Materials Literature
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The solution of Poisson's equation is an essential step in the formulation of self-consistent calculations. An efficient method of solution is presented for a system of arbitrary geometry. The charge density and potential within a cell of arbitrary shape are expanded in spherical harmonic series. A truncation function…
The complete Raman spectra of single-crystal synthetic zircon and thorite are reported for the first time. Results are presented for thorite at 295K and zircon at 295 and 90K. The temperature-dependent study was essential for distinguishing between weak first-order bands and second-order features which can have narrow…
The problem of the collapse of a vapour/gas bubble attached to a solid wall and initially perturbed from a hemispherical shape is solved numerically by the variational method, in which the bubble's viscosity and compressibility in liquid are neglected. The effects of surface tension on the collapsing bubble are taken…
Abstract We present a comprehensive theoretical survey of defect structures and energies in uranium dioxide and related non-stoichiometric phases. Our work is based on accurate computational methods of simulating defects in insulators. Such simulations require reliable lattice models for the material investigated. Our…
Abstract Bei der Umsetzung der Zinkkomplexe der 5‐Oxonia‐ und 5‐Thioniaporphine 1a–c mit Aminen, Sulfiden oder Methoxiden wurden die entsprechenden 1‐ oder 19‐substituierten Biliverdin‐Derivate 2c–r gebildet. Deren chemische und spektroskopische Eigenschaften ähneln im allgemeinen denen der Biliverdinate 2a und b . Ei…
Dynamical compression tests in the temperature range of 300 to 500 °C are carried out and discussed for single crystals of the intermetallic compound MgZn2. The influence of temperature and chemical composition of the crystals within the range of homogeneity on the plastic behaviour is investigated. The yield drop obs…
For [001]- and [011]-oriented pure NaCl single crystals the total dislocation density ϱtot and the densities of the primary (ϱp), the orthogonal (ϱo), and the remaining dislocations (ϱr) are determined as a function of the flow stress τ. The total dislocation density varies according to \documentclass{article}\pagesty…
In Part I of this paper a cluster model was proposed allowing to explain the geometrical features of diffuse intensity contours observed in electron diffraction patterns from binary substitutionally disordered systems. According to this model the ordering state, termed “transition state”, can be considered as being bu…
The influence of substituted elements, such as Ti, Mn, Ni, Cu, Ge, on the DO3 type structure is investigated by electron microscopy and Mössbauer spectroscopy. The results lead to the assumption that titanium and presumably manganese substitute into the β-sublattice while nickel substitutes, in an ordered manner, into…
Vaporization measurements by the Knudsen technique and by mass spectrometry have been performed on the incongruently vaporizing titanium monoxide at the stoichiometric composition. Over this sample at 1806 K Ti(g) has a higher pressure than TiO(g) by a factor of about 3.5. The free energy difference between TiO(g) and…
Optical linear and nonlinear properties of single crystals of m-aminophenol, m-nitroaniline, m-chloronitrobenzene, and m-bromonitrobenzene have been studied. The second order optical susceptibilities have been measured with a Nd–YAG laser using a generalization of the Maker fringes technique to the case of biaxial cry…
Excitation profiles of depolarized modes (blg, b2g) in Ni etioporphyrin I exhibit marked 0–0 resonance Raman intensity upon Q-band excitation. By contrast, inversely polarized Raman scattering (a2g) is stronger with 0–1 excitation. Within the crude Born–Oppenheimer approximation, a theoretical model is presented which…
A theory for the photoemission from an electron gas due to the Drude energy absorption is presented. The theory, for both $p$- and $s$-polarized incident light, is based upon the three-step photoemission model and exhibits significant effects of the second-order matrix elements involved. Photoyields, energy distributi…
Stress gradients generated by electromigration in aluminum films were measured at 340 °C. The stresses were measured by combining x-ray topography to record the effects of the film stress and scanning electron microscopy to measure the information on the topographs. At the electromigration threshold the stress gradien…
Self-consistent pseudopotentials are used to investigate the electronic structure of $\ensuremath{\alpha}$-quartz. We present calculations for the band structure, electronic density of states, optical response functions, pseudocharge densities, and x-ray emission spectra. We find excellent agreement between theory and…
Optical-reflectivity data are presented for Rh and Ir for a photon energy range between 0.2 and 40 eV. Strong interband structures are observed in the calculated dielectric functions and optical conductivities, and these are discussed in terms of recent energy-band calculations. The dielectric functions are used to ca…
Analysis of the $H$-point magnetoreflection spectra of graphite is shown to be sensitive not only to the magnitude, but also to the sign of the Slonczewski-Weiss-McClure band parameter $\ensuremath{\Delta}$. The demonstration that $\ensuremath{\Delta}$ is small and negative provides a definite assignment for the large…
Raman scattering measurements on bulk amorphous As and thin-film sputter-deposited amorphous As and Sb indicate differences in the vibrational character of the systems. The polarization properties of amorphous As indicate quasimolecular character with differences between the bulk and sputtered material attributed to l…
We study the vibrational density of states of glassy $A{X}_{2}$ systems such as Si${\mathrm{O}}_{2}$ and Ge${\mathrm{S}}_{2}$ which consist of tetrahedra linked together to form a random network. We show that the higher-frequency modes can be well represented by a model with a single-nearest-neighbor central force. Th…
Normal-incidence reflectivity spectra in the photon energy range 4.5 to 14 eV have been measured on the basal faces of single crystals of the layered disulphides and diselenides of Ti, Zr and Hf. The spectra are interpreted in terms of chemical trends in the band structures, and based on this interpretation, models fo…