Materials Literature
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The valence band offsets at the heterointerfaces of the CdF2/CaF2/Si(111) structure grown by molecular beam epitaxy were evaluated using x-ray photoelectron spectroscopy, and the energy band diagram of this heterostructure was proposed. It was found that the interface of CdF2/CaF2 has large conduction band offset: 2.9…
Crystallization of a suspension of hard spherical polymer particles is measured by following the evolution of the main Bragg reflection from the close-packed planes. Crystal growth, evident below the melting concentration, is effectively suppressed at higher concentrations due to superlinear rates of crystal addition.…
Unlike conventional crystals, quasicrystals are predicted to be elastically isotropic. To confirm this prediction experimentally, one must distinguish the quasicrystal from nearly isotropic crystals, which requires a high degree of precision. We report the use of resonant ultrasound spectroscopy to determine that the…
Carbon nitride thin films have been successfully grown on nickel substrates by a novel arc-plasma jet chemical vapor deposition. These films were characterized by Auger electron spectroscopy, transmission electron microscopy, and Raman spectroscopy. Small grains (∼0.1 μm) as well as nanocrystallites found in the films…
The forces of capillary interaction between two thin cylindrical rods or two spherical particles placed at a liquid/air interface and immersed partially in the liquid are measured by a sensitive torsion microbalance. Cylindrical rods of radii 50, 165, and 365 \ensuremath{\mu}m are used. The spheres have radius 600 \en…
To study the incorporation of nitrogen, diamond films were prepared by chemical vapor deposition homoepitaxially on {100} and {111} oriented diamond substrates. 50 ppm of isotopic 15N2 was added to the process gas. Nuclear reaction analysis was applied to determine quantitatively the concentration of incorporated 15N.…
ac initial magnetic susceptibility, thermal expansion, and magnetostriction measurements were performed on a polycrystal of ${\mathrm{La}}_{0.60}{\mathrm{Y}}_{0.07}{\mathrm{Ca}}_{0.33}{\mathrm{MnO}}_{3}$ manganese oxide. We observed a spontaneous volume magnetic contribution ( $\ensuremath{\cong}1\ifmmode\times\else\t…
Als erster Aquakomplex eines Elements der Gruppe 15 konnte das [Bi(H 2 O) 9 ] 3+ ‐Ion im Bismuttrifluormethansulfonat‐Enneahydrat nachgewiesen werden. Damit schließt sich die letzte Lücke in der Systematik von Aquakomplexen der Hauptgruppenmetalle. Das zentrale Bi 3+ ‐Ion im C 3h ‐symmetrischen Koordinationspolyeder ‐…
Abstract Eine Schlüsselreaktion der belebten und unbelebten Welt ist die gesteuerte Verknüpfung von einfachen (molekularen) Bausteinen, eine Reaktion, mit der man grundsätzlich mesoskopische Gebilde, z.B. solche mit Hohlräumen und beliebigen gewünschten Eigenschaften, erzeugen kann, aber auch Verbindungen mit typische…
Visible photoluminescence from porous silicon induced by infrared multiphoton excitation was observed at room temperature. Luminescence resulted from carrier excitations in the surface region of the sample. With the pump in the mid-infrared, excitation was effective only when the pump frequency was near resonance with…
A pyrrole ring of a porphyrin as an intramolecular proton donor: compound 1 (depicted below), with a deprotonated pyrrole ring, has been isolated as an intermediate in the oxidative transformation of the corresponding air-sensitive 21-telluraporphyrin into 21-oxaporphyrin.
Abstract Since the fundamental works of D. C. Bradley and R. C. Mehrotra, metal alkoxides have attracted attention because of the diversity of their low‐ and high‐molecular‐weight structures; they are also generating increasing interest as precursor compounds for solving technical materials problems. The understanding…
The potential energy surface (PES) of dissociative adsorption of H_2 on Pd(100) is investigated using density functional theory and the full-potential linear augmented plane wave (FP-LAPW) method. Several dissociation pathways are identified which have a vanishing energy barrier. A pronounced dependence of the potenti…
Semiquinone radical anions are prototype compounds for contact ion pair formation with metal counter cations. In order to investigate the still open question whether bulky alkyl groups can sterically interfere, diphenoquinone derivatives O=C(RC=CH) 2 C=C(HC=CR) 2 C=O with R = C(CH 3 ) 3 , CH(CH 3 ) 2 and CH 3 have bee…
Surface melting of extended chain crystals of a flexible segment containing liquid crystal polymer followed by quenching is shown to result in the epitaxial crystallization thereon of folded chain lamellae, i.e. self decoration. It is proposed that the initial extended chain lamellae form by chain folding in the mesom…
The commercially available closed-cell cellular plastic insulations are typically faced by gaseous impermeable metal foil to prevent transfer of gases from inside and from outside of the foam. Thus, the long-term aging properties of the foams will be different from the unfaced situation. In this research, it has been…
Creep tests of Hastelloy XR (a modified version of the conventional Hastelloy X) were carried out in simulated high-temperature gas-cooled reactor (HTGR) helium at 800, 900 and 1,000°C. The test results up to about 50,000 h showed no significant degradation in creep properties. The creep-rupture strength obtained thro…
2-Dicyanomethylene-1,3-dithiole-4,5-dithiolate (DCDD) has been prepared and used for the synthesis of transition metal complexes (Bu4N)2[M(DCDD)2], M = Ni, Cu, Zn. The redox properties of the nickel complex are similar to that of (Bu4N)2[Ni(dmit)2] (dmit: 1,3-dithiole-2-thione-4,5 dithiolate). Oxidation of (Bu4N)2[Ni(…
Abstract Sulfur/olefin copolymers are known as vulcanizing agents for rubber, but synthetic procedures for these materials are poor and there is little in the literature to relate the structure of the copolymer with the vulcanizate properties of the rubber. This study discusses a new suspension process for the prepara…
Thin polymer films were grown in radio frequency discharges containing C2H2. Actinometry revealed the trend in the plasma concentration of the CH species as a function of the operating pressure. The C–H bond density in the films, revealed by infrared analysis, was found to increase with the pressure of C2H2 in a simil…