Materials Literature
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Nuclear quadrupole resonance is a recently developed branch of radio-frequency spectroscopy which is concerned with magnetic resonance absorption in crystals. This absorption is due to reorientation of the nonspherical atomic nuclei against crystalline electric fields. Related phenomena in isolated molecules are brief…
Near 35°K the internal friction of vitreous silica reaches a peak value which increases with frequency. The temperature curves of the torsion and Young's moduli are concave upward with minima near 65°K and are independent of frequency. These effects are reversible with temperature. Their cause cannot be the usual type…
In a recent paper Taylor has shown that three distinct hydration levels exist within the ‘calcium silicate hydrate (l)’ group of artificial preparations (Taylor, 1953 a , p. 168). The individual hydrates may be distinguished from the position of the 002 reflection in X-ray powder photographs. The d spacings correspond…
Abstract The G. I. Taylor dynamic compression test consists of firing a cylinder of the material to be tested at a target of hardened armor plate, and deducing the dynamic yield stress from the resulting deformation. In the interpretation of the results, interest is concentrated on the wave front of initial plastic st…
Abstract Measurements are described of the dynamic properties of rubber, loaded with various amounts and types of filler, when subjected to mechanical vibration in simple shear at amplitudes from 0 to 3 per cent shear in the frequency range 20 to 120 c.p.s. The decrease of dynamic modulus with increasing amplitude is…
Using evaporation conditions adjusted for the deposition of true silicon monoxide, a series of films ranging in thickness from 0.03 to 10 microns was prepared on fused quartz, glass, rock salt, and highly reflecting aluminum surfaces. The optical constants of the films were computed in the wavelength region from 0.24…
About eighty transition metal compounds comprising borides, carbides, nitrides, oxides, silicides, and germanides of metals of Groups 4A, 5A, and 6A were tested for superconductivity down to 1.20\ifmmode^\circ\else\textdegree\fi{}K, using a magnetic method. Among the specimens were most of the known compounds of the a…
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The Mohs hardness scale consists of ten minerals arranged in increasing order of hardness such that each mineral will scratch the one on the scale below it, but will not scratch the one above it. Although these minerals are generally considered to be brittle, experiments show that under local indentation and during sl…
Zwischen der Streuung von Elektronen und Röntgenstrahlen an Atomen besteht bekanntlich eine enge Verwandtschaft: In die Berechnung der elastischen (kohärenten) Streuung geht derselbe Streufaktor ƒ, in die der unelastischen (inkohärenten) dieselbe Streufunktion S ein. Für die Röntgenstreuung hat sich die Berechnung von…
Abstract n-Paraffins from C7H16 to C36 H74 and polyethylene polymers (Polythene and Winnothene) have been subjected to atomic pile radiation. For the paraffins there is a decrease in the melting-point, until, for a radiation dose R, they no longer melt at temperatures of 160° C or above. At about this same radiation t…
Secondary emission by electron bombardment has been measured for single crystals of Ge with $p\ensuremath{-}n$ junctions. Maximum yield was found in the range $\ensuremath{\delta}=1.15\ifmmode\pm\else\textpm\fi{}0.03$, at ${V}_{p}\ensuremath{\approx}500$ volts and room temperature. Increasing temperature decreased the…
Magnetic resonance experiments performed on $\ensuremath{\alpha}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ confirm the existence of a highly anisotropic, weak ferromagnetism which disappears below -15\ifmmode^\circ\else\textdegree\fi{}C. The anisotropy energy has been studied as a function of orientation.
Infrared absorption bands characteristic of the crystal lattice were investigated for germanium and silicon. The absorption was found to be insensitive to lattice imperfections due to impurities (\ensuremath{\sim}${10}^{18}$ ${\mathrm{cm}}^{\ensuremath{-}3}$) and due to disorders (\ensuremath{\sim}${10}^{19}$ ${\mathr…