bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Optical Investigation of Growth‐Induced Inhomogeneities of Synthetic Hg2Cl2 Monocrystals
Authors: Ramlau R. , Reiche M. , Heydenreich J.
Published: January 2007

The submicroscopic structure of synthetic Hg2Cl2 monocrystals was investigated by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), indirect imaging of surfaces (Pt/C replica technique) as well as by application of supplementary methods. As already reported by NEUMANN et al., TEM‐images show a periodic stripelike contrast whose period varies from 0.1 m̈m to 0.2 m̈m. It proved that the stripelike contrast arises from a periodic chemical inhomogeneity of the synthetic crystals. The chemical inhomogeneity probably consists in periodic deviations from the stoichiometric composition of Hg2Cl2. By reason of the orientation on {110}‐, (001)‐, and {114} faces a reconstruction of arrangement of the structures in the crystals is carried out. According to that, the stripes have to be interpreted as intersection lines of 2‐dimensional formations with the corresponding faces.
New Types of Polarizers Made from Crystals of the Calomel Group
Authors: Barta Č. , Trnka J.
Published: January 2007

The present work deals with the applicability of the mercurous halide crystals to the production of polarizers of light. The wide transmission region of these crystals mainly in the infrared region allows to use them for wavelenghts up to about 20 m̈m for mercurous chloride and 30 m̈m for mecrurous bromide. Especially high double refraction allows a construction of classical polarizer types having very advantageous parameters, i.e. small thickness of the element and large angle of splitting of the ordinary and extraordinary ray. Besides, high double refraction allows an original design of single‐piece (monolithic) polarizers which are characterized by relatively simple treatment, high quality and low losses.
Properties of Surface Layers in Single Crystals of Calomel
Authors: Barta Č. , Brožek V. , H´jek B. , Barta Č.
Published: January 2007

Within the framework of the systematic study of differences in physical properties of the calomel (Hg2Cl2) single crystals before and after surface treatment, the differences in the microhardness, the residual stress in the surface layer, and the chemical etching rate were investigated on the (110) and (001) crystal faces. It has turned out that Beilby layer (B‐layer) formed during surface treatment is softer, and, on the cleavage surface is harder than the underlying bulk material. The thickness of the B‐layer in these samples ranged between 5 anf 7 m̈m. Further it has been found that a tensile residual stress s̀ = 14 Nm‐2 prevails in the surface layer of a polished (110) face to a depth of 70 m̈m and, after grinding, to a depth from 90 to 200 m̈m. On the other hand, a compressive stress has been found in the natural cleavage plane. Experiments on etching the Hg2Cl2 crystals with HCl + HNO3 etching solution have shown that the rate of chemical etching is 2 to 4 times larger on the (110) face than on the (001) face. Differences are very strongly dependent on the experimental conditions and on the real structure of a given surface.
The Morphology of Hydrothermally Grown Plagioclase
Authors: Franke W. , Ghobarkar H.
Published: January 2007

Plagioclase crystals Ab20An00 and nearly pure anorthite were grown on the surface of artificial melts by hydrothermal treatment at 2 kb. The average crystal size was 0.002 to 0.008 mm. In the temperature range of 400° to 600°C a pseudohexagonal habit was observed for anorthite while a lath‐like habit due to the prevalence of {010} was found for the Ab20An80 composition. Dominating faces are {010} {130} {110} {100} {110} {130} in the zone [001] and {021} {111} {111} {021} {111} {111} together with {001}.
Melt‐Growth of Single Crystals of Cadmium Iodide and Study of Their Polytypsim by X‐ray Diffraction
Authors: Chaudhary S.K. , Trigunayat G.C.
Published: January 2007

Single crystals of cadmium iodide have been grown from melt using Bridgman‐Stockbarger system and their polytypism studied by X‐ray diffraction. The initially grown crystals were found to stick to the walls of the ampoule and had black specks of impurity suspended in them. A systematic study has been carried out to determine the effect of degree of vacuum, material of the ampoule and quality of raw material on crystal growth. It has been concluded and later verified using zone‐refined material that the observed sticking essentially stems from the presence of impurities in the raw material. From X‐ray diffraction it is found that all crystals belong to the most common polytype 4H alone.
Crystalloluminescence and Mechanoluminescence Spectra of Ba(ClO3)2 · H2O and 2 K2SO4 · Na2SO4 Crystals
Authors: Chandra B.P.
Published: January 2007

Crystalloluminescence and mechanoluminescence of Ba(ClO3)2 · H2O and 2 K2SO4 · Na2SO4 crystals are investigated. The crystalloluminescence spectra are almost similar to the photoluminescence spectra; however, they differ completely from the mechanoluminescence spectra. The crystalloluminescence excitations may take place due to the various processes: (i) the recombination of ions, (ii) from amorphous to crystalline transition, (iii) from the phase change during the crystallization, and (iv) from the dielectric breakdown by the electric field produced due to the creation of microfracture during the crystal growth. It is concluded that the crystalloluminescence excitation in Ba(ClO3)2 · H2O and 2K2SO4 · Na2SO4 crystals may be chemical in origin.
Morphological Lattice and Reciprocal Crystal. Remarks on Morphology of Barite and Cerussite
Authors: Follner H.
Published: January 2007

The relationship between partitions of the three‐dimensional space into Dirichlet domains of morphological points and the face forms observed on crystals will here be examined. Dirichlet domains, the central points of which are to be found on the exterior net plane, can be connected two or one‐dimensionally through face‐sharing or they occur as isolated groups. If the crystal faces are arranged according to the proportion of these surface polyeder on the total surface of the net plane, the order of rank of barite and cerussite agree excellently with the experimental observations. The packings of space filling polyeder allow conclusions on growth mechanisms.
Morphological Stability of Vapour Grown Metal Single Crystals
Authors: Nanev Ch R. , Iwanov D.
Published: January 2007

