Materials Literature
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The photophysical properties of CdSe and ZnS(CdSe) semiconductor quantum dots in nonpolar and aqueous solutions were examined with steady-state (absorption and emission) and time-resolved (time-correlated single-photon-counting) spectroscopy. The CdSe structures were prepared from a single CdSe synthesis, a portion of…
Single-crystalline ${\mathrm{Co}}_{2}\mathrm{MnSi}$ Heusler alloy films have been grown on GaAs(001) substrates by pulsed laser deposition (PLD). The best crystallographic quality of the ${\mathrm{Co}}_{2}\mathrm{MnSi}$ films has been achieved after deposition at 450 K. The films exhibit in-plane uniaxial magnetic ani…
Broadband dielectric spectroscopy is applied to investigate the electrical properties of disordered perovskite-like ceramics in a wide temperature range. From the x-ray diffraction analysis it was found that the newly obtained (Na 0.75 Bi 0.25 ) (Mn 0.25 Nb 0.75 )O 3 ceramics consist of two chemically different phases…
Using complementary experiments we show that the room temperature ferromagnetism observed in anatase $\mathrm{Co}\ensuremath{\mathbin:}{\mathrm{TiO}}_{2}$ films is not carrier mediated, but coexists with the dielectric state. TEM and x-ray absorption spectroscopy reveal a solid solution of Co in anatase, where Co is n…
$p$-type doping of ZnO has thus-far proved difficult. Some reports indicate that Li substituting for Zn would be a shallow acceptor, with work on ferroelectric material showing that Li can be incorporated at the atomic percent concentrations. However, Li doping typically increases the resistivity of otherwise $n$-type…
We synthesized a group of silole regioisomers 1(x,y), whose photoluminescence varied dramatically with its regiostructure. By internally hindering the intramolecular rotation, we succeeded in creating a novel silole (1(3,4)) that is strongly luminescent in solutions and whose fluorescence quantum yield in acetone is a…
Transition metal (TM) atoms bound to fullerenes are proposed as adsorbents for high density, room temperature, ambient pressure storage of hydrogen. ${\mathrm{C}}_{60}$ or ${\mathrm{C}}_{48}{\mathrm{B}}_{12}$ disperses TMs by charge transfer interactions to produce stable organometallic buckyballs (OBBs). A particular…
All types of homogeneous sphere packing and interpenetrating sphere packings and layers were derived that correspond to point configurations of the 15 trivariant hexagonal lattice complexes. The respective sphere packings are assigned to 147 types. In total, sphere packings of 170 types can be realized with hexagonal…
Abstract Processing issues and the electrical and mechanical properties of a novel combination of a natural carbonaceous filler, Karelian shungite, and a water soluble thermosetting polymer, melamine‐formaldehyde, were investigated. Two types of shungite with different carbon contents were investigated and compared to…
Abstract Summary: Polypeptide‐shelled poly(propylene imine) dendrimers were realized by ring‐opening polymerization of α ‐amino acid N ‐carboxyanhydrides, initiated by dendrimers as core molecules. Polypeptides with 2nd generation core were used as model compounds to investigate interior complexes between metal ion an…
All articles of this category Corrected by: Copper- and Palladium-Containing Perovskites: Catalysts for the Ullmann and Sonogashira Reactions Synlett 2005; 2005(09): 1490-1490 DOI: 10.1055/s-2005-869842
Details of the recently developed 'zone technique' for the absolute measurement of lattice parameter and strain in single-crystal solids and thin films are presented. The method is based on measuring X-ray rocking curves from a few equatorial planes within a suitable zone and correcting their peak positions at once wi…
Abstract Summary: A new crystal morphology ( δ form) of poly(3‐hydroxypropionate) (PHP) is found in cast and melt‐crystallized PHPs with low molecular weight, in which the PHP chains possibly adopt a 2 1 helix rather than the trans conformation found in the β or γ form. The fusion temperature‐ and the crystallization…
By using [Mn(2,6-Cl(2)TPP)Cl] (1) as a catalyst and Oxone/H(2)O(2) as an oxidant, we have developed an efficient method for erythro-selective epoxidation of acyclic allyl-substituted alkenes, including allylic alcohols, amines, and esters. Up to 9:1 erythro selectivities for terminal allyllic alkenes could be achieved…
Abstract Polybutadiene (PB), polyisoprene (PI), and styrene–butadiene rubber/organic montmorillonite (OMMT) nanocomposites (NCs) were prepared by in situ anionic intercalation polymerization. The intercalation structure, chemical constitution, and morphology of the rubber/OMMT NCs were characterized with X‐ray diffrac…
Multicanonical (MUCA) sampling is a powerful approach for simulating large domains of thermodynamic macrostate space that relies on mapping out either the density of states or a free energy of the system as a function of a suitable "order parameter." The purpose of this study is to extend and apply to more complex sys…
A diffusion-barrier model described the early evolution of size-dependent photoluminescence emission from CdSe quantum dots formed by organometallic synthesis. Emission peak widths, emission redshift rates, and nanocrystal growth rates all decreased to a minimum at a reaction completion time. Growth after the completi…
Fluorocarbon films have low surface energy and can be used as antistiction coating for microelectromechanical systems. By using the passivation process in a deep reactive ion etcher, the fluorocarbon films can be deposited and integrated with other processes in the clean room. The properties such as wettability, surfa…
Third-harmonic generation (THG) spectroscopy was performed for oligo(1,4-phenyleneethynylene)s (OPEs) with terminal donor-acceptor (DA) substitution and compared to the results of merely donor substituted OPEs and regular OPE chains with 2,5-dipropoxy benzene rings. Both, extension of the conjugation and push-pull eff…
We propose a photonic switch employing a liquid-crystalline material. The material exhibits a change in the sign of the dielectric anisotropy switching from a positive to a negative value at a certain crossover frequency. By application of an electric field this phenomenon can be used to alter the orientation of the s…