Materials Literature
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Se 1-x Te x semiconducting glasses have been prepared and characterized by optical, electrical and X-ray measurements. It is found that homogeneous Se 1-x Te x glasses can only be prepared, without any trace of detectable crystallinity, up to x approximately=0.30 by the usual conventional quenching technique. Due to t…
The twin, intrinsic and extrinsic stacking fault energies together with the FCC-HCP structural energy difference are calculated for Al by means of the total energy pseudopotential method. The influence of supercell geometry is controlled by extrapolating the calculated data to infinite cell size. All calculations incl…
Polychalcogenide compounds with open polymeric frameworks are rare, and they represent a class of compounds in which microporosity might be achieved. Microporous frameworks that are not oxide-based are now attracting interest because of the combination of catalytic and electronic properties they may simultaneously pos…
A stability analysis, expressed within the framework of a density functional theory, is employed to calculate the wavelength of the pitch of a chiral nematic liquid crystal. The chiral bodies are represented by a hard convex twisted ellipsoidal core, with and without an encircling isotropic square well. In the present…
Abstract We study the limiting behaviour of the solution of the Cahn-Hilliard equation using ‘energy-type methods'. We assume that the initial data has a ‘transition layer structure’, i.e. uϵ ≈ ± 1 except near finitely many transition points. We show that, in the limit as ϵ → 0, the solution maintains its transition l…
A new class of promising composite materials consisting of sol-gel processed inorganic oxides and organic polymers has been developed over the last several years. These materials have been shown to be homogeneous, mechanically stable and have excellent optical properties. Second-order nonlinear optical properties are…
A novel quarterwave-thick narrow-bandwidth antireflective coating has been developed for both plastic and vitreous substrates by a sol-gel route. This coating has revealed pronounced scratch- and climatic-resistances under adverse conditions. The single-layer coating consists basically of a composite material made of…
A general expression for the energy loss probability in scanning transmission electron microscopy (STEM) is derived. The method uses a Green's function for the incident and scattered electrons and then folds the specimen into a local response function. Our expression is appropriate to any target geometry and dielectri…
Both the temperature and the pressure dependences of the b 4 0 spin-Hamiltonian parameter for RbCaF 3 , CsCaF 3 , RbCdF 3 and TlCdF 3 doped with Gd 3+ have been reported. On the assumption that b 4 0 depends on the metal-ligand distance according to a law b 4 0 approximately r k the following values of k were obtained…
The magnetic structure of TiFe 2 which crystallizes with the C15 Laves phase structure has been determined from neutron diffraction measurements made on both single-crystal and polycrystalline samples. In the antiferromagnetic structure the Fe2 atoms in the (6h) sites with the same z coordinate are coupled ferromagnet…
Atomic force microscope images show that self-assembled monolayers of octadecyltrichlorosilane form on mica by nucleating isolated, self-similar domains. With increasing coverage, the fractal dimension of the growing domains evolves from 1.6 to 1.8. At higher coverage, continued growth is limited by adsorption from so…
Dynamics of faradaic processes in polypyrrole(PPy)fims depending on the thickness of the films and on applied dc potentials have been investigated by ac electromodulation spectroscopy techniques The comparison of the capacitance plots derived from the impedance plots with the modulated transmittance (color admittanceT…
Abstract The transmittance, flexure strength, Young's modulus, and Vickers hardness of poly(methyl methacrylate) (PMMA), filled with fumed silica, was measured. Transmittance decreased with increasing content of filler. At 2 vol % filler content, composites had a higher transmittance with a lower surface area of fumed…
Abstract The effect of the solvent 1‐methyl‐2‐pyrrolidinone (NMP) on the curing of polyimide resins synthesized from pyromellitic dianhydride (PMDA) and 4,4′‐oxydianiline (ODA) has been investigated. Three polyimide precursors, i.e., the polyamic acid (PAA), with controlled amount of NMP were prepared. The study was a…
One hypothesis for the origin of the nanometer-size diamonds found at the Cretaceous-Tertiary (K-T) boundary is that they are relict interstellar diamond grains carried by a postulated asteroid. The (13)C/(12)C and (15)N/(14)N ratios of the diamonds from two sites in North America, however, show that the diamonds are…
High performance lignocellulosic composites with uniform densities, durability in adverse environments, and high strength can be produced by using fiber technology, bonding agents, and fiber modification to overcome dimensional instability, biodegradability, flammability, and degradation caused by ultraviolet light, a…
Article The crystal structure of a rare earth bearing leucophanite: (Ca,RE)CaNa2Be2Si4O12(F,O)2 was published on December 1, 1992 in the journal Zeitschrift für Kristallographie - Crystalline Materials (volume 202, issue 1-4).
XPS measurements are presented for poly (methyl methacrylate). The data include the valence band region and the principal core levels.
XPS measurements for poly (ethyl methacrylate). The data include the valence band region and the principal core levels.
Abstract Coaquandite, a new antimony oxy-sulphate hydrate, occurs as spheroidal knobs of silky fibres or, rarely, as tiny transparent colourless lamellar crystals on stibnite at the Pereta mine, Tuscany, Italy; it is associated with klebelsbergite, peretaite, valentinite, sulfur, gypsum, stibiconite, and senarmontite.…