Materials Literature
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A model of relaxors as superparaelectrics with a distribution of the local transition temperature has been investigated. The necessary model parameters are obtained from the analysis of the static polarization response of lead magnesium niobate and then employed in simulations of the frequency-dependent dielectric pro…
A method of surface treatment was found to enhance diamond chemical vapor deposition nucleation on nondiamond substrates such as Si, SiO2, and Al2O3. The nucleation density obtained by ultrasonic abrasion with diamond powder alone was found to be enhanced by a few orders of magnitude using a mixed slurry consisting of…
The bias-enhanced nucleation (BEN) technique has been applied to TiC(111) substrates and resulted in deposition of oriented diamond particles. The orientation was observed via scanning electron microscopy. A dense region of oriented particles was not observed on the samples, presumably due to the excessive twinning of…
The spatial distribution of Mg solute in polycrystalline, single-phase Al2O3 has been obtained, using a secondary ion imaging technique. Segregation of Mg to the Al2O3 grain boundaries is clearly observed—strong evidence that the principal role of MgO is to reduce the grain boundary mobility via a solute-drag mechanis…
A thermodynamic linear perturbation theory for the Gay–Berne intermolecular potential has been developed which is able to predict the occurrence of isotropic liquid-vapour coexistence as well as the stability of a nematic phase. The theory can be regarded as a generalisation to molecular fluids of the Weeks, Chandler,…
We use numerical self-consistent field (SCF) calculations to determine the interfacial behavior of AB diblocks in a blend of immiscible homopolymers, A and B. In particular, we compare the compatibilizing effect of relatively short and long AB copolymers. In the calculations, we explicitly take into account the format…
The interference of the time-invariant magnetic-dipole contribution with the time-noninvariant electric-dipole contribution to the second harmonic (SH) provides a mechanism which is sensitive to the reduction of symmetry of Cr2O3 by antiferromagnetic ordering of spins. A pronounced polarization dependence of the SH on…
Monte Carlo simulations are used to show that the steady state of the d=2, two-temperature, diffusive XY model displays a continuous phase transition from a homogeneous disordered phase to a phase with long-range order. The long-range order exists although both the dynamics and the interactions are local, thus indicat…
We examine weakly segregated blends of $\mathrm{AB}$ diblock copolymer and $A$ homopolymer using self-consistent field theory. The addition of homopolymer to a diblock melt is found to stabilize new ordered morphologies: close-packed spheres, hexagonally perforated lamellae, and bicontinuous cubic ( ${\mathrm{Q}}_{\ma…
The crystal structure of urease from Klebsiella aerogenes has been determined at 2.2 A resolution and refined to an R factor of 18.2 percent. The enzyme contains four structural domains: three with novel folds playing structural roles, and an (alpha beta)8 barrel domain, which contains the bi-nickel center. The two ac…
We present a new technique aimed at preventing plane-wave based total energy and stress calculations from the effect of abrupt changes in basis set size. This s cheme relies on the interpolation of energy as a function of the number of plane waves, and on a scaling hypothesis that allows to perform the interpolation f…
An effective Hamiltonian for the ferroelectric transition in $PbTiO_3$ is constructed from first-principles density-functional-theory total-energy and linear-response calculations through the use of a localized, symmetrized basis set of ``lattice Wannier functions.'' Preliminary results of Monte Carlo simulations for…
We use ab initio pseudopotential total energy calculations with a plane wave basis set to investigate the structural energetics of various phases of polymorphic NbN. Particular attention is given to its recently discovered superconducting phase with a $T_c$ of 16.4 K, reported to have the NbO structure type. Results o…
The projection of the eigenfunctions obtained in standard plane-wave first-principle electronic-structure calculations into atomic-orbital basis sets is proposed as a formal and practical link between the methods based on plane waves and the ones based on atomic orbitals. Given a candidate atomic basis, ({\it i}) its…
The cutting of γ′-particies during shear creep deformation on the macroscopic crystallographic {111} 〈110〉 shear system at T = 1025 °C and τ = 85 MPa is studied using transmission electron microscopy (TEM). It is observed that two matrix channel dislocations with different Burgers vectors join and form a superdislocat…
The evolution of dislocation structures in technological high strain deformation of ‘wavy glide’ metals is studied by the examples of pure aluminium, nickel, copper and hot deformed stainless steel, and compared with the earlier observations by Langford and Cohen on drawn iron wire and Wert et al. on rolled aluminium…
An attempt to introduce a thermodynamic classification of dislocation structures produced by cyclic deformation is made. A fundamental division is proposed for all types of dislocation structures into two classes: 1. those in equilibrium and 2. strongly non-equilibrium self-organized dislocation structures (“SODS”). I…
The microstructural evolution is followed in pure aluminium and nickel cold-rolled over a large strain range. A number of dislocation configurations are characterized and classified and it is found that dislocation rotation boundaries are the dominant feature which subdivide the grains on a finer and finer scale as th…
Abstract Polyaniline/polypropylene composites were prepared by oxidative polymerization of aniline in biaxially stretched polypropylene microporous films with ammonium persulfate as the oxidant. A continuous permeation/diffusion polymerization process was used in order to incorporate more polyaniline in the composite.…
Abstract A thermoset type anisotropic conductive adhesive film (ACAF), which electrically connects an ITO glass and a flex circuit both having conducting pattersn of less than 100 μm in pitch, has been developed. In this development, bisphenol A and bisphenol F epoxy resins were tested to formulate an ACAF with easy‐t…