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。
On the basis of present investigations, copper(II) compounds with subnormal magnetic moments can be roughly divided into two types. Those with direct copper-to-copper interaction have short copper-to-copper distances. In these compounds, of which copper(II) acetate monohydrate is an example, the bonding is postulated…
Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans the biological, physical, and social sciences.
A systematic study of impurity segregation in spherulitic crystallization is described. The experiments deal principally with high polymers, in which the role of ``impurities'' is fulfilled by stereoirregular molecules or by molecules of low molecular weight. It is shown that these species are rejected preferentially…
The theory of the work-hardening curve of a pure single crystal is discussed. An outline is given of the experimental methods available for the study of the mechanism of plastic deformation and work hardening. An attempt is made to correlate existing theories of work hardening. The theory is illustrated by discussions…
Abstract Combined X-ray topographic and phase-contrast micrographic studies of natural diamond octahedral faces show that pyramidal trigons are always associated with dislocation outcrops. No dislocations outcrop at flat-bottomed trigons. On the other hand, absence of trigons does not necessarily imply absence of outc…
Fission fragment angular distributions have been measured with gold surface barrier detectors for proton-induced fission of ${\mathrm{U}}^{233}$, ${\mathrm{U}}^{234}$, ${\mathrm{U}}^{235}$, ${\mathrm{U}}^{236}$, ${\mathrm{U}}^{238}$, ${\mathrm{Np}}^{237}$, and ${\mathrm{Pu}}^{239}$. Absolute fission cross sections wer…
The spectrum of the recombination radiation from diamond has been measured over the photon energy range 4.9-5.5 eV at 90, 160, 207, and 320\ifmmode^\circ\else\textdegree\fi{}K. At 90\ifmmode^\circ\else\textdegree\fi{}K, recombination emission has been detected from ten samples out of a batch of fifteen single crystals…
Received 17 February 1964DOI:https://doi.org/10.1103/PhysRevLett.12.275©1964 American Physical Society
The physical model of two-dimensional p-electron delocalization proposed by Bersohn for crystalline iodine is examined. The principal features of the model are adopted, including the Hückel method for writing one-electron orbitals and the restriction to nearest nonbonded neighbor interactions. Crystal symmetry is expl…
The vaporization behavior of the systems boron—carbon and boron—carbon—silicon has been studied with a mass spectrometer. In addition to the gaseous species characteristic of graphite, silicon carbide and boron, the molecules BC2, B2C, BCSi, BSi2, BC, and BSi were identified and their atomization energies measured. Th…
By classifying particle center positions with a hexagonal grid, evaluation of the two-dimensional rigid sphere partition function is reduced to a special lattice statistics problem, with precisely defined nearest-neighbor effective pair interactions. The hexagonal cell size is chosen to be the maximum consistent with…
A framework for interpreting experiments on Doppler shifts in light scattering from pure liquids and polymer solutions is presented. The spectral density of the light scattered into a given frequency range and angle by a liquid composed of identical, isotropic particles much smaller than the wavelength of the incident…
ONE-DIMENSIONAL DISOI~DER IN SODIUM 2-OXOCAPRYLATE respectively are normal.These contacts are as follows : C(x, y, z)-C(~, ~, z) 4.02 A C(x, y, z)-C(~, 1-y, z) 4.29 C(x, y, z)-C(~, y, z-½) 4-12 C(x,y,z)-C(5, y,z+½) 4.12The structure analysis has been only recently completed, and it has therefore not yet been possible…
The formation of a silver ferrite of empirical formula AgFeO~ by reactions involving iron hydroxides and silver compounds in aqueous suspensions was reported by The initial interest of these authors was in use of the red-colored silver compound in identification of specific iron hydroxide compounds. The products obtai…
Crystals of MgSO~. 6H20 are monoclinic, space group C2/c, with 8 formula units in the unit cell with dimensions a=10.110, b=7.212, c=24.41 A; fl=98.30 .
Oxygen vacancies and their effects on electrical conduction in some metal oxides were considered through an exact solution of the equilibrium relations between oxygen partial pressure in the ambient gas and concentrations of oxygen vacancies and conduction electrons in the oxide. The mass-action law was assumed but no…
Magnetic resonances and susceptibilities are calculated for various allowed magnetic structures in orthoferrites and similar magnetic perovskites. The calculation is based on a general form for the free energy which includes canting contributions from both single-ion anisotropy and antisymmetric exchange, and which as…
In this paper the dispersion relation for second sound in solids is derived. The starting point of the analysis is a Boltzmann equation for a phonon gas undergoing a temperature perturbation $\ensuremath{\delta}{T}_{0}{e}^{i(\mathbf{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbf{x}\ensuremath{-}\ensuremath{\omega…
Abstract Some molecular complexes of the salt type have been prepared from phenazinium chloride or methosulfate and pyrene or p-hydroquinone. It has been confirmed that (1) the constitution, the color and the melting point of the molecular complexes varied with the drying conditions; (2) the ultraviolet absorption spe…
Abstract The density of polyethylene produced by free‐radical‐initiated batch polymerization at elevated pressures and temperatures was found to be determined by the amount of short‐chain branching and the molecular weight. The short‐chain branching was shown to depend solely upon the pressure and temperature of polym…