical treatment. They find applications in devices ranging from rechargeable batteries to "smart windows". This thesis mainly deals with the synthesis and investigations on the electrical properties of (i) certain organbc protonic conductors derived from ethylenediamine and (ii) substituted polyanilines