bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the volume transformation kinetics of cellular precipitation in f.c.c. nickel‐indium alloys
Authors: Budurov S. , Bojinov V. , Russew Kr. 
Published: July 2007

AbstractThe volume transformation kinetics of cellular precipitation in f.c.c Ni‐In alloys is studied. Precipitation occurs by instantaneous nucleation of two phase pearlite type cells on the grain boundaries. The experimental data was treated on the base of modified by Cahn Kolmogorov‐Avrami rate law for the case of grain boundary nucleation with site saturation in the earliest reaction stage. – The precipitation of the dissolved in the supersaturated matrix indium is governed by cell boundary diffusion; the activation energy was found to be about 65000 cal/mole.
Brittle fracture of single crystals and active structure of cleavage surfaces
Authors: Distler G. I. 
Published: July 2007

AbstractBy the method of vacuum decoration at an electronmicroscopic scale with the use of lowangle electron diffraction the dependence of brittle fracture of alkali halide crystals and of the active structure of cleavage surfaces on the character of ordered distribution of point defects in crystals has been studied. The occurrence of cleavage steps reflects the presence in crystal volume, where brittle fracture took place, of a high degree of periodicity of point defects mainly in one crystallographic direction. The smooth areas of the cleavage surface reflect the existence in these places of a periodic distribution of point defects in two mutually perpendicular crystallographic directions. Coincidence of periods between the cleavage steps with the periods in the arrangement of point defects on smooth areas of the cleavage surface allows the steps to be regarded not only as elements of the geometric microrelief but primarily as electrically active linear elements of the crystal surface, reflecting the linear arrangement of point defects. Together with cleavage steps exhibiting a stable in time activity there arise cleavage steps with an extremely high, but rather shortlived activity being the consequence of the brittle fracture process proper. The electrically active linear elements of the point defect lattice – linear elements of the potential relief of the surface – play a most important role in heterogeneous processes, in particular crystallization processes.
A study of the influence of short‐range order, clustering and crystal lattice defects on positron annihilation in α and α + β brass
Authors: Dlubek G. , Brümmer O. 
Published: July 2007

AbstractA theoretical model is proposed allowing the consideration of the influence of local neighbourhood of an atom on the positron density enhancement at one or another type of atom in a binary alloy. With the help of this model the direction of the change of angular correlation peak height caused by appearance of short range order or clustering can be predicted. Cu–Zn‐alloys containing 5.4, 15, and 37 weight % Zn are investigated. The peak height of samples quenched from 300°C. show a weak minimum at 90°C. This seems not to be caused by the increase of short‐range order but rather by a process of clustering. probably by segregation of Zn atoms at stacking faults and dislocations. The observed recovery of plastically deformed brass can be well explained by annealing out of vacancies and following recrystallization, where the α + β brass shows characteristic deformation induced properties. Peak height measurements of recovery of crystal lattice defects in binary alloys seems to be only weakly influenced by effects such as short‐range order or tendency of clustering. The formation energy of monovacancies in Cu‐37 wt% Zn is determined to be (0.81 ± 0.02) eV.
Die Züchtung homogener Mischkristalle mit großer Segregationsneigung nach dem Bridgman‐Verfahren am Beispiel des pseudobinären Systems CdxHg1–xTe
Authors: Dittmar G. 
Published: July 2007

AbstractBei der Erstarrung von CdxHg1–xTe im Bridgman‐Ofen mit geringer Ziehgeschwindigkeit wachsen wegen der erheblichen Unterschiede zwischen Liquidus‐ und Solidustemperaturen Kristalle mit sehr unterschiedlicher molarer Konzentration x. Bei höheren Ziehgeschwindigkeiten kristallisieren die Barren mit gleichmäßigerer molarer Konzentration x. Die Ursache der verbesserten Qualität der Barren und die Ergebnisse der praktischen Untersuchungen werden beschrieben und diskutiert.
Beitrag zur Züchtung von ZnSiP2 unter nichtstöchiometrischen Bedingungen aus der Gasphase in Auswertung mikroanalytischer Untersuchungen
Authors: Baum H. , Winkler K. 
Published: July 2007