The formation of shallow cavities on the faces of zinc (and cadmium) single crystals after reaching some critical size during growth from vapours in inert gas (Ar, H2) atmosphere has been discussed. New experimental facts concerning cavity form and the diffusion origin cause of the phenomenon have been reported. A satisfactory good semi‐quantitative agreement with the theoretically predicted critical sizes (CHERNOV, CAHN) has been found as a result of the precise discussion of the experimental results. The conclusion has been drawn that the diffusion in the parent phase plays unambigously a decisive role by the formation of the morphological peculiarities during vapour growth in inert gas atmosphere.
Crystallization of Sulphides in KSCN Melts
Authors: Bohac P. , Tanner V. , Gaeumann A.
Published: January 2007

The melt of potassium thiocyanate can be used as solvent and as supplier of sulphur for the preparation of crystals of sulphides and complex sulphosalts. The solubilities of some sulphides in the KSCN melt were determined at 250°C. Small crystals of sulphides of Cu, Ag, Tl, Hg, Pb, Ni and of ternary As‐ and Sb‐sulphosalts of these metals could be obtained from this flux in a temperature gradient. Moreover, crystals of sulphides were formed by a direct slow reaction of metals with molten KSCN.
Changes of the Surface Structure of Quartz Monocrystals as a Result of the Influence of Sodium Salts at High Temperature
Authors: Sokoll R.
Published: January 2007

In Ergänzung zu der früher beschriebenen Überstrukturbildung auf Quarzeinkristall‐Oberflächen infolge ihrer Wechselwirkung mit einfachen Gasen, wird über Strukturveränderungen berichtet, welche bei der Einwirkung von Natriumsalzen auf die große Rhomboederfläche (1011) und die Prismenfläche (1010) von Quarz ablaufen, Neben schon bekannten Erscheinungen bildet sich auf der Prismenfläche infolge der Einwirkung von NaNO3 eine bisher noch nicht beobachtete Überstruktur aus. Als Untersuchungsmethode dient die streifende Beugung hochenergeitischer Elektronen (RHEED).
Crystal Growth in Magnetic Fields (II) Crystallization of Co(NH4)2(SO4)2 · 6 H2O from Aqueous Solutions in High Magnetic Fields
Authors: Kuschel F. , König AN
Published: January 2007

The displacement rate of (110) single crystal faces of Co(NH4)2(SO4)2 · 6 H2O has been measured in dependence on the supersaturation of aqueous solutions in the zero field and at magnetic flux densities of 7 T. The results show that in a given external field measurable effects near the equilibrium don't occur (thermostatic field effect). On the contrary a marked influence at extreme relative supersaturations can be observed (kinetic field effect).
Growth and Characterization of GaP Substrates for Liquid Phase Epitaxy
Authors: Moravec F. , Novotný J. , Kirsten P. , Siegel W. , Koi H.
Published: January 2007

GaP light‐emitting diodes were prepared by a single LPE process on LEC and SSD substrates. Red LEDs with a maximal efficiency of 5% could be grown reproducibly on SSD substrates with grains. The effciency of the best LEDs on substrates grown by the conventional LEC method is essentially lower (0.5%) but it can be improved considerably by a modification of the growth conditions. The substrates were characterized by structural, chemical, electrical and optical measurements and the observed differences in the luminescence efficiency between the LEDs grown on LEC and SSD subtrates, respectively, were discussed under consideration of these investigations.
The Growth Kinetics and Surface Morphology of GaN Epitaxial Layers on Sapphire
Authors: Malinovsky V. V. , Marasina L. A. , Pichugin I. G. , Tlaczala M.
Published: January 2007

The growth kinetics of GaN on Sapphire was analyed on the base of some experimental data such as: the growth rate temperature depandence, on the base of some experimental data such as: the growth rate temperature dependence, the grwoth rate dependence on the gas flow velocity, the growth rate depandence on the crystallographic and spatial orientation of the substrate. The limiting stage of the epitaxy process was established at different growth conditions. The morphology of GaN epitaxial layers obtained at these conditions is described.
Germanium Incorporation in Ga1–xInxAs LPE Layers and GaAs Bulk Crystals
Authors: Müller K. , Mothes W. , Jacobs B. , Butter E.
Published: January 2007

Atomic absorption spectroscopy (AAS) is used to determine the Ge concentration in Ga1–xInxAs and GaAs. The orientation dependence of Ge incorporation in (111)A‐and (111)B oriented samples has been studied. The distribution coefficients for both the orientations were determined to be kGe(111)A = 2.6 · 10−2 and kGe(111B = 1.4 · 10−2 for Ga1–xInxAs with 0 ≦ x ≦ 0.13. The differences between the two orientations are explained with the aid of the band bending model. Doping gradients in thick epitaxial layers and along crystal length of polycristalline TGS‐grown GaAs ingots have been investigated too. In Ga1–xInxAs layers any Ge concentration gradient couldn't be observed, but in TGS compact crystals Ge concentration increases with crystal length because the melt composition changes significantly during solidification. The results are compared with those of electrical measurements.
On the Density of Synthetic Glasses in the System Soda Melilite – Gehlenite/Ákermanite
Authors: Teichert G. , Strohmann R. , Paufler P. , Schreiter P.
Published: January 2007

