Materials Literature
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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…
Physical and dynamic viscoelastic properties of the blends of polyphenylene-ether (PPE) and aromatic low molecular weight compounds with specific chemical structure were studied. As a result, flexural modulus increase was observed by blending aromatic phosphates, phthalic esters, or aromatic amine, which had similar c…
Thermogravimetry, differential scanning calorimetry, and wide-angle X-ray scattering techniques were used to study changes in the composition, relative heat of fusion, and mean crystal size of blends made from low-density polyethylene (LDPE) and sugar cane bagasse (SCB), before and after exposure to the fungus Phanero…
Homopolymers and copolymers of acrylamide (AA) and acrylic acid (AAc) were synthesized by the free radical solution polymerization technique. Feed ratios of the monomers were 85 : 15 (w/w), 65 : 35 (w/w), and 50 : 50 (w/w) of acrylamide and acrylic acid, respectively, for synthesis of copolymers. All reactions were ca…
Poly(tetrafluoroethylene) (PTFE) surface was modified by the graft polymerization of sodium vinylsulfonate, and the chemical composition of the graft-polymerized PTFE surface was analyzed by X-ray photoelectron spectroscopy. Peroxides were formed on the PTFE surface by a combination procedure of argon plasma irradiati…
Film formation of three different latices was studied using atomic force microscopy. The latices were made from a mixture of butyl acrylate, styrene, and acrylic acid using either a polymerizable or an unreactive anionic surfactant as an emulsifier. Sodium 11-crotonoyloxyundecan-1-ylsulfate and sodium 3-(sulfopropyl)t…
An apparatus for measuring the pressure—volume—temperature (PVT) properties of polymers using a metal bellows has been developed at temperatures from 313 to 623 K and pressures up to 200 MPa. A calibration of the device was performed by measuring PVT of mercury and water. The experimental uncertainty of specific volum…
We study lead nanodroplets containing 147 to 1415 atoms at temperatures ranging from the bulk melting point up to the beginning of the evaporation regime. Molecular dynamics simulation and an embedded atom potential are used. The structures, total energies, and mobility of atoms in the clusters are analyzed. We found…