Materials Literature
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The evolution of three-dimensional strain states and crystallographic domain structures of epitaxial colossal magnetoresistive La0.8Ca0.2MnO3 films have been studied as a function of film thickness and lattice mismatch with two types of (001) substrates, SrTiO3 and LaAlO3. In-plane and out-of-plane lattice parameters…
We use a Monte Carlo bond-switching method to study systematically the thermodynamic properties of a ``continuous random network'' model, the canonical model for such amorphous systems as $a$-Si and $a\ensuremath{-}{\mathrm{SiO}}_{2}$. Simulations show first-order ``melting'' into an amorphous state, and clear evidenc…
We use the dynamical mean field method to study the high-temperature resistivity of electrons strongly coupled to phonons. The results reproduce the qualtiative behavior of the temperature and disorder dependence of the resistivity of the 'A-15' materials, which is commonly described in terms of saturation, but imply…
The diffusivity of tagged particles is demonstrated to be heterogeneous on time scales comparable to or less than the stress relaxation time $\ensuremath{\cong}{\ensuremath{\tau}}_{\ensuremath{\alpha}}$ in a highly supercooled model liquid. The particle motions in the relatively active regions dominantly contribute to…
The achievement of high-quality continuous polycrystalline silicon (poly-Si) layers onto glass substrates by using aluminum-induced crystallization is reported. The crystallization behavior of dc sputtered amorphous silicon on glass induced by an Al interface layer has been investigated above and below the eutectic te…
Miscibility studies of poly(vinyl pyrrolidone)–polystyrene and poly(vinyl pyrrolidone)–poly(methyl methacrylate) in mixed common solvent (dimethyl formamide + cyclohexanone) have been carried out in different percentages of the blend components. The ultrasonic velocity, viscosity, density, and refractive index have be…
The present work compares the nucleation and crystallization process of poly(ethylene terephthalate) (PET) in bulk and when it is finely dispersed in a polycarbonate (PC) matrix. Two types of 80/20 PC/PET immiscible blends were prepared by twin-screw extrusion at different screw rotation rates in order to produce fine…
MQ silicone resins were synthesized through hydrolytic condensation of ethyl polysilicate and hexamethyldisiloxane. The structure of the MQ resins was characterized by NMR and GPC. The concentration of an acid catalyst was essential for the capping of functional groups with the monofunctional units. The acid-catalyzed…
A series of new polymethacrylate–silica chemical hybrid dental fillers has been prepared by the sol–gel reactions of poly[methyl methacrylate-co-3-(trimethoxysilyl) propyl methacrylate] or poly[3-(trimethoxysilyl)propyl methacrylate] with tetraethyl orthosilicate at various compositions. In these hybrid fillers, the p…
Efficacy evaluation of various coupling-agent-treated sisal fibers was made by contact angle measurements and Fourier transform infrared spectroscopy. It was found that high contact angle and reduced hydroxyl groups on titanate-treated fibers favor its better hydrophobicity over the other treatments. The presence of a…
The dynamic variations of molecular structure and properties of natural rubber (NR) during the accelerated storage have been studied. The results showed that, with the prolonging of the storage time, the average molecular weight and the gel content increased, the width index of molecular weight distribution decreased,…
Full-interpenetrating polymer networks (IPNs) were prepared from epoxy and castor oil-based polyurethane (PU), by the sequential mode of synthesis and were characterized by different techniques: swelling test, scanning electron microscopy (SEM), thermomechanical analysis (TMA), thermogravimetric analysis (TGA), tensil…
The conductance-voltage spectrum of molecular nanostructures measured by scanning tunneling spectroscopy (STS) is generally assumed to reflect the local density of states of the molecule. This excludes the possibility of observing negative differential resistance (NDR). We report here the observation of NDR in the sca…
In this paper we report measurements of 1/f noise in a crystalline metallic oxide with perovskite structure down to 4.2K. The results show existence of localized excitations with average activation energy $\approx$ 70-80 meV which produce peak in the noise at T $\approx$ 35-40K. In addition, it shows clear evidence of…
We study the spin polarised tunnelling mechanism through magnetisation and magnetoresistance in the granular polycrystalline colossal magnetoresistive manganite, La0.55Ho0.15Sr0.3MnO3. This system has a ferromagnetic transition temperature (Tc) of 255 K associated with a metal-insulator transition around the same temp…
Helical polyacetylene was synthesized under an asymmetric reaction field consisting of chiral nematic (N*) liquid crystals (LCs). The chiral nematic LC was prepared by adding a chiroptical binaphthol derivative as a chiral dopant to a mixture of two nematic LCs. Acetylene polymerizations were carried out using the cat…
Self-assembly of block copolymers is attractive for nanodevice fabrication because the association of different polymers by covalent bonding and the interplay between the sequences allows one to generate a variety of structures with well-defined shapes. We present a straightforward approach to generate self-organized…
Measurements are reported of small-angle neutron scattering (SANS) from lightly cross-linked poly(vinyl acetate) gels swollen in good and ϑ solvents. In all the solvent conditions investigated the scattering response can be described satisfactorily by two characteristic length scales: a thermodynamic correlation lengt…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTQuantifying the "Neutrality" of Good Solvents for Block Copolymers: Poly(styrene-b-isoprene) in Toluene, Benzene, and THFChing-i Huang, Bryan R. Chapman, Timothy P. Lodge, and Nitash P. BalsaraView Author Information Department of Chemical Engineering & Materials Science and De…
Magnetic exchange interactions have been calculated in the framework of the density functional (DF) theory for the quite rare exchange coupled binuclear compounds in which the magnetic centers belong to the 4d series: [{Mo V (O)(Tp*)Cl} 2 (μ-X)], (where X is one of the dihydroxybenzene bridging ligands [1,4-OC 6 H 4 O…