The solid density has been determined at 25°C by hydrostatic weighing along the binary systems Sm–Ge50Åk50 and Sm–Ge70Åk30. The molar volume V decreases linearly with increasing mole fraction of GemÅkn, xB, according to δV/δxB = −5.08 cm3 mol−1 and −4.40 cm3 mol−1 for Ge50Åk50 and Ge70Åk30, respectively. The results enable the molar fraction xB to be determined from density measurements with an absolute error of ±5 mol%.
Dielectric Relaxation in Low Temperature Smectic Phases of 4‐n‐Alkyloxy‐benzylidene‐amino‐4′‐cyanobiphenyls
Authors: Gajewska B. , Kresse H. , Weissflog W.
Published: January 2007

The dielectric behaviour of five homologous 4‐n‐alkyloxy‐benzylidene‐amino‐4′‐cyanobiphenyls was investigated. Especially, we were interested in the dielectric relaxation frequencies of the smectic low temperature phases SB and SE as well as the dielectric behaviour in the solid state. We have found in all liquid crystalline phases a low frequency relaxation region explained by a hindered rotation of the molecules around their short axes. By supercooling of the hexyl and heptyl derivatives a new liquid crystalline phase can be obtained. A dielectric relaxation in the solid phase could not be found.
Time‐varying Temperature Profile CVD Methods for Growing CuInS2 and CdIn2S4 Crystals
Authors: Paorici C. , Zanotti L. , Curti M.
Published: January 2007

A time‐varying temperature profile method is reported for growing crystals in horizontal closed‐tube arrangements by vapour phase iodine transport. After an initial stage, during which the temperature is linearly raised with time in the source region of the container, in such a way as to control the primary nucleation (a limited number of seed crystals can thus be produced), a second stage follows during which the source temperature is allowed to oscillate in order to favour the secondary nucleation (only the first grown seed crystals are then allowed to grow). A proper choice of the frequency and amplitude of the temperature cycle is shown to control the growth up to the obtainement of solitary crystals per run of CuInS2 and CdIn2S4. The role of the slow growing faces in favouring good performances of the method is emphasized.
The recovery of Quenched‐in Vacancies in Fe–Al (6.3 to 28.3 at.%) Alloys studied by Positron Annihilation
Authors: Dlubek G. , Brümmer O. , Möser B.
Published: January 2007

Measurements of the peak height of the 2γ‐angular correlation curve were carried out during constant rate heating of Fe–Al alloys with an Al‐content between 6.3 and 28.3 at.%. The samples had been quenched form 1000°C into water at room temperature. Two recovery stages are observed. The first stage at 100 to 200°C shows a small decrease of the peak height. The main stage at 300 to 400°C is attributed to the migration and disappearance of monovacancies. From isothermal measurements the migration enthalpy of vacancies is estimated to (1.15 ± 0.1) eV in Fe–Al (19.9 at.%) and to (1.31 ± 0.1) eV in Fe–Al (24.4 at.%). – In samples with an Al‐content between 13.8 and 28.3 at.% a minimum in the peak height at 400°C is found. Obviously a particular stage is formed in these samples during migration of quenched‐in vacancies. Possible causes of the effect are discussed.
Locally Detailed Electroluminescence for Thin Optical Fiber Coupling to LEDs
Authors: Hesse L. , Zehe A. , Navarro H.
Published: January 2007

Locally detailed electroluminescence properties of a single heterojunction (SH) light emitting diode (LED) are reported. The knowledge and consideration of such properties is of major interest when thin optical fibers are to be attached to a side face of a Fabry‐Perot structure. The virgin electroluminescence spectrum inside the active region was calculated and is taken as reference for the local emission spectrum at near‐field points at a side face. Considerable peak shifts, up to 120 meV. and intensity reductions occur for the transmitted spectrum, when proceeding from the n‐side of the junction to the p‐side.
Autodoping during the deposition of epitaxial Silicon layers from the gas phase (I). Autodoping from the gas phase
Authors: Kühne H.
Published: January 2007

The doping profile within the autodoping range of epitaxial layers deposited on lowresistance substrates, is considered the result of redistributing a substrate doping fraction through the substrate layer boundary, of incorporating a limited amount of dopants from the gas phase, originating from the preepitaxial process, and the result of incorporating dopants, externally admitted to the gas flow during the deposition. Assuming a special incorporation equilibrium to exist for the gas phase fraction of autodoping an analytic expression is derived, correlating the autodoping profile characteristic to the limited amount of dopants in the gas phase. The extent is discussed, to which the gas phase fraction of autodoping may be influenced by varying the deposition process.
Strength and microstructures of Benzoic Acid‐Benzamide system
Authors: Sharma B. L. , Sharma N. K. , Bassi P. S.
Published: January 2007

Pure end products in their binary eutectic of a benzoic acid‐benzamide system, grownunidirectionally and randomly, exhibited marked anisotropy in their peculiar properties particularly if the growth is carried out in some periodic manner. Modulus of ruptures of eutectic composite and the constituent materials for both the growths have been determined. Directional‐growth of the composite yields a bending strength quite larger than that can be obtained from an anomalous growth. Pure components also offer slighly greater strength in an ordered growth. Microphotographs of grown materials are related to the mode of crystallization of the materials.
Application of holographic interferometry to the study of properties of Bi2Se3 crystals
Authors: Kaplanová M. , Synek J. , Horák J.
Published: January 2007