AbstractDas aus der Gasphase abgeschiedene röntgenographisch einphasige und stöchiometrisch zusammengesetzte ZnSiP2 besitzt einen spezifischen Widerstand > 103 Ωcm und örtlich begrenzte Lumineszenzspektren. Die Existenz von Fremdphasen, vorhandene Inhomogenitäten sowie Stöchiometrieabweichungen im ZnSiP2 waren mögliche Ursachen für diese physikalischen Eigenschaften. Es wurde versucht, fremdphasenhaltiges ZnSiP2 aus der Gasphase abzuscheiden. Die ZnSiP2‐Synthese und ‐Kristallisation erfolgte deshalb mit nichtstöchiometrischen Siliziumeinwaagen. Der Phasenaufbau der Kristalle wurde lichtmikroskopisch und mit Hilfe der Elektronenstrahlmikroanalyse untersucht. Bei unterstöchiometrischer Siliziumeinwaage (– 50 mol% Si) enthält die ZnSiP2‐Matrix die binären Phasen ZnP2 und Zn3P2. Unter überstöchiometrischen Bedingungen (> 100 mol% Si) scheiden sich ZnSi13P2‐Schichten auf dem ZnSiP2 ab. Eindeutige Unterschiede in den physikalischen Eigenschaften konnten zwischen stöchiometrischem einphasigem und fremdphasenhaltigem ZnSiP2 nicht nachgewiesen werden.
Dielectric, piezoelectric, elastic properties and internal friction of TGSe crystals with large unipolarity
Authors: Varikash V. M. , Tarasevich E. V. , Pupkevich P. A. 
Published: July 2007

AbstractIn this work we have studied influence of temperature and external electric field on dielectric, elastic, piezoelectric properties and internal friction of D, L‐α‐alanine doped triglycine selenate crystals. Experimental result analysis allows to conclude that ferroelectric materials with stable physical properties may be created on doping crystals foundation.
Powder feeder for crystals of large diameter grown by the verneuil technique
Authors: Falckenberg R. 
Published: July 2007

AbstractTo grow crystals of large diameter ( ≈ 50 mm) by the flame fusion process it is necessary to feed powder with a flow rate of ≈ 2 g/min into the gas stream, the grain size being as small as possible. The properties of vertically and horizontally excitated sieves are compared. A sieve arrangement with horizontal and vertical vibration is described, which at a mesh width of 90 μm has a powder flow of up to 5 g/min. The long range constancy was within ± 8%. Sieves with a mesh width < 90 μm can be used if an ultrasonic disintegrator is mounted above the feeder sieve. Sapphire and Mg–Al spinel crystals up to 65 mm in diameter could be grown.
Growth and characterization of mixed Sr: Ca tartrates
Authors: Patel A. R. , Arora S. K. 
Published: July 2007

AbstractSingle crystals of Sr1−xCaxC4H4O6 · 4 H2O of different compositions and forms were grown by controlled diffusion of ions through suitable silica gels and characterized. Pycnometer density, lattice parameter, dislocation density, dissolution, cleavage, etc. are some of the interesting features which distinguish mixed crystals from the pure ones.
Zum Problem der Zweikristall‐Topographie von kleinen Defekten mit Bragg‐Bragg‐Reflexion
Authors: Kies J. , Köhler R. , Möhling W. 
Published: July 2007

AbstractDas Kontrastverhalten kleiner Defekte, wie sie bei Oxidation an Silizium‐Oberflächen entstehen, wurde mittels Zweikristalltopographie in Rückstrahlanordnung untersucht.Offensichtlich durch Oberflächenrelaxation des Spannungsfeldes bedingt, ändert sich der Kontrast wesentlich stärker mit der Eindringtiefe als mit der Orientierung der reflektierenden Netzebenen zu möglichen Burgersvektoren. Da die Eindringtiefe für unterschiedliche Reflexe stark variiert, scheint ohne Computer‐Simulation keine überzeugende Ermittlung der Natur der Defekte möglich zu sein.
Surface tension of soluble inorganic salts, from crystallization measurements
Authors: Söhnel O. 
Published: July 2007

AbstractA method is suggested for the determination of crystal‐solution interfacial tension σ on the basis of data obtained when studying the mechanism of a layer‐wise growth of the soluble‐salts crystals. The essential data for calculating the values of σ by this method are the height and distance of the individual steps on the surface of a growing crystal. The values of σ were evaluated for NH4H2PO4, KH2PO4, CdI2 and Pb(NO3)2.
Advances in energy dispersive X‐ray microanalysis
Authors: Wendt M. 
Published: July 2007

AbstractSome of the recent advances in energy dispersive X‐ray microanalysis of bulk specimens are reviewed with special emphasis on the developments having led to more accurate results. Following a brief description of instrumental developments the sources of background counts and the background correction are discussed. The final chapter deals with some useful applications of the background. In conclusion, one can state that in many cases the energy dispersive spectrometer yields results the accuracy of which is comparable to that of crystal spectrometers. In special cases the reproducibility achievable with the EDS can even be better.
Micromorphology and defects of non‐doped gallium arsenide layers
Authors: Astakhov V. M. , Toropov A. I. , Stenin S. I. , Zaletin V. M. , Korzhov V. I. 
Published: July 2007

