Einfluß von magnetischen und elektromagnetischen Feldern auf die Kristallisation aus wäßrigen Lösungen

It was stated that the quality of α-HJO₃ and TGS crystals is raised, when crystal grow from aqueous solutions influenced by magnetic fields of about 35 Oe or when the crystallization apparatus is shielded off electromagnetic waves of frequencies ≧ 10⁵ Hz. The quality of the crystals was determined by means of dislocation density.     

Ein Beitrag zur Züchtung von Alkalihalogeniden aus Lösungen

The authors performed preliminary investigations on the possibility of lowering the inclination of alkali halides to nucleation during crystallization from aqueous solutions. The increase of the metastable region and lowered inclination to nucleation was investigated by means of influencing the degree of order of the solution. It was proved that in the presence of dissolved oxygen, with higher concentration of hydrogen ions and in the absence of visible light the inclination to nucleation can be considerably lowered.     

Holographische Abbildung von Kristallwachstumsprozessen in bewegten Lösungen

The formation of aggregates in technical crystallizers is an important element in technical crystallization, but the investigation is very difficult. A device for direct observation of aggregation in stirred solutions is published.     

Untersuchungen an Systemen aus Salzen und gemischten Lösungsmitteln (XII) Kristallographische Eigenschaften und Zersetzung der Methanolsolvate des MgSO4

This paper informs on microscopic and IR-spectroscopic properties of MgSO₄ · 2 CH₃OH and MgSO₄ · 2 H₂O · 2 CH₃OH, structural composition, microscopic observation of thermal decomposition and some kinetic values of desolvating process.     

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.     

Wachstumsformen von tetragonalen Erdalkaliwolframaten in Schmelzlösungen und deren Deutung

Investigations on solubility of CaWO₄ in NaCl melts (ANIKIN ) were extended to BaWO₄ and SrWO₄. – Crystals of tungstates of Ca, Ba, and Sr from NaCl and KCl fluxes respectively were grown at temperatures from 950 to 650°C at cooling rates from 2 to 50 grd. h⁻¹. Marked differences in the forms of these tungstates did not occur. Among many whiskers bipyramidal crystals grew with dendritic, sceletal and hollow transitions forms. The theoretically calculated morphological succession (PBC model) is realised by the faces of the whiskers and platelets ([110] and [100] zones). The remaining crystals – due to face specific adsorption – show other forms similar to those in nature. – Verneuil grown crystals, however, developed – free, from adsorption phenomena – {110} and {001} forms respectively.     

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.     

Bestimmung von Diffusionskoeffizienten aus der Röntgen-Kleinwinkelstreuung und Lichtstreuung von Gläsern

It is shown how to conclude from small angle X-ray scattering and light scattering of phase separated glasses what kind of phase separation process is occurring in the glass. In the cases of diffusion controlled particle growth and of spinodal decomposition, methods were presented permitting to find out from diffraction experiments the diffusion coefficients underlying these decomposition processes. The methods were demonstrated with three different glasses.     

Optimierung der Kühlungskristallisation mittels Vermischung einer kalten und einer warmen Lösung

Heated saturated solutions were directly mixed with cold ones in a fluidization crystallizer. Crystals were continuously drawn from the fluid layer, and the outflowing mother liquor of the upper part of this layer recooled and inflown into the crystallizer again. A model enabled to determine that optimum common temperature referring to the given initial solutions, and the temperature of the outflowing mother liquor, when the main part of the crystals precipitates. — The portions of crystals referring to the theoretically found optimum common temperature of the solution in the crystallizer and to the whole circulation process, were determined. We examined the validity of the theoretically found values by experiment and the influence of cooling parameters on crystal size distribution as well as on the productivity of the crystallizer.     

Physikalische Eigenschaften von nach einer modifizierten Kyropoulos-Methode gezüchteten NaCl- und KCl-Kristallen

The physical properties of NaCl and KCl crystals prepared from melts by the Kyropoulos method are described. The material was firstly refined by phosgen (COCl₂) by which the anion impurities were removed from the melt. The measurements of the absorption in UV and IR region, the microhardness and CRSS, the dislocation densities, the ionic conductivity and the study of the kinetics of colour centres show that crystals prepared by the described modified Kyropoulos method are not only free from OH⁻ ions but also from all other foreign anions with oxygen.     

