Materials Literature
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The temperature evolution of the frequencies and absorption cross section of the infrared-active phonons near 795 cm -1 and 695 cm -1 and the Raman-active mode near 355 cm -1 follow that of the symmetry-breaking order parameter of the alpha - beta phase transition in quartz. The IR signal at 695 cm -1 and the Raman si…
In the present paper, dielectric, polarization, and Raman results have been combined to identify the existence of a ferroelectric phase transition in the substitutionally disordered dipolar system, ${\mathrm{KTa}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Nb}}_{\mathit{x}}$${\mathrm{O}}_{3}$, for low Nb concentra…
The elasticity and hardness of a-C and a-C:H are related to their mean network coordinations. It is shown that ${\mathit{sp}}^{2}$ sites contribute no rigidity if they form graphitic clusters, as suggested by experiment and electronic structure calculations, despite their having coordinations above the critical value…
Superconductors are considered in which there occur fluctuations of one crystallographic structure inside another. The role of these heterostructural fluctuations on superconducting properties are analysed. The occurrence of these fluctuations explains anomalous saggings of Mössbauer factor at phase transition in high…
An optical architecture is proposed that uses two modified liquid-crystal televisions (LCTV's) to control amplitude and phase modulation independently. Two applications in pattern recognition are discussed.
A number of unnatural amino acids and amino acid analogs with modified backbone structures were substituted for alanine-82 in T4 lysozyme. Replacements included alpha,alpha-disubstituted amino acids, N-alkyl amino acids, and lactic acid, an isoelectronic analog of alanine. The effects of these electronic and structura…
Preface 1. Shape and growth of crystals P. Nozieres 2. Instabilities of planar solidification fronts B. Caroli, C. Caroli and B. Roulet 3. An introduction to the kinetics of first-order phase transition J. S. Langer 4. Dendritic growth and related topics Y. Pomeau and M. Ben Amar 5. Growth and aggregation far from equ…
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…
A simple density functional theory for the various liquid-crystalline phases of parallel hard spherocylinders is formulated on the basis of Pynn's ansatz for the direct correlation function of the spherocylinders. Fair agreement with the computer simulations is found.
The geometrical structure associated with visible points in a lattice is investigated. It appears to be the Mobius transform of the original lattice. The related symmetry group and structure factor are explicitly derived.
We present electronic-structure calculations for various rational approximants to icosahedral quasi-crystals. We show that structure-induced minima in the electronic DOS exist in all phases. This pseudogap leads to a lowering of the structural energy by a Hume-Rothery-like mechanism.
The photovoltaic (PV) power system for Space Station Freedom (SSF) uses solar array blankets which provide structural support for the solar cells and house the electrical interconnections. In the low Earth orbital (LEO) environment where SSF will be located, surfaces will be exposed to potentially damaging environment…
The electronic band structure for the ferrimagnetic state of Mn 2 Sb has been calculated using the augmented plane-wave method. The energy splitting between the spin-up and spin-down bands cannot be described by a rigid splitting of the nonmagnetic band. It has been found that the width of 3d band of Mn(II) atoms is n…
We have made carbon K edge reflectivity and absorption measurements using synchrotron radiation on diamond crystals and chemical vapor deposited diamond films to determine their electronic structures. Our spectra of diamond films show that both sp2 and sp3 bonded carbon atoms are formed during initial nucleation and g…
The temperature dependence of the nonergodicity parameter ${\mathit{f}}_{\mathit{q}}$ in the ``fragile'' glass-former propylene carbonate has been investigated using a wide-frequency-window Brillouin-scattering technique. A critical decrease of ${\mathit{f}}_{\mathit{q}}$ is revealed at temperatures well above the cal…
The mechanism of copper chemical vapor deposition from Cu(II)bis-hexafluoroacetylacetonate [Cu(hfac)2] and 1,5-cyclooctadiene-Cu(I)-hexafluoroacetylacetonate (COD-Cu-hfac) has been determined. The results explain the different processing conditions required for deposition from the precursors. Both molecules react at r…
Epitaxial BaTiO3 thin films were grown in situ on (100) LaAlO3 by low-pressure organometallic chemical vapor deposition using the precursors Ba (hexafluoroacetylacetonate)2 (tetraglyme) and titanium tetraisopropoxide. The phase composition and epitaxial quality were sensitive to the reactant partial pressures and grow…
A series of rare-earth iron carbides were prepared by heat treatment of R2Fe17 compounds in methane. The nominal composition of these carbides is R2Fe17Cx, x∼2.5. The carbides retain the original Th2Zn17 or Th2Ni17 structure with a 6.5% volume expansion over the carbon-free unit cell. For Sm2Fe17C2.5, the Curie temper…
Studying the dynamic structure factor of polybutadiene in the first valley of S(Q) we observed a decoupling of microscopic and macroscopic time scales about 40\ifmmode^\circ\else\textdegree\fi{} above ${\mathit{T}}_{\mathit{g}}$. At higher temperatures the time scale set by the viscosity scales with the microscopic sc…
The ordering in thin films of symmetric diblock copolymers has been studied by neutron reflectivity as a function of temperature and film thickness. Exponentially damped oscillatory variations in the concentration are shown to propagate into the specimens from both surfaces with decay lengths increasing with decreasin…