AbstractElectron microscopy was used to study non‐doped GaAs layers obtained in a chloride system Ga‐AsCl3‐H2. Electron concentrations is 1013–1015 cm−3, mobility at liquid nitrogen temprature reaches 200000 cm2/v. sec. It is shown that a fraction of the growth surface taken with (110) faces is less for films with less electron concentration. The main type of defects in pure GaAs layers is precipitates at pinning centres of growth steps. Estimations based on microdiffraction patterns and irradiation effects show that the impurity concentration in them is 1016–1019 cm−3. The impurity in precipitates is assumed to be electrically non‐active, mainly, in interstitial positions.
Impurity diffusion of 114In in Cu
Authors: Krautheim G. , Neidhardt A. , Reinhold U. 
Published: July 2007

AbstractUsing the tracer‐standard sectioning technique the impurity diffusion of indium in copper has been investigated in the temperature range from 798.1 to 1081.0°C. For the frequency factor and the activation energy, respectively, the following values were determined: D02 = 1.87 cm2 · s−1; Q2 = 2.034 eV. The results are compared with predictions of theoretical models of the impurity diffusion in metals.
Kinetics of precipitation of nickel ammonium sulphate hexahydrate from aqueous solutions
Authors: Söhnel O. , Mullin J. W. 
Published: July 2007

AbstractThe precipitation of nickel ammonium sulphate [Ni(NH4)2(SO4)2·6H2O] prepared by mixing of equimolar aqueous solutions of (NH4)2SO4 and NiSO4 has been studied at 25 °C. Precipitation induction periods and the number of crystals formed per unit volume have been determined experimentally as functions of supersaturation for values of Sa, H < 2.6. The mechanisms of nucleation and crystal growth are assessed by comparing the experimental results with theoretical predictions. In this system, heterogeneous nucleation and crystal growth are assessed by comparing the experimental results with theoretical predictions. In this system, heterogeneous nucleation appears to operate at Sa, H < 1.3, whereas at Sa, H > 1.6 crystals are generated predominantly by homogeneous nucleation and grow by a polynuclear mechanism. The interfacial tension of nickel ammonium sulphate crystals in contact with their supersaturated solution is estimated to be about 20 mJ/ m2.
Gyrotropic properties and birefringence of Smx Tb1−xFeO3 in spin reorientation range
Authors: Sirota N. N. , Lomako I. D. 
Published: July 2007

AbstractThe polar diagrams of the SmxTb1−xFeO3 system taken for the crystallographic directions [110] and [001] have been investigated. The gyrotropic measurements data are compared to the values of the bond angles θ1 and θ2 calculated in terms of the lattice parameters. The correlation between the crystallographic and optical properties change as a function of composition has been obtained for the system under investigation. ‐The temperature measurements of the gyrotropic properties of SmFeO3 and Sm0.8Tb0.2FeO3 have shown that with temperature rising a change of shape and character of the polar diagrams takes place. The birefringence temperature dependence for Sm0.8Tb0.2FeO3 in the transparency and absorption range has been determined. The results of the study show the existence of the interrelation between the crystallographic, optical and magnetic characteristics and indicate that the temperature range of spin reorientation can be reliably determined from the optical measurements.
Texturtopographie
Authors: Born E. 
Published: July 2007

AbstractBei Verwendung der streng monochromatischen Röntgenstrahlung eines Johannsson‐Monochromators registriert die vorgeschlagene Methode die gebeugte Strahlung nicht am Ort ihrer Fokussierung gemäß der Guiniertechnik, sondern im doppelten Abstand, wo der Strahl wieder defokussiert ist. Wenn man z.B. eine polykristalline Metallplatte mit inhomogener Textur untersucht, so erhält man ein Röntgen‐Texturtopogramm mit strenger Zuordnung von Reflexionsort zu Abbildungsort auf dem Film. Voraussetzung ist das Einfügen eines Soller‐Stapels zwischen Präparat und Film zum Aussondern der nicht in der Fokussierungsebene liegenden Strahlen aus dem Beugungskegel.
Dislocation density in InxGa1–xAs films grown on GaAs substrates with intermediate buffer layer InGaAsP of variable composition
Authors: Bolchovityanov J. B. , Bolchovityanova R. I. , Yudaev V. I. 
Published: July 2007

