Materials Literature
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A classification of A +2 B+'03 com pounds has been made on t he basis of ionic radii of the cons tituent ions. A grap h of t his type for t he perovski te compounds can be ~ivide d in~o orthor hombic, pseud ocubic, a nd cubic fi elds, wit h an area of ferroelectn c and antlferroelectnc compounds s uperimposed on the c…
Merz's picture of spike-shaped domains of reversed polarization emerging from an electrode is analyzed with particular attention to its electrostatic aspects, taking into account the inhomogeneous piezoelectric distortions which accompany domain formation. The depolarization energy of a domain is evaluated. The intera…
Abstract According to the Jahn-Teller theorem, symmetrical molecules with degenerate electronic states are unstable. Such molecules therefore take up a distorted shape. If there is near-degeneracy, the symmetrical shape may also be unstable. We have studied the distortion in some particular cases. The approach is to m…
The hyperfine splittings of the electronic ground states of the stable copper isotopes ${\mathrm{Cu}}^{63}$ and ${\mathrm{Cu}}^{65}$ have been measured by the atomic beam magnetic resonance method. The magnitudes of these splittings are $\ensuremath{\Delta}\ensuremath{\nu}({\mathrm{Cu}}^{63})=11733.83\ifmmode\pm\else\…
Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans the biological, physical, and social sciences.
It has been found recently that in ferromagnetic resonance experiments performed in inhomogeneous rf exciting fields at a fixed frequency, absorption of power takes place at a number of distinct magnetic fields. This is ascribed to the existence of long-wavelength modes of oscillation of the ferromagnetic sample. The…
Exper ments have been carried out to examine the effects of cold-working on the rate of precipitation in binary polycrystalline Cu-Ti, Cu-Cr and Cu-Fe alloys by measurements of electrical resistance, microhardness and thermoelectromotive force. In Cu-Ti alloys (1.72%Ti), in which the existence of the intermediate phas…
Samples of copper alloys containing chromium up to 1.02% were prepared by vacuum melting and casting with which the author studied the effects of chromium addition upon the softening temperature and mechanical properties at elevated temperatures, furthermore the effects of quenching temperatures, aging conditions and…
par HmmY GERMAIN C'est avec un sentiment de vive gratitude que je dedie l'espi•cc nouvelle puhliee dans la presente nole à mon maître le Chanoine Bioret donl nous regrettons tous l'ahscnce à celle Srssion de la Société holanique rle France, t'n Anjou, el jl' suis lr(•s heureux de pouvoir l'associer ainsi à nos travaux…
If we look at an electron micrograph like Fig. 1 representing a thin cellulose membrane hanging from a fibre that has been dried, we may at first suppose that this picture represents an artefact formed during the preparation or within the electron microscope. Pictures similar to this one found by Stemsrud on the membr…
C. H. S. Hitchcock, F. G. Mann and A. Vanterpool, J. Chem. Soc., 1957, 4537 DOI: 10.1039/JR9570004537
Oxidation tests on powdered green silicon carbide, mainly of the Type 6 H with 13.4μ or 21.6μ diameters, were carried out in dry oxygen of one atmospheric pressure for about 50 hours in the range of temperature from 810° to 1400°C. The result show that the oxidation increases with temperature.An empirical equation for…
J. A. Elvidge, J. H. Golden and R. P. Linstead, J. Chem. Soc., 1957, 2466 DOI: 10.1039/JR9570002466
Water vapour atmospheres are known to raise the temperature of the endothermic reaction of clay minerals in differential thermal analyses. In isothermal kinetic studies of dehydroxylation, it is shown that a stationary state is attained depending on the operating temperature. The rate of dehydroxylation is a function…
A nearly linear relationship has been found to exist between the optical density and the thickness of evaporated carbon films. The determination of film thickness by density measurements is shown to have a number of advantages over measurement by interferometry, particularly for very thin films.
Adsorption–desorption cycles of water vapour on ‘stabilized’ standard cellulose from dryness to saturation have been determined at 20°C, 30°C and 40°C. The 4O°C and 30°C adsorption isotherms are closer together than the 30°C and 20°C ones. The hysteresis loop at low relative humidity is considerably wider at 40°C than…
A new type of scanning electrometer is described which is capable of measuring the charge on areas as small as 0.3 cm2 at a rate fast enough to show changes in charge distribution on a dielectric surface within intervals of the order of 30 msec. The minimum charge density which can be measured is about 0.6×10−9 coulom…
An account is given of what the author believes to occur when static charges are generated on polymeric insulating surfaces by contact with other surfaces. The subject is approached by trying to predict what will happen, for subsequent comparison with experiment, rather than by taking existing data and trying to expla…
An investigation of some substitution reactions of 1-methylpyrrole has indicated that the α-directing effect of the hetero nitrogen during nitration is even less than it is in pyrrole. 3-Nitro-1-methylpyrrole has been prepared together with the 2-isomer by direct nitration of 1-methylpyrrole as well as indirectly. The…
The Curie point of polycrystalline barium titanate is found to increase proportionally to the square of an applied planar (two-dimensionally isotropic) compressive stress.Received 29 June 1956DOI:https://doi.org/10.1103/PhysRev.105.57©1957 American Physical Society