Materials Literature
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The multiwall carbon nanotubes (MWNTs) synthesized by microwave plasma enhanced chemical vapor deposition in 0.1% CH4 (H2 dilution) reaction gas were shaped in curly structures with the blocked nanoholes and closed caps. On the contrary, the carbon nanotubes with different structures could be obtained in oxygen loaded…
Single crystals of a pseudoquaternary Heusler alloy, Ni52Mn16Fe8Ga24, have now been synthesized. The substitution of Fe for Mn strengthens the magnetic exchange interactions, increasing the Curie temperature to 381 K. The Fe also increases the Ni magnetic moment to 0.41 μB relative to that in the stoichiometric Heusle…
Polycrystalline boron carbon nitride (BCN) films are synthesized at various temperatures by plasma-assisted chemical-vapor deposition. BCN films are characterized by x-ray photoelectron spectroscopy, transmission electron microscopy, and transmission electron diffraction. The dielectric constant is estimated from the…
Pure, selected samples of antigorite (#7 and #18, from Elba Island veins, Italy, with superperiodicities of 38 and 49 Angstrom, respectively) have been analyzed by Mossbauer and infrared spectroscopies. Mossbauer data indicate that most of the iron is present as ferrous iron (88.6% Fe2+ in #7 and 83.2% Fe2+ in #18). B…
Fast ultraviolet photoresponse is observed in ZnO thin films prepared by unbalanced magnetron sputtering. Films with a porous microstructure and a mixed (100), (002) and (101) crystallographic orientation exhibit photoresponse with good linearity and minimal aging effects. A fast rise time of 792 ms and a fall time of…
We have fabricated single-crystalline thin films of perovskite-type iron oxide SrFeO3 which include high valent iron (Fe4+). The fabrication is accomplished on the lattice-mismatched substrates of SrTiO3 [(STO), 1.4% tensile strain] and (LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7 [(LSAT), 0.5% tensile strain] by pulsed-laser depos…
Ultrathin multilayer films consisting of the polyoxotungstoeuropate cluster K12[EuP5W30O110] (EuP5W30) and poly(allylamine hydrochloride) (PAH) have been prepared by the layer-by-layer self-assembly method. The (EuP5W30/PAH) multilayer films have been characterized by small-angle X-ray reflectivity measurements, X-ray…
Using the Landau–Ginzburg–Devonshire approach, the longitudinal piezoelectric coefficient in an arbitrary direction, d33*(θ), was calculated as a function of temperature in tetragonal BaTiO3 crystals. The direction along which d33*(θ) is maximum is a function of piezoelectric dij coefficients referred to the crystallo…
A method to electronically modulate the energy gap and bandstructure of semiconducting carbon nanotubes is proposed. We investigate this bandstructure modulation mechanism using tight-binding and density functional theory (DFT). Results show that the energy gap of a semiconducting nanotube can be narrowed, when the tu…
Emission gain narrowing has been observed for single crystals of a thiophene/phenylene co-oligomer. The hexagon flake crystals were placed on a quartz substrate with the crystals’ face in close contact with the substrate plane. These crystals were irradiated with a N2 laser with a 337.1 nm wavelength at a repetition r…
The electrical conduction mechanism of (Ba0.5,Sr0.5)TiO3 (BST) as a function of the temperature was studied. Au/BST/Pt metal–insulator–metal capacitors were fabricated. The temperature range was from 300 to 423 K. The conduction current depended on the voltage polarity. At high electrical field (>800 kV/cm) and…
Microelectromechanical systems (MEMS) create an opportunity for the development of smaller, cheaper, and more precise biomedical instrumentation and devices. Little is known, however, about the hemocompatibility of the materials used to fabricate these devices. Because of the potentially harmful consequences of thromb…
By employing density-functional theory calculations we predict graphitic and tubular forms of silicon carbide (SiC) and proposes their synthesis. The present calculations suggest that the metastable SiC tubes can be synthesized by using a technique of extreme hole injection [J. M. Schön, Ch. Kloc, and B. Batlogg, Natu…
The syntheses of [Fe(L1H)2]X2 (L1H = 2,6-di(pyrazol-1-yl)pyridine [L1H]; X− = BF4−, PF6−) are described. Solvent-free [Fe(L1H)2][BF4]2 shows an approximately D2d-symmetric metal centre in the crystal, and undergoes an unusual abrupt spin-state transition centered at 261 K in the solid, or at 248 K in acetone solution.…
A stochastic discrete drift-diffusion model is proposed to account for the effects of shot noise in weakly coupled, highly doped semiconductor superlattices. Their current-voltage characteristics consist of a number stable multistable branches corresponding to electric field profiles displaying two domains separated b…
We report electrical spin injection from a ferromagnetic metal contact into a semiconductor light emitting diode structure with an injection efficiency of 30% which persists to room temperature. The Schottky barrier formed at the Fe/AlGaAs interface provides a natural tunnel barrier for injection of spin polarized ele…
We examine the feasibility of a simple description of Mn ions in III-V diluted magnetic semiconductors (DMSs) in terms of two species (components), motivated by the expectation that the Mn-hole exchange couplings are widely distributed, expecially for low Mn concentrations. We find, using distributions indicated by re…
We extend a lattice Boltzmann algorithm of liquid crystal hydrodynamics to include an applied electric field. The approach solves the equations of motion written in terms of a tensor order parameter. Back-flow effects and the hydrodynamics of topological defects are included. We investigate some of the dynamics releva…
We report measurements of electrical resistivity, thermopower, thermal conductivity, and Hall coefficient of polycrystalline Eu-doped CoSb3-based skutterudites with compositions Eu0.20Co4Sb12, Eu0.43Co4Sb11.59Ge0.31, and Eu0.42Co4Sb11.37Ge0.50. The relatively high mobility of these compounds, as compared to that of La…
Doping wide-gap materials p type is highly desirable but often difficult. This makes the recent discovery of p-type delafossite oxides, ${\mathrm{CuM}}^{\mathrm{III}}{\mathrm{O}}_{2}$, very attractive. The ${\mathrm{CuM}}^{\mathrm{III}}{\mathrm{O}}_{2}$ also show unique and unexplained physical properties: Increasing…