AbstractInxGa1–xAs films with x = 0.03 and 0.05 were grown from an InGaAsP liquid phase. Because of high value of distribution coefficient of P we have heterojunction GaAsInyGa1–yPzAs1–x–InxGa1–xAs. The influence of Phosphorus atom fraction (Xp) in liquid phase on dislocation density in the top InxGa1–xAs layer was studied. It was found that dislocation density (Nd) as a function of Xp is a curve with some minima. The minima of Nd for substrates of (111) A and (111) B orientations are observed in the different intervals of Xp axis. — The width of Nd minimum is decreased if the substrate is misoriented from the (111) plane. — It was supposed that the clusters exist in the liquid phase. On the basis of this assumption one can explain the influence of substrate position over or under the melt on the film perfection. The diameter of these clusters is estimated to be about 500 Å.
Kinetics of the irregular binary alloys crystallization
Authors: Cherepanova T. A. , Kiselev V. F. 
Published: July 2007

AbstractWith the help of Monte‐Carlo computer simulation method we have investigated the growth of binary crystals having the structure anomally depended on temperature and the liquid phase composition. The dependences of the growth rate and component concentrations in the crystal volume on temperature for different liquid phase compositions were obtained. Kinetic phase diagrams are found here too. A comparison with the results obtained from analytical calculations was also made in this work.
Neutron diffraction analysis of rolling texture and its development in steels with a micro‐duplex structure
Authors: Schreiter U. , Kleinstück K. , Tobisch J. , Mücklich A. , Hötzsch G. , Klimanek P. 
Published: July 2007

AbstractIn this paper first neutronographic texture investigations for two‐phased steels are presented. From each of the phases three complete pole figures were measured. The analysis were carried out by means of the series expansion method. The three‐dimensional orientation distribution functions of all specimens are of tubular shape. For the interpretation of the differences to single‐phased steels the relationships for transformation by Kurdjumov‐Sachs and by Nishiyama were utilized.
Process Induced Crystal Defects in Dislocation‐Free n‐Type Silicon Material
Authors: Fischer W. , Heymann G. 
Published: July 2007

AbstractThis paper describes investigations on process induced crystal defects in n‐type silicon material of both Czochralski‐ and zone‐floating‐techniques (dislocation‐free). The heating and cooling processes, the oxide thickness, mechanical stresses near the diffusion windows, the mask pattern geometry concerning diffusion and the surface concentration of the doping material have been specially investigated. The influence of those technological parameters on the generation of crystal defects in the production of electronic devices is investigated and discussed.
Zur Frage der seitlichen Ionenstreuung bei der Implantation in amorphen und polykristallinen Festkörpern
Authors: Seidowski E. , Mamaev G. I. , Ledovskoj V. P. 
Published: July 2007

AbstractIn der Arbeit werden Gesetzmäßigkeiten für die seitliche Ionenstreuung in amorphen und polykristallinen Festkörpern angegeben. Im Unterschied zu bekannten Lösungen der LSS‐Theorie erlauben diese Gesetzmäßigkeiten die Berechnung der mittleren quadratischen seitlichen Ablenkung der Ionen bei beliebigen Massenverhältnissen von Targetatomen und auftreffenden Ionen in einem breiten Energiebereich, von einigen MeV bis zu Energiewerten nahe der Bindungsenergie der Atome im Festkörper.Die theoretischen Abschätzungen der mittleren quadratischen seitlichen Ionenablenkung befinden sich in guter Übereinstimmung mit experimentellen Werten verschiedener Autoren.
Dilatometric Studies of Thermal Expansion of Anthracene Crystals
Authors: Jakubowski B. 
Published: July 2007

AbstractThe thermal expansion of anthracene plates cut along the cleavage plane and having different crystalographic orientations was studied by means of a quartz dilatometer. The expansion tensor cross‐section in cleavage plane has been determined. It is shown that there is a correlation between the compressibility tensor orientation and the thermal expansion.
Desymmetrization of OD Structures
Authors: Ďurovič S. 
Published: July 2007

AbstractIt has been shown that the symmetry and structure of individual OD layers may depend on their actual stacking in a (polytypic) OD structure, leading to significant deviations from the ideal OD symmetry. This phenomenon has been called “desymmetrization of OD structures”; its significance for polytypism and for crystallochemistry is discussed.
The OD Structure of Dinitrosylcobalt Chloride, [Co(NO)2Cl]2
Authors: Kuban R.‐J. , Sedlacek P. 
Published: July 2007

