Materials Literature
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The impedance of the cubic perovskite BaZr 0.9 Y 0.1 O 3‐δ has been systematically investigated in dry and wet atmospheres at high and low oxygen partial pressures. In the grain interior, conductivity contributions from oxygen ions, electron holes, and protons can be identified. Below 300°C, proton conduction dominate…
The formation of nanostructured materials by using colloidal crystals as templates is a relatively new but rapidly growing area of materials science. Colloid crystalline templates are three-dimensional close-packed crystals of submicrometer spheres, whose long-ranged ordered structure is replicated in a solid matrix,…
Carbon nanotube (CNT) dopants can improve both the strength and conductivityof polypyrrole (PPy), as reported here. A novel electrochemical method is described for the synthesis of these CNT–PPy composites. Evidence is presented that PPy forms remarkably uniform coatings on individual CNTs, and can also join one coate…
For small-angle scattering, of X-rays (SAXS) and neutrons (SANS), the importance of absolute calibration has been recognized since the inception of the technique. The work reported here focuses on SAXS measurements using Kratky slit systems. In former days, only molecular weights or scattering per particle were determ…
Polycrystalline bulk samples of Ti 3 Al 1.1 C 1.8 have been fabricated by reactively hot isostatically pressing a mixture of titanium, graphite, and Al 4 C 3 powders at a pressure of 70 MPa and temperature of 1400°C for 16 h. The hot isostatically pressed samples are predominantly single phase (containing ∼4 vol% Al 2…
Ordered arrays of nickel nanowires have been prepared using pulsed electrodeposition. Two self-patterning anodization processes were used to fabricate alumina pore matrices into which nickel was deposited from a Watts bath: two short millisecond deposition pulses followed by a long delay yielded almost 100 % filled po…
The perovskitelike ferroelectric system ${\mathrm{PbZr}}_{1\ensuremath{-}x}{\mathrm{Ti}}_{x}{\mathrm{O}}_{3}$ (PZT) has a nearly vertical morphotropic phase boundary (MPB) around $x=0.45--0.50.$ Recent synchrotron x-ray powder diffraction measurements by Noheda et al. [Appl. Phys. Lett. 74, 2059 (1999)] have revealed…
The article presents the state-of-the-art of alternating physisorption of oppositely charged polyelectrolytes, the so-called “layer-by-layer” method or “electrostatic self-assembly” (ESA), for the preparation of thin polymer coatings. In comparison to other, more established self-organization techniques, this recent m…
An overview of one of the most successful conducting polymers, poly(3,4-ethylenedioxythiophene) (PEDT) and its derivatives, is presented, detailing its early development, the synthesis of numerous hybrid and derivative materials, along with a description of the broad array of properties accessible and a description of…
We study theoretically the equilibrium properties of a rod−coil diblock copolymer melt confined between two flat plates. We assume that the system forms lamellae in the bulk. The plates may have a preference for either the rods or coils. We investigate whether the preferred alignment of the lamellae is parallel or per…
The role of the physical network in the dynamics of macromolecules is considered. It is shown that experimental data are often inconsistent not only quantitatively but also qualitatively with the results obtained in terms of the widespread reptation model based on the concept of network entanglement. Evidence is given…
The X-ray crystal structures of K6[CoII W12O40]·~16H2O and K5[CoIIIW12O40]·~16H2O are reported. The compounds are isostructural, hexagonal, space group P 6222, and have Z 3 with a 19.118(7), c 12.383(9) Å, V 3919.6(35) Å3 , and a 19.111(2), c 12.509(2) Å, V 3956.6(9) Å3 , respectively. Both anions exhibit the standard…
Three explicit mathematical models have been developed to predict glass transition temperatures of binary polymer−diluent and polymer−salt systems as well as ternary polymer−diluent−salt systems based on the configurational entropy model and the Flory−Huggins theory. In the presence of salt, the specific ionic interac…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTComplete Assignment of 1H and 13C NMR Spectra of Poly(N-vinylcarbazole)Aglaia Karali, George E. Froudakis, Photis Dais, and Frank HeatleyView Author Information NMR Laboratory, Department of Chemistry, University of Crete, 714 09 Iraklion, Crete, Greece Department of Chemistry,…
The dendritic growth of crystals under gravity influence shows a strong dependence on convection in the liquid. The situation is modelled by the Stefan problem with a Gibbs-Thomson condition coupled with the Navier-Stokes equations in the liquid phase. A finite element method for the numerical simulation of dendritic…
The dynamics of cross-linked polymer chains in solution near the gelation threshold has been investigated by dynamic light scattering. The time−intensity correlation function (ICF) was obtained as a function of initial monomer concentration, C NIPA, and cross-linker concentration, C BIS, where NIPA and BIS denote N -i…
A series of fourteen derivatives of adamantane was synthesised. The new compound 4-(adamant-1-ylmethoxycarbonyl)phthalanhydride obtained from 1-adamantane-methanol and trimellitic anhydride chloride appeared very useful for preparation of a number of N-substituted phthalimides. Antimicrobial activity of the newly obta…
[formula: see text] New unsymmetrically substituted DB24C8-phthalocyanines, which are able to form complexes with suitable dialkylammonium cations, have been prepared. These complexes most probably have a pseudorotaxane geometry.
Crystallization and solidification in polymers is a problem of great importance to the polymer processing industry. In these processes, the melt is subjected to deformation while being cooled into the desired shape. The properties of the final product are strongly influenced by the deformation and thermal histories an…
The sub-glass-transition viscoelastic and physical aging responses of an amorphous poly(ethylene naphthalate) (PEN) have been studied using uniaxial tension stress relaxation experiments. It is known that PEN exhibits a strong β relaxation that overlaps the α relaxation in the experimental time and temperature ranges…