Die Löslichkeiten von GaP und GaAs in Sn und Bi

The pseudo-binary GaAs Bi, GaPs Bi and GaP Sn phase diagrams were investigated by Differential Thermal Analysis (DTA), and a theoretical analysis on the basis of the regular solution model for Ga GaAs Bi, Ga GaPs Bi and Ga GaP Sn has been presented. The solubilities of GaAs and GaP in Sn and Bi in the temperature range of 600–1200°C were determined. The solubility of the compounds decreases in the order Sn Ga Bi.     

Untersuchung der lokalisierten magnetischen Momente und der Nahordnung in Fe-Cr-Al- und Fe-Mn-Al-Legierungen mittels Neutronenstreuung

Short range order effects of two ferromagnetic alloy systems with low electrical conductivity (Fe–Cr–Al, Fe–Mn–Al) and the localized magnetic moments of Fe, Cr, and Mn have been investigated by magnetic diffuse neutron scattering. For Fe–Cr–Al the short range order parameters of the first three neighbour shells are given. The distribution of Al and Mn in the Fe-Mn-Al system has been qualitatively discussed. The cross section of the magnetic diffuse neutron scattering on systems with short range order was extended from binary to ternary alloys.     

Punktdefekte und Überstrukturerscheinungen in CdSe-Epitaxieschichten

Transmission electron diffraction patterns with superstructure reflections are observed with high vacuum deposited films of CdSe onto cleaved planes of CaF₂. These superstructure phenomena are interpreted by a regular distribution of point defects and compared with calculations according to the Debye-Hueckel theory. It is shown, that due to deviations from the stoichiometric composition in many cases the existence of the zincblende and wurtzite structures can not be explained in terms of the dielectric structure theory of PHILLIPS and VAN VECHTEN alone.     

Beitrag zur Kationenverteilung und Diffusion in 5A-Zeolithen

On the basis of literature data on structure of the unit cell of zeolites typ A the positions of lattice elements and step by step exchange of Na- by Ca- and Mg-ions are discussed. By means of different cation distribution models conclusions are elaborated for the diffusion of adsorbat molecules in 5A-zeolites.     

Zur Diffusion von Hf und Ti in Ni

The diffusion coefficients and solubilities of Hf in Ni were measured with the electronprobe at sandwich samples. The temperature dependence of the diffusion coefficients of Hf in Ti was compared with the corresponding values of the system Ti in Ni. In both systems was found a good accordance with the Arrhenius relation within four orders of magnitude. The solubility of Hf in Ni is found to be nearly by the factor 2 larger than the values known from earlier papers.     

Morphologie und Wachstum von Magnetitkristallen in Schlacken von Kupferschmelzen

The magnetite skeletal crystals found in the copper production slags of the plant „Georgy Damianov”︁ in Bulgaria are investigated and described in the present work. The magnetite crystals were microscopically studied by means of reflected light on polished specimens, and as a result it was found out that every single skeleton represents a combination of an oktahedral skeletal multi-edge form and a tetragontrioctahedral skeletal multiplane one. The morphology of the described form and its deviations from the ideal one are analysed in detail.     

Struktur und Energie der Phasengrenzen in gerichtet erstarrten NiAl-Cr-Eutektikum

Morphology, crystallography and interface structure of the rod-like directionally solidified NiAl–Cr eutectic were examined by transmission electron microscopy. Regular arrays of misfit dislocations of pure edge type on the cylindrical interface between the chromium rods and the NiAl matrix has been observed. The spatial arrangement and the Burgersvectors of the dislocation networks were analysed. Measurements of the distances between the misfit dislocations yielded a mean value of 1480 Å and a mean misfit of 0.195% in 〈100〉 directions. The experimental results were used to calculate the misfit-dependent part of the interfacial energy in different ways and to prove the applicability of the interfacial theory proceeding from the work of van der Merwe to the case of directionally solidified eutectics.     

