Materials Literature
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An apparatus is described whereby Poisson's ratio may be measured for fibers whose diameter is approximately 250μ. The apparatus is used in conjunction with an Instron Testing Machine so that stress vs. strain measurements can be made at the same time Poisson's ratio vs. strain measurements are made. The measurements…
Mass spectrometric studies of the gaseous species in sodium hydroxide vapor have shown that in the temperature range 300°C to 450°C, NaOH (1) vaporizes mainly as gaseous dimers. A thermodynamic treatment of ion current data yields for the reactions: 2NaOH(l)=Na2(OH)2(g)ΔH660∘K0=28±3 kcal/mole of dimerNaOH(s)=NaOH(g)ΔH…
Abstract From cation‐exchange capacity, specific surface, thermal, and elemental analysis data, formulas were derived for typical soil montmorillonites selected on the basis of X‐ray diffraction analysis after removal of free iron oxides and amorphous constituents. The formula of montmorillonite in the fine clay from…
We have confirmed the appearance in iron whiskers of domain walls which apparently violate the restriction that the normal component of magnetization must remain constant across the wall. These walls sometimes have a dotted or serrated appearance. We have found such walls in a closure domain structure which permits th…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSome Properties of Polymer Networks Formed from Oriented Chains of Natural RubberD. E. Roberts and L. MandelkernCite this: J. Am. Chem. Soc. 1958, 80, 6, 1289–1297Publication Date (Print):March 1, 1958Publication History Published online1 May 2002Published inissue 1 March 19…
The abnormal plots of reduced magnetization vs temperature for ferrites containing zinc are found to be associated with a concentration gradient in zinc that is generated by the preferential loss of zinc during sintering. The variation of the gradient in samples of zinc-iron spinels is correlated with sintering and an…
A model is proposed to explain the large part of the ferromagnetic anisotropy energy of CoxFe3−xO4(where x is small) which is caused by the presence of Co2+. The residual orbital angular momentum α(∼) of Co2+ is constrained by the crystal field to lie parallel to the axis of threefold symmetry. Spin-oribt energy λL·S…
Summary The layer structure of the kaolin mineral dickite has been shown to differ significantly from the idealized arrangement of regular tetrahedra and octahedra. Since the structure of kaolinite can be studied only by X-ray powder methods, it cannot be refined beyond the idealized arrangement. By applying the dicki…
Below the transition point 109°K a crystal plate of NaNH 4 -tartrate shows a domain structure under a polarizing microscope if viewed in the direction parallel to the b axis. The polarization in each domain lies parallel to + b or - b axis, and can be reversed by shearing stress. The spontaneous polarization is 0.21µ…
A brief review on the ferromagnetic domain wall is first presented, touching on its energy and thickness, its coercive force, and its motion in metal loops, tapes, and wires, as governed by eddy currents and by relaxation processes. Next to be presented are the experimental results of an extension of the Sixtus-Tonks…
Because both manganese and iron assume multiple valences in oxide structures, it is possible to fabricate spinels over a continuous range of composition from Mn3O4 to Fe3O4. Magnetic-moment data for samples fabricated within this range are reported and an interpretation of the data in terms of the distribution of ions…
The increase in linear dimensions of a 99.999% copper foil upon deuteron irradiation was measured directly as a function of integrated flux. Two bombardments were made on the same specimen with integrated fluxes of 3.14\ifmmode\times\else\texttimes\fi{}${10}^{16}$d/${\mathrm{cm}}^{2}$ and 7.68\ifmmode\times\else\textt…
A study has been made of the magnetic properties of the system of quenched magnesium ferrites (MgxIIFe1−xIII) · (Mg1−xIIFe1+xIII)O4, where x, the fraction of magnesium ions in tetrahedral sites, varies from 0.14 to 0.26. Included among the properties examined are: saturation moment, Curie point, initial permeability,…
Line broadening because of crystalline anisotropy and the random orientation of the crystallites is investigated for the case in which the anisotropy field is much larger than the saturation magnetization. The theory predicts an absorption line with shoulders on each side which correspond to grains in which a hard or…
The uniaxial magnetic anisotropy induced in iron-nickel alloys by a magnetic anneal has been determined as a function of the composition, annealing temperature and duration. It was found that the result is consistent with the Néel-Taniguchi theory.
The magnetocrystalline anisotropy constant (K1) and saturation magnetization (Ms) of magnesium-iron ferrite monocrystals containing 6 to 50 mole percent magnetite were measured as a function of temperature (T) and ionic distribution. For crystals containing 6 to 25 mole percent magnetite, K1 was found to vary more rap…
The model of the bands recently proposed by Slonczewski and Weiss for graphite single crystals is described in some detail. It is then applied to a study of the cyclotron resonance absorption in graphite, taking into account plasma effects. This theory is then compared to the recent experimental data of Galt et al. Th…
Abstract The elastic modulus of highly oriented crystalline polymers is discussed in terms of a series model. As has been shown previously, if a polymer has fully extended chain configurations within the crystalline regions, the modulus of this phase may be expected to be high. In this case the macroscopic elastic mod…
Abstract It is shown that synthetic rubbers, in contrast to natural rubber, can be vulcanized to soft rubber by a simple thermal treatment without any previous admixture of sulfur or accelerators. This process has been designated as “Thermovulcanization” to distinguish it from the regular vulcanization procedure under…
Abstract Measurements are described of the rate and final extent of crystallization at a temperature of −25°C. in natural rubber which has been modified by the chemical combination of sidegroups to the rubber molecule. The substances added were six thiol acids. Their efficiencies in retarding crystallization are compa…