Materials Literature
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Pulsed IR laser-induced ablation of bulk poly[oxy(tetramethyldisilane-1,2-diyl)], [(CH 3 ) 2 Si(CH 3 ) 2 SiO] n,yields thin polyoxocarbosilane films whose polymeric structure consists of a backbone composed of −(CH 3 ) 2 Si(CH 3 ) 2 SiO− and −O(CH 3 ) 2 SiO− units, which is cross-linked via SiSiC 2 O, C 3 SiO, C 2 SiH…
The cluster [Ag(SC6H2Pri(3)-2,4,6)]10 (1) contains a 20-membered ring of alternating silver and sulfur atoms, which is compactly folded; the sulfur atoms are doubly bridging and each silver atom exhibits linear two-coordination in the primary Ag-S interactions.
Four rate-limiting processes for the formation of single-wall carbon nanotubes (SWCNT) could be identified by varying furnace temperature, gas type, and pressure in a pulsed-laser evaporation setup. One rate-limiting process accounts essentially for all relevant gas-pressure dependencies and can be quantitatively desc…
Arrays of alumina nanopillars with adjustable dimensions (see Figure for a representative example) are fabricated by simple chemical etching of porous anodic alumina with dilute NaOH. The diameter and height of the pillars, as well as interpillar spacing, are a function of the oxide layer thickness, which is controlle…
Variable-temperature (1)H and (13)C NMR measurements of the D(3)-symmetrical triple-helical complexes [Ln(L1-2H)(3)](3)(-) (L1 = pyridine-2,6-dicarboxylic acid; Ln = La-Lu) show evidence of dynamic intermolecular ligand-exchange processes whose activation energies depend on the size of the metal ion. At 298 K, the use…
Highly ordered, vertical carbon nanotubes (CNTs) (see Figure) have been grown on a pre-patterned, porous anodic aluminum oxide (AAO) template using a lithographic patterning method and thermal chemical vapor deposition. The AAO template itself plays a catalytic role in CNT growth and the crystallinity of the CNTs is s…
We examine the local atomic order as well as some dynamic properties of the semiconducting liquid GeTe. We employ hot-neutron two-axis diffraction at three temperatures above the melting point and compare these results with ab initio molecular dynamics simulations. The simulations were based on interatomic forces deri…
In this paper we report first-principles calculations on the ground-state electronic structure of two infinite one-dimensional systems: (a) a chain of carbon atoms and (b) a chain of alternating boron and nitrogen atoms. Meanfield results were obtained using the restricted Hartree-Fock approach, while the many-body ef…
We observe (by optical interferometry) the contact of a rubber cap squeezing a nonwetting liquid against a plate moving at velocity U. At low velocities, the contact is dry. It becomes partially wet above a threshold velocity V(c1), with two symmetrical dry patches on the rear part. Above a second velocity V(c2), the…
Abstract An influence of the structure of a globule of polyethyleneimine on the complex formation of one with the copper(II), nickel(II), and cobalt(II) ions is described. A change of the coordination number from the pH of solution for complexes of ethylenediamine, diethylenetriamine, and polyethyleneimine with metal…
The electronic structure and magnetocrystalline anisotropy energy of strained fcc ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ have been studied by using the linear muffin-tin orbital method within density functional theory. A uniaxial strain applied along the [001] direction of the magnetite is considered. It is found that th…
Laser action in a dye-doped ferroelectric liquid crystal (FLC)—at the edge of the photonic stop band—has been demonstrated for the first time. The FLC used is a multicomponent mixture with a well-controlled short pitch of its helical structure whose periodic is equivalent to visible optical wavelengths. The laser emis…
Using computer simulations, we identify the mechanisms causing aggregation and structural arrest of colloidal suspensions interacting with a short-ranged attraction at moderate and high densities. Two different nonergodicity transitions are observed. As the density is increased, a glass transition takes place, driven…
Rare earth oxide nanotubes (see Figure) templated by dodecylsulfate assemblies have been fabricated for the first time by the homogeneous precipitation method using urea. Conversion into hollow nanotubes with an inner diameter of 3 nm and outer diameter of 6 nm can then be effected by anion exchange treatment to remov…
Adsorption of CO on Ni−ZSM-5 reveals the existence of two kinds of Ni 2+ ions, with the respective stretching frequencies being at 2220 and 2212 cm -1 . The carbonyl complexes are resistant to evacuation at room temperature, which is explained by the high electrophilicity of cations in a ZSM matrix. At 85 K and in the…
Thin polymer films with cylindrical microdomains of controlled size (see Figure for an AFM image) have been produced from diblock copolymer/homopolymer mixtures. It is demonstrated that not only do the spatial order and orientation of the domains remain unperturbed but also that two distinct sizes of pores can be acce…
The discrete nature of the vibrational modes of an isolated nanometer-scale solid dramatically modifies its low-energy electron and phonon dynamics from that of a bulk crystal. However, nanocrystals are usually coupled--even if only weakly--to an environment consisting of other nanocrystals, a support matrix, or a sol…
Using Korringa-Kohn-Rostoker coherent-potential approximation in the atomic-sphere approximation (KKR-ASA CPA) method for taking into account the effects of disorder, Gaspari-Gyorffy formalism for calculating the electron-phonon coupling constant $λ$, and Allen-Dynes equation for calculating T_c, we have studied the v…
The formation of hafnium silicate films (HfSixOy) for use as gate oxides with large dielectric constant by solid state reaction of Hf metal and SiO2 was investigated. Thin, fully reacted silicate films could be formed, and were thermally stable in vacuum to temperatures in excess of 800 C. The interface between a hafn…
The utilization of surface-attached gold nanoparticles as templates for generating Pt-group particles displaying near-optimal surface-enhanced Raman scattering (SERS) characteristics is described. Essentially epitaxial transition metal coatings down to the monolayer level can be prepared, most readily by the spontaneo…