Ergebnisse raster-elektronenmikroskopischer Untersuchungen zur Bruchentstehung und Bruchausbreitung in Fe-Cr-Legierungen

Crack nucleation and fracture propagation in an iron-25wt.% chromium alloy were investigated by examination of the fracture surfaces in a scanning electron microscope. In most cases the fracture was initiated by cleavage of grain boundaries which are covered with carbide and/or nitride precipitates. From the cleaved grain boundaries the fracture propagated into the ferrite matrix. Oxide inclusions also initiate cleavage fracture, but carbide and nitride precipitates are more critical. In connection with the mechanical properties, the results show that the iron-25wt.% chromium alloy exhibits good ductility, if the carbon and nitrogen content are sufficiently low.     

Untersuchungen zur Konzentration und Ausheilkinetik von Kristallbaufehlern in Metallen mit Hilfe der Positronenannihilation. Kurzer Abriß und Literaturübersicht

The basis and the use of the positron annihilation method for the study of crystal lattice defects in metals is shortly described. It follows a structured review on publications of last years.     

Anwendung der Reaktionskristallisation in der Hydrometallurgie und der anorganisch-chemischen Technik

With respect to several technical reaction crystallizations (jarosite, goethite, alunite, ammonium hexavanadate, calcium carbonate, zine carbonate) some fundamental problems of the reaction crystallization from solutions are discussed: 1) Adjustment of the rates of reaction and growth; 2) Selection of the chemical compounds according to their solubility; 3) Selection of suitable reactants; 4) Selection of the range of pH. The morphology of precipitates has been examined. With the use of low reaction rates and concentrated initial solutions homodisperse crystallite agglomerates were found to be characteristic of the precipitates.     

Statistische Untersuchungen zum Wachstum und Habitus von Fluor-Amphibol-Kristallen in Oxid-Fluorid-Gemengen

The habit of fluor-richterite crystals growing in oxide-fluoride-mixtures is determined by the character and composition of melting phase developping in the mixtures. Firstly it depends on the nucleation rate of crystals growing within the melt. Factors governing habits are the contents of chlorine and fluorine respectively and the physical preparation of batches. Most fibrelike crystals grow in mixture containing 10% NaCl, which are heated in the interval between 950 and 1050°C.     

Zusammenhang zwischen Gitterdeformation und Verfärbungserscheinungen in synthetischen Quarzeinkristallen

In synthetic quartz monocrystals with fringes of smoky colouration perpendicular to the growth direction a connection, between the absorption in the optical range and the change of the lattice parameter in areas of different colouration exists in that kind that they are proportional to each other.     

Mehrphotonen-Absorption in Kristallen und ihre Anwendungen. Will Kleber zum Gedenken

The paper summarily reports on absorption phenomena occurring in crystalline matter, whereby excitation states are obtained with more than one photon participating in the elementary excitation act. This is possible both by simultaneous multiphoton absorption and by a consecutive, step-by-step absorption of a number of photons (2 photons in most reported cases). Among possible applications of these phenomena, laser or 2-photon spectroscopy, infrared quantum counters (IRQC) and infrared frequency converters (frequency up conversion) have raised particular interest recently.     

Effektive Masse und Beweglichkeit der Löcher in p-ZnSiAs2

The density of states effective mass of the valence band and impurity parameters in p-ZnSiAs₂ were determined from the temperature dependence of the Hall coefficient. The density of states effective mass of holes in ZnSiAs₂ is (0.21 ± 0.03) m₀. Three acceptor levels located at 15 meV, 40 meV and 200 meV upper the valence band edge were found. A mobility analysis was carried out taking into account the interaction of the current carriers with the large number of longitudinal optical branches existing in chalcopyrite structure. The experimental values are in good accordance with the theoretical mobility curves in the temperature range from 77 K up to 600 K.     

Zum Zusammenhang von Verfärbungserscheinungen und Gitterdeformationen in synthetischen Quarzeinkristallen

Synthetic quartz monocrystals with fringes of smoky colouration perpendicular to the growth direction show maxima of the reflected intensity of X-rays (reflection 0003) on places where the absorption of visible light varies strongly. Detectable components of the displacement vektor are parallel to the growth direction. In strongly coloured regions the lattice is expanded.