Materials Literature
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Thermoelectric power of annealed β-Ag2Se thin films of different thicknesses has been measured both while heating and cooling by the integral method. It is found that it remains practically constant (in β-Ag2Se phase) during heating while it is a function of temperature while cooling. The thermoelectric power in both…
The surface composition of a series of symmetric diblock copolymers of polystyrene (PS) and polymethylmethacrylate (PMMA) was studied using x-ray photoelectron spectroscopy (XPS). Each copolymer was composed of N segments where N ranged from 270 to 5200. At large N, where the system is highly segregated, the surface i…
Granular alloys of iron with other transition metals have been fabricated in both Al2O3 and SiO2 matrices. Both stable (Fe-Ni, Fe-Co) and metastable (Fe-Cu) alloys have been achieved. Under appropriate deposition conditions, the grains are single-phase alloys ranging in size from 15 to 50 Å. Superparamagnetism and enh…
Angle-resolved photoemission spectra were measured using synchrotron radiation for thin films of the pentatriacontan-18-one molecule [${\mathrm{CH}}_{3}$(${\mathrm{CH}}_{2}$${)}_{16}$CO(${\mathrm{CH}}_{2}$${)}_{16}$${\mathrm{CH}}_{3}$] with their long axes perpendicular to the substrate surface. At the preparation of…
Abstract Polyethylene films were surface grafted with glycidyl methacrylate (GMA) by UV irradiating the film for 5 min together with benzophenone. Poly(ethylene glycol) (PEG) was attached to the grafted surface through reaction with the epoxy groups. This yielded a surface which consisted of 95% PEG as measured with E…
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…