bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of the shear viscosity in garnet high temperature solutions by a cylindrical rotation viscometer
Authors: Sinn E.
Published: July 2007

Garnet high temperature solutions, their solvents and binary systems consisting of lead oxide and one component out of the solute were investigated. The shear viscosity coefficients have been measured in a cylindrical rotation viscometer within the temperature range of liquidus or melting and not exceeding 1270°C. The logarithm of the shear viscosity in the simple systems PbO or PbOB2O3 linearily depends on the reciprocal absolute temperature, however, the relationship in phase systems containing Fe2O3 or Ga2O3 is more complex. The shear viscosities of Y3Fe5O12 or (Y, Sm)3 (Fe, Ga)5O12 solutions suitable for LPE experiments amount 0.20 to 0.23 g cm−1s−1 near the liquidus temperatures. An effective average activation energy for shearing flow was estimated, its dependence on the temperature points to chemical equilibria reactions in the solutions.
Eine neue absolute sin ϕi/sin ϕj‐Methode für die Bestimmung von Gitterparametern
Authors: Vavrda J.
Published: July 2007

Die reziproken Quadrate von Gitterparametern werden für ein‐, zwei‐ und dreiparametrige Gitter durch die Lösung von Lineargleichungen ermittelt. Die systematischen Abweichungen werden bei dieser Arbeitsweise total unterdrückt. Die Methode ist für viele Aufnahmenverfahren universell anwendbar.
The effect of impurities on the β → α transformation process in tin
Authors: Brick V. B. , Larikov L. N. , Falchenko V. M.
Published: July 2007

This article presents data on the impurities influencing the β → α transformation of high purity tin (99.9995%): temperature of the α → β transition‐T0, nucleation and α‐crystal growth.
Effects of doping of Ca and Ba on the dislocation distribution in melt grown KCl crystals
Authors: Inoue T. , Komatsu H. , Takei H.
Published: July 2007

The effects of doping of Ca and Ba (∼ 0.02 at %) upon the dislocation distribution in melt grown KCl crystals without cellular segregation were studied by an etch pit method in connection with the dispersion state of the dopants, which was examined by the dark field illumination. – (1) In the Ca‐doped crystal, in which the dopants were distributed uniformly, the formation of subboundaries was completely suppressed and dislocations were distributed at random. (2) In the Ba‐doped crystal, however, the dopants were non‐uniformly distributed and the dislocations tended to form subboundaries. The dislocations within the subgrains were distributed in a non‐uniform manner. (3) The dislocation density in the Ba doped crystal was higher than that of undoped or Ca‐doped crystal. This was explained by the mechanism similar to the Tiller's prediction. – Finally, the stress distribution due to the concentration fluctuation was examined by the birefringence patterns.
Crystal growth of potassium perchlorate in gelatin gels
Authors: Patel A. R. , Rao A. Venkateswara
Published: July 2007

The suitability of gelatin gel for the growth of good quality single crystals of potassium perchlorate has been investigated. Growth in a more rigid and simple apparatus has been accomplished and described here. The grown crystals were identified by X‐ray analysis. A study of the relation of crystal morphology to concentration of feed solutions and growth temperature has also been made. Studies made on chemical etching of the cleavages have revealed that the crystals are relatively perfect. At times, large liquid inclusions which introduce stresses in the crystals are responsible for a large dislocation concentration.
Oxidation kinetics of BaF2 single crystals
Authors: Aronova A. M. , Berezhkova G. V.
Published: July 2007

Oxidation of BaF2 single‐crystals as a result of annealing in air in the temperature range 600° to 900 °C leads to mechanical strengthening. The process kinetics was investigated. It is shown that oxidation takes place in the bulk of crystals owing to oxygen diffusion by formation and growth of oxidation centres. These centres are precipitates of a BaO phase which were revealed by chemical etching.
Thin thermosensitive film coating
Authors: Komitov L. , Hiebaum G.
Published: July 2007

Thin film thermosensitive coatings are obtained, representing liquid crystal microdroplets dispersed in a polymeric matrix. Gelatin is chosen as a polymeric material. The obtaining of microdroplets is carried out by condensation of the solution of liquid crystal in organic solvents at their mixing with gelatin aqueous solution. The obtained coating distinguishes with temperature stability, homogeneity of the colouring, stability of the time indicators.
Cold rolling texture development in Zn, Cd and Mg
Authors: Ivaniji V. S. , Moroz I. A.
Published: July 2007

Studied are the regularities of preferred orientations in the process of rolling of zinc, magnesium, and cadmium. On the basis of the data obtained and analysis of crystallographic mechanism of Cd, Zn and Mg crystals a “dynamic” model of the rolling texture formation in zinc and cadmium as well as a “monotonic” one in magnesium are suggested.
H3PO4 — etching of {001}‐faces of InP, (GaIn)P, GaP, and Ga(AsP)
Authors: Gottschalch V. , Heinig W. , Butter E. , Rosin H. , Freydank G.
Published: July 2007

This paper shows that hot H3PO4 is a suitable etchant for the production of dislocation etch pits on {001}‐InP, (InGa)P, GaP, Ga(AsP), and {111}‐GaP. The effects upon etch pit morphology of the misorientation of samples and the type of dislocations are investigated in detail.
Investigation of 1 S1/2O,1 S1/2C and 2 P3/2Ni states of argon ion implanted nickel metal
Authors: Gumanski G. A. , Chodasewitsch V. V. , Brümmer O. , Wagner N.
Published: July 2007