A holographic interferometry method for visualisation of structure non‐homogeneities in large Bi2Se3 monocrystals with Cd and In admixtures is presented. The natural cleavage (0001) faces of Bi2Se3 monocrystals were used for preparation of samples for surface quality investigation. The interference patterns obtained with double‐exposure method show the deformation field distribution caused by a suitable formed temperature gradient. The interferogram obtained by the described method make it possible to select a perfectly homogenous part of prepared monocrystalline sample which is inevitable for measurements of optical and electric conductivity properties.
An X‐ray diffraction refinement of the structure of natural thomsonite
Authors: Pechar FrantiŠek
Published: January 2007

Thomsonite Na2Ca4Al10Si10O40, orthorhombic Pncn, a = 1.3124 nm, b = 1.3078 nm, c = 0.662 nm, V = 1.1369 nm3, Z = 2, Dm = 2.30, Dc = 2.26, μ = 12.4 cm−1. The average length of the bond T–O = 0.1685 nm. The final R‐value for 456 independent observed reflections is 0.085.
X‐Ray topographic study of the influence of thermal annealing on the bending of 49BF2+‐implanted Si wafers
Authors: Vassilev I. S. , Furmanik Z. , Petrov I. N. , Botev P. A. , Auleytner J.
Published: January 2007

The influence of thermal annealing on the image contrast of the boundaries of 49BF2+‐implanted regions in Si is investigated by means of X‐ray topography. The contrast is used for studying the wafer bending and the stress types. It is shown that the final state of deformation is determined by: (1) the expansion of the surface layer caused by the implantation, (2) the contraction of this layer caused by the annealing. Effect (1) or (2) dominates depending on the implantation dose and annealing conditions. The possibility of compensating both effects leading to complete elimination of the bending of the implanted wafers is established. The results are discussed on the basis of the correlation between the deformation state of the wafers and the percentage B atoms occupying substitutionally Si‐lattice sites.
Investigation of the Crystallization Process in the Verneuil Techniques
Authors: Borodin V. A. , Brener E. A. , Tatarchenko V. A.
Published: January 2007

The stability of the process of crystallization in the Verneuil techniques is analyzed, taking into account the geometrical shape of the molten layer surface and specific features of the heat and mass transfer typical for this method of crystal growth. The process is stable for crystal radii below the capillarity constant.
Growth of Potassium Sulphate Crystals by Silica Gel Technique
Authors: Garcia‐Ruiz J. M. , Martin‐Vivaldi Caballero J. L.
Published: January 2007

Single and transparent crystals of potassium sulphate up to 30 × 3 × 3 mm in size have been grown by silica gel technique, using various methods (two‐layers three‐layers and hybrid gel technique) which are described. The effects of the three differents alcohols (used as top solutions) upon the quality and nucleation of crystals are also reported. The “growth and equilibrium” morphologies and microstructures of the habit faces are discussed.
Melting Diagrams of the Quaternary Systems Ga–In–As–Ge and Ga–In–As–Sn
Authors: Müller K. , Apelt R. , Jacobs B. , Butter E.
Published: January 2007

Equilibria between quaternary liquid phases Ga–In–As–Ge(–Sn) and the ternary solid phase Ga–In–As have been calculated by application of the KRUPKOWSKI formalism on the excess free enthalpy. Experimental liquidus data were obtained from solubility experiments in a LPE equipment. Results of calculation and experimental liquidus data are compared.
The Influence of Mineral Impurities on the „Sulphur Puffing”︁ at High Temperature Treatment of Brown Coal Pitch Cokes
Authors: Preiss H. , Born D. , Winkler E. , Olschinka P.
Published: January 2007

Cokes rich in sulphur usually show throughout the high temperature treatment between 1500 and 1800 °C an irreversible dilatation which can be suppressed by additives of inorganic oxides or salts. In brown coal pitch cokes with high content of sulphur and mineral impurities (ash), however, this suphur puffing cannot be observed. Basic ash components (e. g. CaO, Fe2O3, MgO) are responsible for the puffing inhibition. The inhibition is already sufficient if the concerntration of basic ash components equals the suphur conentration.
Electrical Conductivity of BaMoO4 Single Crystals
Authors: Arora S. K. , Trivikrama Rao G. S.
Published: January 2007

Electrical conductivity measurements have been made on the flux grown barium molybdate single crystals in the temperature range 425 to 1000 K. The mechanisms of conduction in the region of lower and higher temperatures have been distinguished.
Spiral growth of potassium bichromate crystals
Authors: Szurgot M. , Sangwal K.
Published: January 2007

Some observations of growth spirals and hillocks on {001} surfaces of potassium bichromate crystals grown from aqueous solutions are presented and discussed. It is shown that a spiral pattern in fact represents a macrospiral developed as a result of the cooperative action of a group of dislocations.
Energetic analysis of partition coefficients for melt crystallization in LnF3–Ln'F3 Systems)
Authors: Urusov V. S. , Grigorash Yu. P. , Karelin V. V. , Sobolev B. P.
Published: January 2007

Energetic theory of isomorphous miscibility is used for interpretation of LnF3–Ln'F3 phase diagram types and values of coefficients of Ln' distribution between crystals and melt. Such an analysis supplies the information for estimates of unknown properties of solid solutions of hexagonal tysonite or orthorhombic yttrium fluoride types and binary melts. Besides that there is a possibility of prediction of phase equilibria in many of those LnF3–Ln'F3 system of 105 possible ones which are not yet studied experimentally.
Impurity distribution in natural diamond crystals
Authors: Aleksandrov L. N. , Gafitullina D. S. , Khaidarov A. A.
Published: January 2007