AbstractThe OD groupoid family of the structure of dinitrosylcobalt chloride, [Co(NO)2Cl]2, is characterized by the symbol: magnified imageThe OD groupoid family 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. The determination of the structure of the ordered orthorhombic form (MDO2) has been determined from Weissenberg data obtained by JAGNER and VANNERBERG refined with OD full‐matrix least‐squares methods, based on a total of 150 reflections and anisotropic temperature coefficients. An R value of 0.13 has been obtained. The assumption of JAGNER that the structure is composed of dimers has been found to be justified.
On the Application of Direct Methods in X‐Ray Structure Analysis: Survey on Number and Kind of Solved Acentric Equal Atom Structures
Authors: Messerschmidt J. 
Published: July 2007

AbstractA statistical analysis of all acentric equal atom structures solved by direct methods and reported in Acta Crystallographica from January 1968 to November 1978 has been carried out. The most frequently applied direct methods programs are the MULTAN, SAP and SHELX. About 80% of all considered structures belong to the space groups P212121 and P 21. Problems with direct methods can arise if the number of the nonhydrogen atoms per asymmetric unit is greater then about 40 and/or the space group belongs to a category in which the definition of the enantiomorph is difficult.
Evolution of Structure in Deformed Single Crystals of fcc Metals at Heating
Authors: Kopezky C. V. , Kokhantchik L. S. 
Published: July 2007

AbstractThe paper deals with conditions resulting in formation of dislocation structures of different types as well as with the change of these structures at subsequent heating which ends in the recrystallization center formation and growth. The measurements were carried out on single crystals of fcc metals. The principal experimental technique was electron microscopy including the annealing of deformed foils directly in the column of electron microscope with accelerating voltage 150 and 1000 kv. Special attention is given to research of the initial stage of recovery in dislocation structures during annealing — the dislocation recovery as the most universal mechanism occurring at any type of structure even when polygonization and recrystallization are hampered. Studies of initial recrystallization stages were mainly carried out while annealing the deformed single crystals of copper. A high degree of local lattice curvature is shown to be a necessary condition for nucleation, and mechanism of the nucleus formation in regions of a high local curvature differs according to the type of the dislocation structure formed during deformation.
Non‐Arrthenius Behaviour and Divacancy Contribution in Self‐Diffusion of 64Cu in Cu
Authors: Krautheim G. , Neidhardt A. , Reinhold U. , Zehe A. 
Published: July 2007

AbstractThe self‐diffusion of 64Cu in Cu was investigated in the high temperature range (1078 to 1348 K), applying the tracer‐standard sectioning technique. For the frequency factor D0 and the activation energy Q0 we found D0 = (0.68)cm2 · s−1 and Q0 = (2.17 ± 0.02) eV. A slight bending of the Arrhenius plot suggests a divacancy contribution to the self‐diffusion of copper. Data sets used in an numerical analysis are in good accord with published results.
Effects of the Crystal Diameter on the Dislocation Density in KCl Crystals Grown by the Czochralski Method
Authors: Inoue T. , Komatsu H. 
Published: July 2007

AbstractThe dependence of dislocation density on the crystal diameter of the Czochralski grown KCl crystals (both pure and Sr doped) was investigated by the method of the etch pit and X‐ray topograph. (1) The dislocation density drastically decreased with the decrease in diameter (D) for small D (D < 2 mm, Fig. 2). (2) The dislocation density in the Sr doped crystal was lower than that of pure component in the diameter examined. (3) Many helical dislocations and dislocation loops were observed in the thin crystals (D ∼ 0.5 mm) of the pure KCl and Sr doped one, respectively, by X‐ray projection topography. These results were discussed in connection with the dislocation generation mechanisms due to thermal stresses or supersaturated point defects.
Thermodynamic properties of strontium tungstate crystal growth from sodium tungstate melts
Authors: Roy B. N. , Handa V. K. 
Published: July 2007

AbstractEnergy (E), enthalpy (ΔHa), entropy (ΔSa) and free‐energy (ΔGa) of activation and the pre‐exponential factor (k0) of the ordinary Arrhenius equation kDl = k0e–E/RT were estimated for diffusion‐controlled crystal growth of SrWO4 from Na2WO4 melts. E increased slightly with increased cooling rates (RT). k0 was parallel to kDl and increased with increasing RT. ΔHa, ΔSa, and ΔGa did not change with the changes in RT and crystallization temperature (T0). The distance (d12), between a diffusing particle and its host necessary for a successful diffusion, was estimated. Such distances slightly increased with T0 and RT.