Materials Literature
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A number of silicon phthalocyanine bis-esters have been synthesized and characterized, with axial ligands containing one or more tetrathiafulvalene groups. Variations in the substitution positions around a central aromatic "hinge" within the ligands lead to different molecular geometries, and the fluorescence of the m…
We report on the out-of-plane piezoelectric response (d33), measured via piezoresponse scanning force microscopy, of submicron capacitors fabricated from epitaxial PbZrxTi1−xO3 thin films. Investigations on 1 μm2 and smaller capacitors show that the substrate-induced constraint is dramatically reduced by nanostructuri…
We report the formation of poly(acrylic acid) (sodium salt) (PAA) and poly(allylamine hydrochloride) (PAH) multilayers on polystyrene (PS) and melamine formaldehyde (MF) colloid particles by the layer-by-layer (LbL) assembly technique. The use of different solution processing conditions (e.g., pH and ionic strength) w…
Amorphous SiO/SiO2 superlattices were prepared by reactive evaporation of SiO powder in an oxygen atmosphere. Infrared absorption and photoluminescence spectra were measured as a function of annealing temperature. Three photoluminescence emission bands were observed. A band centered at 560 nm is present in as-prepared…
We study few-particle interactions in GaN-coupled quantum dots and discuss how the built-in field characteristic of these structures strongly reinforce dipole-dipole and dipole-monopole interactions. We introduce a semi-analytical model which allows for a rapid and easy estimate of the magnitude of few-particle intera…
As is well known, the extrusion rate of polymers from a cylindrical tube or slit (a ``die'') is in practice limited by the appearance of ``melt fracture'' instabilities which give rise to unwanted distortions or even fracture of the extrudate. We present the results of a weakly nonlinear analysis which gives evidence…
Abstract The preparation and characterization of melt‐intercalated poly(vinylidene fluoride) (PVDF)/clay nanocomposites are reported. Organophilic clay (clay treated with dimethyl dihydrogenated tallow quaternary ammonium chloride) was used for the nanocomposite preparation. The composites were characterized with X‐ra…
Abstract Blends of amorphous poly(DL‐lactide) (DL‐PLA) and crystalline poly(L‐lactide) (PLLA) with poly(methyl methacrylate) (PMMA) were prepared by both solution/precipitation and solution‐casting film methods. The miscibility, crystallization behavior, and component interaction of these blends were examined by diffe…
Abstract Morphology, thermal and rheological properties of polymer‐organoclay composites prepared by melt‐blending of polystyrene (PS), poly(methyl methacrylate) (PMMA), and PS/PMMA blends with Cloisite® organoclays were examined by transmission electron microscopy, small‐angle X‐ray scattering, secondary ion mass spe…
The shear induced microstructure for electrostatic and Brownian suspensions are compared using in situ small angle neutron scattering (SANS). The dispersions consist of 75 nm Stöber silica coated with 3-(trimethoxysilyl) propyl methacrylate (TPM) and have a zeta potential of −42.6±4.7 mV. Neutralizing the surface char…
Successful synthesis of room-temperature ferromagnetic semiconductors, Zn1−xFexO, is reported. The essential ingredient in achieving room-temperature ferromagnetism in bulk Zn1−xFexO was found to be additional Cu doping. A transition temperature as high as 550 K was obtained in Zn0.94Fe0.05Cu0.01O; the saturation magn…
A calorimetric method of obtaining directly the fragility of liquids from the fictive temperatures of variably quenched glasses, is outlined. “Steepness indexes” m, have been determined for a group of molecular liquids of diverse character, and vary in the range 50–150. The values obtained mostly agree well with those…
The effects of polymer−particle and particle−particle interactions on viscoelastic properties of nanocomposite materials are investigated using narrow molecular weight distribution poly(ethylene oxide) (PEO) containing isotropic silica nanospheres. Nanocomposites are prepared using a “freeze-drying” method to guarante…
The structure of lead tartrate, Pb(2+).C(4)H(4)O(6)(2-), has been solved from X-ray powder diffraction data. The cation exhibits ninefold coordination and the tartrate groups are linked through Pb.O contacts to form a three-dimensional network.
The Bi 3.25 La 0.75 Ti 3 O 12 (BLT) thin films were prepared by metalorganic decomposition method. The effect of grain size on the ferroelectric properties during crystallization were investigated by x-ray diffraction and field emission scanning electron microscope. The grain size and the roughness of BLT films increa…
Abstract A synthesis procedure for and characterization of a tetra‐ ortho ‐methyl substituted three‐ringed cyanate ester monomer, 4,4′‐[1,3‐phenylenebis(1‐methylethylidene)]bis[2,6‐dimethyl]phenylcyanato, and the corresponding cured resin are described with comparative characterization of the resin analogue without th…
This paper addresses the key requirements for fusion materials, as these have emerged from studies of commercial fusion power plants. The objective of the international fusion programme is the creation of power stations that will have very attractive safety and environmental features and viable economics. Fusion power…
The crystallization of amorphous Sm x Fe 80−x B 20 melt spun ribbons is studied over an extended range of composition (0 < x < 8). Differential scanning calorimetry scans reveal different endo- and exothermic effects depending upon the composition. X-ray diffraction and Mössbauer studies for samples annealed at temper…
The double perovskite Ba 2 FeMoO 6 has been studied by neutron powder diffraction, Mössbauer spectrometry and x-ray absorption spectroscopy, and is compared with Sr 2 FeMoO 6 . It is shown that the size of the A-site cation has a large effect upon the nature of the low-temperature state, favouring the majority Fe 2+ /…
The structural, magnetic and transport properties of the compounds Sr 2 (Fe 1−x Mn x )MoO 6 (0 ≤ x ≤ 0.45) have been studied. The saturated magnetization, Curie temperature and low-field magnetoresistance of the compounds decrease with x , while the resistivity increases by several orders of magnitude when x exceeds a…