An activation analysis and neutron autoradiography have been applied to study the impurity distribution in natural diamond crystals. The impurity incorporation pattern has been studied on 〈100〉 and 〈110〉 lamellal cut from crystals of an octahedral, rhombododecahedral, and cubic habit having a zonal texture. Cobalt impurities, unlike other elements, concentrated in the centre of the middle regions of diamonds irrespective of the crystal growth shape. A heterogeneous mechanism has been suggested for natural diamond genesis.
Logarithmic Anomaly in the Debye‐Waller Factor and Thermal Expansion Coefficient at Ferroelectric Phase Transition in KDP
Authors: Zvirgzds J. A. , Zvirgzde J. V.
Published: January 2007

Temperature dependence of the thermal expansion coefficient and the Debye‐Waller factor along the polar axes in KDP were investigated by means of X‐ray diffraction. A logarithmic anomaly was observed in the range from Tc up to 6 K above Tc.
On Unstable Directions of Dislocations in the Intermetallic Compound V3Si
Authors: Paufler P. , Boehnke O.
Published: January 2007

The angular dependence of the reciprocal elastic energy of a straight dislocation in the superconductor V3Si has been computed for different temperatures and slip systems taking elastic anisotropy into account. Regions of instability have been found which depend on temperature. Crystallographic slip planes may be unstable against climb.
Structures of Azomethine Imines of the Pyrazolidone‐(3)‐type, (IV) The Structure of 1‐(4‐Methoxybenzylidene)‐pyrazolidone‐(3)‐betaine
Authors: Kulpe S. , Seidel I. , Geissler G.
Published: January 2007

C11H12N2O2, Pcam, a = 14.512(6) Å, b = 10.516(2) Å, c = 6.812(3) Å, Z = 4, U = 1039.4 Å3, Dx = 1.30 g cm−3, μ(MoKα) = 0.999 cm−1, F(000) = 864.0, crystal size 0.5 × 0.3 × 0.25 mm, λMoKα = 0.71069 Å, crystals colourless. Final R = 0.039 for 831 independent reflections excluded those with |F0| < 10 σ(F0).

The intensities were measured with an automatic diffractometer. The electron structure of the molecule can be explained by assuming that the molecule consists of the azomethine imine unit with polymethinic character and the methoxybenzylidene unit with aromatic character, both units are linked via the C(4)–C(5) bond (1.440 Å). The whole molecule is exactly plane. All non‐hydrogen atoms lie exactly on the mirrorplanes perpendicular to the z‐axis with the plane distance 3.406 Å. Instead of the general Z = 8 there is the special Z, 4. There exist intermolecular C–H … 0 hydrogen bridges in the planes of the molecules.
Studies on Nickel Oxide Mixed Catalysts (X) Thermoanalytical Investigations on NiO/SiO2 Catalysts and Nickel Layer‐silicates
Authors: Wendt G. , Siegel H. , Schmitz W.
Published: January 2007

The processes occurring at the thermal decomposition of NiO/SiO2 catalysts prepared by precipitation deposition of nickel talc and nickel antigorite were investigated by means of DTA/TG method, high temperature X‐ray diffraction and infrared spectroscopy. In the case of NiO/SiO2 samples X‐ray amorphous nickel layer‐silicates (mixtures of nickel antigorite/nickel talc) were formed in the process of preparation. Nickel hydroxide was observed at NiO contents > 40 mol%. Nickel talc and nickel antigorite decompose at increasing temperatures successively to the following phases: nickel talc, nickel antigorite → X‐ray amorphous phase → nickel oxide, nickel olivine, cristobalite.

The dehydroxylation temperatures of the X‐ray amorphous nickel layer‐silicates are markedly lower than those of nickel talc and nickel antigorite.

Es wurde die thermische Umwandlung durch Fällen hergestellter NiO/SiO2‐Katalysatoren, von Nickeltalk und von Nickelantigorit durch die Anwendung von DTA/TG‐Methoden, der Hochtemperatur‐Röntgendiffraktometrie und der Infrarotspektroskopie untersucht. Bei den NiO/SiO2‐Proben wurden im Verlaufe des Fällungsprozesses röntgenamorphe Nickelschichtsilikate (Nickeltalk/Nickelantigorit‐Gemische) gebildet. Nickelhydroxid wurde bei NiO‐Gehalten > 40 mol‐% beobachtet. Nickeltalk und Nickelantogorit zerfallen bei Temperaturerhöhung folgendermaßen: Nickeltalk, Nickelantigorit → → röntgenamorphe Phase → Nickeloxid, Nickelolivin, Cristobalit. Die Dehydroxylierungstemperaturen der röntgenamorphen Nickelschichtsilikate sind beträchtlich niedriger als die von Nickeltalk und Nickelantigorit.
A Multipurpose Graphite Boat for LPE Growth of Multilayer Heterostructures
Authors: Bolkhovityanov Yu. B. , Bolkhovityanova R. I. , Hairi E. H. , Chikichev S. I. , Yudaev V. I.
Published: January 2007

In the paper the results of the authors' work are summarized on the preparation of multilayer A3B5 heterostructures with the use of originally designed graphite boat. The main scheme of the boat design is described in detail and it is shown that the growth apparatus combine the favourable features of the known LPE growth techniques: epitaxy from thin solution layer, sliding boat technique and the technique based upon the displacement of one melt by another.
Effect of an External Electric Field on Polytypic Growth of CdI2 Crystals from Solutions
Authors: Pałosz B. , Przedmojski J.
Published: January 2007