Polycristalline Ni samples were bombarded by 30 keV Ar ions with dose rates from 1016 ions/cm2 to 1017 ions/cm2. The investigation of the electronic states 1 S1/2O, 1 S1/2C and 2 P3/2Ni was made by X‐ray photoemission spectroscopy (XPS). The XPS core level spectra show features refering to different chemical compounds of oxygen and carbon with nickel. We have studied the change of this spectrum structure dependent on distance of the sample surface for various doses of implantation.
On the interpretation of the determination of particle size and distortion of crystallites with a screw dislocation
Authors: Röll H.
Published: July 2007

For an infinitely long cylindrical crystallite with an axial screw dislocation the roentgenographic distribution function of distortions is calculated. This distortion distribution essentially differs from the Gaussian distribution underlying the Warren‐Averbach procedure by a dependence on the Fourier order, a maximum with distortions different from zero, as well as a cutt‐off radius reciprocally proportional to the Fourier order. Further it is shown that for the mentioned distortion model the conception of a particle size independent on the Fourier order is correct.
Zur Bestimmung der Kristallitgrößenverteilung von Metallen auf Katalysatorträgern aus Röntgenweitwinkelmessungen (II). Direktberechnung von Kristallitgrößenverteilungen aus Röntgenbeugungsprofilen
Authors: Spindler H. , Ackermann W.‐G.
Published: July 2007

Es werden Verfahren angegeben, welche die Sehnenlängenverteilung — bzw. bei kugelförmigen Teilchen auch die Durchmesserverteilung — von Metallkristalliten in Trägerkatalysatoren ohne Differentiation direkt als Transformation von Funktionen zu berechnen gestatten, die unmittelbar aus den Intensitäten von Röntgenweitwinkelinterferenzen abgeleitet werden. Es wird gezeigt, daß zur Beschreibung des Kristallwachstums das erste Moment der Sehnenlängenverteilung geeignet ist. Für das Wachstum von Platinkristallitenin PtAl2O3‐Katalysatoren wurde in inerter Atmosphäre ein Zeitgesetz 2. und in oxydierender Atmosphäre ein Zeitgesetz 4. Ordnung gefunden.
On the decomposition behaviour of Al‐Zn(4.5 at.%)‐Mg(2;3 at.%) alloys during continuous cooling from the temperature range of homogeneity
Authors: Radomsky M. , Kabisch O. , Löffler H. , Sackewitz K.‐H. , Honyek G. , Ungár T. , Lendvai J. , Kovács I.
Published: July 2007

The decomposition processes taking place in the Al‐Zn (4.5)‐Mg(2;3) alloys were studied by means of XSAS and resistivity measurements and by TEM investigations after continuous slow cooling to certain temperatures Ti and during an isothermal ageing at Ti following the continuous cooling procedure. During the cooling between 380 °C and 320 °C mostly particles of the η‐phase are growing. The formation of particles homogeneously distributed in the matrix starts at 165 °C in the alloy with 2 at.% Mg and at 175 °C in the one with 3 at.% Mg. Below these temperatures new subcritical GP zones are formed and particles already present in the matrix are growing. The dominating process depends on Ti.
Epitaxial layers of CuGaTe2 on GaAs
Authors: Schumann B. , Tempel A. , Kühn G. , Neumann H. , Peters D. , Hörig W.
Published: July 2007

CuGaTe2 thin films with thicknesses in the range from 0.1 to 0.2 μm were deposited onto semi‐insulating (111) A‐oriented GaAs substrates by flash evaporation under controlled growth conditions. Epitaxial growth begins at a substrate temperature of Tsub = 695 K. In the range Tsub = 695 … 820 K the films have the chalcopyrite structure, at Tsub = 820 to 840 K a second phase was observed besides the chalcopyrite phase. At Tsub > 840 K the films become polycrystalline. All epitaxial films were p‐type conducting and showed an increase of the hole concentration with rising substrate temperature. The measured mobilities indicate to the presence of a high concentration of neutral impurities or defects.
On the mechanical stresses caused by growth centers
Authors: Malicskó L.
Published: July 2007

The question of the development of mechanical stresses in crystals during their growth is investigated. The mechanical stress field is calculated which can be caused by a radially inhomogeneous impurity concentration distribution existing around growth centers. For the case of KCl: Pb crystals it is shown that depending on growth condition these stresses can be very considerable.
Determination of the crystallite size in epitaxial layers of PbTe by means of X‐ray diffraction rocking curves
Authors: Schäfer P. , Berger H.
Published: July 2007

To prove the influence of the crystallite size (dimension of coherent regions parallel to the reflecting lattice planes) on the rocking curve of single crystals, half widths measured on epitaxial layers of PbTe have been evaluated. It results from statistical analysis of the data that there exist a significant influence of the crystallite size. The crystallite sizes have been calculated from these data using two simple models. The values have orders of magnitude as expected and agree with data from electron microscopy. The method as described here can be applied in suitable cases to get an additional parameter for characterizing the structural perfection.
Microscopy with an ellipsometric arrangement
Authors: Löschke K.
Published: July 2007

A method is given to observe a sample with an ellipsometer equipment allowing a microscopical observation of a reflecting surface. The microscopical images are contrasted by the elliptical polarization and reflect the inhomogeneity of the optical properties of the surface. The contrast is of the high resolution of the ellipsometrical method registrating very low variations of optical properties of the reflecting sample. In this paper we give par example an observation of a step of a native oxide film on GaAs of only three Ångstroms.
Physical Properties of Pb0.8Sn0.2Te :In Epitaxial Layers
Authors: Kaljuzhnaya G. A. , Mamedov T. S. , Herrmann K. H. , Wendt M.
Published: July 2007

