Materials Literature
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Ks.sHI.5(SbW6024).6H20, Mr = 1933.48, trigonal, P3ml, a = 13.672 (3), c = 12.908 (5) A, V = 2089 (1)/~3, Z = 2, D,,, = 3.20, Dx = 3.07 g cm-3, A(Mo Ka) = 0.71069 A, # = 182.25 cm-~, F(000) = 1706, T = 298 K, final R = 0.060 and wR = 0.080 for 1089 independent reflections. The (5bW6024) 7- anion shows the Anderson-type…
A highly anisotropic Heisenberg spin one-half Hamiltonian is derived for the organometallic charge-transfer ferromagnet DMeFc-TCNE and its effective exchange parameters are estimated. Its relationship to the generally adopted McConnell picture of ferromagnetic interaction in such systems is established and particular…
The valence-band ultraviolet photoemission spectrum of ${\mathrm{VO}}_{2}$ has been studied above and below the semiconductor-metal phase-transition temperature (\ensuremath{\approxeq}340 K) as a function of exposure to hydrogen. Evidence is found for a partial reduction of the surface, leading to formation of adsorbe…
The role of resonance centers in obtaining large size matrices via an artificial intelligence (AI) search is discussed. The results are used to develop for an AI search an evaluation function which takes cognizance of isolated internal resonances in these many-state systems. The effect of later-accepted states on reso…
Abstract The isothermal crystallization from the melt of unreinforced poly(phenylene sulfide) (PPS) and of model carbon, aramid, and glass‐fiber‐reinforced PPS composites was studied by differential scanning calorimetry and optical microscopy. Crystallization was studied as a function of temperature, and the fiber con…
The rounding of the charge-density-wave depinning transition by thermal noise is examined. Hops by localized modes over small barriers trigger ``avalanches,'' resulting in a creep velocity much larger than that expected from comparing thermal energies with typical barriers. For a field equal to the T=0 depinning field…
An ab initio pseudopotential density-functional study of magnetic iron using both the standard local-spin-density approximation and a generalized gradient-expansion approximation is described. The core-valence overlap in this material is found to be important and is treated carefully in the calculation. A mixed-basis…
Quasiparticle excitation energies are calculated using the GW method for diamond under hydrostatic pressures up to 500 GPa and for one tetragonal configuration under an assumed additional stress in the [001] direction. The self-energy operator is approximated with a model for the static screened Coulomb interaction an…
Our previous work on time evolution of the interfacial structure for a near critical mixture of polybutadiene and polyisoprene undergoing the spinodal decomposition (SD) [T. Hashimoto, M. Takenaka, and H. Jinnai, J. Appl. Crystallogr. 24, 457 (1991)] was extended to explore the behavior as a function of temperature T,…
The glass transition of a two-dimensional melt of lattice polymers is discussed. The glass temperature Tg is determined by the free volume approach, by the isothermal compressibility as well as by other methods. The decay of the bond autocorrelation function displays typical glasslike behavior. The time temperature su…
Abstract The reaction of maleic anhydride (MAH) with molten 2 MI poly(ethylene‐ co ‐butene‐1) (LLDPE) at 160°C in the presence of peroxyesters ( t 1/2 < 10 s) as catalysts resulted in the formation of a mixture of cross‐linked and trichlorobenzene‐soluble LLDPE‐ g ‐MAH. The soluble fraction constituted more than 50…
The coadsorption of oxygen and carbon monoxide on the stepped Pt(112) surface has been studied using electron stimulated desorption–ion angular distribution (ESDIAD), temperature programmed desorption (TPD), and low energy electron diffraction (LEED). It has been possible to preferentially adsorb different isotopic CO…
Spectral shapes of optical absorptions in the charge density wave states of halogen-bridged mixed-valent metal complexes are theoretically determined for the first time, using a one-dimensional extended Peierls-Hubbard model. Two important effects beyond the mean field theory are taken into account; the electron-hole…
We present theoretical studies of the electronic and optical properties of free-standing Si quantum wires which exist in porous Si. We use a second-neighbor empirical tight-binding model which includes d orbitals and spin-orbit interaction. The excitonic effects are included within the effective-mass approximation. We…
Recent reports describing photoluminescence in porous silicon have heightened the level of interest in it as a unique electronic material, and have created a need for a more complete understanding of the mechanism of porous silicon formation. The various models describing porous silicon formation are reviewed and the…
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” opt…
Polarized electrons were scattered from zinc, cadmium and indium atoms which were unpolarized. Elastic scattering asymmetries were observed at energies ranging from 0.3 (for Cd) to 14 eV and at angles from 30' to 125'. For indium inelastic scattering asymmetries were also measured. Comparing the asymmetries obtained f…
This paper presents experimental results of space-charge distribution in cross-linked polyethylene (XLPE) by a pulsed electroacoustic method. The influence of polarity reversal on space-charge distribution in degassed XLPE and as-received XLPE is studied to understand the transport and injection of charges under DC vo…
It is shown that the diffusion of Cu into the Ni layer of a Ni/Cu bilayer film after thermal annealing is significantly reduced when the deposition temperature of the Ni layer is raised from approximately 50 to 200 °C. The effect of the deposition temperature on the physical structure of the Ni layer and the possible…
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1992.