bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Preparation and Crystal Structure of MgP4
Authors: Gibiński T. , Cisowska E. , Żdanowicz W. , Henkie Z. , Wojakowski A. 
Published: July 2007

AbstractIn the systematical study of the A11BV semiconducting compounds the Mg‐P system has been examined. Among the products of crystallization from BiPbSn alloy the crystals of a new compound MgP4 have been identified. It has been found that these crystals are isostructural with CdP4. The crystal structure refinement from X‐ray data has been performed. The lattice constants are: a = 5.141 Å, b = 5.079 Å, c = 7.518 Å, β = 98.64°; Z = 2; space group P21/c.
Konstruktion der stereographischen Projektion des Kossel‐Reflexsystems für beliebige Orientierung eines kubischen Kristalls
Authors: Alex V. 
Published: July 2007

AbstractEin teils rechnerisches, teils zeichnerisches Verfahren zur Konstruktion der stereographischen Projektion von Kossel‐Kegeln in einer beliebigen Projektionsebene wird beschrieben. Die Schnittpunktlagen der Kossel‐Kreise auf den Großkreisen der Einheitskugel werden berechnet und mit Hilfe des Wulffschen Netzes in das Stereogramm eingetragen. Durch die Punkte werden die Kossel‐Kreise gezeichnet, deren Topologie die zuvor konstruierte stereographische Projektion auf die (001)‐Ebene angibt.
Zur Bestimmung der Gitterkonstanten und der Orientierung nichtkubischer Kristalle mit der Pseudo‐Kossel‐Technik
Authors: Kämpfe B. , Klimanek P. 
Published: July 2007

AbstractDie Pseudo‐Kossel‐Technik eignet sich besonders für die Untersuchung kleiner einkristalliner Probenbereiche. In dieser Arbeit wird über ein Auswertungsverfahren für Transmissionsaufnahmen berichtet, bei dem der Abstand Röntgenstrahlquelle — Film nicht benötigt wird. Die Ermittlung des Filmmittelpunktes erfolgt im Verlauf der Auswertung; die Probe kann gegenüber der Filmebene eine beliebige Orientierung besitzen. Das Verfahren gestattet die Bestimmung des reziproken Gitters kubischer, tetragonaler, hexagonaler und rhombischer Kristalle, ohne daß Näherungswerte der Gitterparameter bekannt zu sein brauchen, und der Kristallorientierung. Gitterkonstantenbestimmungen sind mit einer Ungenauigkeit Δa/a ≈ ≈ ± 1 · 10−4 auch bei relativ kleinen Glanzwinkeln möglich. Die Methode wird am Beispiel des tetragonalen ZnSiP2 demonstriert.
Piezoelectricity Effect Detector
Authors: Grochowski J. , Stasicki B. 
Published: July 2007

AbstractAn apparatus for the detection of the piezoelectricity effect in non‐conducting crystals is described. It is possible to mark the crystal resonance frequency and show the resonance curve on the oscilloscope, both with or without mechanical contact between the crystal and electrodes. For the urotropine crystals the section of the surface of the longitudinal piezoelectric effect with (110) plane was determined without mechanical contact.
Untersuchung der Phasenumwandlung von Aluminiumoxid im Temperaturbereich von 500 bis 1200°C
Authors: Wintruff W. 
Published: July 2007

AbstractMit Hilfe der Phasenanalyse, der immersionsmikroskopischen Analyse und der Elektronenresonanzspektroskopie wird die strukturelle Umwandlungsfolge des Aluminiumoxids im Temperaturbereich von 500 bis 1200°C untersucht. Als Sonde für die Aufnahme der EPR‐Spektren wurden Fe3+‐Ionen gewählt (Al2O3/0,586 Mol% Fe2O3). In dem untersuchten Temperaturbereich wurden γ‐, ϑ‐ und α‐Al2O3 festgestellt, die als diskrete Phasen zu betrachten sind. Bei dem Mechanismus der strukturellen Umwandlungen handelt es sich um diskrete übergänge. Auf der Grundlage der Ergebnisse wurden die Existenzbereiche der γ‐, ϑ‐ und α‐Phase und ihre prozentualen Anteile in dem Oxidgemisch bei den entsprechenden Temperaturen bestimmt.
Zur dynamischen Untersuchung elastischer und elektromechanischer Eigenschaften von Kristallen
Authors: Beige H. , Schmidt G. 
Published: July 2007

