Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
We conduct a theoretical study of the temperature dependence of the spin polarization ( P) and the magnetoresistance (MR) ratio using the double exchange (DE) model for ferromagnetic tunnel junctions with half-metallic systems. It is shown that the strong exchange coupling in the DE model plays an important role in th…
Silicon (Si) nanocrystallites have been synthesized using pulsed-laser ablation in inert background gases, for studying the structures and optical properties as one of the quantum confinement effects. We extracted a process condition where well-dispersed Si nanocrystallites devoid of droplets and debris are prepared,…
Squashing brings circumferentially separated areas of a carbon nanotube into close proximity, drastically altering the low-energy electronic properties and (in some cases) reversing standard rules for metallic versus semiconducting behavior. Such a deformation mode, not requiring motion of tube ends, may be useful for…
We here study electronic structure and magnetic properties of disordered CoPd and CoPt alloys using Augmented Space Recursion technique coupled with the tight-binding linearized muffin tin orbital (TB-LMTO) method. Effect of short range ordering present in disordered phase of alloys on electronic and magnetic properti…
We present calculations of the one- and two-particle excitations in silicon nanocrystals. The one-particle properties are handled in the GW approximation, and the excitonic gap is obtained from the Bethe-Salpeter equation. We develop a tight binding version of these methods to treat clusters up to 275 atoms. The self-…
A theory of scattering by charged dislocation lines in a two-dimensional electron gas (2DEG) is developed. The theory is directed towards understanding transport in AlGaN/GaN high-electron-mobility transistors (HEMT), which have a large number of line dislocations piercing through the 2DEG. The scattering time due to…
The full set of partial structure factors for the prototypical network glass GeSe2 was measured using the method of isotopic substitution in neutron diffraction. The basic building block of the network is the Ge(Se(1/2))(4) tetrahedron in which 34(5)% of the Ge reside in edge-sharing configurations. The intrinsic chem…
Two transitions in the bonding are found in tetrahedral amorphous carbon (ta-C) films as a function of deposition temperature. The total sp3 fraction shows a sharp decrease at a transition temperature of order 250 °C. In contrast, visible Raman finds that the sp2 sites show a gradual ordering into the graphitic cluste…
A highly substituted side chain NLO poly( p -phenylene) (∼70.1 wt % NLOphore) has been prepared by the nickel-catalyzed coupling of 4‘-( N, N -diethylamino)-2,5-dichlorobenzophenone. Poly((4‘- N, N -diethylamino)-2,5-benzophenone), PDEABP, is a modest molecular weight material ( M n = 5300) that is thermally stable up…
IM7 PAN-based carbon fibers, with a proprietary surface treatment applied by the manufacturer, were analyzed by X-ray photoelectron spectroscopy (XPS). The surface treatment applied by the manufacturer was removed by heating in a vacuum. The fibers detreated in this manner were then subjected to electrochemical treatm…
The development of cost-effective nanopowder production methods has been a major obstacle to the development and industrial utilization of nanostructured materials. This paper describes a new cost-effective production technology for these materials which combines both pulsed electrochemistry and pulsed ultrasound. Thi…
The Suzuki polycondensation of the amphiphilically equipped dibromobenzene derivatives 8 and 11 with benzene diboronic acid ester 12 to the new kind of polymeric amphiphiles 13 and 14 is described. They carry at each repeat unit either a hydrophobic alkyl chain and a hydrophilic dendron with oligoethyleneoxy chains (…
Polythiophene−transition metal hybrid materials based on cobalt salen have been prepared and shown to catalyze the reduction of O2. The conjugated nature of the polymer backbone allows for facile electron transfer from the polymer surface to the active metal centers to affect this reduction. Rotating ring−disk measure…
A chiral cyclohexane containing two photochromic diarylethene units was synthesized in an attempt to use it as a dopant for a photoresponsive liquid crystal. A stable photoswitching between nematic and cholesteric phases could be induced by the addition of a small amount of the chiral cyclohexane to a nematic liquid c…
Rheological behavior of the first eight generations of bulk polyamidoamine (PAMAM) dendrimers, having nominal molecular weights from about 500 to over 116 000, was investigated under steady shear, shear creep, and dynamic oscillatory shear within the temperature range from T g + 15 °C to T g + 105 °C. It was found tha…
Phosphatidylcholine vesicles provide reaction compartments for the synthesis of nanometer-size CdS, Zn y Cd 1 - y S, and Hg y Cd 1 - y S particles with size- and composition-tunable absorbance and luminescence features. Spectrophotometric and spectrofluorimetric measurements are consistent with crystalline, monodisper…
Nonlinear optical dendritic macromolecules, called azobenzene dendrons, were synthesized, and their conformational properties and molecular nonlinear optical properties were clarified by second-order nonlinear optical measurement. The synthesized molecules were modified by introducing 1−15 numbers of azobenzene branch…
Nanocrystals of ZnO have been produced by an alkoxide based synthesis involving diethylzinc, tert -butyl alcohol, ethanol, and water. The resulting ZnO is in the form of a powder made up of zincite crystallites in the size range of 3−5 nm. These crystallites aggregate together to form larger spherical particles. These…
A bulk polycrystalline sample of YBa_(2)Cu_(3)O_(7-δ) (δ\approx 0.1) has been irradiated by γ-rays with ^{60}Co source. Non-monotonic behavior of T_{c} with increasing irradiation dose Φ(up to 220 MR) is observed: T_{c} decreases at low doses (Φ< 50 MR) from initial value (\approx 93 K) by about 2 K and then rises, fo…
Stability constants are reported for the coordination of pyridine and substituted pyridines to the alkylcobalt(III) complexes of octaethylporphyrin (OEP), t-octaethylchlorin (OEC), and ttt-octaethylisobacteriochlorin (OEiBC) in toluene solution. The stability constants correlate with the base strength of the nitrogeno…