Materials Literature
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The structure of the electronic energy bands and Brillouin zones for graphite is developed using the "tight binding" approximation. Graphite is found to be a semi-conductor with zero activation energy, i.e., there are no free electrons at zero temperature, but they are created at higher temperatures by excitation to a…
Abstract Barium titanium oxide, which is tetragonal at room temperature, changes about 120° C to a cubic structure. This change has been followed in detail by means of X-ray powder photographs taken in a 19 cm. powder camera at intervals of a few degrees over a range covering the transition point. The unit cell, whic…
The mechanical behavior of grain boundaries in metals has been a subject of constant controversy. The present research is designed to examine thoroughly the mechanical behavior of grain boundaries in metals in a quantitative manner. A simple torsional apparatus has been devised for measuring four types of anelastic ef…
A bstract The surface tension of a number of optical glasses made at the National Bureau of Standards was measured by a modification of the anchor ring method. The values for the flint glasses at 1300 °6, were in the range 210 to 230 dynes per cm., the barium crowns ranged from 260 to 310, while the other types of gla…
Abstract Durch die Überlegungen in Kap. 1 wird zunächst festgestellt, daß die Coulombsche Abstoßung das Verhalten des "Fermi-Gases" der Leitungselektronen im Metall entscheidend beeinflußt. Zwar spielt diese Abstoßung keine allzu wichtige Rolle für die Elektronen, deren Energie kleiner ist als die Grenzenergie des Fer…
A bstract The results on barium‐strontium titanates are given for heat‐treatment, absorption, shrinkage, thermal expansion, dielectric constant, K , at minus 60° to 85°C. and also for Q (the reciprocal of the power factor) at 25°C. for frequencies of 50 kc. per sec. to 20 mc. per sec. A few measurements of K and Q wer…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation and X-Ray Diffraction Studies of a New Cobalt Carbide1L. J. E. Hofer and W. C. PeeblesCite this: J. Am. Chem. Soc. 1947, 69, 4, 893–899Publication Date (Print):April 1, 1947Publication History Published online1 May 2002Published inissue 1 April 1947https://pubs.a…
Abstract The viscoelastic properties of plasticized Vinylite VYNW were studied over a wide range of time scale by means of the tensile creep test. A number of different plasticizers were compared as to their plasticizing effectiveness. It was found that different plasticizers imparted distinctly different shapes to th…
Abstract The behaviour of complex materials under stress is described in terms of entities which are not strictly ‘physical properties’. These so-called ‘quasi-properties’ range from entities hardly distinguishable from dimensionally true physical properties to concepts which are much less clearly defined. Quasi-prope…
Abstract Detailed interpretations of the X -ray diffraction patterns of fibres and sheets of 66 and 6.10 polyamides (polyhexam ethylene adipamide and sebacamide respectively) are proposed. The crystal structures of the two substances are completely analogous. Fibres of these two polyam ides usually contain two differe…
Abstract Early in the investigation of butadiene-styrene copolymers as synthetic rubbers, this laboratory became interested in copolymers containing much more styrene than any of the American or German synthetics. This interest was soon directed to the resinous copolymers obtained when the styrene content is increased…
X-ray and microscope investigations of numerous specimens of so-called klaprothite from copper-bismuth ores of the type locality Schapbach valley, Baden, Germany and other localities, show that the specimens are actually wittichenite and emplecite and other known minerals.
The theory of the scattering of x-rays at small angles is given for a continuous distribution in size of randomly spaced and oriented spheroidal particles having arbitrary, but fixed, shape. Families of scattering curves are presented for spheres, and for spheroids ranging in shape from flat disks to long rods. Both M…
The name ‘halloysite’, first used in 1826 by Berthier, is derived from that of Omalius d'Halloy, who found the mineral in Angleur, Liége, Belgium. In 1935, Mehmel discovered that there were two distinct substances included under the name halloysite, one of which contains loosely bound water and shows a 10 Å. basal ref…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhysical and Chemical Properties of Pure FluorocarbonsR. Fowler, J. Hamilton, Jr., J. Kasper, C. Weber, W. Burford III, and H. AndersonCite this: Ind. Eng. Chem. 1947, 39, 3, 375–378Publication Date (Print):March 1, 1947Publication History Published online31 January 2005Publ…
An important delayed-fracture effect is found for mineral glass. A likely cause might be the gradual spread of Griffith cracks, but a theorem due to Griffith states that cracks do not spread below a certain average stress, and that at this stress they spread catastrophically. In the present paper, Griffith's theorem i…
The general approximate theory of x-ray scattering at small angles by finely divided solids is reviewed. It is assumed that the x-ray scattering data can be interpreted in terms of a particle size distribution, with particle-to-particle scattering negligible. Scattered intensity curves for Maxwellian, Gaussian, and re…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCONDENSATION OF AROMATIC ALDEHYDES WITH α-PICOLINE METHIODIDEARTHUR P. PHILLIPSCite this: J. Org. Chem. 1947, 12, 2, 333–341Publication Date (Print):March 1, 1947Publication History Published online1 May 2002Published inissue 1 March 1947https://pubs.acs.org/doi/10.1021/jo01…
The properties of dislocations are calculated by an approximate method due to Peierls. The width of a dislocation is small, displacements comparable with the interatomic distance being confined to a few atoms. The shear stress required to move a dislocation in an otherwise perfect lattice is of the order of a thousand…
Abstract It is shown that the theory of dielectric breakdown in solids previously developed by the author is correct only below a critical temperature Tc. This temperature is defined in such a way that above Tc the density of electrons (in strong fields) is so high that mutual collisions between electrons are more fre…