Materials Literature
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Paramagnetic-resonance absorption has been observed in complexes of acetylacetone with the trivalent transition metals titanium, chromium, iron, molybdenum, and ruthenium. The symmetry of the field perturbing the metal ion is predominantly axial. For the complexes of Ti+3 and of Ru+3, the axial potential is negative.…
Examination of small euhedral crystals of α-Al2O3 (sapphire) that were observed following oxidation of aluminum and an aluminum alloy in wet hydrogen at high temperatures showed that growth probably occurs by decomposition of AlO on an Al2O3 surface. Rapid growth occurs on the tips of needles and the edges of platelet…
Abstract An x‐ray diffraction study has been made of cellulose triacetate II. Small films of highly crystalline triacetate with good fibrous orientation and a fair degree of biaxial orientation have been prepared by repeated rolling at successively higher temperatures between 160 and 215°C. The x‐ray diffraction patte…
Abstract A general criterion for gelation in polycondensations having like groups of unequal reactivity has been formulated. In its simplest form, the criterion is that, for gelation, the expectation that a given structure will be propagated is unity, or greater. Several specific cases are treated, and literal express…
Power factor, loss factor, dielectric constant, volume resistivity, surface resistance, and dielectric strength of epoxies, varying in viscosity and reactivity and cured with several types of hardeners, have been determined and form the basis for this report. The effect of cure, temperature, and frequency on electrica…
The anisotoropy of the galvanomagnetic effects in the single crystals of pure bismuth was investigated at the temperatures between -160° and 45°C. The results were analysed by the phenomenological theory of the galvanomagnetic effects. Two components of the resistivity tensor, two components of the Hall tensor, eight…
Abstract A method is presented for the analysis of a reaction between a porous solid and a gaseous reactant where the kinetic expression is linear in the concentration and where appreciable concentration gradients are established in the pore system as a result of diffusive transport rate. Two cases are treated mathema…
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Samples of both $n$-type and $p$-type ${\mathrm{Bi}}_{2}$${\mathrm{Te}}_{3}$ containing from 3\ifmmode\times\else\texttimes\fi{}${10}^{17}$ to 5\ifmmode\times\else\texttimes\fi{}${10}^{19}$ extrinsic carriers were prepared and the phase diagram in the region about ${\mathrm{Bi}}_{2}$${\mathrm{Te}}_{3}$ has been clarif…
Abstract The results reported in part I, together with similar results for sodium chloride, have been analyzed in terms of the spectrum of harmonic vibrations of the crystalline lattice; since the zero-point energy proves to be small, the analysis should conform fairly closely to that of a static lattice. ʘ0 and the c…
The resistivity change induced by electron irradiation of zone-refined copper maintained at \ensuremath{\sim}10\ifmmode^\circ\else\textdegree\fi{}K has been measured over the range of bombarding electron energies from 0.70 to 1.37 Mev. The cross section for damage production is shown to be insensitive to the choice of…
The collapse of foams produced under controlled conditions by bubbling carbon dioxide through beer has been studied with particular reference to the rate at which liquid separates from them. If the volumes of the sample and of the foam produced from it are suitably adjusted, liquid is found to separate at a logarithmi…
The general chemical composition of untreated fibers of hemp, jute. and kapok has been studied, and the results have been compared to the composition of the corresponding α-celluloses and of the cellulose nitrates obtained by direct nitration of the original materials. After correction for nonglucose sugar residues, t…
An alloy of high magnesium content, 0.008 to 0.1% beryllium and 0.25% alumninum, is reported. Calcium may aleo be present (0.02 to O.44%). The alloys could be melted in their oxide skin in air without taking fire, e.g., for aircraft landing mats. (auth)