A study was made of dislocation density, Hall effect, conductivity, and photoeffects in In‐doped Pb0.78Sn0.22Te epitaxial layers. From an analysis of RH vs T the existence of resonant as well as deep levels is concluded, dependent on In content and defect structure. Samples with about 0.4 at.% In which are not compensated, exhibit photoresponse as well as luminescence.
Dielektrische Eigenschaften und Phasenübergänge von M2SbF5 ‐Kristallen
Authors: Grigas J. , Dawidowitsch R. , Petscheliunaite A. , Urbonawitschius W.
Published: July 2007

In der vorliegenden Arbeit sind die Ergebnisse der Untersuchung der dielektrischen Eigenschaften und elektrischen Leitfähigkeit von M2SbF5‐Kristallen dargestellt. In diesen Kristallen wurden kleine Anomalien der niederfrequenten ϵ′yy, ϵ″yy‐Werte und elektrischen Leitfähigkeiten, die auf die Phasenübergänge hinweisen, gefunden. Es wird das Wesen dieser Phasenübergänge diskutiert.
Effective Nucleation Rate in Size Dependent Growth Systems
Authors: Rojkowski Z.
Published: July 2007

Using of MSMPR technique for simultaneous obtaining crystal growth and nucleation data poses a problem in the case of size dependent growth systems. Namely, the necessary extrapolation of experimental population density plot down to zero size is dubious because of its very steep and varying slope. Thus only some effective nucleation rate can be determined accurately. The proposed method of calculating it comprises cutting population plot at some effective size Le chosen as a fraction of dominant size of mass weighted CSD of product from MSMPR crystallizer. Such a point of reference enables to compare nucleation rates even of different systems. Correlations of experimental data for aluminium ammonium alum are presented.
Zur Beeinflussung von Tracht und Habitus von Harnstoffkristallen (I)
Authors: Gaedeke R. , Wolf F. , Bernhardt Gudrun
Published: July 2007

Es konnte gezeigt werden, daß Harnstoff beim Kristallisieren aus wäßrigen Lösungen mit NH4Cl Mischkristalle, Adsorptionsmischkristalle und epitaktische Aufwachsungen ausbildet. Das Ausmaß der Mischkristallbildung wird durch die Zusammensetzung der Ausgangslösungen bestimmt. Die Harnstoff/NH4Cl‐Mischkristalle wirken im Sinne von Morphologiewandlern auf Tracht und Habitus des auskristallisierenden Harnstoffs, wodurch anwendungstechnische Vorteile bezüglich Transport‐ und Lagereigenschaften resultieren.
Dendritic Growth of Potassium Dihydrogen Phosphate Crystals in Silica Gels
Authors: Joshi M. S. , Antony A. V.
Published: July 2007

Dendritic growth of potassium dihydrogen phosphate (KDP) crystals in silica gels at room temperature is reported. Branching along directions perpendicular to the arms and dendrites growing in mutually perpendicular 〈100〉 and 〈010〉 directions are illustrated. Initial stages and surface of a dendrite are illustrated and described. Also explained are the crystallites growing on the dendrite which finally lead to the formation of platelets.
Measurement of Microcrystal Size by Means of Diffraction of X‐Rays
Authors: Pučálka V.
Published: July 2007

The diffraction function expressing the dependence of the intensity of the diffracted X‐rays on the angle of diffraction ϱ is derived. On the basis of this equation two methods of measuring the microcrystal size in the direction of the normal line onto the beam of coherently diffracting atom planes are elaborated. Further, the methods for measuring the diffraction line enlargement owing to the experimental conditions are given here.
Crystal and Molecular Structure of Non‐hydrated and Hydrated Piperidinium‐acet‐o‐Cl‐anilide‐chloride
Authors: Reck G. , Kretschmer R. G.
Published: July 2007

Crystallizations from water and alcoholic solution respectively yield different crystal and molecular structures of Piperidinium‐acet‐o‐Cl‐anilide‐chloride. The non‐hydrated compound crystallizes from alcoholic solution in the space group P 21/c with 4 formula units C13H18N2OCl2 in the unit cell of dimensions a = 12.352 Å, b = 6.864 Å, c = 19.018 Å and β = 113.98°. The hydrated modification has the space group C 2/c with 8 formula units C13H18N2OCl2 and 8 H2O molecules in the unit cell. The lattice constants are a = = 24.159 Å, b = 8.966 Å, c = 14.179 Å and β = 90.50°. The X‐ray structure analyses were carried out to investigate the hydrogen bonds and the change of the molecular conformation caused by linking of water molecules to the drug molecules.
The Crystal Structure of 3‐Methoxy‐estra‐1,3,5(10)‐triene‐16α Br,17β OH
Authors: Szulzewsky K. , Seidel I.
Published: July 2007

The steroid 3‐Methoxy‐estra‐1,3,5(10)‐triene‐16αBr,17βOH crystallizes in the tetragonal space group P 41 with the lattice constants a = b = 10,358(2) Å, c = 32,591(5) Å. The crystal structure contains two symmetry independent molecules. Significant differences for the two molecules occur in all the four rings of the steroid sceleton. The molecules are linked by hydrogen bridges and Br…︁ Br contacts. The differences between the two symmetry independent molecules are interpreted as due to different intermolecular interaction.
Investigation of Semiconductor Materials and Devices by High Voltage STEM Techniques
Authors: Cosslett V. E. , Fathy D. , Sparrow T. G. , Valdrè U.
Published: July 2007

This paper reviews work carried out in‐situ on semiconductor devices by means of a high voltage electron microscope equipped with facilities for scanning transmission electron microscopy, electron beam induced conductivity and energy loss spectrometry. These combined techniques have allowed simultaneous and unambiguous correlations to be established between crystallographic, electrical and elemental properties of semiconductor materials and devices. Examples of these correlations are given, and mention is made to facilities (scanning deep level transient spectroscopy and cathodoluminescence) which may further increase the potential of high voltage scanning transmission electron microscopy.
High Temperature In‐situ Investigation in HVEM — Deformation, Irradiation, and Recrystallization. Instrumentation and Applications to Materials Science
Authors: Valle R. , Benty G. , Marraud A.
Published: July 2007

High temperature in‐situ experiments not only require a conventional equipment, but also special devices such as a double tilting straining holder, a double tilting heating holder (1500 K), a high vacuum specimen chamber (a few 10−6 P ≅ 10−8 Torr) and a low light level, high resolution, visualization and recording system.