AbstractZur Bestimmung elastischer und piezoelektrischer Koeffizienten sowie der mechanischen Güte hat sich der piezoelektrische Resonator als eine besonders einfache und zuverlässige Methode erwiesen. In diesem Artikel werden einige Möglichkeiten zur Verbesserung der Genauigkeit dieser Methode und für deren Anwendung für schwach piezoelektrische Kristalle sowie zur Messung elastischer Koeffizienten höherer Ordnung aufgezeigt. Bei dynamischen Messungen an elektrostriktivem Material (elektrostriktiver Resonator) kann man in entsprechender Weise verfahren.
Kinetics of a Single Crystal Growth from Supersaturated Liquid Solution. An Attempt on the Analytical Description of the State of Solution
Authors: Dals K. 
Published: July 2007

AbstractThe attempt was made at formulating a mathematical model describing the state of the supersaturated liquid solution circumfluenting a single crystal, as well as the transport processes occurring in that solution. As the result of a suitable computation procedure, numerical values of velocity components, concentrations, temperatures and the normal components of the mass flux in the vicinity of the crystal surface have been obtained.
The Precipitation of Barium Chromate with Slow Development of Supersaturation. Kinetics of the Crystal Growth
Authors: Packter A. 
Published: July 2007

AbstractSlow barium chromate precipitation was studied in well‐stirred solutions — final concentration 0.002 mole 1−1 — at 20°C at mixing rates varying from 0.2 to 2 · 106 mole 1−1 sec−1; the kinetics of the crystal growth process were studied by chemical analysis and by optical microscopy. The crystal growth started after induction periods; regular growth then took place on the nuclei formed during these periods. For the main growth, up to about seventy percent precipitation time, growth rates at any time depended on the (residual excess solute concentrations in solution)2. Immediately after the induction periods, crystal lengths varied with growth time according to the relation,
equation image
for the main growth, crystal lengths varied with growth time according to a more complex relation,
equation image
where kl is the rate constant for surface growth, Rc is the rate of development of metal salt concentration and K is a constant that depends on the number of precipitate crystals.After some growth time τ = τ*, when lτ = lτ*, all fresh solute added to the solution was utilised immediately and was deposited onto the growing crystals; then, for the final thirty percent precipitation, crystal lengths varied with growth time according to the relation,
equation image
.
Einfluß von magnetischen und elektromagnetischen Feldern auf die Kristallisation aus wäßrigen Lösungen
Authors: Barta Č. , Beljajev L. M. , Dobržanskij G. F. , Kreinin S. L. , Schaskolskaja M. P. , Žemlička J. 
Published: July 2007

AbstractEs wurde festgestellt, daß die strukturelle Perfektion von α‐HJO3‐ und TGS‐Kristallen, die aus Lösungen gezüchtet wurden, unter der Wirkung eines Gleichstrom‐Magnetfeldes von 35 Oe und unter Abschirmung gegen elektromagnetische Wellen ≧ 105 Hz sich wesentlich verbessern. Der Grad der Perfektion wurde an der Zahl der Versetzungen in den gezüchteten Kristallen gemessen.
A Method of Determining the Liquid Phase Epitaxial GaAs Growth Mechanism Based on Growth Rate Measurements
Authors: Bryśkiewicz T. , Herman M. A. 
Published: July 2007

