Materials Literature
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High-field electron-spin-resonance (ESR) experiments have been carried out in single crystals of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ in the concentration range $0<~x<~0.175.$ Different quasioptical arrangements have been utilized for frequencies $40<~\ensuremath{\nu}<~700…
A new model of crystal growth is presented that describes the phenomena on atomic length and diffusive time scales. The former incorporates elastic and plastic deformation in a natural manner, and the latter enables access to time scales much larger than conventional atomic methods. The model is shown to be consistent…
We describe measurements of the stiffness and Young’s modulus, Y of single crystals of molybdenum-based compounds. Atomic force microscopy is used first to image, and then to perform stiffness measurements on crystals which are growing up out of a substrate. Y is extracted by comparing the measured stiffness with that…
Von schwach blau zu intensiv blaugrün: Diese Veränderung der Emission ist die Folge der Reaktion von [RuCl2(POC4Pyr-P,O)2] mit Kohlenmonoxid. Der Grund ist die Bildung des gezeigten Dicarbonylkomplexes, in dem CO das labile Koordinationszentrum des hemilabilen Liganden POC4Pyr verdrängt hat. Die höhere Flexibilität de…
In the present work we report on the detailed structural features of the chiral N21- and N22-substituted benzyl and picolyl derivatives of tris(pentafluorophenyl)corrole [H3(tpfc)]. The main difference between the isomers is that substitution on N22 creates a much more crowded environment, reflected in higher deformat…
Abstract Highly oriented poly(trimethylene terephthalate) (PTT) fiber has a low birefringence that is unexpected for an aromatic polyester with a high refractive index. To explain this observation, the intrinsic birefringence Δ n of PTT crystal was calculated from its bond polarizabilities to be 0.029. This Δ n is alm…
Response properties of photoinduced gratings were studied in planar cells of liquid crystal doped with multiwalled carbon nanotubes. The grating formation time deduced from beam-coupling measurements was obtained to be ~30 ms. Absorption spectroscopy implies that the permanent gratings are associated with periodically…
The mechanism of stoichiometric enantioselective alkene epoxidations by the D4- and D2-symmetric homochiral trans-dioxoruthenium(VI) porphyrins, [RuVI(D4-Por*)O2] (1) and [RuVI(D2-Por*)O2] (2a), in the presence of pyrazole (Hpz) was studied by UV/Vis spectrophotometry and analysis of the organic products. The enantios…
Polycrystalline boron carbon nitride (BCN) films are synthesized by plasma-assisted chemical vapor deposition. The dielectric constant is estimated from the accumulation region of capacitance–voltage characteristics of Cu/BCN/p-Si samples. It is found that the dielectric constant of the BCN film is reduced by annealin…
Well-aligned boron nanowire arrays were grown vertically on silicon substrates over areas up to several tens of square centimeters using radio-frequency magnetron sputtering of highly pure boron. During growth and self-assembly of boron nanowire arrays, no template or catalyst was needed. The morphology, structure, an…
Edle Partikel: Durch einfaches Mischen bei Raumtemperatur von Ag-, Au-, Pd- oder Pt-Salzen mit reduzierten Polyoxometallaten, die als Photokatalysatoren und Stabilisatoren dienen, ließen sich ultrafeine Metall-Nanopartikel erhalten (siehe Reaktionszyklus).
The dielectric properties of (1−x)Pb(Mg1/3Nb2/3)O3−(x)PbTiO3 (PMN–PT) crystals have been investigated over a temperature range of 4 to 450 K at various frequencies. At low temperatures, an unusual frequency dependent plateau region in the absorption was observed between 75 and 175 K. At both higher and lower temperatu…
The substrate electronic effects on the selectivity in the catalytic epoxidation of para-substituted cis stilbenes 2a-i were investigated by using (R,R)-[N,N'-bis(3,5-di-tBu-salicylidene)-1,2-cyclohexanediamine]manganese(III) chloride 1 in benzene as the catalyst with iodosobenzene as the terminal oxidant. A Hammett s…
The anomalous enhancement in dielectric (ε&gt;6000) and piezoelectric constant (d33&gt;600 pC/N) in the tetragonal side (x=35%) of morphotropic phase boundary (MPB) has been observed in polycrystalline (1−x)Pg(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT). On the other hand, x-ray peak position shifts under electric field (E…
A series of chiral double hydrophilic block copolymers (DHBCs) was synthesized and employed as additives in the crystallization of calcium tartrate tetrahydrate (CaT). We found that appropriate polymers can slow down the formation of the thermodynamically most stable racemic crystals as well as the formation of one of…
Epitaxial CrO2(100) island films have been grown on TiO2(100) substrates by a chemical-vapor deposition technique. Well-controlled surface and interface properties of the CrO2(100) films were confirmed by scanning tunneling microscopy and transmission electron microscopy, respectively. Spin- and angle-resolved photoem…
Entscheidend ist die Mikrostruktur: Der erstmalige Einsatz von zwiebelförmigem Kohlenstoff in der heterogenen Katalyse belegt die Leistungsfähigkeit solcher Materialien in Anwendungen wie der hier untersuchten oxidativen Dehydrierung von Ethylbenzol zu Styrol (siehe schematische Darstellung).
Fein abstimmbare Eigenschaften: Eine Familie dreidimensionaler Gerüst-Indiumchalkogenide wird vorgestellt, die nicht auf Clustern basiert. Die Zusammensetzung des Gerüsts ist hoch flexibel und kontrollierbar. Solch eine Vielfalt bei der Zusammensetzung ermöglicht die Abstimmung struktureller, elektronischer und optisc…
Dendritische Multichromophore auf der Grundlage eines starren Polyphenylen-Gerüstes enthalten bis zu drei verschiedene Rylen-Chromophore: im fokalen Punkt, im Gerüst und an der Peripherie des Dendrimers. Dadurch wird ein Energiegradient zwischen der Peripherie und dem Dendrimerkern erzeugt, und intramolekularer Transf…
Eng verwandt mit der (P)2.614-Helix von γ-Peptiden: Das Harnstoff-Heptamer 1 nimmt in Lösung eine stabile, 2.5-helicale Sekundärstruktur ein, die durch eine Ganghöhe von etwa 5.1 Å sowie 12- und 14-gliedrige Wasserstoffbrückenringe charakterisiert ist. N,N′-verknüpfte Oligoharnstoffe gehören somit zu der wachsenden Fa…