Materials Literature
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Abstract The blends of epoxidized natural rubber (50 mol %) (ENR) and poly(ethylene‐ co ‐acrylic acid) (PEA) (6 wt %) are demonstrated to be partially miscible up to 50% by weight of PEA and completely miscible beyond this proportion. The miscibility has been confirmed by a DSC study which exhibits a single second‐ord…
Ab initio local-density-functional-theory calculations of formation energies, surface stress, and multilayer relaxations are reported for the (111), (100), and (110) surfaces of Rh. The study is performed using ultrasoft pseudopotentials and plane waves in a parallel implementation. Calculated values are in good agree…
Diamond thin films, 5 μm in thickness, were grown selectively on patterns of porous silicon by hot-filament chemical vapor deposition (HFCVD). Monocrystalline p-type silicon substrates, with (100) orientation and resistivity 5–15 Ω cm, were patterned by conventional photolithography to provide a photoresist mask for s…
A range of amorphous hydrogenated carbon (a-C:H) samples have been studied using inelastic neutron spectroscopy (INS) and Fourier transform infrared (FTIR) spectroscopy. Using these complementary techniques, the bonding environments of both carbon and hydrogen can be probed in some detail, with the INS data providing…
The results of a comprehensive positronium annihilation study of the phase behaviour of carbon dioxide in porous Vycor glass are presented. Isobaric measurements of the 3 gamma :2 gamma annihilation ratio show that on cooling, the gas-liquid phase boundary is raised by ~5 K while the liquid-solid transition is depress…
Both the Young`s modulus sound velocity (V E ) and the internal friction (Q -1 ) have been measured for a polycrystalline sample of LiMn 2 O 4 in the temperature range between 35 and 350 K, using a vibrating-reed technique. The resonance frequency (f r ) employed for the measurement ranged from 0.81 kHz to 2.69 kHz at…
Interaction between two partial 90\ifmmode^\circ\else\textdegree\fi{} edge dislocations is studied with atomic-scale simulations using the effective-medium tight-binding method. A large separation between the two dislocations (up to 30 \AA{}), comparable to experimental values, is achieved with a solution of the tight…
A theory is presented for core hole polarization probed by spin polarization and magnetic dichroism in resonant photoemission. The resonant photoemission is considered as a two-step process, starting with an excitation from a core level to the valence shell, after which the core hole decays into two shallower core hol…
Characteristics of Schottky barriers formed on homoepitaxial diamond film have been studied. Current–voltage characteristics of Al contacts on both the as-grown film and the oxidized film show rectification. On the other hand, ohmic property is observed on Au/as-grown film while Au/oxidized film shows rectification. T…
The entropic depletion force in colloids arises when large particles are placed in a solution of smaller ones and sterically constrained to avoid them. We calculate the interaction between two hard spheres (of radius $R$) in a semidilute solution of hard rods of length $L$ and diameter $D$ ($D\ensuremath{\ll}L\ensurem…
A series of mixtures composed of a symmetric $A\ensuremath{-}B$ diblock copolymer and a symmetric blend of $A$ and $B$ homopolymers was investigated by small-angle neutron scattering. Mean-field theory predicts that a line of lamellar-disorder transitions with wave-vector instability ${q}^{*}>0$ will meet a line of…
This work investigates the temperature dependence of GaAs/AlAs thin-film structures. Based on an ac calorimetric method, the thermal diffusivity of a 700 Å/700 Å GaAs/AlAs periodic structure is measured from 190 to 450 K. Thermal conductivity of the structure is derived from the experiment. The results demonstrate tha…
The magnetic transitions in ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}\mathrm{Mn}{\mathrm{O}}_{3}$ ($x=0.25, 0.50$) were studied by synchrotron x-ray and neutron powder diffraction. For $x=0.25$ the large $\ensuremath{\Delta}V=0.13%$ at ${T}_{C}$ is due to the simultaneous insulator-to-metal transition. For $x…
We report measurements of the de Haas-van Alphen (dHvA) effect in the quasi-two-dimensional organic metal κ-(BEDT-TTF) 2 Cu(NCS) 2 by means of a capacitive torquemeter. The experiments were carried out in magnetic fields up to 29.5 T, at temperatures down to 0.4 K and for tilt angles θ between -35° and 80°. In the ang…
It is shown that the guided-mode resonance effects associated with waveguide gratings can be used to realize transmission bandpass filters. The key idea is the integration of the resonant waveguide gratings into a dielectric multilayer structure that efficiently reflects the off-resonance spectral components while pas…
An array of polymer grid triodes connected by a common grid functions as a “plastic retina,” providing local contrast gain control for image enhancement. This simple device, made from layers of conducting polymers, functions as an active resistive network that performs center-surround filtering. The polymer grid triod…
A theory based upon normal mode analysis (NMA) is used to calculate the self-diffusion constant, D, in the unit density Lennard-Jones liquid. The theory, which uses no adjustable parameters, is in good agreement with computer simulation over the reduced temperature range 20≥T≥0.42. Thus NMA appears applicable to syste…
The characteristics of the solid/liquid transition for a modified Simple Point Charge model of water have been determined using free energy calculations supported by nonequilibrium Molecular Dynamics (NEMD) simulations. We have considered the behavior of liquid water and of a variety of ice phases. Unlike real water,…
The specific interactions between sulphonic acid protonated polyaniline (PANI) and solvents are here studied both by the semiempirical AM1 method and experimentally. Phenolic solvents are shown to have a relatively large interaction with the sulphonate anions of the counterions and with the amines in PANI. In addition…
We report on a novel approach to the Deam-Edwards model (1976) for interacting polymeric networks without using replicas. Our approach utilizes the fact that a network modelled from a single non-interacting Gaussian chain of macroscopic size can be solved exactly, even for randomly distributed crosslinking junctions.…