AbstractIt has been proved that the dependence of the growth rate V of a LPE GaAs layer on the relative supersaturation σ of the solution at the interphase boundary can be determined on the basis of growth rate measurements of this layer in the case when crystallization is controlled by the kinetics of surface processes. The relation V = f(σ) obtained for homoepitaxial GaAs layers grown at different solution cooling rates are compared with the theoretical relations derived by BRICE making use of a single growth mechanism assumption.Based on the above and by use of the experimental data of MUSZYńSKI the growth mechanism of homoepitaxial GaAs layers on a substrate oriented in the [100] direction is determined. The results are in accordance with the crystallization model of AIIIBV semiconductor compounds from the liquid phase proposed by FAUST and JOHN.
The Catalysed and Uncatalysed Nucleation of Gypsum Crystals from Aqueous Solution
Authors: Konak A. R. 
Published: July 2007

AbstractGypsum (Calcium Sulphate Dihydrate) has been precipitated by mixing aqueous solutions of calcium chloride, sodium sulphate and sodium chloride at 25°C. In the absence of solid gypsum, classical nucleation theory predicts rates reasonably well only at the expense of some adjustable parameters like surface energy term. This has been attributed to the difficulties associated with the application of equilibrium thermodynamics to a process of kinetic origin. The presence of solid matter acts as a catalyst and decreases the induction period. In this case, the habit as well as the quantity of gypsum added greatly influences the induction period. Possible reasons for this have been given.
Elektronenmikroskopische Untersuchungen zur Oxidkeimbildung an Reineisenoberflächen
Authors: Bewilogua K. , Wetzig K. 
Published: July 2007

AbstractBeim Glühen von reinen α‐Eisenkristallen im Hochvakuum (po2 = 1 · 10−4 bis 1 · 10−6 Torr) entstehen auf den Oberflächen der Kristalle einzelne Oxidkeime, die als γ‐Fe2O3 identifiziert wurden. Die einheitliche Form der Keime auf (100)‐Flächen von α‐Eisen sowie ihre Orientierung bezüglich des Eisengitters deuten auf ein epitaktisches Aufwachsen nach dem bekannten Verwachsungsgesetz (100)Fe∥ (100)Oxid; [100]Fe∥ [110]Oxid hin. Eingewachsene Versetzungen, Oberflächenstufen und Korngrenzen der Matrix wurden durch Oxidkeime dekoriert. An Durchstoßpunkten frischer Versetzungen erfolgte dagegen keine Oxidkeimbildung.
Investigation of InxGa1−xAs films grown from thin solution layer
Authors: Bolchovitianov Yu. B. , Zembatov H. B. 
Published: July 2007

AbstractInxGa1−xAs films with x⩽0.12 were grown from a thin solution layer between substrates. The calculation of final film thickness as a function of liquid phase composition, based on supposition of film deposition only on the substrate, is in a good agreement with experimental results. The dependences between compositions of liquid and solid phases at 800°, 750° and 700°C were determined.The morphology of the film surface was investigated as a function of liquid phase composition and (100), (111) A, (111) B substrate orientations. Dislocation density increases from 104 cm−2 to 107 cm−2 with change of x from 0 to 0.12.
Growth of Epitaxial Layers of GaN from GaBr3 · 4 NH3 Complex
Authors: Żytecki J. , Łappa R. 
Published: July 2007

AbstractA method of obtaining GaN from GaBr3 · 4 NH3 by radiation heating of the substrate is described. The results of investigations are given concerning the growth rate of polycrystalline GaN layers on [111] oriented silicon substrates in dependence on the changes of the temperature of reaction, evaporation temperature of GaBr3 · 4 NH3, and the rate of gas flow. The results of X‐ray investigations and light absorption coefficient are described. Some facts were observed, namely a considerable influence of the nozzle form on the kinetics of the transporting gas stream on the growth rate of GaN, as well as the fact that not the whole complex undergoes pyrolysis on the substrate at temperatures below 500°C.
Effect of Stressed State Type on Work Hardening and Evolution of Dislocation Structure in Magnesium Single Crystals
Authors: Pokhil Yu. A. 
Published: July 2007

