Materials Literature
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We have fabricated semiconductor-based magnetic superlattices (SLs) containing GaAs:MnAs granular material in which MnAs nanoclusters are embedded in GaAs, and have characterized their structural, optical, and magneto-optical properties. SLs consisting of GaAs:MnAs and AlAs are shown to have good crystalline quality a…
Monte Carlo simulations of amorphous polyethylene (PE) nanoparticle have been performed on the second nearest neighbor diamond lattice by including short and long-range interactions. A droplet can be either obtained from equilibrated PE bulk or from nanofiber snapshots by modifying periodic boundary conditions. The pr…
Abstract The reaction of Te, TeCl 4 and BiCl 3 in a sealed evacuated glass ampoule in a temperature gradient 160 to 90 °C yields Te 8 [Bi 4 Cl 14 ] as black platelike crystals with a golden lustre which are deposited in the temperature zone 150 to 130 °C. The best yield is obtained with a Te/TeCl 4 /BiCl 3 molar ratio…
Self-assembling systems confined in slit-like pores of a width L are studied. We focus on phase transitions between uniform and ordered periodic phases. As shown by previous experimental and theoretical studies, the periodic phases respond elastically to the applied stress when the size λ of the unit cell is much larg…
Polypyrrole was prepared by chemical methods (in water by mixing a solution of pyrrole with an oxidizing solution of FeCl3) and by electrochemical methods. FTIR spectroscopy was used for determining the structure and reaction mechanisms. The main aims were first to prepare some conductive polymers by applying new, eff…
cis-Cyclotetrasiloxanes of the formula cis-[PhSi(O)(OSiMe2 R)]4 with R = Me, CH2Cl, CH CH2 and cis-[ClC6H4Si(O)(OSiMe3)]4 were synthesized and investigated in terms of their thermotropic phase transitions. Two ordered phases were observed for the cis-cyclotetrasiloxanes, one at lower temperature exhibiting the propert…
Magnetic properties of single crystalline Ga1−xFexSe have been measured. This material is in the new class of diluted magnetic semiconductors based on the III–VI semiconductors. The magnetization versus field for an x=0.05 sample deviates from the linear response seen previously in Ga1−xMnxSe and Ga1−xMnxS and reaches…
Hyperbranched aromatic polyamides and copolymers were prepared by direct polycondensation in the presence of condensation agents. Three strategies were described: (1) self-polycondensation of AB x -type monomers, (2) copolymerization of AB 2 and AB monomers and (3) polymerization of A 2 and B 3 monomers. The self-poly…
The morphology of the diglycidyl ether of bisphenol-A/poly(3-aminopropylmethylsiloxane) (DGEBA/PAMS) reactive blends was studied by fluorescence techniques as a function of the initial composition. Some fluorescence results were compared with those from optical and electron microscopy investigations. Several morpholog…
The growth of (010)-oriented CrO2 thin films on Al2O3(0001) substrates leads to a higher grain boundary density than the growth of (100)-oriented CrO2 thin films on isostructural TiO2(100) substrates. For both types of films an intrinsic linear contribution to the high field magnetoresistance (MR) due to spin disorder…
The need to destabilize foams and control their formation arises in many industrial processes. Mechanical foam breakers, mechanical vibration and ultrasonic vibration are examples of physical destructive techniques which do not suffer from the drawbacks associated with the use of chemical antifoams and defoamers. This…
Frozen-in phason fluctuations in single grains of icosahedral Al-Pd-Mn quasicrystals have been studied by high-resolution coherent X-ray scattering. Bragg peak widths scale as expected for a distribution of uniform phason strains. Strong relaxation of the uniform phason strain is observed after sample annealing. Large…
Low impurity content is the essential requirement to many applications of vitreous arsenic chalcogenides as a material for optoelectronics. Investigations carried out in last ten years in-creased the knowledge volume about the nature and origin of impurities in chalcogenide glasses, their effect on glass properties, e…
The replacement of organometallic rhenium species (e.g., CH(3)ReO(3)) by less expensive and more readily available inorganic rhenium oxides (e.g., Re(2)O(7), ReO(3)(OH), and ReO(3)) can be accomplished using bis(trimethylsilyl) peroxide (BTSP) as oxidant in place of aqueous H(2)O(2). Using a catalytic amount of a prot…
Abstract The essential work of fracture (EWF) method has aroused great interest and has been used to characterize the fracture toughness for a range of ductile metals, polymers and composites. In the plastics industry, for purposes of practical design and ranking of candidate materials, it is important to evaluate the…
This new architectural class of macromolecules has received substantial attention during the past decade. Three dendritic subclasses, which include: (a) random hyperbranched (i.e. one-pot AB x polymerizations), (b) dendritic grafted (i.e. Combburst® polymers) and (c) regular dendrons/dendrimers (e.g., Starburst® dendr…
In the present work, electrochemical noise (EN) was measured in three different types of experimental set-ups in order to obtain and compare various types of corrosion. Simultaneously with EN measurements, a parallel technique was used, regarding the type of experimental set-up: a computer visualization system combine…
Abstract Ultrasonic degradation of poly(methyl methacrylate) (PMMA) was carried out in several solvents and some mixtures of solvents. The time evolution of molecular weight distribution (MWD), determined by gel permeation chromatography, is analysed by continuous distribution kinetics. The rate coefficients for polym…
A new kink diimide-dicarboxylic acid, 2,2-bis[4-(4-trimellitimidophenoxy)phenyl]diphenylmethane (BTPDM), was synthesized by the condensation reaction of bis[4-(4-aminophenoxy)phenyl]diphenylmethane (BAPDM) with trimellitic anhydride. A series of new poly(amide-imide)s were prepared by direct polycondensation of BTPDM…
The adsorption behavior of a hydroxypropyl methyl cellulose (HPMC) polymer in aqueous suspensions of alumina, silica, kaolin, and talc powders, two‐component combinations, and one three‐component combination was determined. Powders were well characterized by chemical analysis, XRD, DRIFT, SEM, particle size, surface a…