Materials Literature
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Abstract We report the synthesis of block and alternating thiophene/phenylene co‐oligomers that is based either on the Suzuki coupling reaction or on the Grignard reaction. These reaction schemes enable us to obtain the target compounds at reasonably high yields. The resulting materials have been fully characterized t…
Recent measurements on ion-conducting glasses have revealed that conductivity spectra for various temperatures T and ionic concentrations n can be superimposed onto a common master curve by an appropriate rescaling of the conductivity and frequency. In order to understand the origin of the observed scaling behavior, w…
Molecular dynamics simulations have been performed to understand true atomic resolution, which has been observed on the Si(111)-7$\times$7 surface by dynamic force microscopy in ultra high vacuum(UHV). Stable atomic-scale contrast is reproduced in simulations at constant mean height above a critical tip-sample separat…
We describe an empirical, self-consistent, orthogonal tight-binding model for zirconia, which allows for the polarizability of the anions at dipole and quadrupole levels and for crystal field splitting of the cation d orbitals. This is achieved by mixing the orbitals of different symmetry on a site with coupling coeff…
A partially exfoliated bisphenol A polycarbonate nanocomposite has been prepared by using carbonate cyclic oligomers and ditallow dimethyl exchanged montmorillonite (B34). Wide-angle X-ray diffraction (WAXD) indicated that exfoliation of this organically modified layered silicate (OLS) occurs after mixing with the cyc…
Since the process of building and refining a model of a biomacromolecule based on crystallographic data is subjective, quality-control techniques are required to assess the validity of such models. During the 1990s, much experience was gained; the methods used and some of the lessons learned are reviewed here. In addi…
The past years have witnessed impressive advances in electronic structure calculation, especially in the complexity and size of the systems studied, as well as in computation time. Linear scaling methods based on empirical tight-binding Hamiltonians which can describe chemical bonding, and have a computational time pr…
A study of the surface-enhanced infrared absorption (SEIRA) spectroscopy of para-nitrobenzoic acid (PNBA) adsorbed on thermally evaporated silver films has been conducted to determine the effect of film architecture on the magnitude of the SEIRA enhancement. Ordered arrays of uniformly sized silver nanoparticles, term…
Selective functionalization of the internal and external surfaces of MCM-41 silica has been achieved using a topochemical molecular engineering approach. Functionalization is carried out in a stepwise process, the groups becoming selectively attached via silane coupling reactions and through use of a template to produ…
Polystyrene $(\mathrm{PS})/o\ensuremath{-}\mathrm{terphenyl} (o\mathrm{TP})$ solutions confined to nanometer scale pores were studied by differential scanning calorimetry to investigate size and confinement effects on the glass transition. We observed two glass transitions ${T}_{g}$ in all thermograms for materials co…
This paper addresses the modeling of hysteresis in magnetostrictive transducers in the context of control applications that require an accurate characterization of the relation between input currents and strains output by the transducer. This relation typically exhibits significant nonlinearities and hysteresis becaus…
Control over the morphology of Y2O3:Eu phosphor particles has been achieved using colloidal seed-assisted spray pyrolysis, with yttrium and gadolinium hydroxy carbonate sols as nucleation seeds. These particles, which have important applications in display technology, showed spherical and filled morphology (see Figure…
Biotemplating—a new concept for preparation of ceramic composite materials with biomorphic microstructures will be described. Biological carbon preforms (CB-templates) were derived from different wood structures by high-temperature pyrolysis at temperatures between 800 and 1800 °C and used as templates for infiltratio…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTAn Approach to Glycerol Dendrimers and Pseudo-Dendritic PolyglycerolsRainer Haag, Alexander Sunder, and Jean-François StumbéView Author Information Freiburger Materialforschungszentrum und Institut für Makromolekulare Chemie, Albert-Ludwigs-Universität, Stefan-Meier-St…
The effect of copolymers on the breakup and coalescence of polybutadiene (PB) drops in polydimethylsiloxane (PDMS) is studied using a four-roll mill flow cell. Copolymers are produced at the interface by a reaction between functionalized homopolymers. They reduce the interfacial tension and thus enhance breakup; they…
Four magnetization models, now considered as classical, are presented: the Stoner-Wolhfarth model, the Jiles-Atherton model, the Globus model, and the Preisach model. The paper describes the methods each model uses to simulate the magnetization mechanisms, reversible and irreversible processes, major and minor loops,…
We studied the femtosecond dynamics of colloidal gold nanorods encapsulated in micelles after excitation with 400 nm pulses of 100 fs duration. It is found that the laser heating of the electron gas of gold nanorods with an average aspect ratio of 3.8 leads to the bleaching of both the transverse and longitudinal mode…
Slow photoconductivity transients were comprehensively studied in ZnO films prepared by spray pyrolysis of the zinc-nitrate solution. Surface charge controlled the film conductivity, and it was possible to reversibly change the conductivity by many orders of magnitude using short-term annealing in hydrogen and oxygen.…
The domain structures and phase transitions of relaxor-based piezo-/ferroelectric (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 [PMNT] single crystals, grown from high temperature solutions, have been analyzed by polarized light microscopy using an optical crystallographic approach. The substitution of Ti4+ ions for the B-site comple…
The controlled deposition of individual V2O5 nanowires on chemically modified SiO2 substrates is reported here. Electrical transport measurements were performed on individual fibers (see Figure) and on thin fiber networks, and the conductivity of an individual V2O5 nanowire was estimated to be ∼0.5 S/cm at room temper…