AbstractThe type of stressed state (compression, simple shear) is shown to effect the parameters of a work hardening curve for Mg single crystals under basic slip. The electron‐microscopic results for the dislocation structure are indicative of the fact that work hardening at stage A of the work hardening curve is connected with the basis‐basis dislocation interaction, while the to‐B‐stage transition and a rapid growth of strain stress are due to the interaction between basic dislocations and “forest” dislocations in the {1010} {1120} systems, the latter dislocations arising from the stress relaxation in the primary slip system.
Temperature and Strain Rate Effects on Work‐Hardening of KCl Single Crystals
Authors: Tabachnikova E. D. 
Published: July 2007

AbstractThe influence of temperature and strain rate on work hardening of a KCl crystal has been investigated. Using the experimental data on flow stress relaxation, the activation “volume” for dislocation motion and internal counteracting stresses have been calculated in the temperature range of 300 to 40 K. Estimation has been carried out for the variation of a number of mobile dislocations ϱ2/ϱ1, when the strain rate is changed by a factor of four.
Preparation, Morphology and Structure of Cadmium Telluride Epitaxial Layers on Germanium Substrates
Authors: Kamadjiev P. R. , Mladjov L. K. , Gospodinov M. M. , Vassilev I. S. 
Published: July 2007

AbstractGrowth conditions of cadmium telluride single crystal layers on germanium (111), (110), (100), (112) substrates in quasi‐closed “sandwich” system in a hydrogen atmosphere, were investigated in this paper. The peculiarities of layer morphology for the different orientations are presented.
The Crystallisation of Calcium Molybdate and Tungstate from Lithium Chloride Melts by Continuous Cooling. The Kinetics of Crystal Growth in Alumina Crucibles
Authors: Packter A. , Roy B. N. 
Published: July 2007

AbstractThe kinetics of crystallisation of calcium molybdate and tungstate from unstirred supersaturated solutions in lithium chloride melts — in alumina crucibles — was studied by continuous cooling from initial temperature T0 = 800°C down to room temperature at cooling rates RT = 20° to 200°C hr−1. The solutions were analysed chemically and the crystals were examined by optical microscopy. Crystal growth started practically immediately after the onset of cooling: at first, the amount of material deposited onto crystals was far less than the amount of excess solute developed within the supersaturated solutions but crystallisation rates then increased as the crystal sizes increased. Then, after some time t* (at about seventy percent crystallisation), all excess solute was deposited onto growing crystals.
Radiation Defects Research in Single Crystals of Lithium Niobate
Authors: Antonov V. A. , Arsenev P. A. , Baranov B. A. , Barinova N. D. , Kustov E. F. , Linde I. G. 
Published: July 2007

AbstractAn information is given on the kinetics of developing ionization defects by γ‐radiation, as well as on the destroying of these defects as a result of thermal treatment in oxidizing atmosphere at different temperatures. The presence of several types of ionization defects developing by γ‐radiation is found out. Values of diffusion factor for each type of defects are given.
X‐ray crystal orientation determination for semiconductor single crystals
Authors: Keppler U. , Meier M. , Neifeind A. , Rohmer C. 
Published: July 2007

AbstractAn improved method to measu reorientation angles of flat single crystals was developed taking Buerger precession technique. The method is described and compared with Laue‐ and goniometer techniques. Advantages are low costs and short measuring time. An easy evaluation of the records allows to take this method as a routine angle determination for semiconductor manufacturing.
A method of investigation of heterostructure for junction lasers based on photoluminescence measurements
Authors: Bryśkiewicz T. , Herman M. A. , Lewandowski W. 
Published: July 2007

AbstractA four layer GaAs–AlxGa1–xAs heterostructure photoluminescence spectrum measured at 77K has been compared with the results of investigations concerning the composition of this heterostructure, performed by using the electron microprobe JXA‐50A. The application of photoluminescence investigations of such heterostructures as a simple and convenient control method that can be used during the performance of a heterostructure laser has been proposed.
Strahlende und nichtstrahlende Rekombination am neutralen Silizium‐Akzeptor in n‐Ga0,2‐Al0,8As
Authors: Zehe A. , Hänsel T. 
Published: July 2007

