Materials Literature
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Most realistic, off-lattice surface simulations are done canonically--- conserving particles. For some applications, however, such as studying the thermal behavior of rare gas solid surfaces, these constitute bad working conditions. Surface layer occupancies are believed to change with temperature, particularly at pre…
Intensities of LEED and PED are analyzed from a statistical point of view. The probability distribution is compared with a Porter-Thomas law, characteristic of a chaotic quantum system. The agreement obtained is understood in terms of analogies between simple models and Berry's conjecture for a typical wavefunction of…
We present a high voltage extension of the Tersoff-Hamann theory of STM images, which includes the effect of the electric field between the tip and the sample. The theoretical model is based on first principles electronic structure calculations and has no adjustable parameters. We use the method to calculate theoretic…
A method is presented for selecting the type of actuator best suited to a given task, in the early stages of engineering design. The selection is based on matching performance characteristics of the actuator, such as force and displacement, to the requirements of the given task. The performance characteristics are est…
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” opt…
The photovoltaic (PV) effects from sandwiched porous silicon (PS), fabricated using electrochemical etching processes, have been investigated. Contacts were made by bonding to semi-transparent coatings of Au via a secondary supportive Al contact. The contribution of the PV effects from the junctions of the metal (Au)/…
An oscillatory instability is experimentally evidenced in directional solidification of nominally pure succinonitrile in a unity P\'eclet number regime. It involves long-time oscillations of both cell width and cell tip position in a nearly phase quadrature and at a wavelength equal to twice the cell spacing. The inst…
We report results on an improved growth process for cubic boron nitride (c-BN) films. The films are deposited on a dc-biased silicon substrate using ion-assisted sputtering. First, we grow a BN template layer at a bias voltage which maximizes the sp3 content. After this template layer attains a thickness of ∼500 Å, co…
Antiferromagnetic resonance has been observed in powders of the conducting alkali fulleride linear polymers, ${\mathrm{RbC}}_{60}$ and ${\mathrm{CsC}}_{60}$, at high frequencies (75, 150, and 225 GHz). This is proof for an antiferromagnetically ordered ground state and shows that these systems are not spin glasses. Th…
We have investigated the structural and optical properties of rare earth-doped zinc tellurite glasses modified by the substitution of ZnF2. Raman and phonon sideband spectroscopies were employed to characterize changes in the glass structure as well as to probe vibrational behavior in the immediate vicinity of the rar…
Weak field piezoelectric coefficient and strain were investigated in ferroelectric SrBi2Ta2O9 (SBT) thin films by means of optical interferometry. Though the maximum polarization and dielectric constant were small enough (7 μC/cm2 and 150, respectively), the piezoelectric coefficient attained 17 pm/V under the dc elec…
We have measured the effect of a depolarizing field on the properties of a ferroelectric capacitor. By systematically adjusting the amount of charge available to compensate the polarization, we can control the strength of the field inside the ferroelectric. We find that even a few percent of uncompensated polarization…
Raman scattering from single-walled carbon nanotubes is examined in detail theoretically and compared with experiments. Within a simple tight-binding model the Raman matrix elements are evaluated explicitly, and the shape of the resonance in the scattered intensity due to interband electronic transitions is derived. T…
Ferroelectric thin films of BaxSr1−xTiO3 with compositional gradients normal to the growth surface have been formed by the successive deposition and annealing of films having step-variable Ba to Sr ratios. By suitably tailoring the magnitude and sense of the gradient in Ba to Sr ratio, directional potentials can be bu…
Carbon nanotubes dispersed in ethanol are aligned by an electric field. Due to the orientation of these elongated particles, the dispersion exhibits anisotropic behavior. Transmission experiments show rotation of the linear polarization of an incident laser beam. Alignment and relaxation times and the influence of the…
The title compounds (R = La, Pr, Nd, Sm, Eu, Tb, Ho, Er) have been prepared in polycrystalline form by a citrate technique and, excepting the Sm and Eu phases, structurally studied by high-resolution neutron powder diffraction. All the materials are isostructural (space group Pbam, Z = 4) and contain infinite chains o…
Abstract Barium Sulfate scale deposition in the near-well-bore, perforations or production tubing has severely affected well productivity in many North Sea Fields. This is due to the commingling of the sulfate-rich seawater used for reservoir sweep with formation water containing high concentrations of barium ions. Mi…
Abstract ScaleSoftTM is a new software package developed with a consortium of production and service companies for the prediction, control, treatment, and management of scale deposits in oil and gas fields. This software has been tested extensively with numerous well data and yields results more accurate and realistic…
Abstract This paper presents the results from recent laboratory studies on barium sulphate scale inhibition in high [Ba2+] produced waters and scale inhibitor thermal degradation/stability. In the barium sulphate inhibition experiments, the synergistic effect of different inhibitor molecules on scale inhibition is exa…
Aminopropyl-terminated polydimethylsiloxane (PDMS)-bisphenol-A polycarbonate block copolymers were synthesized by interfacial phosgenation reaction of 2,2-bis(4-hydroxyphenyl) propane (BPA) and aminopropyl-terminated PDMS. A new synthetic procedure shows better conversion yield of PDMS oligomer. IR, 1H, 13C, and 29Si…