Materials Literature
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It is shown in detail how the magnetoelectric effect depends quadratically on the spin-orbit interaction. The effect is discussed in Cr2O3 using the spin Hamiltonian for the cases of an applied field parallel and perpendicular to the crystalline c axis.
The intermetallic compound UFe2 is ferromagnetic. A considerable number of magnetization isotherms have been obtained from 200°K down to 4.2°K with applied field up to 14 000 Oe. The Curie temperature has been determined to be 172°K and the Bohr magneton number 1.02 per UFe2 molecule. Several hysteresis loops at diffe…
Abstract The acid‐catalyzed condensation of formaldehyde and aromatic nitrile has been investigated. Methylenebis( p ‐carboxyphenyl)amide was synthesized in 90% yield by the interaction of p ‐cyanobenzoic acid with formaldehyde under the influence of conc. sulfuric acid. Polycondensation of methylenebis( p ‐carboxyphe…
Abstract Urethane polymers comprise one of the most rapidly expanding areas of the organic chemical industry. Polyurethane production, estimated at about 100 million lb in 1960, is expected to rise to 500 million lb in 1965 and to have an ultimate potential in excess of a billion lb. The polymers are used in foams (fl…
Well-defined exchange splittings of the R lines of Cr3+ in Cr2O3 have been observed in absorption at low temperatures. The majority of the transitions originate on the lowest (Ms=−32) component of the A24 (ground) state and terminate on the four (exchange split) components of the two E2 levels. The lines show strong p…
Evidence has been found which suggests the existence of high‐temperature crystalline modifications of both zirconium carbide and tantalum carbide. The high‐temperature inversion in zirconium carbide, indicated by a sharp decrease in spectral emisivity, in electrical resistivity, and in density, was reversible. No perm…
An abrupt magnetic transition in MnSn2 was reported by Kouvel and Hartelius1 about one year ago. The salient features of the magnetic behavior are a smooth susceptibility maximum at 86°K and an almost discontinuous decrease in susceptibility at 73°K. At the suggestion of Kouvel, a neutron diffraction study was made to…
Abstract A study of the ultraviolet absorption spectrum of polyvinyl alcohol (PVA) was made. Spectral examination of the solvolysis products of vinyl acetate and 1‐methoxyvinyl ester copolymers shows unequivocally that the absorption bands in PVA at 225, 280, and 330 mμ are related to carbonyl‐containing structures. T…
The experimental and theoretical effects of magnetocrystalline anisotropy upon the magnetic first-order phase transition in the compound MnAs are here described. A 3°C orientation-dependent difference in the transition temperature is observed near 20 kOe for a single-crystal specimen. Anisotropy measurements using She…
Abstract Styrene has been grafted onto cellulose in the form of cotton linters, cotton cloth, and rayon by ionizing radiation. Styrene was brought into intimate contact with cellulose by extension of the “inclusion” technique of Staudinger and Krässig, and graft copolymers were prepared by exposure to high energy elec…
The magnetization and electrical resistivity of the ordered alloy MnRh were measured during a complete temperature cycle between 4.2° and 700°K. At all temperatures the magnetization is proportional to field. From 700°K down to about 170°K, the susceptibility rises according to a Curie-Weiss relation, χ=C(T−θ)−1, wher…
The thermodynamics of magnetic processes in several compounds undergoing ferro- or ferrimagnetic to antiferromagnetic transitions are studied using critical field-transition temperature data obtained with a miniature-coil, pulsed-field technique. The zero-field transition entropy change in each material is calculated…
The phenomenon of rotatable anisotropy (RA) in Ni–Fe films refers to a reorientation of the easy axis along the direction of a previously saturating magnetic field in a time <1 sec at room temperature. The effect was first unambiguously observed by Lommel and Graham in Ni films and attributed by them to ferroma…
The spatial distribution of the covalent spin density in MnF2 has been obtained from a measurement of the ``forbidden'' magnetic scattering in the nuclear reflections using polarized neutrons. A partial Fourier map of the projected covalent spin on the basal plane was prepared. A model representing the covalent spin b…
Recently the lateral width of the cellulose microfibril has been estimated as 30 A rather than about 150 to 200 A, by extrapolation of data from model shadowing experiments. The difference was attributed to a layer of metal deposited during shadowing. However, direct photographs of the same microfibrils parallel and p…
Results from an experimental study on rayon and nylon tire cords embedded in rubber are reported. Stress-strain curves in tension and compression on thick-walled cylinders of such materials show that much higher moduli of elasticity are exhibited by cords under tension than by cords in compression. However, the compre…
The magnetic moments and susceptibilities of the piezoelectric-ferromagnetic compounds Ga2−xFexO3 have been measured over a temperature range from 4.2° to 350°K. The saturation moment at 0°K and the Curie temperature follow a linear compositional relationship. The magnetic properties of these compounds are sensitive t…
Magnetic field induced magnetoelectric (ME) effects in Cr2O3 and (Cr2O3)0.8·(Al2O3)0.2 have been examined with an ac method as a function of temperature and magnetic field. The ME effect parallel to the c axis reverses in sign at low temperatures for both materials, and is linear in H for all temperatures up to the sp…
A new apparatus for the investigation of the dynamic friction of fabric is described. The apparatus is designed so that frictional forces may be recorded as a function of the orientation of the fabric relative to a specified direction. Most of the experimental data have been obtained for the friction of a fabric on it…
Abstract From x‐ray diffraction data, a pseudohexagonal unit cell with a = b = 14.94 A. and c = 7.93 A. has been obtained for partially dried precipitate of amylose and tertiary butyl alcohol. Geometrical considerations establish a helical amylose configuration which has seven glucose residues per helix turn.