Materials Literature
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The interaction between two neighboring localized magnetic moments in the transition metals and alloys in studied by using the Anderson model generalized to the case of five-fold degenerate d-orbitals. The effective exchange energy and the change of the localized moments due to the d-d covalent admixture are calculate…
Abstract The linear thermal expansion of molded PTFE samples of various crystallinities was measured in the vicinity of the transition at about 400°K. In the plot of length of the specimen versus temperature, an inflection of the straight line was observed in the temperature range from 388 to 402°K., the mean value be…
Abstract Heats and entropies of fusion of polymers are customarily evaluated through melting point depression measurements with the assumption that the observed and thermodynamic melting points are nearly identical. However, it has recently become evident that the crystal surface free energy is not negligible, so that…
Optical absorption, fluorescence, and paramagnetic-resonance experiments on single crystals of $\ensuremath{\beta}$-${\mathrm{Ga}}_{2}$${\mathrm{O}}_{3}$ doped with chromium were performed from room temperature down to a few degrees Kelvin. All the important low-lying energy levels have been identified from the optica…
Wavelength and intensities are reported for the Al K series using primary excitation. Included in the tabulation are the diagram lines α1α2 and β1, and the nondiagram lines α′, α3, α4, α5, α6, β′, β″, and β″′. Spectra are shown and line positions and intensities are detailed using both aluminum metal and aluminum oxid…
Intersecting faults on basal (0001) and prismatic (1210) planes in A1N (hexagonal, wurtzite structure) have been studied by diffraction contrast with the electron microscope. The faults on (1210) had fault vectors 3/2 p + 1/2 c=½[1011], as deduced from the observed vanishing conditions. The expected stair-rod dislocat…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMacrocyclic PolydimethylsiloxanesJohn F. Brown Jr. and George M. J. SlusarczukCite this: J. Am. Chem. Soc. 1965, 87, 4, 931–932Publication Date (Print):February 1, 1965Publication History Published online1 May 2002Published inissue 1 February 1965https://pubs.acs.org/doi/10.…
Abstract The conventional “string‐of‐beads” statistical model for flexible chain polymers is modified for derivation of configurational and thermodynamic properties of long‐chain ring molecules (i.e., flexible linear chains with ends joined) in dilute solution near the Flory temperature. The effect of the intramolecul…
The suggested phase diagrams for the system B 2 O 3 ‐SiO 2 as drawn from the findings of previous investigators are presented. These diagrams show the wide controversy regarding this system. The principal difficulties in obtaining reliable equilibrium data are the volatilization of B 2 O 3 , the hydration of B 2 O 3 ‐…
Measurements of thermal conductivity for the range 3° to 300°K are reported for both pure and heavily doped n- and p-type GaAs single crystals, and n-type heavily doped polycrystalline GaAs1−xPx crystals with six compositions between x=0 and x=0.5. The alloy ingots have much lower K values due to alloy scattering, wit…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Effect of Molecular Weight on the Melting Temperature and Fusion of Polyethylene1J. G. Fatou and L. MandelkernCite this: J. Phys. Chem. 1965, 69, 2, 417–428Publication Date (Print):February 1, 1965Publication History Published online1 May 2002Published inissue 1 February…
Type 310 stainless steel in thin sections was embrittled by hydrogen. The temperature and strain rate dependence of this embrittlement was almost analogous to that well-established for hydrogenated body- centered cubic (b.c.c.) metals, differing only in that at low temperatures and relatively high strain rates complet…
Measurements have been made of coercive force, susceptibility, isothermal remanence, thermoremanence and thermal and alternating field demagnetization of annealed magnetite powders in nine size ranges from 1·5 μ to 120 μ. The samples were dispersed in plaster to occupy a few per cent by volume of the specimens and thu…
Plastically deformed diamond single crystals were irradiated with fast electrons and their optical absorption spectra determined. The results suggest that preferential irradiation damage occurred in regions of high strain and that the group B absorption bands in type I diamonds are associated with strain.
<div class="htmlview paragraph">Studies were conducted using spark-ignited reciprocating engines to evaluate ammonia as an alternate fuel for certain military applications. Conventional engines were found to perform poorly on ammonia. Several practical methods for improving engine performance while burning ammon…
The characteristics of the ``synchrotron light'' emitted by electrons in the NBS 180-MeV electron synchrotron were studied in detail. The electron beam cross section was approximately 1×2 mm. The angular distribution and polarization properties were determined for the visible radiation; photoelectric techniques result…
CONTENTS I. Introduction 46 II. Short description of the methods for the preparation of pyrographite 47 III. Physicochemical processes occurring during the preparation of pyrographite 47 IV. Structure of pyrographite 50 V. Properties of pyrographite 52 VI. Uses of pyrographite 56
Abstract The acid strengths of organometallic compounds were determined by the color reactions with H AMMETT indicators. The acid strength of triethylaluminum was enhanced by the modification with water. The triethylaluminum/water system showed the maximum acid strength at about 1:1 molar ratio of water/triethylalumin…
Abstract A new technique for performing electron nuclear double resonance experiments, based on the observation of electron spin echoes, has been developed. Radio-frequency resonance transitions are induced during the time interval between pulses II and III of a stimulated echo sequence, and cause a fall in the echo s…
A family of synthetic elastic fibers, designated spandex fibers, has been developed, providing new degrees of sheerness and effective "power" in elastic fabrics. These fibers have segmented polyurethane structures. They are durable, they are white and accept dye readily, and they can be set by heat. The development of…