Materials Literature
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We have studied the size-dependent optical properties of confined excitons in chainlike Si-backbone polymers with 5--110 Si atoms. The blueshift of the lowest exciton state was observed with decreasing number of Si atoms. In chains having 20 Si atoms or less, the oscillator strength per Si atom for the lowest exciton…
Cristallisation dans P4 2 /mnm avec a=7.596, c=8.027A, Z=2; affinement jusqu'a R=0.039. L'ion Cu 2+ est dans une coordination octaedrique deformee constituee de deux ions Cl a 3.000A, deux ions Cl a 2.257A et deux molecules d'eau a 1.969A aux positions equatoriales du plan carre. Chaque molecule d'eau est coordinee de…
Abstract We measured the thermal conductivity of a polyethylene/polystyrene blend containing SEBS block copolymer, which has two components of polystyrene block and hydrogenated polybutadiene block, and discussed the effect of phase inversion on the thermal conductivity by observing the morphorogy of the blend. Furthe…
A formalism for obtaining the zero-temperature structure of monocomponent solids in the grand-canonical ensemble is developed. The new methodology, grand-canonical simulated quenching, is validated by simulating systems initially containing a vacancy and an interstitial. As a first application, the reconstruction of a…
Spectroscopic properties of Ni2+ ions substituted in the unidimensional compound CsCdBr3 were investigated from 9 to 300 K. The structured features of the absorption spectrum have been interpreted on the assumption of a trigonal distortion of the Ni2+ site. Four emissions were observed and assigned to the 1T2 →3T2,3T1…
Abstract The kinetic data obtained by differential scanning calorimetry for the isothermal crystallization from the melt of unreinforced poly(phenylene sulfide) (PPS) and of model carbon, aramid, and glass fiber‐reinforced PPS composites has been analyzed and modeled on the basis of the Avrami equation. The classical…
The electronic band structures of PdO and PtO are calculated using the augmented-spherical-wave method and the local-density approximation. Our results are consistent with the widely held view of these materials as conventional band insulators with the crystal-field splitting of metal d states primarily responsible fo…
The electronic band structures of MgSe, CaSe, and SrSe have been calculated by the Hartree-Fock method with correlation corrections included. Our results are compared to optical data on these rocksalt-structure insulators predicting that CaSe is a direct-gap material while both MgSe and SrSe are indirect-gap materials.
The ground state energies of the group IB hexamer (Cu6, Ag6, and Au6) for four possible structural models, namely, 1A1 with a capped pentagonal structure (C5v), 1A1 with a tripyramidal structure (C2v), 1A1g with a circular ring structure (D6h), and 3T2g with an octahedral structure, as well as the positive ions, Cu+6,…
We present a detailed experimental study of the effects of finite crystal size, impurities, and temperature on the properties of charge-density waves (CDW's) in ${\mathrm{NbSe}}_{3}$. Finite-size effects in ${\mathrm{NbSe}}_{3}$ are controlled by the crystal thickness t. They are large in crystals of ordinary thicknes…
Flow microcalorimetry has been used to study microporous silicon produced by electrochemical corrosion of bulk p-type silicon wafers in highly concentrated (50 wt %) aqueous hydrofluoric acid. Calorimetry data on pore size and hydrophobicity of freshly etched crystalline silicon structures are compared with similar me…
In this work the optical properties of natural (IIa) and p-type semiconducting (IIb) diamonds were studied in the neighborhood of the first direct gap, at about 7 eV, whose energy position, nature, and origin are still under debate. The complex dielectric function \ensuremath{\epsilon}(\ensuremath{\omega}) of these ma…
The density of states of pregraphitic (disordered) carbon has been investigated using a tight-binding description of the electronic structure. The tight-binding Hamiltonian has been diagonalized using the recursion method for different stackings of graphene layers. The density of states of \ensuremath{\pi} electrons i…
The structure and dynamical properties of oxygen conductor yttria stabilized zirconia, (ZrO 2 ) 1- x (Y 2 O 3 ) x , are investigated for three dopant concentrations of 4.85, 10.2 and 22.7 mol%Y 2 O 3 using a method of molecular dynamics simulation. It is shown that a Y–O nearest neighbor distance is longer than that f…
A molecular dynamic computer simulation of the cooling of liquid silica to form an amorphous solid (glassy) phase was performed using the potential of Tsuneyuki, Tsukuda, Aoki, and Matsui, which was found to be consistent with the structure of several crystalline phases of silica. In the simulations, at low temperatur…
Abstract Interactions between cellulose and chitosan molecules in cellulose–chitosan blend films, prepared using trifluoroacetic acid as a cosolvent for the two polysaccharides, were studied by X‐ray diffraction and Raman analyses and by measurements of mechanical properties of the blend films. Crystallinity of cellul…
Abstract The effects of sodium alginate on the physical properties of fibroin membranes, such as rupture elongation, rupture strength, water absorption, and thermal properties, were investigated. The experimental results showed the β‐form crystal and β‐form molecular conformation increased due to the increase of inter…
The room temperature, photoluminescent properties of manganese-doped zinc sulfide films deposited by spray pyrolysis are reported. These films were deposited on Pyrex glass substrates at atmospheric pressure using air as a carrier gas. All films were polycrystalline with a wurtzite (hexagonal) structure. The manganese…
The deposition of thin Pb(ZrxTi1−x)O3 films by sol-gel and by metallo-organic decomposition (MOD) processes has been studied. Powders obtained from different precursor solutions were analyzed with respect to their decomposition and crystallization. Using a spin-coating technique, Pb(ZrxTi1−x)O3 films with zirconium co…
The electronic properties of simple hexagonal graphite have been studied in the framework of the density-functional technique, using nonlocal ionic pseudopotentials and a large number of plane waves. This work leads to a first-step qualitative understanding of the electronic properties of nonperiodic structures such a…