Materials Literature
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In a single-component material, a chemical potential gradient or a wind force drives self-diffusion. If the self-diffusion flux has a divergence, the material deforms. We formulate a continuum theory to be consistent with this kinematic constraint. When the diffusion flux is divergence-free, the theory decouples into…
A method of stepwise assembling thin polymer/single-walled carbon nanotube (SWCNT) films using donor−acceptor interactions is demonstrated. When the affinity that amine groups have for nanotubes were utilized, films were formed by the sequential adsorption of polyethylenimine and polyallylamine followed by SWCNTs onto…
A SiC nanowire/Tyranno‐SA fiber‐reinforced SiC/SiC composite was fabricated via simple in situ growth of SiC nanowires directly in the fibrous preform before CVI matrix densification; the purpose of the SiC nanowires was to markedly improve strength and toughness. The nanowires consisted of single‐crystal β‐phase SiC…
Various physical mechanisms are involved in an electromigration (EM) process occurring in metal thin film. These mechanisms are electron-wind force induced migration, thermomigration due to temperature gradient, stressmigration due to stress gradient, and surface migration due to surface tension in the case where free…
Abstract Grafting of methacrylic acid (MAA) on starch, poly(vinyl alcohol) (PVA), and a mixture of starch and PVA, using a potassium persulfate/ sodium thiosulfate redox initiation system was carried out. Polymerization was studied with respect to graft yield, homopolymer formation and total conversion. These polymeri…
For a given fiber spun to pre-determined yarn specifications, the spinning performance of the yarn usually varies from mill to mill. For this reason, it is necessary to develop an empirical model that can encompass all known processing variables that exist in different spinning mills, and then generalize this informat…
CuO nanowires and nanorods were synthesized through a novel controllable solution-phase hydrothermal method using a nonionic surfactant polyethylene glycol (PEG) as the structure-directing template. The lengths of obtained 1D CuO nanostructures could be successfully controlled through choosing different molecular weig…
Tetra(phenylethynyl)tin is an efficient initiator for the ring-opening polymerization of lactide, with or without the addition of isopropanol as a coinitiator, providing high activity and high molar mass polymers.
Diffractive optical elements to form one-parameter directivity diagrams are designed using the geometric optics. The field ray structure corresponding to the line-shaped directivity diagram is analyzed and curvilinear coordinates for calculating the eikonal are proposed. A new simplified formula for the eikonal functi…
A significant amount of work has been done in the past decade to reveal the unique structural and mechanical properties of carbon nanotubes and to explore what might be the key applications of these novel materials. Due to the difficulty in developing experimental techniques, there is still no report on the measured v…
We have recently proposed a nonlocal continuum crystal plasticity theory that is based on a statistical-mechanics description of the collective behaviour of dislocations. Kinetic equations for the dislocation density fields have been derived from the equation of motion of individual dislocations and have been coupled…
Abstract Two series of solid catalysts in which a chiral palladium or nickel complex with Schiff bases as ligands have been immobilized on ordered mesoporous silica supports (MCM‐41), delaminated ITQ‐2, ITQ‐6 zeolites and amorphous silica have been prepared. Hydrogenation of alkenes and imines was studied with the hom…
The successful commercialization of MRAM will rely on providing customers with a robust and reliable memory product. The intrinsic reliability of magnetoresistive tunnel junction (MTJ) memory bits and the metal interconnect system of MRAM are two areas of great interest due to the new materials involved in this emergi…
Abstract Starting with a BST (Ba 0.6 Sr 0.4 TiO 3 ) nanopowder with a mean diameter of about 50 nm, the average grain size increases from the nanometer to the micrometer range (from 70 nm to 1–2 μm) by thermal annealing between 700 and 1400 °C. The dielectric properties of these pressed powders has been determined, sh…
The surface of a liquid near a moving contact line is highly curved owing to diverging viscous forces. Thus, microscopic physics must be invoked at the contact line and matched to the hydrodynamic solution farther away. This matching has already been done for a variety of models, but always assuming the limit of vanis…
Adsorption in porous solids at room or low temperature is one of the possible storage modes of hydrogen gas. The storage efficiency in these materials depends on their physical properties and characteristics, the most important being their adsorption capacity, porosity, density, and the endo- or exothermic character o…
For the first time combined X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) experiments were carried out to probe the short- and long-range order in lanthanum-modified PbTiO 3 ceramic materials (Pb 1 - x La x TiO 3 ) for x ranging from 0 to 30 atom % of La. XRD results show that a tetragonal structure…
Abstract Based on finite element formulations for the strain gradient theory of microstructures, a convergence criterion for the C 0–1 patch test is introduced, and a new approach to devise strain gradient finite elements that can pass the C 0–1 patch test is proposed. The displacement functions of several plane trian…
We have studied the nanostructural and nanochemical changes occurring in pure ceria (CeO2) and CeO2–zirconia (ZrO2) catalysts during reduction. The reduction is carried out in an environmental transmission electron microscope in dry H2 at 2 Torr up to 800°C. We use in-situ electron-energy-loss spectroscopy to follow c…
The origin of the improvement of the ferroelectric and piezoelectric properties of KNbO 3 ceramics by the addition of small amounts of La and Fe has been investigated. The La/Fe-codoped KNbO 3 ceramics formed a single (K 1- x La x )(Nb 1- x Fe x )O 3 solid solution, and their unit-cell volume decreased significantly w…