Materials Literature
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At rest between parallel plates, cholesteric liquid crystals commonly exhibit a characteristic twisted orientation pattern, the axis of twist being perpendicular to the plates. Also, this orientation pattern appears possible in nematic liquid crystals, since it is consistent with continuum theory(1) for both types of…
Liquid crystals are considered as gases of long barlike molecules. Variables describing the position and orientation of individual molecules are introduced. These are used to arrive at a microscopic definition of the order in liquid crystals in terms of a symmetric traceless tensor. The Frank and Leslie-Ericksen direc…
A fluid of hard rods is considered as a model for nematic liquid crystals. A direct application of the scaled particle approach results in an inconsistent thermodynamics. A simplified version which is consistent gives an integral equation for the orientational distribution which has the same form as that used by Onsag…
Molecular dynamics experiments made on a system of 864 particles interacting through a Lennard-Jones potential for various high-density states are used to study the self-correlation in classical fluids. The self-diffusion constant is computed and interpreted in terms of a hardsphere model. The memory-function formalis…
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The volume changes accompanying extension of peroxide vulcanizates of natural gum rubber were measured using a dilatometer technique. Measurements of the force-extension behavior and compressibilities were made on the same samples for the range of extension and volume change covered in the volume experiments. A consta…
The temperature dependence of the lattice parameters of ZnO was measured by x-ray powder-diffraction methods. Retrograde behavior was found to occur perpendicular to the c axis at 93°K. Lattice parameters at 4.2°K were a0=3.24826±0.00015Å, c0=5.2033±0.0018 Å. These results are compared with those for some other II-VI…
Initial sintering of several materials was studied by measuring powder compact densification at constant rates of heating (CRH). The CRH technique was extremely sensitive to the particle size distribution and other characteristics of the compacts. Although the CRH method circumvents several problems encountered in iso…
Summary The results obtained by the author in the study of clay‐minerals diagenesis are compared critically with the principal publications in this field, giving a general picture of the transformation of sheet silicates. Kaolinite minerals are related to the surficial zones of the earth's crust where they are formed.…
We have measured the temperature dependence of the intensity and spectrum of light scattered by fluctuations in the nematic phase of $p$-methoxy-benzylidene $p\ensuremath{-}n$-butylaniline. Our measurements are interpreted using two phenomenological theories of nematic liquid crystals.
The wavelength modulation spectrum of Cu is presented at 7\ifmmode^\circ\else\textdegree\fi{}K in the range of $2.0<~\ensuremath{\hbar}\ensuremath{\omega}<~6.0$ eV. The band structure of Cu calculated by the empirical pseudopotential method is used to compute the imaginary part of the dielectric function ${\ensu…
Ni-Br, Ni-Cl, Mn-Cl, and Zn-Cl boracites have been studied with electron and polarization microscopy. Among others 180° head-head or tail-tail domains are found in the orthorhombic phase of Ni-Br, Ni-Cl, Mn-Cl, and Zn-Cl boracite. They may be due to growth stacking faults on {100} planes. The orientations of strain-fr…