The effect of an external steady electric field on polytypic growth of CdI2 crystals was investigated. Crystals were grown at four temperatures: 5, 25, 35, and 50°C with the use of four solvents: H2O, C2H5OH, 3 H2O + 1 C2H5OH and 1 H2O + 1 C2H5OH. The electric field of the intensity 500 to 2500 V/cm was oriented in two directions: perpendicular or parallel to the c‐axis of hexagonal plates of CdI2 crystals. The analysis of the effect of the field on polytypism of CdI2 was based on the analysis of the structure of about 800 crystals grown in the presence of electric field and of about 1000 crystals grown in neutral conditions. It was established that the weak electric field used for crystallization of CdI2 does not influence noticeably the relative stability of basic polytypes (2H, 4H) and of complex polytypic structures (ordered and disordered). The electric field may influence the structure of CdI2 crystals in two ways: (i) the polytypes formed in the presence of the field have on average two times larger cells than the polytypes formed in neutral conditions, (ii) the polytypes formed in neutral conditions have usually hexagonal cells; only 6 to 30% of polytypes are of rhombohedral type. When the electric field was used the percentage of rhombohedral polytypes increased to about 65%.
Effect of Different Parameters on the Liesegang Ring Formation of Lead Carbonate Crystals
Authors: Mohanan Pillai K. , Vaidyan V. K. , Ittyachan M. A.
Published: January 2007

Influence of different parameters like concentration of the outer electrolyte, age of the gel and impurities added to the outer electrolyte on the periodic precipitation of lead carbonate crystals in silica gel are presented. Increase of outer electrolyte concentration has the effect of increasing x2/t value while it decreases with increase of the gel age. Impurities added to the outer electrolyte delay the time of formation of the rings. All these observed results are explained.
Reciprocal Morphological Lattices and Growth Forms of Crystals
Authors: Follner H.
Published: January 2007

Crystals are based on a morphological lattice, which – as a rule – possesses a higher symmetry than the structureal one. The morphological lattice is a Fourier transform of crystal morphology. The polyhedron resulting from the planes which perpendicularly bisect the lines between all symmetrically equivalent morphological points is referred to as reciprocal crystal. Through a Fourier transform of the reciprocal crystal the crystal space is recovered. In case of simple morphological lattices – the determination of central distances from the reciprocal morphological translation groups is possible here – the crystals can be shown in a Wulff‐plot. The procedure is to be discussed on different examples.
Microhardness and Resistivity Anisotropy of ZnO Plastic Deformation
Authors: Regel V. R. , Sizova N. L. , Chernysheva M. A. , Dohnovskaya S. I. , Kuzmina I. P. , Lazarevskaya O. A. , Nikitenko V. A.
Published: January 2007

In the work is shown that hydrothermally grown ZnO crystals are characterized by the mosaic structure of ‘columnar’ type. The experimental and theoretical data about geometry of the slip systems in ZnO crystals are obtained and also anisotropy of the microhardness is measured.
X‐ray Studies on the Liquid Crystalline Phases of the 4‐[4‐n‐Heptyloxy‐Benzylidene‐Amino]4'‐cyanobiphenyl
Authors: Diele S. , Jaeckel D. , Demus D. , Sackmann H.
Published: January 2007

By means of X‐ray diffraction studies of oriented and non‐oriented samples the lattice parameters of the orthorhombic cell of the SE phase as well as of the hexagonal cell of the SB phase were determined. By packing considerations a bimolecular building unit with oppositely arranged cyano‐groups was assumed in the case of the SE phase.

The SB phase is characterized by an ABAB sequence of the smectic layers in which the molecules are hexagonal arranged. The increasing mobility of the molecules at increasing temperature offers the possibility for a part of the molecules to slide in a more stable dimerized form. In the NR and SA phase the existence of monomers as well as of dimers is assumed.

In this way a conception of the phase transitions SE → SB → NR → SA is given on the base of a decrease by steps of the dipole‐dipole repulsion.
OD interpretation of the crystal structure of lithium tellurite, Li2TeO3
Authors: Kuban R.‐J.
Published: January 2007

The OD groupoid family of the structure of lithium tellurite, Li2TeO3, is characterized by the symbol: magnified image.

The OD groupoid of the structure is deduced from the observed arrangement of points in reciprocal space, the symmetry of the intensity distribution and the systematic absences. The structure is built of OD layers of one kind. Any OD layer is idendical to a Li2TeO3 double sheet. The assumption of Folger that the structure is an OD structure has been found to be justified.
Growing of local smectic C monocrystals from an initially twisted nematic phase
Authors: Petrov M. , Komitov L.
Published: January 2007

The growing of smectic C single local monocrystals was investigated from an initially twisted nematic phase with smectic C ordering (p‐n‐alkoxybenzoic acid). Characteristic longitudinal and transverse dislocation lines have been observed at growth in a thin liquid crystal cell, single local monocrystals are discussed. The evolution was studied of the smectic C phase from cybotactic groups in a nematic phase toward needlike nuclei near to the nematic‐smectic C phase transition and after that after that toward the local single monocrystals.
Peculiarities of the melt growth of metal single crystals with specified crystal‐geometric and structural parameters
Authors: Kazarov Yu. G. , Lavrentev F. F.
Published: January 2007

This paper describes the authors' modifications of Kapitza and Bridgman apparatus and growth methods of metal single crystals with specified crystal geometric and structural parameters. The effects associated with defect formation are discussed. The features of the effects in their relation to the crystal lattice types and crystallographic orientation are indicated. It is concluded that one of the main factors responsible for the defect formation during single crystal growth in the mould is strain. This is due to thermomechanical stresses arising during the crystal growth and cooling to room temperature, from the difference in thermal expansion coefficients of the crystal and mould materials.
Mechanism of melilite formation during a sintering process
Authors: Böhme O. , Paufler P. , Schreiter P.
Published: January 2007

