Materials Literature
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We show that single-crystalline Sr3Ru2O7 grown by a floating-zone technique is an isotropic paramagnet and a quasi-two dimensional metal as spin-triplet superconducting Sr2RuO4 is. The ground state is Fermi liquid with very low residual resistivity (3 micro ohm cm for in-plane currents) and a nearly ferromagnetic meta…
We suggest a random field based model for calculation of physical properties of mixed ferroelectric relaxors. Our model naturally incorporates the different orientations of electric dipoles (related to different solid solution components) as well as the contribution of nonlinear and correlation effects of random field…
Summary The behaviour of lignin in wood delignification by oxygen in acidic media in the presence of the molybdovanadophosphate heteropolyanion [PMO 7 V 5 O 40 ] 8− as studied using wet chemistry methods, solid and liquid state 13C NMR spectroscopy. Lignin is oxidised by [PMO 7 V 5 O 40 ] 8− almost completely to carbo…
A nonlinear description of the interaction of charged particles penetrating a solid has become of basic importance in the interpretation of a variety of physical phenomena. Here we develop a many-body theoretical approach to the quadratic decay rate, energy loss, and wake potential of charged particles moving in an in…
We present a first principles account of Bloch Walls on the basis of relativistic Spin-Density Functional Theory in the Local Density Approximation (LDA). We argue that calculations based on this description will provide useful and novel informations about the physics of this important element of micro-magnetics. To i…
The possibility of bonding clean diamond surfaces covalently in ultrahigh vacuum is investigated by molecular dynamics simulations based on a tight binding model. Our simulations predict that strong covalent bonding is possible for C(001)-2×1 surfaces. C(111)-2×1 surfaces will bond very weakly and debond already at mo…
Der dünnstmögliche Bor-Polymerstrang liegt in LiBx vor (0.82<x<1.0, siehe Bild) und lässt sich durch die beiden mesomeren Fromeln=[B−=]nB−= und −[B− beschreiben. Die Struktur von LiBx besteht aus einer Anordnung solcher „Bordrähte”︁ in einer Lithiummatrix. Jedes Boratom trägt zudem eine negative Ladung und ist somit i…
A new class of saturated hydrocarbons, in which a spiropentane-type unit is bound by a cyclic hydrocarbon, has been investigated by using ab initio molecular orbital calculations at the B3-LYP and MP2 levels. These molecules have been given the trivial name hemispiroalkaplanes. Hemialkaplanes, which are analogous mole…
Polyglutamic dendritic porphyrins of the general formula H2PophGlu(N)OR (H2Porph = free-base meso-tetra-4-carboxyphenylporphyrin (H2TCPP), Glu=dendrimer layer composed of L-glutamates, N= 1-3: dendrimer generation number, R = terminal group (All, H)) were synthesized and characterized with NMR and MALDI-TOF mass spect…
The synthesis of the shape-persistent macrocycles 10a and 10b with two bipyridine units in opposing sides by Hagihara/Sonogashira cross-coupling chemistry of suitably functionalized building blocks is reported. X-ray analysis of single crystals of 10b shows a layered structure with channels filled with solvent molecul…
It is found that an icosahedral quasicrystalline phase is directly formed in a Zr80Pt20 binary alloy during rapid solidification from the melt. The size of the icosahedral particles lies in the diameter range below 10 nm, and the particles are distributed homogeneously. The formation of the nanoscale icosahedral phase…
Zweizähnig verbrückendes molekulares Diiod wurde erstmals in [Rh2(O2CCF3)4I2]⋅I2 nachgewiesen, das durch Abscheidung aus der Gasphase erhalten wurde. Einer Kristallsturktuanalyse zufolge liegt eine Zickzack-Polymerkette aus alternierenden [Rh2(O2CCF3)4]- und I2-Molekülen vor (siehe Bild); ein weiteres Diiod-Molekül is…
The degradation behavior of integrated Pt/SrBi2Ta2O9/Pt capacitors by hydrogen impregnation during the intermetal dielectric deposition and passivation is investigated. The hydrogen ions generated as a reaction byproduct from the SiH4-based deposition processes of the dielectric films induce reduction in the remanent…
Investigations of the frequency dependence of the P–E (polarization versus field) and ε–E (strain versus field) behavior have been performed on soft 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 polycrystalline ferroelectrics at various maximum field strengths below and above that of the coercive field (Ec). For E&lt;Ec, a strong…
A precious metal cartwheel is one way to describe the novel heteronuclear compound [Au6Ag(μ-C6H2iPr3)6]CF3SO3 (see picture, isopropyl groups are omitted) which displays an unusual planar hexacoordination for the silver(I) center. A convenient and simple synthesis of new gold heterometallic clusters is presented.
The surface Debye temperature of the NiMnSb (100) epitaxial films has been obtained using low energy electron diffraction, inverse photoemission, and core-level photoemission. The normal dynamic motion of the (100) surface results in a value for the effective surface Debye temperature of 145±13 K. This is far smaller…
CdSe quantum dots, in the form of colloidal nanocrystals, are bound to the surface of a gold electrode by bisulfide spacer molecules. The distance dependance of the electron transfer rate between the CdSe and the electrode was investigated by a time-resolved optoelectronic method and related to the length r of the spa…
An experimental method based on the 3ω technique has been developed to measure thermal conductivity of porous Xerogel films as a function of porosity. The results show that the thermal conductivity of these porous dielectric films can be an order of magnitude smaller than that of SiO2. To account for the porosity depe…
The postulated low thermal conductivity and the possibility of altering the electronic conductivity of metal-doped clathrates with semiconducting host elements have stimulated great interest in exploring these compounds as promising thermoelectric materials. The electronic and thermal properties of the prototypical Na…
The first five generations of the stilbenoid dendrimers 1(n) (n = 1-5) have been prepared by a combined coupled synthesis (between the generations of the dendrons 8-12) and convergent synthesis. Wittig-Horner reactions together with a protecting group technique yield monodisperse compounds of high constitutional and c…