Materials Literature
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Several compounds with m = 2, 3, 4, and 5 in the general formula (Me 2 ′O 2 ) 2+ (Me m–1 R m O 3m+1 ) 2– were synthesized, a number of them for the first time. They possess a layer‐type crystal structure. Bi 3+ may be the only suitable ion for the Me′ sites; R may be Ga s+ , Ti 4+ , Nb 5+ , or Ta 5+ . The restrictions…
The exchange interaction that gives rise to ordered magnetic states depends upon interatomic spacing. If the lattice is deformable, then a spontaneous distortion of the lattice will occur in the ordered state. We have calculated, in the molecular field approximation, the properties of a system in which the exchange en…
Bacteria-free clones of the small centric diatom Cyclotella nana Hustedt were isolated, three from estuarine localities, one from Continental Shelf waters, and one from the Sargasso Sea. Detonula confervacea was isolated from Narragansett Bay. Morphology of all clones was studied with the light and electron microscope…
Abstract The thermal transformations which take place in solid ammonium nitrate have been studied with the following techniques: differential thermal analysis, measurement of d.c. electrical conductance, optical microscopy, X-ray diffraction and nuclear magnetic resonance. It has been found that in dry ammonium nitrat…
The structures of the clay minerals are reasonably well known, but greater detail and more precision are needed if the properties of clays and soils are to be fully understood. For example, the selective adsorptive and catalytic properties and the reaction with organic materials vary with the character of the clay min…
The Zeeman-split quadrupolar resonances for Ba137 in BaBr2·2H2O were measured by using coincident enhanced proton resonance as a detector. The principal axes of the electric field gradient were found to be oriented thus: x parallel to b, y parallel to c, and z perpendicular to the bc plane. a, b and c are the crystall…
A generalized formulation of the diffusion-kinetic model of track effects in radiation chemistry is presented and criticized. It permits consideration of complex mechanisms, arbitrary initial distributions and radical correlation effects. Methods for the numerical integration of the associated differential equations o…
Localized lattice modes can contribute to the strain at a paramagnetic impurity and thus influence the spin-lattice interaction. Their contribution to the spin relaxation is estimated. It is governed by the rate with which a local mode attains equilibrium with the phonon continuum, estimated in a previous paper. Studi…
The microwave losses in both pure and doped SrTi${\mathrm{O}}_{3}$ have been investigated as a function of frequency and temperature. It is found that the loss tangent is proportional to frequency in the range 3-36 kMc/sec. Above the phase transition at 112\ifmmode^\circ\else\textdegree\fi{}K, the temperature dependen…
Neutron diffraction measurements were made on polycrystalline and single crystal samples of anhydrous Mn${\mathrm{I}}_{2}$ at sample temperatures from 298\ifmmode^\circ\else\textdegree\fi{}K to 1.3\ifmmode^\circ\else\textdegree\fi{}K. The results show an unusual type of antiferromagnetic order below the N\'eel tempera…
This paper describes a method to distinguish between two mechanisms that may cause weak ferromagnetism in the orthoferrites, i.e., antisymmetric exchange and single-ion magnetocrystalline anisotropy. The free energy of a magnetic crystal is expressed as a series in the applied field. The condition of invariance of the…
A series of ${\mathrm{Mn}}_{4}$N-type compounds has been investigated by means of magnetic saturation measurements and neutron diffraction experiments. Reinvestigation of ${\mathrm{Mn}}_{4}$N has given revised moments with $3.85{\ensuremath{\mu}}_{B}$ at the corner of the cubic unit cell antiparallel to the three face…
An analysis of the temperature dependence of the microwave loss in SrTi${\mathrm{O}}_{3}$ is presented using the linear chain model of a ferroelectric as a basis for discussion. It is shown that a plausible explanation of the temperature dependence of the microwave loss tangent above liquid air temperature is possible…
A single analytical expression to represent the published values of the atomic scattering amplitudes for electrons fe(x) is given, and the parameters are determined for elements Z = 1-18 and 20-104.
Abstract A direct numerical technique has been used to investigate the kinetics of impurity precipitation on dislocations making full allowance for diffusion and with a strong elastic interaction between the solute atoms and the dislocations. A distinction is made between the growth of discrete precipitate particles a…
Abstract Computations are presented for the analytic perturbation solution for the growth of a Maxwellian impurity atmosphere round a dislocation. The kinetics of growth of these atmospheres are related to the various physical processes involved. A direct numerical technique is then described for the case when the int…
Ferromagnetic resonance measurements have been carried out on single-crystal nickel films obtained by epitaxial evaporation on NaCl under various evaporation conditions. Resonance measurements on thin films by previous investigators have yielded anomalous values of 4πM which have tentatively been attributed to stress…
Abstract It is well known that polymeric materials in general creep with increasing time under a given constant stress and that stress relaxes with increasing time under a given constant strain. Recently, theoretical studies en these phenomena have been made in detail for polyisobutylene, vulcanized natural rubber and…
The electron paramagnetic resonance of ${\mathrm{Co}}^{2+}$ in single-crystal rutile (Ti${\mathrm{O}}_{2}$) has been investigated at 3-cm wavelength and 4.2\ifmmode^\circ\else\textdegree\fi{}K. The angular dependence of the resonance pattern indicates that the ${\mathrm{Co}}^{2+}$ ion enters substantially for the ${\m…
(1962). The Temperature Dependence of the Viscosity of Liquid Metals. Nuclear Science and Engineering: Vol. 12, No. 3, pp. 436-439.