Materials Literature
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The total decay rate of the 6 I 7/2 term level of Gd 3+ in YOCl and LiYF 4 is studied as a function of temperature. This rate is described as a termal average of the difference contributions of the crystal field components. The difference between the rates in YOCl and LiYF 4 is discussed.
In disordered superconducting Cu-Zr alloys with dilute magnetic impurities, we have observed a new type of resistance anomaly which gives rise to strongly increased scattering of conduction electrons in a narrow temperature range above ${\mathit{T}}_{\mathit{c}}$ and appears to be due to interaction between supercondu…
The phonon free energy is calculated for several silicon carbide polytypes using a valence overlap shell model. The three most commonly observed polytypes, i.e. (2), (23) and (3), are shown to be thermodynamically stable, with (2) and (3) as the low- and high-temperature phases, respectively, and (23) in between. The…
The relaxed structures of the (1), (2), (23) and (3) polytypes of silicon carbide are calculated using the pseudopotential total-energy technique with norm-conserving pseudopotentials and the local density approximation to the exchange-correlation energy. A 'tension model' is proposed to account for the atomic forces…
Using neutron-spin-echo and time-of-flight spectroscopy we have investigated the precise temperature dependence of the elastic (nonergodic) fraction in the spectrum of density fluctuations of the glass-forming polymer polybutadiene. With increasing temperature we found a critical decrease of the normalized elastic int…
Visible photoluminescence was observed in ultrafine Si particles at room temperature. Transmission electron microscopy revealed that Si microcrystallites were embedded in a Si oxide matrix for the sample which emitted the light. The emission energy depended on crystallite size in the range from 2.8 to 5 nm. The invers…
Abstract Various clay stabilizers are discussed, and methods are proposed for evaluating their effectiveness. Laboratory tests are used to rate the relative efficiency of potassium chloride vs other salts and organic compounds. Advantages and limitations of the various clay stabilizers are described. These studies sho…
Abstract The high strain rate response of polycarbonate (PC) and polymethyl methacrylate (PMMA) are measured using a split Hopkinson torsion bar for shear strain rates Ẏ from 500 s-1 to 2200 s-1, and temperatures in the range —100°C to 200°C. The yield and fracture behaviours are compared with previous data and existi…
The authors study finite-size corrections to the free energy in a two-dimensional random tiling model. This model is equivalent to an asymmetric six-vertex model and exhibits commensurate-incommensurate phase transitions of the Pokrovsky-Talapov type. They calculate finite-size scaling amplitudes of the free energy in…
Abstract Review: (discussion of the investigation methods (i.e.
Abstract The thermal degradation of samples of cotton, cotton oxidized by ceric ion, cotton grafted with vinyl acetate and methyl acrylate having different percent grafting yield, poly(vinyl acetate), and poly(methyl acrylate) has been investigated using the techniques of thermogravimetric analysis (TGA) and different…
Abstract The grafting of polyacrylamide on to guar gum in aqueous medium initiated by the potassium persulfate/ascorbic acid redox system has been studied gravimetrically at the temperature 35 ± 0.2°C in the presence of atmospheric oxygen and Ag + ions. The rate of grafting was found to increase with temperature, conc…
A perovskite-type oxideLaO5SrO5CoO3wa8prepared by ceramic coprecipitation and drip pyroysis methods The pellet-shaped oxide was fired at temperatures between900and13000C for O5tp100h The
The mean square displacement of a tagged particle in a liquid is known to exhibit a diffusive linear time dependence beyond a microscopic timescale. By making use of simple mode-coupling concepts the authors derive a set of analytic self-consistent equations for the relevant dynamical quantities in this regime, namely…
Pt/Co multilayers are an attractive candidate for a magneto-optical recording medium. However, films sputter deposited in Ar have coercivities too small (100–350 Oe) to be practical in recording. By sputter depositing multilayers in Kr or Xe instead of Ar, we achieved coercivities ∼1000 Oe, suitable for recording. We…
The authors measured the positron annihilation average lifetime in the sintered mullite-ZrO2 ceramic material at different ratios A/Z and including Cr2O3 and at three temperature values. The experimental results show that the positron lifetime can sensitively reflect the influence of different ratios A/Z and different…
The complex permittivity of a composite dielectric containing conducting inclusion is derived. The shape of the inclusions is described by their aspect ratio. The resultant equations describe the frequency dependence of the permittivity exactly, without recourse to empirically derived parameters.
We use a 9-carbon model compound to describe a proposed mechanism for homoepitaxial growth of diamond from methyl radicals on a hydrogenated, electrically neutral (100) surface. We estimate enthalpy and entropy changes for each step in the mechanism using group additivity methods, taking into account the types of bond…
The thermal properties of 4-cyanophenyl 4-(3,4-dialkoxybenzoyloxy)benzoates (1), 4-(3,4-dialkoxybenzoyloxy)phenyl 4-cyanobenzoates (2), 4-cyanophenyl 4-(2,4-dialkoxybenzoyloxy)benzoates (3) 4-(2,4-dialkoxybenzoyloxy)phenyl 4-cyanobenzoates (4), and some related compounds have been examined. Series 1 and 2 show a smect…
Scale Inhibitor Evaluations And A Mechanism Of Inhibition Of Sparingly Soluble Salts Mason B. Tomson; Mason B. Tomson Rice University Search for other works by this author on: This Site Google Scholar J. Matty; J. Matty Central Michigan University Search for other works by this author on: This Site Google Scholar J.E.…