Materials Literature
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A brief review is given of model theories of the displacive structural instability in ferroelectrics. Particular attention is paid to the idea of compensation of the contributions of the short-range forces and the long-range internal field dipole forces to the square of the frequency of critical lattice vibrations. A…
A detailed model is developed for calculating the local distortion near Eu 2+ impurity sites in the alkali halides. The ionic positions obtained using this model are then used to carry out a superposition model analysis of the spin-Hamiltonian parameters. The results are consistent with results obtained for Eu 2+ and…
We have studied the dynamics of the phase separation between a dilute lyotropic lamellar phase (smectic) and an isotropic phase in a quaternary (water, sodium dodecyl sulfate, pentanol, dodecane) system. Observation of the phase separation with small-angle light scattering on an oriented sample allows us to demonstrat…
A density-functional theory for the transitions from isotropic to plastic crystal and to nematic fluid in a fluid of prolate hard ellipsoids is presented. Direct correlations are computed with a variational technique based on the Percus-Yevick equation for the correlation functions. As anisotropy is increased from the…
Fifty different mineral samples were tested as potential heterogeneous or epitaxial nucleants for four commonly crystallized proteins. It was found, by conventional protein crystallization techniques, that for each protein there was a set of mineral substrates that promoted nucleation of crystals at lower critical lev…
The authors describe a model of halogen-bridged mixed-valence linear chain complexes (transition-metal ions bridged by halogen ions) incorporating electrons coupled to on-site and inter-site phonons. They show that the charge-transfer situation appropriate to many members of the class corresponds to a charge-density w…
The tetragonal-orthorhombic phase transition in arsenic pentoxide has been studied by X-ray powder diffraction and is found to be a proper ferroelastic transition. The spontaneous strain behaves as the order parameter following Landau theory with epsilon s varies as mod T c -T mod beta , beta = 1 / 2 , T c =578 K. The…
Previously collected high-resolution neutron-diffraction data from KH 2 PO 4 (KDP) at room temperature have been re-analysed, including careful correction for thermal diffuse scattering, absorption and extinction and similar, new data have been obtained from 95%-deuterated KH 2 PO 4 (DKDP). This has made possible, for…
Received 16 November 1987DOI:https://doi.org/10.1103/PhysRevLett.60.238©1988 American Physical Society
In situ Fourier-transform infrared spectra of polyaniline give clear evidence for an insulator-to-metal transition in the first oxidation step and a metal-to-insulator transition in the second oxidation step. The former originates from a pure protonic mechanism without intercalation of counter ions whereas in the latt…
An amorphous silicon structure is obtained with a computer simulation based on a new moleculardynamics technique in which the interatomic potential is derived from a parameter-free quantum-mechanical method. Our results for the atomic structure, the phonon spectrum, and the electronic properties are in excellent agree…
Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text Brian L. McIntyre and Christopher L. Dennis, "Low-cost electron-beam lithography package for the scanning electron microscope," Appl. Opt. 27, 196-196…
The magnetic susceptibilities χ( Q ) are calculated numerically for some tight binding band structures with semiconducting property by means of Rath-Freeman method, in which the band structures are fitted to those obtained by APW method for LaN, LaP and GdN. From these calculations, the followings are found. (i) The b…
Most quasicrystals are found in alloys which have Frank-Kasper phases. These Frank-Kasper phases are characterized by a network of interpenetrating polyhedra, with coordination numbers (CN) 12, 14, 15, and 16. While the CN-12 (icosahedral) polyhedra cause icosahedral and decagonal quasicrystalline order, the CN-14 pol…
Thin films of ${\mathrm{Se}}_{80}$${\mathrm{Te}}_{20}$ were prepared by vacuum evaporation of the polycrystalline bulk alloy at a fast rate onto replicating tape pieces held at room temperature in a vacuum of 5\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}5}$ Torr. The alloy films were separated from…
We calculate the electronic resistance of a finite one-dimensional Fibonacci-sequence quasicrystal. We find that as a function of the electron energy (or, equivalently, the applied voltage) the electrical resistance of such quasicrystals shows strong fluctuations as resonant tunneling occurs through allowed energy sta…
Preparation and properties of the dc reactively sputtered tungsten oxide films have been investigated in relation to the oxygen concentration in sputtering atmosphere. The films with 1500–20 700 Å thickness were deposited on the glass substrates maintained at 200 °C by dc reactive sputtering from a metallic tungsten t…
The critical properties of the Ising model on the Penrose lattice of a size up to 439,204 sites are studied by means of the Monte Carlo simulation. We make an analysis of a phenomenological Monte Carlo renormalization group based on finite-size scaling. The critical temperature T c and the magnetic critical exponent y…
Data on the internal pressure of hard-sphere and hard-disk fluids have been available for some time from computer simulations, even at densities above the freezing density. These results for the metastable fluids suggest that the pressure diverges at the density of random closest packing. However, our examinations of…
Electromagnetic waves can discriminate between objects of different handedness due to their transverse nature, which implies that the origin of chirality necessarily need not be molecular as in the case of optically active media. By embedding chiral microstructures in a host medium, effectively chiral composites can b…