Materials Literature
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Reversible modification of the optical and electrical properties of V 2 O 5 × n H 2 O gel films under the action of an electric field is studied. It is shown that under cathodic polarization ( I = 10 -6 -10 -5 A, t ~10min, film thickness ~10 µm), the films turn from brownish-yellow to red. This internal electrochromic…
Neutron-diffraction measurements in ${\mathrm{L}\mathrm{a}\mathrm{C}\mathrm{r}\mathrm{S}\mathrm{b}}_{3}$ show a coexistence of ferromagnetic and antiferromagnetic sublattices below ${T}_{C}=126\text{ }\text{ }\mathrm{K}$, with ordered moments of 1.65(4) and $0.49(4){\ensuremath{\mu}}_{B}/\mathrm{\text{formula unit}}$,…
A hierarchical self-assembly in comb-shaped supramolecules of conjugated rodlike polymers is reported. The supramolecules consist of poly(2,5-pyridinediyl), acid dopants, and hydrogen bonded alkyl side chains. A thermotropic smectic state with an exceptionally large coherence length is formed without additional solven…
The a.c. conductivity σ ac of polyaniline prepared with a.c. plasma polymerization was studied recently at low angular frequencies (ω⩽1 MHz) (Mathai J et al 2002 J. Phys. D: Appl. Phys. 35 240). The data were analysed considering a power dependence of the a.c. conductivity on frequency σ ac ∝ω n , n ⩽1. It was found t…
Boron carbide nanorods were prepared on a large scale directly from the reaction of carbon nanotubes with boron powder at 1150 °C. The bent carbon nanotubes transform into straight nanorods during the reaction. The atomic ratio of B to C in the nanorods is very close to 4 ∶ 1, corresponding to the compound B4C. Carbon…
We present experimental measurements of sound velocity and absorption in a commercial shaving foam. We observe that both quantities evolve with time as the foam coarsens increasing its mean bubble radius <R>. By varying the acoustic frequency we probe the foam from the large wavelength regime, lambda approximately 150…
An anisotropic liquid crystal gel with low operating voltage, high contrast ratio, broad bandwidth, wide viewing angle, and fast response time was demonstrated. In the voltage-off state, the gel is highly transparent. When the gel is activated by an electric field, light scattering occurs for the polarization along th…
Electronic band structures of single-crystal and single-layer ${\mathrm{WS}}_{2}$ are investigated by first-principles calculations based on local-density-functional theory using a plane-wave basis with ultrasoft pseudopotentials. The band structure calculated for the single crystal corresponds very well with experime…
Nanocomposite films containing silver particles embedded in SiO 2 matrix were prepared by high pressure (~40 Pa) d.c. sputtering technique in an argon plasma on fused silica substrate. Particle size and metal volume fraction were tailored by varying the substrate temperature ( T s ~233-300 K) and deposition time (15-2…
We have investigated the generalized susceptibility $\ensuremath{\chi}(\mathbf{q})$ and Fermi-surface-nesting of the ferromagnetic shape-memory alloy ${\mathrm{Ni}}_{2}\mathrm{MnGa}.$ As the temperature is lowered below the Curie point, a premartensitic transformation takes place when the magnetization reaches about 8…
Carbon nanotube metal–insulator–semiconductor capacitors are examined theoretically. For the densely packed array of nanotubes on a planar insulator, the capacitance per tube is reduced due to the screening of the charge on the gate plane by the neighboring nanotubes. In contrast to the silicon metal–oxide–semiconduct…
We discuss applicability of the variable stripe length method to experimental investigation of optical gain in a luminescent layer that behaves like a planar waveguide. We show that an interplay between the output direction of guided light modes and the numerical aperture of the collection optics may lead to an artifa…
Pure and iodine-doped polyaniline thin films are prepared by ac plasma polymerization technique. Doping of iodine is carried out in situ as well as by employing iodine chamber methods. The structural analyses of pure and iodine-doped polyaniline thin films are carried out by FTIR spectroscopic studies. Optical bandgap…
A new dizinc-monoalkoxide complex supported by a dinucleating ligand was structurally characterized and shown to be a highly active catalyst for the controlled polymerization of lactide.
Recent experimental and theoretical reports on the structure of lead zirconate titanate $[\mathrm{Pb}({\mathrm{Zr}}_{x}{\mathrm{Ti}}_{1\ensuremath{-}x}){\mathrm{O}}_{3}$ (PZT)] ceramics with compositions in the vicinity of the morphotropic phase boundary are discussed. There has been ambiguity concerning the low-tempe…
Two polymer–montmorillonite (MMT) nanocomposites have been synthesized by in situ intercalative polymerization. The styrene monomer is intercalated into the interlayer space of organically modified MMT, a layered clay mineral. Upon the intercalation, the complex is subsequently polymerized in the confinement environme…
We have computed the local magnetic moments of manganese and neighboring arsenic for various cluster configurations on the (001) surface of GaAs bulk crystal using a cluster of 512 atoms. We obtained for manganese a substantial local magnetic moment of 3.66 Bohr magnetons for all cases considered. The induced magnetic…
The electronic structures of zig-zag and arm-chair single-walled carbon nanotubes interacting with a transitional-metal atomic nanowire of Ni have been determined. The Ni nanowire creates a large electron density of states (DOS)at the Fermi energy. The dependence of the enhanced DOS on the spin state and positioning o…
Polycrystalline MgB2 samples with 10 wt % silicon powder addition were prepared by an in-situ reaction process. Two different Si powders, one with coarse (44 mm) and the other with nano-size (<100 nm) particles were used for making samples. The phases, microstructures, and flux pinning were characterized by XRD, TEM,…
Electroluminescence in organic light emitting diode (OLED) materials occurs via the recombination of excitonic electrons-hole pairs Only the singlet excitons of commonly used OLED materials, e.g., Aluminum trihydroxyquinoline (AlQ$_3$), decay radiatively, limiting the external quantum efficiency to a maximum 25%. Thus…