Some preliminary conclusions, regarding the representativeness of the in‐situ experiments in HVEM, may be derived from the recrystallization and deformation tests performed at ONERA. The fact that the results of these experiments are in good agreement with those obtained through macroscopic tests, a posteriori demonstrates that the former experiments are representative of the bulk material.
Helium‐Cooled Straining Stage for the AEI EM7
Authors: Taylor G. , Saka H.
Published: July 2007

This paper describes a gas/liquid cooled, side‐entry straining stage designed for use with the normal air‐lock on the AEI EM7 HVEM. Tensile test specimens with a 1 mm gauge length can be deformed <40% strain and tilted ± 10° about one axis. Temperature is measured with a thermocouple and controlled by regulating the gas flow through the flexible transfer tube which also incorporates a radiation stop.
The Free Surface Effect on the Dislocation Mobility in Molybdenum Single Crystals
Authors: Novikov I. I. , Yermishkin V. A. , Kantor M. M. , Timofeev V. N.
Published: July 2007

The in‐situ high voltage electron microscopic method has been used to study the phenomenon of spontaneous screw dislocation accelerations near the wedge‐like edges of molybdenum single crystal specimens. The effects of either of the free wegde surfaces on dislocation mobility have been included in the discussion of this phenomenon. The experimental data were used to evaluate the surface image forces.
An In‐situ Investigation of the Creep Mechanisms of Aluminium at Intermediate Temperatures
Authors: Myshlyaev M. M. , Martin J. L. , Caillard D.
Published: July 2007

In‐situ deformation experiments are performed at 150 °C and 200 °C after a macroscopic creep test in polycrystalline aluminium. The significant microscopie events which take place during the constant strain rate stage of creep are subboundary migration and destruction, dislocation multiplication, interaction of individual dislocations with the three dimensional network inside the cells and with the subboundaries. The observations are discussed in terms of different models interpreting the measured activation energy and area.
In‐situ Straining Experiments on Glass Foils in the HVEM
Authors: Hopfe J. , Appel F. , Schmidt V.
Published: July 2007

Crack propagation in Na2OCaOSiO2 glass foils with thicknesses between 0.4 μm and 4 μm was studied by HVEM in‐situ straining experiments. The propagation of cracks could be achieved by a stepwise loading of the glass foils in a quantitative HVEM tensile tilting stage. The contrasts observed in front of the crack tips indicate a plastic deformation of the glass foils. The influence of the imaging electrons on the mechanical properties of the foil material is discussed.
The Nature of Dislocation Damage in Electron Irradiated Al‐1% Cu and Stainless Steels
Authors: Smith B. , Fahad I. , Smallman R. E. , Loretto M. H.
Published: July 2007

Specimen of Al‐1% Cu aged to contain θ′ and stainless steels of various Ni and Cr contents have been irradiated in an HVEM. It has been found that the nature of the dislocation damage in the stainless steels is a complex function of composition and temperature; very irregular faulted loops, regular faulted loops and regular unfaulted loops are formed in varying proportions. In the Al‐1% Cu, aged for varying times at 190 °C to produce θ′, the ageing times influences the amount of radiation damage in a complex manner. Virtually all the visible damage in these alloys is found either at the precipitate interface or at the electron entrance surface.
Veränderung der Oberflächenstrukturen von Quarzeinkristallen infolge ihrer Wechselwirkung mit einfachen Gasen bei hohen Temperaturen (I) Behandlung mit Argon und Sauerstoff
Authors: Sokoll R. , Müller B.
Published: July 2007

Es wurde die Struktur der drei wichtigsten Oberflächen von Quarzeinkristallen [(1011), (0111), (1010)] nach der Wechselwirkung mit Argon und Sauerstoff bei Temperaturen zwischen 773 K und 1223 K (p = 760 Torr) mittels der Beugung hochenergetischer Elektronen in streifendem Einfall (RHEED) untersucht. Dabei konnte festgestellt werden, daß sich die Oberflächenstrukturen infolge dieser Wechselwirkung irreversibel verändern. Und zwar entsteht im Fall beider Gase auf den Rhomboederflächen eine (2 × 2)‐Überstruktur, und auf der Prismenfläche eine (1 × 4)‐Überstruktur. Die Bildung dieser Überstrukturen wurde in Abhängigkeit von Temperatur sowie Reaktionsdauer untersucht, und anhand von Literaturdaten erfolgt eine Diskussion der möglichen Wechselwirkungs‐mechanismen zwischen Kristall und Gas.
Lanthanum manganite phase diagram
Authors: Karavay A. P.
Published: July 2007

Based on neutron diffraction studies the magnetic moments have been calculated and the magnetic phase relation has been determined in the lanthanum manganite samples (LaMnO3) with different degree of crystallographic lattice distortions. It is established that with the decrease of the distortions the ferromagnetic phase content increases at the expense of the antiferromagnetic phase. The lanthanum manganite phase diagram has been plotted from the obtained data.
Infrared light scattering and absorption microscopy investigations at dislocations in GaAs crystals
Authors: Löschke K. , Tempel A.
Published: July 2007