AbstractAls effektiver bandkantennaher Übergang in Si‐dotiertem n‐Ga1–xAlxAs (x ∼0,8) tritt in der Katodolumineszenz bei T = 80 K die Rekombination eines freien Loches mit einem gebundenen Elektron auf. Die Effizienz dieser Bande wird durch einen 300 meV niederenergetischeren Paarstrahlungsübergang beeinflußt. Unter Bedingungen einer steigenden hohen Anregungsdichte wird die Paarstrahlung zugunsten der Frei‐Gebunden‐Emission getilgt. Beide Lumineszenzpeaks verschieben sich in Richtung kurzwelliger Strahlung, das Paarband um etwa 45 meV, der Frei‐Gebunden‐Übergang um etwa 3 meV. Die Erscheinungen werden auf der Basis eines Dreizentren‐Auger‐Prozesses, an dem die auf Akzeptorzuständen eingefangenen Löcher beteiligt sind, erklärt.
The precipitation of calcium carbonate powders from aqueous solution with slow development of supersaturation. Induction periods, crystal numbers and final sizes
Authors: Packter A. 
Published: July 2007

AbstractThe precipitation of calcium carbonate was studied by slow addition of anion solution to excess cation solution and by slow mixing of equivalent cation land anion solutions at 20 °C: the final solute concentrations (Cfin were varied from 0.01 to 0.75 mole 1−1 while the rates (R) of addition of ions were varied from 0.06 to 6 · 10−3 ion 1−1 sec−1. At first, mainly heterogeneous nuclei formed continuously during induction periods; then, as the metal salt concentration in solution increased, some more heterogeneous nuclei formed but homogeneous nucleation soon predominated. The second nucleation process probably attained its maximum rate when the metal salt concentratio in solution reached its maximum value (Cmax) and then probably terminated quite rapidly. Some further nuclei also formed during the growth process when crystal growth was prolonged. The final nucleus numbers (N) (and thence the crystal numbers) for slow precipitations from dilute solutions were then rather higher than the optimum number N∞ (het) of heterogeneous nuclei in the solution; nucleus numbers then increased with increasing maxing rate according to the relations

.These numbers were similar to those noted for rapid precipitation – onto homogeneous nuclei – from calcium carbonate solutions of concentrations somewhat lower than the Cmax values. The final average crystal lengths of any precipitate then generally varied with mixing rate according to the relations,

. where l1 values increased with (Cfln)0.33.
The effect of solute supersaturation on the ageing process of an Al 59,5 wt% zn alloy
Authors: Ciach R. , Dutkiewicz J. , Kroggel R. , Löffler H. , Wendrock G. 
Published: July 2007

AbstractThe effect of the solution treatment temperature on the mechanism of the decomposition at room temperature of an quenched Al 59,5 wt.‐% Zn alloy has been examined. The investigations were carried out using X‐ray techniques, optical and transmission electron microscopy and measuring the changes in the dimensions, electrical resistivity and the hardness.The sequence of the phase transformations in the alloy quenched from 370°C were as follows.The transformation begins with spinodal decomposition. After some development of the spinodal structure, which is associated with increase in wavelength, the heterogenuous nucleation and growth of the zinc‐rich particles occur within the spinodal structure. Simultaneously the discontinuous transformation was observed to grow into the spinodal structure.The decomposition of the same alloy quenched from 300°C (miscibility gap region) took place much more rapidly than when quenched from 370°C. Directly after quenching the spinodal structure was also observed using JEM‐1000, coincidental with a remarkable increase of electrical resitivity. At the same time the heterogenuous nucleation and growth of the zinc particles, on the interfaces of the α‐α′ phases was observed. The discontinuous transformation was also found within the α′ supercooled phase.The decomposition of the Al 38 at.‐% Zn alloy quenched from 300°C appeared to be divided into two stages. In the first the decomposition of the zinc‐rich α′ phase takes place and in the second one the transformation of the zinc‐poor a phase occurs. These two transformations are distinctly marked on the curves of the changes in the dimensions, electrical resistivity as well as in the intensity of the (101) reflexion of the zinc phase.
Lumineszenzeigenschaften von pyrolytisch abgeschiedenem GaN
Authors: Petzke W.‐H. , Zehe A. 
Published: July 2007

