Materials Literature
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One of the most important factors determining the properties of a solid polymer is the packing order. Crystallization is a means to control the degree and morphology of packing. There is a great difference between "free” and “induced” crystallization.The “free” crystallization leads to quasi-isotropic products, which…
The authors find the dispersion relation of the coupled magnetic-electromagnetic modes in a ferromagnetic slab in the Voigt geometry (applied static field H 0 and magnetisation M 0 in the plane of the slab, propagation in the perpendicular direction in the plane). The results differ significantly from those found by H…
Abstract Measurements are reported of the decay time of photoluminescence from the N3 centre: an impurity centre commonly found in natural diamond. The intrinsic decay time at low temperature is found to be 41 ± 1 ns. The decay time is specimen dependent, decreasing with increasing concentrations of pairs of substitut…
Abstract Hypotheses are reviewed on the origin of the magnesium-rich Triassic clays which characterize the Germanic facies of western Europe and north Africa. Relations between clay minerals, megafacies and stratigraphy are described from 28 localities in the Triassic Keuper Marl, Tea Green Marl and Rhaetic sediments…
A study is made of the growth of the $F$ band in Mg${\mathrm{F}}_{2}$ crystals irradiated with $^{60}\mathrm{Co}$ $\ensuremath{\gamma}$ rays as a function of irradiation time at room temperature. It is shown that a rapid initial-growth stage in the form of a saturating exponential occurs for crystals containing iron (…
A theory for describing the angle-resolved photoemission spectra from the bulk bands of solids is developed which views the photoemission process as a single-step coherent emission of electrons from atomic sources into a final state of well-defined momentum. The final state is assumed to be free-electron-like except i…
Negative ions resulting from electron attachment to van der Waals polymers of water are reported. The most prominent ions observed consititute a homologous series with the stoichiometric formula OH−(H2O)m. They and the positive ions H+(H2O)m are ascribed to ion–molecule half-reactions. The ionization of van der Waals…
The photoluminescence of plasma-deposited amorphous silicon is investigated. The luminescence intensity and spectral line shape are shown to be sensitive to many deposition variables, in particular the power coupled into the discharge, the concentration of silane in the gas stream, and the deposition substrate tempera…
The angular-resolved energy distributions for photoelectrons emitted from the (100), (110), and (111) crystal faces of aluminum are presented for photon energies in the range 7.0-11.6 eV. The emission in this photon energy range is dominated by surface photoemission excited by the normal optical field or the surface-p…
The nature of the electronic states through which band-to-band excitations or excitons evolve into $F\ensuremath{-}H$ pairs is central to an understanding of defect production in halide crystals. The present paper develops a recent empirical model in which a self-trapped exciton becomes an $F\ensuremath{-}H$ pair thro…
Angle-resolved energy distributions for photoelectrons emitted from the (111), (110), and (100) crystal faces of Au are presented for photon energies in the range 7.0-11.6 eV. The variation of peak-energy positions as a function of photon energy and electron emission angle has been studied. We have found very good qua…
The diffusion of a labeled particle on a one-dimensional chain is discussed. It is shown that the long-time behavior is dominated by density fluctuations leading to a ${t}^{\frac{1}{2}}$ dependence of the mean-square deviation in agreement with Monte Carlo results of Richards.
We report optical absorption measurements made on thick, highly pure crystals of ${\mathrm{Cu}}_{2}$O at 1.6 K. For the first time direct evidence is provided for a phonon-assisted paraexciton absorption edge. The relative strengths of phonon-assisted paraexciton and orthoexciton absorption edges are discussed.
The ferroelectric and dielectric properties of La, Sr, Zr, Fe and Mn doped BaTiO 3 ceramic are measured within wide limits of the amplitude E approximately of the external electrical AC field. At sufficiently low E approximately the losses are not ferroelectric in origin but are rather determined by the low frequency…
This book describes two-, three-, and four-dimensional crystallographic groups, primarily by the use of tables. Complete groups of four-dimensional tables are presented for the first time. The description of the four-dimensional crystallographic groups provides a clearer insight into dimension-independent crystallogra…
During the past 15 years, surfaces have been increasingly studied on the atomic scale. As a result, their atomic structure and composition and the dynamics of gas-surface interactions are much better understood. Modern surface science is beginning to have an impact on many technologies. Techniques are readily availabl…
Electron-optical properties of a gun with a point cathode are determined numerically by tracing a greater number of electron trajectories. In order to calculate the beam current density distribution, an attempt was made to describe the properties of the gun in terms of the parameters describing the initial conditions…
We explore the properties of a one-dimensional diatomic chain of atoms, where one species may occupy one of two off-center lattice sites. For a fixed configuration of atoms, this leads to a problem in lattice dynamics with disorder in the atomic force constants. Through use of perturbation theory, the vibrational free…
Abstract Die Korrosion von Aluminium unter Sauerstoff verläuft praktisch unabhängig vom pH‐Wert, und zwar sowohl unter Sauerstoffverbrauch als auch unter Wasserstoffentwicklung. Dieses Verhalten wird sowohl in einer Acetatpuffer/Natriumchloridlösung als auch in anorganischen (Salpeter‐, Schwefel‐Phosphor‐ und Salzsäur…
Abstract The glass transition temperatures ( T g 's) of several polystyrenes and styrene–alkyl methacrylate copolymers and terpolymers were measured using thermomechanical analysis (TMA) and differential scanning calorimetry (DSC). The polymers studied had number‐average molecular weights from 3000 to 250,000 g/mole.…