Materials Literature
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Nanoparticles of nickel have been obtained in solution through reaction of an organometallic precursor, Ni(COD)2 (COD=cycloocta-1,5-diene), with dihydrogen, in the presence of various stabilizing agents. X-ray diffraction studies evidence a face-centered-cubic structure for all samples. Spherical isolated superparamag…
Abstract Coarse‐grained molecular dynamics simulations of stacks of two‐dimensional platelets immersed in a polymer melt were performed to investigate aspects of the polymer matrix that promote the formation of intercalated or exfoliated nanocomposite structures. Such factors include temperature, copolymer architectur…
Bicomponent nanophase-separated poly(2-hydroxyethyl methacrylate)- linked -polyisobutylene (PHEMA- l -PIB) amphiphilic conetworks were synthesized by radical copolymerization of methacrylate−telechelic polyisobutylene (MA−PIB−MA) and different amounts of 2-(trimethylsilyloxy)ethyl methacrylate (SEMA) followed by quant…
We use the 3ω method to study the thermal conductivity of composites of nanoscale alumina particles in polymethylmethacrylate (PMMA) matrices. Effective medium theory and data for the changes in conductivity produced by low volume fractions of particle fillers are used to estimate the thermal conductance G of PMMA/alu…
Abstract Four polyhedral oligomeric silsesquioxane (POSS) cages with vinyl groups were linked to a central siloxane core by hydrosilylation. The goal was to obtain filler particles of sizes between those of the POSS cages themselves and the much larger silica particles typically used to reinforce elastomers. The hydro…
Abstract Polyhedral oligosilsesquioxane (POSS)‐reinforced thermosets based on octaglycidyl epoxy polyhedral oligosilsesquioxane cured with 4,4′‐diaminodiphenyl sulfone (DDS) were prepared and studied for their cure, thermomechanical, and microstructural characteristics. Particular attention was paid to nanometer‐scale…
We report fabrication of homostructural ZnO p–n junctions that contain arsenic (As)-doped ZnO (ZnO:As) and intrinsic n-type ZnO layers. We also describe the metallization process for forming ohmic contacts to p-type ZnO. ZnO films were synthesized on n-type SiC substrates by hybrid beam deposition. Ni/Au metal contact…
We have established an optimized growth temperature range, namely, 150 °C<TG<250 °C, where ferromagnetic Fe3Si/GaAs(001) hybrid structures with high crystalline and interfacial quality can be fabricated by molecular-beam epitaxy. The composition of the Fe3Si layers, which can be regarded as a Heusler all…
Abstract The glass‐transition temperatures ( T g 's) of nanocomposites of polystyrene (PS) and single‐walled carbon nanotubes were measured in the bulk and in thin films with differential scanning calorimetry and spectroscopic ellipsometry, respectively. The bulk T g of the nanocomposites increased by approximately 3…
The homogeneous composites of single-wall carbon nanotube (SWNT) and Stycast 1266 epoxy were made with the nanotube concentrations of 0.01–0.21 wt % by using a high frequency sonication method. Direct current conductivities of various mass fractions show typical percolation behavior and the percolation threshold pc is…
The field-induced actuation of Ni–Mn–Ga single crystals through twin-boundary motion has been demonstrated with magnetic fieldpulses of various intensities lasting 620 μs. It is shown that the complete field-induced strain can be obtained in 250 μs, which implies the possibility of full 6% cycling of Ni–Mn–Ga at 2 kHz…
Abstract A series of new poly(butylene succinate) (PBS)/layered silicate nanocomposites were prepared successfully by simple melt extrusion of PBS and organically modified layered silicates (OMLS). Three different types of OMLS were used for the preparation of nanocomposites: two functionalized ammonium salts modified…
The orientation dependence of the longitudinal piezoelectric coefficient, d33*, is investigated as a function of temperature in BaTiO3 and PbTiO3 crystals using the Landau–Ginsburg–Devonshire theory. We show that a presence of the ferroelectric–ferroelectric phase transitions in BaTiO3 leads to enhanced d33* along non…
The properties X (stress, crystallinity, melting temperature, crystallite sizes) of stretched filled and unfilled natural rubber (NR) are compared. The measurements have been done during deformation at equilibrium and at room temperature. From each physical property X in static and dynamic experiments one defines for…
Constitutive rules are developed to include three-dimensional dislocation mechanisms, such as line tension and dynamic junction formation, within a two-dimensional dislocation dynamics formulation. Some of the junctions that form dynamically can operate as Frank–Read sources. Boundary value problems are solved by usin…
When two chemically passivated solids are brought into contact, interfacial interactions between the solids compete with intrabulk elastic forces. The relative importance of these interactions, which are length-scale dependent, will be estimated using scaling arguments. If elastic interactions dominate on all length s…
We present a theoretical study of the optical absorption spectrum of small boron-nitride and carbon nanotubes using time-dependent density-functional theory and the random phase approximation. Both for C and BN tubes, the absorption of light polarized perpendicular to the tube-axis is strongly suppressed due to local…
Magnetism of a misfit layered cobaltite [Ca$_2$Co$_{4/3}$Cu$_{2/3}$O$_4$]$_x^{\rm RS}$[CoO$_2$] ($x \sim$ 0.62, RS denotes a rocksalt-type block) was investigated by a positive muon spin rotation and relaxation ($μ^+$SR) experiment. A transition to an incommensurate ({\sf IC}) spin density wave ({\sf SDW}) state was f…
Amorphous SiO2 (a-SiO2), such as bulk silica glasses and thin films has been one of the key materials in modern optoelectronic industries. These materials are currently used in communication technologies as optical fibers, thin films for electrical insulation in dynamic random access memories (DRAM), and optical lense…
Phase transformation and crystal growth in nanoparticles may happen via mechanisms distinct from those in bulk materials. We combine experimental studies of as-synthesized and hydrothermally coarsened titania (TiO 2 ) and zinc sulfide (ZnS) with thermodynamic analysis, kinetic modeling and molecular dynamics (MD) simu…