In recent years a number of experiments have been published dealing with the light scattering at small particles. All of these experiments have been made in the visible spectral range. In this paper we report an experimental arrangement for infrared light scattering by dark‐field illumination. Preliminary results of the observations of dislocations in GaAs crystals are given. The scattering images are correlated with results obtained by means of absorption microscopy with infrared light. Helix‐like fine structures of dislocations are found mainly arranged in the 〈110〉 directions.
Structural and electrical properties of CuIn0.7Ga0.3Se2 epitaxial layers on GaAs substrates
Authors: Schumann B. , Neumann H. , Tempel A. , Kühn G. , Nowak E.
Published: July 2007

Epitaxial layers of CuIn0.7Ga0.3Se2 could be prepared by flash evaporation onto (111)A‐oriented GaAs substrates in the substrate temperature range Tsub = 745 … 870 K. At Tsub = 745 … 820 K the films had the chalcopyrite structure, at Tsub = 820 … 845 K an additional pseudohexagonal phase was found. Indications to the presence of a sphalerite phase were found at high substrate temperatures. Films grown at Tsub ≦ 750 K were always n‐type conducting and showed a largely pronounced impurity band conduction effect. At Tsub ≧ 860 K the films were always p‐type conducting and two acceptor states with ionization energies of some 10−3 eV and of 125 … 140 meV were found.
Studies on configuration of dislocations and dissolution of cleavage steps of magnesium orthosilicate crystals
Authors: Desai C. C. , John V.
Published: July 2007

(010) cleavages of magnesium orthosilicate crystals have been etched in concentrated hydrochloric acid vapour at room temperature, in the melts of potassium and sodium hydroxides at 400°C, and also in the aqueous solutions of KOH, NaOH, and their mixtures at boiling points. The configuration of isolated dislocations have been described. Bent, branched, stepped and the inclined nature of dislocation lines have been investigated. The effect of dissolution ledges on the size and morphology of etch pits has been discussed. The implications are discussed.
Veränderung der Oberflächenstrukturen von Quarzeinkristallen infolge ihrer Wechselwirkung mit einfachen Gasen bei hohen Temperaturen (II). Behandlung mit Wasserdampf und Chlor
Authors: Sokoll R. , Müller B.
Published: July 2007

Unter den gleichen experimentellen Bedingungen wie im Fall von Argon und Sauerstoff wurde die Struktur der drei wichtigsten Oberflächen von Quarzeinkristallen nach der Wechselwirkung mit den gegenüber SiO2 reaktiven Gasen Wasserdampf und Chlor mittels RHEED untersucht. Dabei entsteht infolge der Wechselwirkung auf den Rhomboederflächen wiederum eine (2 × 2)‐Überstruktur, während sich auf der Prismenfläche sowohl eine (1 × 3)‐ als auch eine zweite Überstruktur mit gedrehter Elementarmasche bilden. Auch hier erfolgt anhand experimenteller Befunde die Diskussion eines möglichen Wechselwirkungsmechanismus, und es werden Aussagen über die Größe der sich strukturell umwandelnden Kristallbereiche getroffen.
Hydrothermal etching of flux grown phenakite (Be2SiO4) single crystals
Authors: Shindo I. , Kawada I. , Kojima H.
Published: July 2007

The etching studies were made on flux grown phenakite (Be2SiO4) single crystals to elucidate the twinning phenomenon and the growth mechanism. The sharp and distinct etch pits and the twin boundaries were successfully obtained after the hydrothermal etching. From the etching and the X‐ray precession experiments, it was conjectured that the phenakite had an inversion twin along the c axis. The twinning should be originated during the earlier stage of growth where the dendritic and acicular crystals were grown and thereafter the twinned crystals grew to the prismatic crystals during the latter stage with decreasing the temperature.
Shape of thermal etch pits and crystal structure in tellurium crystals
Authors: Bhatt V. P. , Trivedi Mira D.
Published: July 2007

During the systematic study of thermal etching of tellurium crystals, various shaped thermal etch pits were observed on the {1010} cleavage faces of this crystal. An attempt has been made to explain the shape of non‐dislocation and dislocation etch pits. A simple model based on crystal structure and bonding of atoms has been suggested to explain the shape of etch pits.
Positron annihilation in oriented single crystals of calcite: Two photon angular correlation
Authors: Ramasamy P. , Gnanam F. D. , Krishnan S. , Laddha G. S.
Published: July 2007

Precision measurements of the angular correlation of two photon annihilation in oriented single crystals of calcite are reported. 10 millicurie Na22 was used as the positron source and the resolution of the angular correlation set‐up was 0.7 milliradian. Measurements were made parallel and perpendicular to optic axis and also for the (100) plane. Using the Goldanskii and Prokopev model for polaron states for positrons in ionic crystals the FWHM is used to calculate the effective masses of positrons and anion effective charges for different crystallographic directions. The observed variations of effective charge must be taken as the direct experimental evidence for charge distortions.
Effect of neutron irradiation on stratigraphy in calcium fluoride single crystals
Authors: Desai C. C.
Published: July 2007

Natural single crystals of calcium fluoride have been cleaved along {111} planes and a number of matched pairs have been obtained. One piece from etch pairs have been irradiated with thermal and pile neutrons, the flux varying from 1.3 × 104 to 3.0 × 1013 neutrons cm−2. After irradiation, the irradiated and their non‐irradiated counterparts have been matched. They were then etched simultaneously in 0.2 N hydrochlorid acid for the same period. The stratigraphical etch patterns produced have been studied optically. There is no exact correspondence of the stratigraphical etch patterns have been observed on the irradiated and non‐irradiated matched pairs. The disappearing in the stratigraphical pattern of the irradiated crystals increases with increase in the dose of irradiation. The implications are dicussed.
On the end products of mica thermic decomposition
Authors: Vasilyev E. K. , Lapides I. L.
Published: July 2007