Solid solutions of melilite were produced by industrial raw materials (phosphorous furnace slag, dolomitic limestone and clay) at temperatures till 1200 K. At this solid state reaction different processes are participating. From the formation rate at constant temperature different processes were recognized by graphical analysis and explained by a mechanism of melilite formation. Some different temperatures were used. The investigations are used to produce a new ceramic material on the base of melilite.
On the delay of thermally activated motion of pyramidal dislocations in zinc
Authors: Gektina I. V.
Published: January 2007

The effect of shear stress and temperature on the delay time, ti, of thermally activated motion of dislocations in the {1122} 〈1123〉 slip system in Zn single crystals is studied. The delay is associated with a higher density of crystal defects at the initial path of dislocation motion.
Special features of optical strength change in melt‐grown NaCl crystals
Authors: Erofeev V. N. , Gorbunov A. V. , Val'Kovskii S. N.
Published: January 2007

The variation of the CO2‐laser pulse induced breakdown threshold has been studied experimentally in melt‐grown NaCl crystals. An increase of the optical strength (up to two order of magnitude) is observed from the „top”︁ towards „bottom”︁ of the large diameter crystal boules, i.e. in the direction in which the impurities are driven away. The dependence of the threshold with the Ca2+ concentration demonstrates a complicated character of the effect of the impurity content on the optical strength of sodium chloride.
Luminescence studies on zeolite crystals
Authors: Joshi M. S. , Bhoskar B. T.
Published: January 2007

Observations and results on studies of photoluminescence in zeolites are reported. Excitation and emission spectra for natrolite, scolecite and thomsonite are illustrated. Peak positions in spectra are summarised in tabular forms. It is shown that principal emission band in natrolite and heulandite increases with increase in iron percentage in them. Absence of this situation in stilbite is explained in terms of Na+ or K+ centre killers. It is established that photoluminescence observed in the present case is due to de‐alumination of zeolites under study.
Analysis of Pb dopant distributions in KCl monocrystals by energy dispersive X‐ray spectrometry
Authors: Krajewski Th. , Malicskó L.
Published: January 2007

The energy dispersive X‐ray microanalysis in combination with the scanning electron microscopy was used for investigations of the microdistribution of Pb dopants in solution‐grown KCl crystals. In applying an absorption filter technique (using an about 30 μm thick aluminium foil arranged into the X‐ray path between the specimen and the detector) the resulting detectability of the Pb minor constituents is improved by a factor of about 3. The minimum detectable content of lead within the KCl matrix could be estimated to have the order of magnitude of 0.1 mole per cent Pb.
Thermodynamic analysis of solute‐solvent interactions in the solubility‐temperature relations of alkaline‐earth metal tungstates and sodium tungstate
Authors: Roy B. N.
Published: January 2007

This paper presents a study of thermodynamic analysis of the solubility‐temperature phase diagrams for solutions of calcium, strontium and barium tungstate in sodium tungstate melts in the temperature range 660 to 1200 °C. At temperatures 1000 °C and above, the solutions were ideal but below 1000 °C the solutions became non‐ideal and the non‐ideality increased with decreasing temperature. At any mole fraction concentration of the solute the excess free energies of mixing and the activity coefficients increased in the order CaWO4 > SrWO4 > BaWO4, whereas the excess chemical potentials decreased in the order CaWO4 < SrWO4 < BaWO4.
Copper precipitation in long‐time diffused silicon
Authors: Gleichmann R. , Mohr U. , Jegerlehner K.
Published: January 2007

The generation of microdefects in FZ‐silicon during long‐time high‐temperature processing, necessary for the production of power devices, has been investigated by etching techniques and transmission electron microscopy. The results prove the defects to be large precipitates, which may generate dislocations and stacking faults. The analysis of Moiré fringes and the interpretation of selected area diffraction patterns indicate the material to be CuSi. The experimental findings are interpreted by the help of an extension of the existing model for the copper precipitation process.
The influence of time dependence of temperature on the kinetics of nucleation
Authors: Kožíšek Z. , Chvoj Z.
Published: January 2007

In this work the influence of time dependence of temperature on kinetic processes during nucleation on a simple model is studied. The nucleation rate and the average effective radius of nuclei R is counted. It is proved that in the case of oscillating temperature the nucleation rate also oscillates and the rate of growth of radius R is directly proportional to frequency of temperature change.
Investigation of the structure of solid solutions of elements of the IV. group (Si, Ge) in gallium antimonide
Authors: Wilke J. , Bublik V. T. , Osvenskii V. B. , Popkov A. N. , Beaginskaya A. G. , Kolchina G. P.
Published: January 2007

Precision measurements of the lattice parameter and the density of Si‐ and Ge‐doped GaSb monocrystals were accomplished. The investigated crystals were Czochralski‐grown from an equiatomic melt (with respect to its own components) and doped with 2 · 1017 to 4 · 1019 cm–3 Si and 2 · 1017 to 4 · 1019 cm–3 Ge, respectively. The concentrations of the dopants were determined spectroscopically. — Hall measurements at room temperature showed that Si as well as Ge in GaSb produce p‐conduction.
Stabilization of the melt composition in GaAlSbAs
Authors: Baranov A. N. , Konnikov S. G. , Popova T. B. , Umansky V. E. , Yakovlev Yu. P.
Published: January 2007

In this work we present a new effect of stabilization of the GaAlSbAs melt composition when it is in contact with the GaAs substrate. It was found that the As content in the GaAlSbAs melt did not depend on the initial Sb concentration when the liquid phase was formed by saturating the GaAlSb melt from the GaAs substrate. This effect is supposed to be due to the change in phase equilibria conditions caused by large lattice mismatch between the substrate and the solid in equilibrium with the liquid.
On the origin of free carriers in high‐conducting n‐GaN
Authors: Seifert W. , Franzheld R. , Butter E. , Sobotta H. , Riede V.
Published: January 2007

