Materials Literature
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Instantaneous normal modes (INM's) are calculated during a conjugate-gradient (CG) descent of the potential energy landscape, starting from an equilibrium configuration of a liquid or crystal. A small number (approximately equal to 4) of CG steps removes all the Im-omega modes in the crystal and leaves the liquid with…
The free energy of the supercooled liquid near freezing is studied in the density-functional approach using the modified weighted density approximation. A class of minima corresponding to heterogeneous structures characterized by weak mass localization are detected. The stability of these structures is found to be gre…
A tight-binding simulation of the atom-by-atom deposition of amorphous carbon (a-C) at 100 eV incident energy is presented. More than 500 atoms were deposited. Chains are observed to form on the surface, some of which are sputtered. The good agreement with the experimental sputter frequency data and observation that a…
The new oxothiomolybdate anion [Mo8S8O8(OH)8[HWO5(H2O)]]3- (denoted HMo8W3-) has been synthesized in aqueous solution by an acido-basic condensation reaction. Four (Mo(V)2S2O2) building blocks are connected through hydroxo bridges around a central [W(VI)O6] octahedron. X-ray and neutron diffraction studies have been p…
The interaction between trivalent lanthanide ions and the polyelectrolyte poly(vinyl sulfonate) (PVS) has been studied in aqueous solutions by monitoring lanthanide luminescence. The existence of specific binding of cations by PVS is indicated by blue-shifts in the maximum of the emission of cerium(III), effects on th…
Bicontinuous cubic (Q II ) phases composed of hydrated lipids are a unique mesoporous organic material. The diameter of the water channels in the range of 5−10 nm could be used as a reservoir for macromolecular therapeutic agents. Here, we describe the synthesis of water-soluble poly(amidoamine) (PAMAM) dendrimer deri…
Hypsochromic or bathochromic? Depending upon the acceptor group (A=H, CN, CHO, NO2) the position and intensity of the absorption maxima of a series of substituted oligo(phenylenevinylene)s change (see picture). Supported by semi-empirical calculations, the extent and direction of the shift (hypsochromic or bathochromi…
124 silver atoms and 57 selenido ligands are contained in the cluster complex [Ag124Se57(SePtBu2)4Cl6(tBu2P(CH2)3PtBu2)12]. The molecule has an approximate diameter of 3 nm. The selenium substructure (see picture) is formed of spheres with a central Frank–Kasper polyhedron (red). Apart from this silver selenide cluste…
We present results reflecting the analogies between the Kob-Andersen model and other glassy systems. Studying the stability of the blocked configurations above and below the transition we also give arguments that support their relevance for the glassy behavior of the model. However, we find, surprisingly, that the org…
New synthesis procedures are described to tetranuclear manganese carboxylate complexes containing the [Mn(4)O(2)](8+) or [Mn(4)O(3)X](6+) (X(-) = MeCO(2)(-), F(-), Cl(-), Br(-), NO(3)(-)) core. These involve acidolysis reactions of [Mn(4)O(3)(O(2)CMe)(4)(dbm)(3)] (1; dbm is the anion of dibenzoylmethane) or [Mn(4)O(2)…
The contribution of interface phonons to first-order Raman scattering in nanocrystals with nonspherical geometry is analyzed. Interface optical phonons in the spheroidal geometry are discussed and the corresponding Fr\"ohlich-like electron-phonon interaction is reported in the framework of the dielectric continuum app…
In this work, the evolution of gas-filled cracks under gas implantation and subsequent annealing is studied on the basis of an elastic continuum approach. The observed growth limitation of He-filled nanocracks in SiC is attributed to their stabilization by the formation of circular dislocation dipoles. The formation a…
Mesoporöse Materialien auf Silicat-Basis wurden erstmals in den frühen neunziger Jahren bei Mobil untersucht. Diese Verbindungen wiesen Porengrößen zwischen 20 und 500 Å sowie spezifische Oberflächen von bis zu 1500 m2 g−1 auf und wurden nach einem neuartigen Flüssigkristalltemplatansatz hergestellt. Die Methode wurde…
Einfach durch Wechsel des Lösungsmittels oder durch andere Bedingungen beim Verdampfen lassen sich die physikalischen Eigenschaften von Polythiophen-Blockcopolymeren und Polyurethanelastomeren gezielt beeinflussen. Die hier beschriebenen Copolymere zeigen hohe Leitfähigkeit sowie ausgezeichnete mechanische und Filmeig…
Mesoscopically ordered silicate−surfactant composite materials of the M41S type synthesized in the presence of a swollen agent have been characterized by in situ and ex situ X-ray diffraction analysis. The key feature of the room-temperature synthesis is the use of a mixture of cationic and anionic surfactants as stru…
Ni nanowire arrays were produced by electrodeposition of Ni into self-assembled porous anodic alumina templates. With different anodization voltages, the wires show different surface morphologies. The temperature dependence of the coercivity and activation volume of wires with regular shape can be explained by thermal…
Reactions of [[MCl2(Cp*)]2] (1: M=Ir, 2: M=Rh) with bidentate ligands (L) such as 1,4-diisocyano-2,5-dimethylbenzene (a), 1,4-diisocyano-2,3,5,6-tetramethylbenzene (b), pyrazine (c) or 4,4'-dipyridyl (d) gave the corresponding dinuclear complexes [[MCl2(Cp*)]2(L)] (M=Ir: 3a, 3b, 5c, 5d; M=Rh: 4b, 6c, 6d), which were c…
A new class of malolactonate polymers and copolymers were synthesized, starting from the corresponding lactones, and then characterized. Different lateral groups were selected for these polyesters to achieve a wide range of materials characteristics and possible biological recognition. The monomers were prepared accor…
We present a review of recent progress in determining the surface structure of quasicrystals, with emphasis on their connections to mathematical tiling models. The review focusses in particular on the five-fold surface of icosahedral Al-Pd-Mn and the ten-fold surface of decagonal Al-Ni-Co. We also assess their potenti…
The glass transition in syndiotactic poly (methyl methacrylate) has been studied through atomistic molecular dynamics simulations performed at temperatures in the range from 297 K to 684 K. The mean squared deviations of atoms, monomers, and molecules from their initial positions were analyzed by means of a technique…