Micas of muscovite‐biotite‐lepidolite series were investigated thermographically. The end products of heating these micas were studied by the X‐ray powder diffraction method. γ‐Al2O3, Quartz, spinels, hematite, leucite, β‐eucryptite, amorphous phase (glass) and α‐kalsilite (probably) are present in the annealed products depending on composition and structural peculiarity of initial micas.
Structure defects investigation of GaAs and AlxGa1−xAs epitaxial layers
Authors: Vasilevskaya V. N. , Konakova R. V. , Melnikov G. D. , Semenova G. N. , Tkhorik Yu A.
Published: July 2007

The paper is concerned with the results of investigation of structure defects in gallium arsenide and Al0.3Ga0.7As epitaxial layers. It was found that structure defects in layers under investigation are responsible for the excess component of the Schottky diode's reverse current.
Hyperfine structure of EPR spectra of Cr5+ ions in irradiated sodium dichromate crystals
Authors: Alybakov A. A. , Gubanova V. A. , Tojchiev N.
Published: July 2007

EPR spectra are studied of X‐irradiated sodium dichromate crystals grown from an aqueous solution by evaporation at 31°C. Doublet lines of EPR‐absorption are attributed to the Cr5+ ions in the CrO43− and CrO3− radicals resulting from radiation decomposition of Cr2O72− and being in the lattice in two unequivalent positions. Hyperfine structure caused by interaction of an unpaired electron with Cr53 nucleus were observed both at liquid nitrogen and room temperatures. For the line, caused by CrO43− radical, gy and Ay directions coincide and angles both between Ax, gx and Az, gz make up ∼ 25°. The spectrum is described by usual spin Hamiltonian for S = 1/2 with following parameters (T = 77 K): for CrO: gz = 1.984, gy = 1.970, gx = 1.961, |Az| = 8.2 · 10−4 cm−1, |Ay| = 13.7 × 10−4 cm−1, |Ax| = 36.1 · 10−4 cm−1; for CrO3−: gz = 1.915, gy = 1.975, gx = 1.985, |Az| = 32.2 · 10−4 cm−1.
Temperature dependence of doping element incorporation with the chemical vapour deposition of epitaxial silicon (V). Incorporation of arsenic
Authors: Kühne H. , Sperling R.
Published: July 2007

Based on the knowledge previously obtained with regard to the incorporation of phosphorus as an equilibrium‐determined process, theoretical values of the enthalpies of the different possible incorporation equilibria are calculated for the incorporation of arsenic into the growing silicon epitaxial layer. The sublimation enthalpies of elemental arsenic, the formation enthalpy of arsine and the enthalpy of solubility enter into the equation. The results compared to the present experimental data of other authors are discussed.
Nitrogen segregation on the (100) surface of an austenitic chromium‐nickel steel studied by LEED and AES
Authors: Fehrmann U. , Müssig H.‐J. , Storbeck F. , Thielsch R. , Uhlmann K.
Published: July 2007

At temperatures above 700 K, the annealing of austenitic stainless steel under ultra‐high vacuum conditions results in the segregation of nitrogen, accompanied by the increase of chromium concentration at the surface. Both the elements enrich at the surface, so that a constant ratio of the detected amounts is reached. Thus we conclude the formation of a chromium‐nitrogen compound. — Due to the segregation of nitrogen, we observed the formation of a p (2 × 2) superstructure in the LEED pattern. From a kinematic interpretation of the (00) beam intensity measured we suppose the nitrogen to be arranged in fourfold sites and to have an atomic radius of 0.054 nm.
Auger spectrometric studies on fracture surfaces of tool steel
Authors: Romhányi K. , Csih Zs. Szász , Gergely G. , Menyhárd M.
Published: July 2007

The fracture surfaces of tool steel K‐13 (Hungarian Standard) were studied by Auger electron spectroscopy. Notched specimens of 3 × 3 mm2 were fractured in UHV (6 × 10−8 Pa) with a fracturer (Riber FR 100) and studied with a CMA analyser (Riber OPC 103). With our modification the fracturer was operated within the −150°C −+230°C temperature range. The fracture surfaces were tested with a scanning electron microscope (JEOL JSM 35). The evaluation of Auger spectra was based on the PHI (PALMBERG et al.). Handbook, however the backscattering correction of Jablonski was applied in some cases. The choice of adequate fracturing temperature proved to be very important. Low temperature fracture of this steel alloy is producing very rigid transgranular fracture. The effects of sample heat treatment and of fracturing temperature as well were studied in details. The Auger spectra of fracture surfaces are strongly affected by the heat treatment of the samples. The grain boundary fracture surface of a sample austenitized at 1100°C quenched and tempered at 600°C exhibited a strong enrichment of P, correlating with the enrichment of Cr, V and Mo. The transgranular fracture surface of the same sample but without tempering corresponded to the bulk composition. In some cases and spots on the fracture surfaces, giant S or P peaks were associated with secondary phases (inclusions) on the SEM pictures.
A unified treatment of thickness homogeneity problems in CVD (II). Cold‐wall reactors
Authors: Arnold H.
Published: July 2007

Chemical vapor deposition in susceptor‐heated horizontal reactors is included into a simple treatment of reactant depletion and its compensation, given previously. Extending the model of EVERSTEYN et al. (including thermodiffusion), the whole range from diffusion control to reaction control is covered. At diffusion control, the condition for constant deposition rate along large reactor lengths cannot be satisfied by the usual tilting of a plane susceptor out of the direction of the main gas stream. From this point of view, the model statements (at least in the approximation that neglects entrance effects) are less favorable than for vertical epitaxy reactors.
On the influence on tracht and habit of urea crystals (II)
Authors: Gaedeke R. , Wolf F. , Bernhardt G.
Published: July 2007

