Materials Literature
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The polar interface interaction between a chiral smectic-A liquid crystal and a solid substrate results in an induced ferroelectric polarization and chiral reorientation of the director in the liquid crystal near the surface.
We employ density functional methods to derive the free energy and grand potential functionals appropriate to homopolymers and blends. The grand potential functionals are minimized by the single-monomer densities of the blends or homopolymers, and the nonideal portions of the free energies possess functional Taylor ex…
In some crystalline and glass ceramic IR upconverting materials, the visible light intensity resulting from the IR excitation can be reduced by a prior x-ray exposure. Such behavior is studied for medical x-ray imaging applications. A model is developed to describe the interactions between the microscopic defects resp…
C 4 H 4 INO 2 cristallise dans P4 1 ou P4 3 avec a=6,339 et c=15,445 A, Z=4; affinement jusqu'a R=0,019. La structure est stabilisee par de fortes interactions intermoleculaires I...O. La polarisation calculee pour un monocristal et les resultats d'un test pyroelectrique de Kundt-Burker conduisent a une attribution de…
(LaS) 1.14 NbS 2 is a misfit layer compound built of alternate double layers of LaS with La in square pyramidal coordination with sulphur and sandwiched with NbS 2 as occurs in 2H-NbS 2 . The electrical transport properties and magnetic properties were determined using single crystals and powder compacts. The compound…
A new type of Monte Carlo algorithm to calculate packing fraction and general particle dispersion characteristics for arbitrary random packs of spherical particles is presented. Given arbitrary quantities of arbitrary sizes with arbitrary mass densities, the algorithms calculate the close random packing fraction. If d…
A gas-phase reaction mechanism is proposed for the chemical vapor deposition (CVD) of amorphous silicon from silane or disilane at atmospheric pressure. The gas stream in the CVD reactor is populated by silanes, silylenes, and disilenes in a variety of sizes. Silylenes form by the decomposition of silanes, and they ra…
In ultrasmall quantum nanostructures the interparticle Coulomb energy is a small perturbation to single-particle confinement and kinetic energies. Third-order perturbation theory has been used to calculate energies of excitons and biexcitons confined in quantum box nanostructures. The confined biexciton is more stable…
Using fully quantal methods, we investigate various manifestations of the geometric phase in bound and free diatom systems. Adiabaticity and degeneracy are not invoked in the discussion.Received 3 May 1989DOI:https://doi.org/10.1103/PhysRevLett.64.256©1990 American Physical Society
Visible luminescence between 2.0–3.5 eV of undoped and boron-doped diamond formed by plasma-assisted chemical vapor deposition has been investigated by cathodoluminescence. Electroluminescence from Schottky diode of boron-doped semiconducting diamond has been observed for the first time and found to be due to the same…
Molecular dynamics calculations have been used to study structural relaxation and dynamical correlations near the glass transition in the system [Ca(NO3)2]0.4[KNO3]0.6. As in a typical molten salt, the overall structure is determined by charge ordering. However, the radial distribution function for Ca2+ ions is unusua…
The electronic structures of NiMnSb and CrO 2 were calculated using a spin-polarised scalar relativistic linear muffin-tin orbital (LMTO) method. The self-consistent calculations were performed for the observed experimental lattice constants. Cubic NiMnSb (MgAgAs-type structure) and rutile-structure CrO 2 are found to…
Both magnetization and thermal expansion measurements have been made on the same samples of Fe x Co 1- x Si alloys. The magnetization data is analyzed on the basis of the spin fluctuation theory developed by Takahashi to obtain information on the nature of spin fluctuations of this system. We found that concentration…
Detailed measurements of the complex dielectric function ε=ε′−iε″ as functions of frequency between 45 MHz and 20 GHz and concentration c are presented and analyzed for LiCl/H2O solutions. In this frequency range, the dielectric response is due to free water molecules and the response of the bound water occurs at lowe…
The crystal structure of the compound, bis(piperidinium)tetrabromocuprate(II) [(pipdH${)}_{2}$${\mathrm{CuBr}}_{4}$] is monoclinic, space group P${2}_{1}$/c, with a=8.487(2) A\r{}, b=17.225(3) A\r{}, c=12.380(2) A\r{}, and \ensuremath{\beta}=99.29(2)\ifmmode^\circ\else\textdegree\fi{}. The structure consists of isolat…
The c-axis resistivity (${\ensuremath{\rho}}_{c}$) and its temperature dependence of highly oriented pyrolytic graphite have been studied in connection with the characteristic stacking-fault structure. In order to account for the observations, the pioneering theory of Ono on the tunneling conduction through the stacki…
The cyclic process of biosynthesis and degradation of poly(3-hydroxyalkanoate) (PHA) was studied in Alcaligenes eutrophus under conditions of nitrogen-limitation of growth. A. eutrophus cells, which had accumulated poly(3-hydroxybutyrate) (PHB) of 55 wt% content within cells from butyric acid, were transferred into a…
We use simple arguments to fix the range of density of randomly distributed defects over which π electrons in a graphite sheet are strongly localized, but the underlying two-dimensional carbon network remains connected. This ‘‘defeated graphite’’ construct leads to simple structural models of both hydrogenated and unh…
We present valence effective Hamiltonian (VEH) calculations on the optical absorptions of a series of phthalocyanine compounds: the metal-free phthalocyanine molecule, a model system for the lithium phthalocyanine molecule, the metal-free phthalocyanine dimer, and model systems for the lutetium diphthalocyanine and th…
Electron emitters in vacuum microelectronic devices need sharp tips in order to permit electron emission at moderate voltages. A method has been found for preparing uniform silicon tips with a radius of curvature less than 1 nm. These tips are formed by oxidation of 5-μm-high silicon cones through exploitation of a kn…