Materials Literature
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We have studied the behavior of a chemically synthesized polypyrrole as electrode material. The different electrochemical methods that we have used for this characterization, namely, cyclic voltammetry, ac impedance measurements, and cyclic chronopotentiometry, have evidenced the role of the low frequency capacitance…
Nb‐doped BaTiO 3 has been prepared with various Ba/(Ti + Nb) ratios such that single‐phase products will be obtained if the charged donor center is assumed to be compensated in turn by Ba vacancies, Ti vacancies, equal concentrations of the two cation vacancies, oxygen interstitials, or electrons. For air‐Fired sample…
Copper single crystals oriented for multiple slip with [001] axes have been deformed in tension and investigated by X-ray line-broadening measurements using {002} Bragg reflections. The intensity distributions of the broadened line profiles of the deformed crystals exhibit an asymmetry whose ‘sign’ depends on the part…
A model was constructed for electromigration failure where both Fickian diffusion and mass transport due to the electromigration driving force are considered concurrently. The solution to the resulting diffusion equation yields a current exponent of 2 and an activation energy consistent with grain-boundary self-diffus…
REVIEWSpresented in this section begin with two papers which sketch how to calculate the forces in hydrodynamic journal bearings and tilting pad bearings.Six papers then address instabilities due to: internal energy dissipation; asymmetries (such as bearing stiffnesses or inertias) which introduce time dependent param…
This work, which follows on others, study the variation of the pH, and likewise the concentrations of the ions Ca (II) and SO4 (II) of the filtered potable water in which there were submerged the test specimens of mortar (1:3) made with a Portland cement (cement 3 < > P-450) and with the mixtures cement 3/slag = 85/15…
Inductively coupled plasma emission spectroscopy technique (ICP) raised as a step forward in traditional emission spectroscopy, has allowed the quantification, even from a trace, of the elements of a sample by means of the elimination of most of the chemical interferences. In this paper, a view of the subject is given…
The influence of aireation on the appearance or elimination of the false setting in industrial portland cements is studied by means of infrared spectroscopy.
For twenty-five years The ASTM method used to determine reductions in concrete durability after freeze-thaw cycling has been C215-60. In this test the fundamental frequencies of a concrete specimen are compared. This test is time consuming, noisy and often inaccurate. In this paper a new method is proposed for measuri…
The magnetocrystalline anisotropy of MnAl and MnAlC alloys, in the range of existence of the ferromagnetic τ phase, has been studied by using the singular point detection technique. The anisotropy field value at 293 K varies from 39 kOe for low manganese and high carbon content to 55 kOe for high manganese and carbon-…
Helmholtz’s theorem for three-vectors is applicable to electrostatics and magnetostatics, but it must be generalized to antisymmetric second-rank tensors to be applicable to electromagnetism. A proof of Helmholtz’s theorem for three-vectors, which is shorter than the usual one, is given. Helmholtz’s theorem is shown t…
Abstract Identification and characterization of coupled diffusional and electrochemical kinetics effects was achieved under potentiostatic anodic dissolution conditions. A one‐dimensional artificial pit geometry with sample wire electrodes embedded in an inert support exposed to NaCl solutions was used to study the di…
The following new or updated patterns are submitted by the JCPDS Research Associateship at the National Bureau of Standards. The patterns are a continuation of the series of standard X-ray diffraction powder patterns published previously in the NBS Circular 539, the NBS Monograph 25, and in this journal. The methods o…
There is some interest in the speciation of water in silicate glasses and melts, and the effect of bulk composition on this speciation. We have obtained infrared and Raman spectra for Si02-H20 glasses with low (1200 ppm) and high (6.3 wt%) water contents. The lowwater-content glass shows an asymmetric band in the fund…
Abstract While polymers are widely used for their excellent insulating properties, there is a growing need for thermally conductive polymer compounds. The thermal conductivity of metal particle, mineral particle, and carbon fiber filled compounds are examined at volume concentrations up to the maximum packing fraction…
The need for flame‐retardant finishing of textiles is examined in the context of the hazards of textile flammability, associated legislation and procedures for assessing textile burning behaviour. The functions of flame‐retardant finishes and durable finishes developed specifically for cellulose, wool and man‐made fib…
Abstract A suite of Georgia kaolinites, ranging from well-ordered to very poorly ordered samples, were studied to explore correlations between degree of structural disorder, geological environment, Fe 3+ content, Fe 3+ electron paramagnetic resonance (EPR) spectrum, and infrared (IR) hydroxyl-stretching band frequenci…
Abstract A Raman microprobe has been used to measure the surface‐enhanced Raman spectra of adenine, guanine, cytosine and thymine. Comparison of the SERS spectrum with solution spectra shows that some line positions are not influenced by the adsorption process while others show large shifts. In the SERS spectrum new l…