It is shown that during crystallization urea forms mixed crystals, adsorption mixed crystals, and epitaxial growth from aqueous solutions with inorganic salts, the lattice parameters of which are lying within the tolerance of efficiency parameters of urea. The extent of the formation of mixed crystals is determined by the composition of the solution. The slats added to the solution affect changes of tracht and habit of urea and thus are important for improving storage and transport properties. Similar results can be found for modified melts of urea.
Investigations on the structural perfection of bridgman‐grown PbTe single crystals
Authors: Mühlberg M.
Published: July 2007

It is reported on the possibility of improving the structural perfection by the Bridgman method, shown with the example of the influence on the low‐angle grain boundary substructures in PbTe arranged in growth direction. In the employed crystal growth apparatus temperature gradients from 15 to 100°C/cm and solidification rates from 0.33 to 4.2 mm/hr could be achieved. The low‐angle grain boundary substructure was characterized by X‐ray‐topographic and etch investigations on (100)‐orientated ingots. The thermal conditions during the growth affect the structural perfection decisively. An axial spot dependence of etch pit density and substructure abundance was observed. By reducing the cooling rate during growth — expressed by the product of temperature gradient G and solidification rate V — it is possible to obtain more perfect PbTe‐crystals. It seems that the diameter l of the substructure cells which was lying between 0.5 and 2 mm, is related to the cooling rate G · V by the functional coherency l ≈ 1/√G · V. The choice of different initial melt combinations up to 1 at.% Te‐surplus exerted no influence on the abundance of the low‐angle grain boundaries. The in literature suggested connection of low‐angle grain boundary substructure with phenomena resulting from a constitutional supercooling could not be established.
Influence of seeding of the solutions on the crystallization of fibrillar sodium trimolybdate
Authors: Hodorowicz S. , Surga W.
Published: July 2007

An effect of the seeding of solutions on the crystallization of fibrillar sodium trimolybdate is described. The crystallization was studied in three solutions of initial molybdenum concentration CMo = 0.250 M and degree of acidity Z = 1.20, 1.25, and 1.33. The abridgment of the total time of the process respects only to the period of nucleation. At the moment of the acidification of the solutions different forms of isopolymolybdates come into existence.
An unusual type of unmixing in NaCl‐KCl mixed crystals at room temperature
Authors: Andreev G. A. , Buritskova L. G.
Published: July 2007

Water‐catalysed decomposition of solid solutions of NaCl–KCl has been investigated at room temperature. The “wet” decomposition proceeds at abnormally high rate as compared to the usual “dry” decomposition. The formation and movement of the decomposition boundary is characteristic of the “wet” process. The influence of divalent impurities and partial decomposition of the usual type has been studied on the rate of the decomposition boundary movement. The mechanism of the unmixing is suggested which involves two interrelated process: the phase separation and formation of a system of interlocking microcracks acting as channels for the water transport from the surface into the bulk of the crystals. The open porosity resulting from the unmixing is confirmed experimentally.
Formation of submicron growth defects during vapour deposition of GaAs films
Authors: Lavrentieva L. G. , Ivonin I. V. , Krasilnikova L. M. , Vilisova M. D.
Published: July 2007

In electron microscopy investigation of the growth surfaces of GaAs films deposited in CVD systems specific growth defects were detected. The form of the defects resembled that of “the pinning sites” observed earlier on silicon films deposited in ultra‐high vacuum (ABBINK et al.; PCHELYAKOV et al.). However, it turned out that the particles which caused the step accumulation and depression formation can move with the growing surface. These defects consisting of liquid particles and depression around them were called “step retardation sites” (SRS). The basic features of defect formation and their influence on the concentrating of impurities and forming of impurity inhomogeneities are discussed.
On the Influence of Short R.T. preageing on the formation of the η′‐phase in an Al‐Zn(4.5 at.%)‐Mg(2.5 at.%) alloy
Authors: Radomsky M. , Löffler H.
Published: July 2007

The influence of short R.T. preageing (1 min) after quenching from 480 °C into RT‐water on the formation of the η′‐phase in an Al‐Zn(4.5)‐Mg(2.5) alloys has been investigated by means of TEM, XSAS, resistivity, and hardness measurements in the ageing temperature range between Ta = 120 °C comparing samples directly quenched (DQ) to Ta and those quenched into RT‐water, kept there for 1 min, and subsequently stored in an oil‐bath of Ta (IQ). At Ta ≦ 170 °C both heat treatments result in finely distributed precipitates of the η′‐phase accompanied by a fairly high hardness value. But at Ta ≧ 180 °C the DQ leads only to few coarse heterogeneously formed η′‐ and η‐precipitates, whilst the IQ yields qualitatively the same precipitation structure as already described at Ta ≦ 170 °C even till 280 °C. These results are interpreted assuming that.

A1) the limitation temperature of homogeneous formation of η′ is located at about Th = 175°c and

A2) during the pre‐ageing at RT “nucleation sites” are formed as already suggested by RYUM, which are able to act as sites for heterogeneous formation of η′ even at Ta > Th.

