Materials Literature
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A variational approximation is obtained for the resistance (or total entropy production) of a circular orifice in a plane diaphragm at which the scattering is specular. It is found that the Ohm's law prediction must be multiplied by a correction factor of the order of unity and added to the `small orifice' Knudsen con…
Abstract The viscoelastic properties of some polyester‐urethanes are compared with the properties of other polymers. The behavior observed is anomalous in that these polyurethanes exhibit an unusually high value of modulus well above their T g , unaccounted for by either crosslinking or crystallinity. Various experime…
A new theory of work hardening in dispersion-hardened single crystals—by which we mean soft crystals containing hard non-deforming particles of a second phase—is described. It is based on the fact that, if the particles do not deform plastically, and the interface between particle and matrix does not fracture, then se…
Abstract A new, general synthetic route to poly‐ p ‐xylylene and substituted poly‐ p ‐xylylenes is described. The key intermediate in the new process is di‐ p ‐xylylene [(2,2) p ‐cyclophane]. It has been found that di‐ p ‐xylylene is quantitatively cleaved by vacuum vapor‐phase pyrolysis at 600°C. to two molecules of…
CONTENTS I. Introduction 817 II. Tautomerism of phenols 818 III. Tautomerism of nitrosophenols 823 IV. Tautomerism of azophenols 825 V. Equilibrium phenol–quinonoid transformations of p -substituted phenols 827
Abstract Endor measurements on a type 1b diamond with paramagnetic nitrogen centres were made at 4.2, 77 and 300 °K by means of a 35000 Mc/s spectrometer. The axially symmetric nitrogen hyperfine coupling and quadrupole coupling parameters at 4.2 °K are Aiso., = 92.228 ± 0.001, Aaniso. = 10.903 ± 0.002, P = – 3.974 ±…
Received 24 October 1966DOI:https://doi.org/10.1103/PhysRevLett.17.1079©1966 American Physical Society
A three-layered rhombohedral form of molybdenum diselenide has been produced by subjecting the normal two-layered hexagonal form to pressures of 40 kilobars and temperatures of 1500 degrees C. The new form is isostructural with rhombohedral molybdenum disulfide.
Abstract The heats of combustion of graphite and diamond have been redetermined in a high precision aneroid calorimeter. It is shown that the result obtained for graphite is consistent with all recently published figures with the exception of that reported by Prosen & Rossini (1944). The latter is significantly hi…
EPR studies at X-band frequencies have been carried out between 300° and 77°K on amorphous and crystalline selenium. Dominating the spectra of the amorphous material were a large number of paramagnetic centers ∼1019/cc which contribute to an unusually broad and inhomogeneous line of width, ΔHp p∼3Kg and g=2.3 to 2.8±0…
The specific heat and dimensional changes of the porous 96% silica glass – water system were measured simultaneously between −35 °C and +2 °C with coverages of 1.6, 4.0, 5.3, and 7.7 molecular layers. The specific heat of the adsorbate below the transition range was found to be higher than that of ice. No phase change…
The crystal structure of the new complex, CH3NH3NiCl3, has been determined. The compound crystallizes in the space group Cmcm with a=6.94, b=14.94, and c=5.95 Å. Each nickel ion has a distorted octahedral coordination with two chloride ions at 2.405 Å and four chloride ions at 2.351 Å. Adjacent octahedra along the c a…
The infrared absorption of single crystals of sodium formate has been measured in the region of 250 cm −1 to 4 000 cm −1 . Thin sections cut perpendicular to the unique axis were employed and spectra were recorded with light polarized at various angles in this plane. It has been possible to assign unambiguously all of…
The heat capacity of high-purity alpha uranium has been determined from 1.7 to 23\ifmmode^\circ\else\textdegree\fi{}K and smoothed into previous data at 25\ifmmode^\circ\else\textdegree\fi{}K. These heat capacities are significantly lower than the values reported by other investigators. The values for $\ensuremath{\ga…
A power series for the free energy is derived in the linear anharmonic approximation. This free energy is expressed in terms of a complete set of microscopic order parameters which determine the ionic displacements in the ferroelectric transition. In general this complete set of microscopic order parameters is larger…
The generation of electrons and holes in anthracene crystals by x rays from a 600-kV pulsed x-ray source was studied. The average energy deposited per electron-hole pair created $W$ was found to be 3\ifmmode\times\else\texttimes\fi{}${10}^{3}$ eV. The number of carriers generated was independent of temperature from --…
The Toyozawa theory of the electronic polaron and the related Haken-Schottky theory of the optical dielectric function are applied to the alkali and silver halides and to the rare-gas solids. It is found that for most of these crystals the above dynamical theories reduce to a static limit. This in turn indicates that…
Experiments with this scanning microscope have produced extremely encouraging results so that we feel Confident in predicting high resolution and high contrast after some obvious modifications are made in the system, such as providing a good objective lens. Experience with conventional lenses indicates that the instru…
Neutron-diffraction measurements have been made on single-crystal specimens of holmium at temperatures ranging from room temperature to 4.2\ifmmode^\circ\else\textdegree\fi{}K. Below the N\'eel temperature of 133\ifmmode^\circ\else\textdegree\fi{}K, the moments order in a helical structure in which the $c$ axis is the…
The dielectric properties of single-crystal and ceramic BaTi${\mathrm{O}}_{3}$ and of single-crystal SrTi${\mathrm{O}}_{3}$ were investigated as functions of hydrostatic pressure to 25 kbar and temperature to 150\ifmmode^\circ\else\textdegree\fi{}C. The Curie point of BaTi${\mathrm{O}}_{3}$ decreased linearly with inc…