AbstractDie pyrolytische Abscheidung von GaN auf isolierenden Substratmaterialien führt zu metallisch schwarzen bis nahezu farblosen Schichten. Morphologie und Wachstumsrate werden beeinflußt durch Wachstumstemperatur Art und Strömungsraten des Trägergases. Im Katodolumineszenspektrum werden charakteristische Emissionsbanden in der Nähe der Bandkante bei 3,54…3,10 eV sowie bei 2,21…2,07 eV erhalten, deren relative Intensitäten von der Strömungsrate des Trägergasstromes abhängen. Bei gelber und farbloser Probe erscheint, z. T. ausschließlich, ein Peak bei 2.48 eV, Die äußere Quantenausbeute ist für dunkle, metallische Proben am größten. Zwischen den Züchtungsparametern und der Vakanzenkonzentration sowie dem Verunreinigungseinbau (Sauerstoff) besteht ein durch die Spektren ausgewiesener Zusammenhang.
Optical properties of Ga1–xInxAs LPE‐layers and p‐n structures
Authors: Zehe A. , Butter E. , Jacobs B. , Stary J. 
Published: July 2007

AbstractThe multiple layer structure nGaAs(n Ga1–xInxAs) p Ga1–xInxAs (0 ≦ × ≦ 0.18) was realized by liquid phase epitaxy from In–Ga–As‐melts on (111)‐oriented GaAs substrates. The InAs‐content of the mixed crystal layers was found to be dominating for crystal perfection and growth rate.The cathodoluminescence spectra of p‐and n‐type Ga1–xInxAs and spectral distribution of the electroluminescence from pn‐junctions were measured at T = 77 K and 300 K.The external quantum efficiency wa found to have a maximum for diodes with x ≈ ≈ 0.006. This is caused by the decrease of the optical absorption with increasing x and increasing dislocation density on the other hand.
Elektronenmikroskopische Untersuchungen am gerichtet erstarrten Al–Al3Ni‐Eutektikum
Authors: Zies G. 
Published: July 2007

AbstractDie Struktur des nach dem vertikalen Bridgeman‐ Verfahren mit Erstarrungsgeschwindigkeiten im Bereich von 6 bis 70 mm/h gerichtet erstarrten stabförmigen Al–Al3Ni‐Eutektikums wurde im erstarrten, zugverformten und wechselbeanspruchten Zustand untersucht. – Die in der Al‐Matrix annähernd parallel zueinander eingewachsenen Al3Ni‐Stäbe erweisen sich als Whisker, deren Morphologie mit der beobachteten kristallographischen Orientierung und der Erstarrungsgeschwindigkeit zusammenhängt. Beobachtungen typischer Versetzungszellstrukturen, welche die Stäbe in der Matrix verbinden, Grenzflächenversetzungen und Moiré‐Muster an der Al/Al3‐Grenzfläche werden vorgestellt und beschrieben. Die theoretischen Abstände zwischen Anpassungsversetzungen und Moiré‐Streifen wurden für einige wichtige Gitterrichtungen berechnet und mit den beobachteten verglichen.
Präparation von Polykristallen der intermetallischen Verbindung MgZn2
Authors: Siegel S. 
Published: July 2007

AbstractThe influence of mechanic vibration treatments on the solidification of the intermetallic compound MgZn2 is investigated. A clear connection exists between velocity of vibrations and resulting grain refinement. A minification factor 50 could be proved as the extreme value for the given apparatus conditions. The grain sizes of the shaken probes follow a logarithmic normal distribution. A minification of already solidified primary crystallites, caused by a friction force between growth batch and front of solidification, is discussed as the decisive mechanism of the grain refinement.