Hints are obtained that the formation of these “nucleation sites” is not so strongly governed by the quenched‐in excess vacancies as discussed in the literature.
On the possibility of strain determination by section topography in the parallel Geometry
Authors: Maciaszek M.
Published: July 2007

A new approach to the problem of strain determination in a crystal by means of X‐ray radiation is presented. In the proposed experiment the border of the windows etched in silicon oxide layer which covers the surface of the silicon crystal, is image using a section topography and geometry in which the edge of the windows is placed parallel to the vertical X‐ray beam axis. That geometry allows to obtain the images giving the possibility of more Precise and easier determination of strains, because the interference fringes (Pendellösung) are considerably narrow. Their position can be defined with better precision.
Influence of chemical composition on dislocation structure and its change by plastic deformation of V3Si single crystals
Authors: Nghiep D. M. , Quyen N. H. , Paufler P. , Bertram M. , Kleinstück K. , Krämer U. , Martin A. San
Published: July 2007

The dislocation structure and its change by plastic deformation of V3Si single crystals has been studied by an etch technique. The solution hardening effect established elsewhere is interpreted in terms of the observed dependence of the dislocation density ϱ(r) and its increment with the plastic deformation on the chemical composition within the range of homogeneity.
Comments on the properties of an NH4OH‐H2O2 etch on epitaxial GaAs
Authors: Radácsi É. , Mojzes I. , Pfeifer J.
Published: July 2007

The etching rate of the NH4OH : H2O2 : H2O = 1:4:20 etch was determined on epitaxial GaAs films and bulk GaAs monocrystals. The etching process has a rather large scattering at the start of the process depending on the origin and properties of films. The etching rate of epitaxial layers approaches the value of 2 μm/min, characteristic of bulk crystals. Surfaces treated with the 1:4:20 etch are applicable to ohmic contacts of Gunn diodes.
Investigations on the growth kinetics of GP zones and a′R‐precipitates in Al‐Zn alloys
Authors: Fabian H.‐G. , Löffler H. , Kroggel R. , Gueffroy B.
Published: July 2007

X‐ray small‐angle scattering (XSAS) and resistivity (R) measurements were particularly done with an Al‐Zn (15 at·,%) alloy in rather wide ranges of both the ageing time ta and ageing temperature Ta, in order to obtain information on the dependence of the growth exponent m of the l = β0tm growth law and the activation energy Eact on ta and Ta.

The XSAS‐measurements yielded that within the range of the GUINIER radius rG between 1 nm and 2 nm the growth is essentially retarded (m < 0.1) and for rG > 2 nm m depends on Ta ranging from 0.15 to 0.23 with a maximum at 175°C. Reasons for these effects are discussed. The differences between the m‐values obtained by means of XSAS‐and TEM‐measurements are explained by the distinctions of the two methods applied.

The Eact taken from XSAS‐ and R‐measurements show a remarkable increase with ta. At the beginning of the decomposition Eact = (0.49 ± 0.05) eV holds well explainable by the migration of quenched‐in VZn pairs, but at the end Eact = (1.05 ± 0.07) eV was found. This value was also obtained from TEM‐investigations (growth of the length). It fits well the Eact of ZnV pairs in thermal equilibrium at Ta.
Evidence of slip in calcium fluoride single crystals
Authors: Desai C. C.
Published: July 2007

Natural single crystals of calcium fluoride have been cleaved along (111) planes and the cleavage faces have been etched in 0.2 N nitric acid solution. Etching produces rows of equally spaced etch pits running in <110>directions. One‐to‐one correspondence of glide bands has been established on the matched faces and on the three different flakes of the same crystal. This is further confirmed by studying the rosette structure produced on a (111) cleavage plane by indenting that plane itself. The active slip planes are found to be {110}. The implications are discussed.
On the reproducibility of the orientation distribution function of texture samples from pole figures (III). Relationship between the ODF f(g) and the reduced ODF f̃T(g)
Authors: Matthies S.
Published: July 2007

The explicit relationship between the ODF f(g) and the reduced ODF f̃T(g) is given and discussed. For the general case of fibre textures the f̃T(g) ↔ f(g) problem does not disappear, but in the special case with GA = D∞f̃T(g) is identical with f(g).
Reactivity of plasma‐treated SiO2 against CF4 and CCl4 — an ESR study
Authors: Tiller H.‐J. , Rudakoff G.
Published: July 2007

SiO2‐surfaces treated by CF4‐r.f.‐discharge exhibit paramagnetic defects quite similar to those appearing after treatment in an Ar‐plasma. The defects react with O2 and H2O but not with CO2, CO and N2. CF4 itself reacts with the defects (even without maintaining a discharge) forming O2 and O2 resp. It has been shown by comparative experiments with CCl4 that CF4 is less reactive than CCl4 in respect to the destruction of the paramagnetic defects.
The pentagonal dodecahedral model of vitreous silica and its compatibility with diffraction experiments
Authors: Herms G. , Steil H.
Published: July 2007

ROBINSON's pentagonal dodecahedral model represents a very interesting non‐crystallographical heterogeneous description of atomic arrangement in vitreous silica. The pair function distribution of this model has been calculated and compaired with a measured pair function distribution of vitreous silica. The pentagonal dodecahedral model seems to be a little better than cristallite models but cannot bear comparison with the continuous random network model.
Glass formation and properties of chalcogenide systems (XXII) the phase diagram of the system PbSeGeSe2 and on the compound Pb2GeSe4
Authors: Feltz A. , Ludwig W. , Senf L. , Simon C.
Published: July 2007

The phase diagram of the system PbSeGeSe2 is studied by X‐ray analysis and DTA. Pb2GeSe4 is the only compound which is formed in the system. It melts incongruently at 590 ± 4°C. The formation of Pb2GeSe4 as a definite compound is supported by studying the phase relations in the corresponding area of the ternary system PbSeGeSeGeSe2.
Stress measurements in aluminium alloy films by the sin2 ψ method
Authors: Skladnikiwitz S.
Published: July 2007

The lattice parameters and the homogeneous elastic stresses in evaporated Al, AlSi and AlCu films 1 μm in thickness with, in part, a high degree of fibre texture have been determined. The stresses measured at room temperature as a function of the substrate temperature can be explained by the difference in the coefficients of thermal expansion between film and substrate in connection with creep processes. The different lattice parameters of the films as compared with bulk aluminium were found to be due to homogeneous elastic stresses and alloying elements.