Materials Literature
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Abstract Samples of crosslinked cis ‐polybutadiene were crystallized at different temperature and drawing degree. The melting behavior of the crystallized samples was analyzed detecting the retractive stress as a function of temperature. The experimental melting data were extrapolated to the equilibrium conditions to…
Abstract The reaction between diisocyanates and diepoxides can produce polyoxazolidones. However, the reaction may be accompanied by concurrent cyclization of isocyanate to produce trimeric isocyanurate. Studies were performed with pure phenyl isocyanate or diphenylmethane‐4,4′‐diisocyanate (MDI) and the diglycidyl et…
Abstract Micro- and macroscopic aspects of large-strain deformation are examined through analyses of shear by using physical and phenomenological models. Past experiments and analyses are first reviewed to reveal current issues and put the present work in perspective. These issues are addressed by a complete set of si…
Abstract The high temperature engineering thermoplastic poly(aryl‐ether–ether‐ketone) (PEEK) has been subjected to dynamic and isothermal thermogravimetry in both nitrogen and air. The dynamic data have been analyzed using both the Kissinger peak maximum technique and an isoconversional procedure developed by Flynn. T…
Abstract The reaction of molten HDPE with MAH at 215 and 250°C using di‐ t ‐amyl peroxide and t ‐butyl cumyl peroxide as catalysts yielded HDPE‐ g ‐MAH accompanied by crosslinked polymer. The formation of the latter, increased by the presence of MAH and insoluble in refluxing xylene, was prevented by the presence of e…
The planar defects which are commonly observed in deposited Co-Cr and Co-Ni-Cr magnetic thin films have been characterized by electron microdiffraction and trace analysis. It was unambiguously shown that these planar defects are (0001) stacking faults, which are thought to be formed to reduce the growth stress of the…
The equilibrium quasicrystal phase of a two-dimensional two-component Lennard-Jones atomic system and two different ensembles of random tilings (binary and uncontrained) are analyzed by means of Monte Carlo simulations. We find that the quasicrystal phase in the atomic system is well described by the random-tiling mod…
We investigate the quasicrystalline state of a two-dimensional binary alloy in a discrete tiling approximation. Through transfer-matrix calculations we determine the configurational entropy over a range of concentrations. We find that the entropy density is maximized by a state with tenfold symmetry at the quasicrysta…
Experimentally it is well known that diamond and zinc-blende semiconductors show an ``unusual'' (i.e., negative) thermal expansion at about 100 K. We performed density-functional-theory calculations of thermodynamic potentials (i.e., total energies and entropies) for perfect crystals, to study the temperature dependen…
Mg 2+ . C 6 H 8 O 8 2- .2H 2 O cristallise dans Cc avec a=7,605, b=8,785 et c=16,404 A, β=92,56˚, Z=8; affinement jusqu'a R=0,052. L'ion galactarate est centrosymetrique et l'ion Mg 2+ a une coordination six (octaedrique). Les distances Mg-O varient de 2,003 a 2,117A
Cristallisation dans Pmnn avec a=5,861, b=20,200 et c=4,501 A, Z=2; affinement jusqu'a R=0,054. U 6+ et Ni 2+ sont localises en feuillets perpendiculaires a [OOz] et entoures d'octaedres. Les atomes B sont en groupes BO 3 triangulaires ou BO 4 tetraedriques et stabilisent la cohesion dans les trois directions. Les oct…
With numerical calculations it is shown that in a Fibonacci superlattice, in a magnetic field parallel to the layers, the self-similarity in the length scale is reproduced in the energy-level structure. In particular, the cyclotron-orbit-center dispersion of the energy levels shows a field-dependent structure which is…
Dipole-forbidden f-f multiplet excitations are found to characterize the electron-energy-loss spectra of Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er when the primary-electron energy is close to the binding energy of the 4d electrons. In Sm and Gd the f-f transitions are also detected at lower primary energies. The identificati…
The occurrence of Yb ions in two charge states (trivalent and divalent) in ZnS is proved with use of the photostimulated electron-paramagnetic-resonance technique. ${\mathrm{Yb}}^{2+}$ is found to form a deep hole-trap center with energy level located at 1.65\ifmmode\pm\else\textpm\fi{}0.05 eV below the bottom of the…
The damage of Sn-doped InP by Ga ion implantation with fluences ranging from 1×1013 to 5×1014 cm−2 and annealing effects (150–650 °C) are investigated by means of Raman scattering. The shift and asymmetrical broadening of a longitudinal optical phonon peak and the appearance of transverse optical mode and disorder-act…
Recently we (J.G.C. and K.S.S.) formulated a tractable ‘‘reference interaction site model’’ (RISM) integral equation theory of flexible polymer liquids. The purpose of this paper is to compare the results of the theory with recent molecular dynamics simulations (G.S.G. and K.K.) on dense chain liquids of degree of pol…
Transparent conducting ZnO films have been prepared by modified S-gun reactive dc magnetron sputtering using an indium doped Zn target. Films with a resistivity of 1.08 x 10(-3) Omega cm and average transmittance of over 80% in the visible region were obtained. The influence of indium content at the surface of Zn targ…
It is shown that the equations of multiple-scattering theory (MST) originally derived for scattering off collections of muffin-tin (MT) potentials, i.e., potential cells bounded by nonoverlapping spheres, remain valid in the case of arbitrarily shaped, nonoverlapping, and particularly space-filling potential cells. Sp…
A small-angle x-ray scattering study of porous layers prepared on lightly doped and heavily doped silicon wafers reveals strong differences according to the dopant type. The p-type silicon layers show a roughness between matter and voids below a space-correlation length of about 10 nm and a fractal dimension of aggreg…
Ising-like interaction parameters are calculated for alloys of Al with the 3d and 4d transition metals. The interactions are obtained by matching to calculated total energies for supercell compounds on an underlying fcc lattice. The dependence of the parameters on the transition-metal d-band filling displays pronounce…