Materials Literature
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Polyacetylene, (CH)x, can be controllably doped p-type (oxidized) or n-type (reduced) by simple electrochemical procedures. Cyclic voltammetry studies on freestanding films of cis-(CH)x show that (CH)x can be reversibly oxidized at ~+3.6V vs. Li and reversibly reduced at ~+1.4V vs. Li. The spontaneous electrochemical…
Abstract The adsorption of sodium, chloride, and phosphate ions by allophane, imogolite, and halloysite has been studied in relation to the surface structure of the mineral samples. The high adsorption of phosphate (>200 μ mole/g) and chloride (10–30 meq/100 g at pH 4) by allophane is ascribed to the small particle…
The surface of a solid dielectric insulator becomes electrically charged when subjected to a high-voltage stress in vacuum. A method for calculating the surface flashover voltage based on the assumption that the discharge occurs in a layer of desorbed gases from the insulator surface is proposed. The electric field st…
Abstract A brief historical review has been made of the values assigned to the binding energy of C 1s electrons from hydrocarbon contamination on sample surfaces. The particular energy calibration technique used for each electron spectrometer on which the C 1s determination was made has been identified. There are nota…
Oxidized and neutral films of polypyrrole have been prepared electrochemically in the absence of oxygen and water. The neutral films are insulating and can be readily oxidized by chemical oxidizing agents to give films of greater conductivity than can be achieved by electrochemical oxidation. Optical spectroscopy prov…
Microcrystalline diamond has been formed on silicon or molybdenum substrates by vapor deposition from a geseous mixture of methane and hydrogen. Cubo-octahedral or multiply-twinned crystals were obtained. The structure of the deposits was identified by electron diffraction and Raman scattering.
The critical exponent γ in the relation between the dielectric constant and temperature (1/ε—1/εm = C'-1x (T—Tm)γ) has been determined precisely for relaxor ferroelectrlics Pb(Mg1/3Nb2/3)O3, Pb(Zn1/3 Nb2/3)O3 and a related solid solution 0.88Pb (Zn1/3 Nb2/3)O3-0. I2PbT103, as well as for normal ferroelectrics BaTiO3 a…
Sulphur concretes have been used for low-cost housing in developing countries and have potential for various other applications. Field trials have been conducted of sulphur-based curbs and gutters, sewer pipes, median barriers, linings for acid containers and road bases. Recent research has been concentrated on stress…
Abstract Electrochemical techniques were used to identify alloys having adequate localized (pit and crevice) corrosion resistance in a 121°C (250°F) - 3.5 MPa (500 psi) CO2 - 11 wt. % NaCl environment. Various molybdenum alloyed iron and nickel base type materials and a titanium alloy were found to be resistant. Concu…
Abstract The erosion behavior of candidate steel alloys for liquid-solid particle slurry service in coal conversion equipment was determined over a range of testing conditions. It was determined that relative erosion reistance of the carbon, low alloy, chromium, and austenitic steels tested could not be readily relate…
The Raman spectrum of lithium diborate (Li 2 B 4 O 7 ) has been recorded for the first time. After correction for polarisation leakthrough, the spectrum is consistent with group theoretical predictions. No anomaly is seen in the Raman spectrum from 100 to 400K or in the low-frequency dielectric constant from 150 to 35…
On the Depolymerization of Poly‐( R )‐3‐hydroxy‐butanoate ( PHB ) From cell‐free PHB or from dried cells of Alcaligenes eutrophus H 16 , which had been grown in an aqueous fructose solution, enantiomerically pure methyl, ethyl, butyl or β‐methoxyethyl ( R )‐3‐hydroxy‐butanoates are obtained in yields ranging from 75–9…
Abstract Corrosion control planning should begin before any well is drilled. The means of controlling corrosion in oil and gas wells are outlined in some detail in this paper. Primary cause of corrosion of metals is contact of metal with corrosive gases in well fluids in the presence of liquid water. Corrosion can be…
The impression creep behaviour of zinc is studied in the range 300 to 500 K and the results are compared with the data from conventional creep tests. The steady-state impression velocity is found to exhibit the same stress and temperature dependence as in conventional tensile creep with the same power law stress expon…
A model for the electronic and geometric structure of the non-bridging oxygen defect center in fused silica is presented. The structure of the center is determined by the dynamic Jahn-Teller effect, which appears as a forming of an additional oxygen-oxygen bond between the non-bridging oxygen atom and another oxygen a…
As2(SO4)3 belongs to the monoclinic system, space group P2~/c, with a = 9.389 (3), b = 5.255 (2), c = 19.355 (6) .i, fl = 91.88 (2) °, V = 954.5 A, 3, Z = 4, D,, = 3.00 (5), D x = 3.05 Mg m -~. The structure has been solved at 293 K with 1922 independent reflexions (2 = 0 .7107/ i , 0 < 32 °) and refined to a weighted…
Expressions for the relaxation rates for three-phonon "resonant" processes are obtained for the first time. It is also demonstrated that the contribution of such processes can be as high as 30% of the phonon resistivity of Ge at high temperatures. Because of the different temperature dependence from the nonresonant pr…
Additional transitions which appear in the absorption and luminescence spectra of heavily doped (\ensuremath{\sim} 1 at.%) Li${\mathrm{Ga}}_{5}$${\mathrm{O}}_{8}$:${\mathrm{Cr}}^{3+}$ originate on nearest-neighbor Cr-Cr ion systems. By analyzing these spectra at different temperatures, values are obtained for the exch…
The electron spin resonance and polarized optical absorption spectra of V4+ have been studied in single crystals of ZrSiO4, HfSiO4, ThSiO4, and ThGeO4, each having the zircon structure. The principal values of g and A in ZrSiO4 and HfSiO4 are found to be anomalous and significantly different from those of ThSiO4 and T…
A thermodynamics is introduced for fluids subjected to a constant shear. The theory is based primarily on the results of computer simulations using the technique of homogeneous shear nonequilibrium molecular dynamics applied to a system of 108 Lennard-Jones particles. It is supported qualitatively by the results of se…