Zur Bestimmung der Kristallitgrößenverteilung von Metallen auf Katalysatorträgern aus Röntgenweitwinkelmessungen (I). Ermittlung primärer Verteilungskenngrößen aus Linienprofilen

Possibilities are investigated to determine the size distribution of metal crystallites in supported catalysts from wide angle X-ray interferences lines. It is shown that for this a Fourier method is suitable, which primarily provides the moments of the chord distribution. From the results distribution functions for the metal crystallites can be derived, which reproduce the experimental lines with high accuracy.     

Oberflächenstörungen und Hohlwachstum bei der Züchtung von β-Kupferphthalocyanin-Einkristallen aus der Gasphase

Hollow crystals are obtained frequently during the growth of copper phthalocyanine single crystals from the vapour phase. This appearance makes some physical investigations impossible. To overcome these difficulties some ways are discussed. The reasons for hollow growth are instabilities in the growth caused by diffusion controlled inhomogeneities in supersaturation on the growth front. This was found by observations of surface defects and by defined growth experiments. By introduction of special methods of growth and use of defined parameters one obtains bulk crystals of larger extent up to 1 mm in cross direction. References are given in the field of hollow crystal growth in the vapour phase of other substances.     

Ätzuntersuchungen an Alaunen mit nichtwäßrigen Lösungsmitteln. Will Kleber zum Gedenken

This paper presents investigations on etching of KAl-, NH₄Al-, KCr- and K(Al, Cr)-alum crystals. The etchant was a solution of tartaric acid in ethyl alcohol which produces well-defined etch pits on {111} faces. The correspondence of etch pits with dislocations was investigated by KAl-alum crystals. Between microscopic holes in the crystals and dislocations are not stated.     

Wärmedurchschlag an Cu2O

The appearance of high temperatures are proved at switching in Cu₂O. The structure of the formed channel are investigated. On the basis of the phase-diagram it is made a simple and qualitative model of the breakdown in Cu₂O for discussion and it is generalized to other metal-oxides.     

Zur Bestimmung der Kristallitgrößenverteilung von Metallen auf Katalysatorträgern aus Röntgenweitwinkelmessungen (II). Direktberechnung von Kristallitgrößenverteilungen aus Röntgenbeugungsprofilen

Procedures are stated for the determination of the chord and the diameter distributions of metal crystallites in supported catalysts without differentiation directly as transformation of functions immediately derived from the intensities of wide angle X-ray interference lines. It is shown that the growth of the metallic crystallites can be described by means of the moments of the chord distribution. A kinetic equation of the second order was found for the growth of platinum on alumina in inert atmosphere and of the fourth order in oxidizing atmosphere.     

Über das Wachstum und den Abbau von Gallium- und CBr4-Einkristallen aus eigener Schmelze

The morphology and the temperature dependence of the velocity of crystal growth and dissolution of gallium- and carbon tetrabromide single crystals are investigated using a capillary technique. These two model substances have a relative low entropy of melting, ΔS_m, which in the case of Ga is above, and in the case of CBr₄ is below the critical value of ΔS_m = 4.0. According to recent theoretical considerations this parameter determines the formation or the absence of an atomically rough crystal-melt interface. Particular interest is given to the dissolution kinetics of Ga and CBr₄. Crystallization and dissolution behaviour of Ga has been shown to be similar to substances having high ΔS_m-values, whereas the morphology, the crystallization and the dissolution of CBr₄ can be explained by assuming an atomically rough crystal-melt boundary.     

Die Lösung von Halbleiterproblemen mit der Elektronenstrahlmikrosonde

The use of electron beam X-ray microprobe testing in the chemical analysis of semiconductor materials and devices and also in the measurement of the p n junction electrical parameters is reported. Results of analyses are presented on the precipitation of impurities and on various effects of the contaminants on device parameters. It is shown that the display of p n junction structure and also the detection of failure types is possible by using the induced current mode method.