Growth experiments with GaN in the system Ga/HCl/NH3/He at different growth temperatures show that the assumption of N‐vacancies to be responsible for the high n‐conductivity is questionable. The dependence of carrier concentration on growth temperature as well as the decrease in carrier concentration when additionally purified NH3 is used indicate that donor impurities are incorporated. The most probable impurity is oxygen, substitutionally incorporated onto N‐sites. The observed growth rate dependence of carrier concentration can well be explained by a kinetically controlled incorporation process.
A study on crystallographic characteristic of Mg‐vicariate fassaites
Authors: Krajewski A. , Foresti‐Serantoni E.
Published: January 2007

Some relationship occurring by isomorphous change of Al3+ for Mg2+, in the presence of some impurities like iron and titanium ions, were studied.

This study tooks shape as a contribution for a mineralogical and geochemical study on the contact paragenesis of Predazzo‐Monzoni's area in the northern of Italy. It reveals itself also useful to drawn‐up informations about the different influence that some network modifier cations bring into the mutual connection of chain systems, even if these cations are randomly dispersed and in a very few amount. This is useful for chemico‐physical evaluations concerning their behaviour in multicomponent silicatic compositions whether in lattice systems as crystals or in random systems as glasses and glazes, very important in the sector of glasses and ceramics where direct informations on cations influence are more and more difficult to make display.

Some results are according to some observations displayed in previous studies on amphiboles (Rossi, Ungaretti), where a certain influence of Ti4+ and Fe3+ on some parameters were observed.
Crystallization of potassium sulfate from pure aqueous solution and in presence of surfactants
Authors: Kuschel F. , König An. , Herold S.
Published: January 2007

The use of surfactants offers an interesting possibility to control the crystallization from solutions. There are already some applications in technical scale. Yet, little knowledge exists on the mechanism of the effect and his dependence on surfactant concentration. Therefore, the displacement rates of selected single crystal faces of K2SO4 in pure aqueous solutions and in presence of different amounts of tensides have been measured. Furthermore, in order to get insight into the state of surfactant solutions existing in the interesting concentration interval, the critical micelle concentrations have been determined. In comparison with growth from pure solution, the admixtures caused at concentrations below 10−5 mol/l no drastic alterations. On the contrary, above a transition region characterized by a very irregular growth, a practically totally inhibition of growth as well as of dissolution was observed. The changes of surface morphology induced by surfactants have been investigated using the phase contrast microscopy.
Estimation of the debye temperature of diamond‐like semiconducting compounds from bulk modul and microhardness
Authors: Deus P. , Schneider H. A.
Published: January 2007

The reliability of estimation of Debye temperature θD evaluated from bulk modul and microhardness is proved for semiconductors with diamond, sphalerite, and chalcopyrite structure. The known linear relations available from the literature do not yield a reasonable agreement between experimental and calculated Debye temperatures. As in the case of the Lindemann rule a better approximation is obtained by use of a more general relation θD = a1x + a2. The constants a1 and a2 are calculated for the substances under consideration. Unknown Debye temperatures are calculated.
Growth of InAs1–ySby solid solutions for obtaining decreased lattice mismatch in the InAs‐GaSb (AlxGa1–nSb) system
Authors: Pramatarova L. D.
Published: January 2007

This paper presents the results of investigation of the technological conditions of LPE growth of InAs1–ySby solid solutions on InAs substrates. It is shown that the chosen regions of composition of InAs1–ySby solid solutions and experimentally determined technological conditions allow the obtaining of InAs1–ySby solid solutions with lattice parameter values close to those of the AlxGa1–xSb (0 ≦ x ≦ 0.2) solid solutions.
Expressions for driving force in crystallisation with special reference to precipitation of barium cromate from homogeneous solution
Authors: de Silva R. L. , Barker P. E. , Creasy D. E.
Published: January 2007

Different expressions used to represent driving force for crystal growth, on the basis of fundamental thermodynamic considerations as well as on empirical grounds, are briefly reviewed. The choice of driving force expression for the crystal growth of barium chromate, when precipitation was carried out from homogeneous solution, is described and the reasons for the final choice are discussed.
On the structure of the rhombohedral α′R‐phase in Al Zn alloys
Authors: Werner M. , Ramlau R. , Löffler H.
Published: January 2007

The lattice parameters α and α of precipitates of the rhombohedral α′R‐phase grown in two AlZn alloys with 10 and 12 at.% Zn, respectively, at elevated temperatures were determined by transmission electron microscopy (TEM). Two approximative methods were derived to evaluate the Moiré fringes occuring in the TEM micrographs. The results obtained by these two methods agree within the range of experimental error with those presented in the literature (mainly gained from X‐ray methods).
Vibrational entropy of substitutional solid solutions
Authors: Urosov V. S. , Kravchuk I. F.
Published: January 2007

Positive deviations of the entropy of mixing from that of the ideal case have been established basing upon the experimental study of ionic substitutional solid solutions, carried out with the help of various techniques. These deviations are attached to the vibrational entropy, corresponding to the negative deviations of Debye temperatures of solid solution from additivity. The existence of linear correlation between the enthalpy of mixing and vibrational contribution to entropy is confirmed. Theoretical basis of this correlation, established empirically for the alkali halogenides, is given. The question is discussed, dealing with the universality of the relations of that kind and independence of vibrational entropy on temperature.