Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
We study the acoustic and electronic properties of one-dimensional quasicrystals. Both numerical (nonperturbative) and analytical (perturbative) results are shown. The phonon and electronic spectra exhibit a self-similar hierarchy of gaps and many localized states in the gaps. We study quasiperiodic structures with an…
The theoretical formalism of Ritchie et al. is used to characterize the electromagnetic properties of plasma oscillations in two-dimensional electron-gas disks, such as those produced lithographically in the GaAs-${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As semiconductor heterojun…
The anharmonic interaction (third-order elastic Hamiltonian) between fractons (short-length-scale vibrational excitations) and phonons (long-length-scale vibrational excitations) is introduced. The relationship between phonon-fracton scattering rates and the thermal conductivity \ensuremath{\kappa} is developed. Two r…
Metal selenide clusters have been made and characterized, using the arrested precipitation colloidal technique. A comparison of sulfide and selenide spectra enables observation of the effect of changes in the highest occupied molecular orbitals upon cluster electronic properties. The first and second excited electroni…
Measurements have been made of the current pulses observed in a negative point-to-plane corona discharge in oxygen. The apparatus was constructed to ultra-high vacuum standards to ensure controllable conditions on the gas purity and the state of the electrode surfaces. The effects of cathode voltage, tip diameter and…
The possibility of roughening in low-angle grain boundaries is investigated. By exhibiting an analogy between grain-boundary steps which do not have long-range strain and steps on solid surfaces, I argue that a grain-boundary roughening transition, of the same type as for solid surfaces, is possible. It is found that,…
By means of quasielastic neutron scattering we show that the H-diffusion mechanism in ${\mathrm{Pd}}_{85}$${\mathrm{Si}}_{15}$${\mathrm{H}}_{7.5}$ is characterized by two well-separated regimes of jump rates, in clear contradiction to present ideas on diffusion in amorphous substances. A semiquantitative interpretatio…
A very simple system with quasiperiodic dynamics is introduced, consisting of a single spin, with spin \textonehalf{}, in a pulsed magnetic field. The pulses are of two types, and the two types alternate in a quasiperiodic way. By adapting renormalization-group and dynamical-systems techniques first introduced in the…
Radiation-induced (dynamic) polarizations of electronic charge distributions on ligands may contribute to both the electric- and magnetic-dipole moments of 4f → 4f transitions in lanthanide complexes. These ligand-polarization effects on magnetic-dipole transition moments are examined in the present study, and their p…
The authors present and describe a new embedded-cluster approach for calculating both the electronic and the spatial structure of point defects in ionic crystals with self-consistent incorporation of the polarisation effects into the eigenvalue spectrum and the total energy of a crystal. For the first time both the el…
The distribution of apparent solid‐liquid dihedral angles, normally observed on planar sections of partial melting experiments, is examined in terms of a normal distribution of “true” dihedral angles present in any sample. A theory for predicting the distribution of apparent angles observed on a random planar section…
Abstract A previously described solid solution in the system Bi2O3-Nb2O5 based on the δ-Bi2O3 structure has been reinvestigated by electron diffraction and high resolution electron microscopy. Four distinct phases have been found, all of which are based upon defect fluorite structures, and the structural principles of…
Abstract Like some other oxides of the actinide elements, uranium dioxide has a fluorite structure and a propensity towards deviation from simple stoichiometry. Because oxygen can be transferred with ease between the UO2 lattice and the ambient gas phase, gross departures from stoichiometry occur readily. Diffraction…
Abstract The gamma‐ray‐induced crosslinking of polyacrylamide was carried out under various conditions. The molecular weight of the polymer before inrradiation was found to be the most important factor for crosslinking. When polymers have low molecular weights such as 80,000, the intensity of radiation, the external p…
Abstract The recent considerable interest in the transport and solubility properties of low‐molecular weight penetrants in elastomers arises largely because a number of important practical applications depend wholly or in part on such phenomena. These applications include various protective coatings, packaging materia…
Abstract A series of cyanoethylated celluloses with various degrees of substitution was prepared by homogeneous reaction of cellulose in PF/DMSO system. Their thermal deformation properties changed regularly with the degree of cyanoethylation. By comparing highly cyanoethylated cellulose in the series with that prepar…
Abstract The effect of precipitation on the molecular weight distributions of cellulose tricarbanilate (CTC) samples prepared from α‐pulp, hydrolyzed α‐pulp, and Avicel was determined using size exclusion chromatography (SEC). Precipitation of the CTC samples in methanol resulted in the loss of a low molecular weight…
Abstract The effects of particle concentration on the shear‐rate‐dependent viscosity, stress relaxation, and stress growth function were investigated for various molecular weight polydimethylsiloxane (PDMS) fluids filled with colloidal fumed silica. Shear‐rate‐dependent stress relaxation was observed for all dispersio…
Abstract Fluorocarbon elastomers exhibit high volume swell in methanol, but not in ethanol or other alcohols. Proton nuclear magnetic resonance (NMR) data indicate that neat methanol exists as a hydrogen‐bonded tetramer with a solubility parameter close to that of the fluorocarbon elastomer, thus causing the high swel…
Abstract The effect of 2,2′‐oxydiethanol (diethylene glycol, DEG) content (ranging from 2 to 15 mol %) and of the annealing temperature (in the range from 100 to 260°C) on the density, calorimetric, dynamic‐ and static‐mechanical and small angle X‐ray scattering (SAXS) behavior of undrawn and drawn samples (granules,…