bluuebunny/crossref_metadata_2025 huggingface dataset:
Strukturelle Umklapp‐Vorgänge in metastabilen β1‐Kupfer‐Zink‐Mischkristallen bei tiefen und höheren Temperaturen (II). Isotherme Phasenumwandlungen
Authors: Kunze Günther
Published: July 2007

Aufbauend auf die gitterdynamische Skizze im ersten Teil, (I), werden im vorliegenden zweiten Teil, (II), isotherme Phasenumwandlungen von metastabilen β1−Cu1−xZnx‐Ein‐ und ‐Polykristallen, insbesondere für die Auslagerungstemperatur Ta = 360 °C, behandelt; der Bericht stützt sich ausschließlich auf mit Röntgenbeugungsexperimenten gewonnene Resultate.

Die gesamte Umwandlung läßt sich in drei Hauptperioden unterteilen, in deren erster und letzter Diffusionsvorgänge und in deren mittlerer diffusionslose Übergänge (Umklapp‐Prozesse) die Reaktionsgeschwindigkeit bestimmen: Vordiffusion / Umklappung / Nachdiffusion.
Untersuchung der Volumenstruktur dünner Bi1–xSbx‐Schichten
Authors: Müller H. , Heinevetter U. , Kaiser N. , Gloede C.
Published: July 2007

Die Volumenstruktur von aufgedampften Bi1–xSbx‐Schichten wurde mit Hilfe der Abdrucktechnik im Elektronenmikroskop untersucht. Die Schichten wurde im treibmittelhaltigen und im treibmittelreduzierten Vakuum hergestellt und bei 150°C getempert. Es deutet sich ein säulenförmiges Kristallwachstum an, was mit der gefundenen Wachstumstextur in 〈00.1〉‐Richtung übereinstimmt. Die Kornvergrößerung beim Tempern wird entscheidend durch den Kohlenwasserstoffgehalt der Schicht beeinflußt. Der größte Teil der Kohlenwasserstoffe wird in der oberen Hälfte der Schicht eingebaut. Durch die Bildung einer Oxidschicht geht der Zusammenhang zwischen Oberflächen‐ und Volumenstruktur verloren.
Untersuchung glasig‐amorpher Strukturen (I)
Authors: Nowak W.
Published: July 2007

Es wurden übermolekulare Strukturen in dem glasig‐amorphen Einkomponenten‐System SiO2mit Hilfe der Laserstreulicht‐Technik nach dem Prinzip des Ultra‐Mikroskops untersucht und die Kohärenzlängen der abgebildeten Amplituden‐ und Phasenstrukturen als eingefrorene nichtthermodynamische, d. h. kritische Dichte‐Fluktuationen interpretiert. Diese Auffassung wird durch Messung des linearen Wärmeausdehnungskoeffizienten im Transformationsbereich eines silikatischen Mehrkomponentenglases gestützt, der in diesem Bereich ein ausgeprägt divergentes Verhalten zeigt. Eine strukturelle Interpretation dieser Divergenz soll im zweiten Teil dieser Mitteilung gegeben werden.
New empirical kinetic equation of size dependent crystal growth and its use
Authors: Rojkowski Z.
Published: July 2007

Size dependent crystal growth kinetic can be measured indirectly in Mixed Suspension Mixed Product Removal Crystallizer by means of differential number balance of crystal product population. Some simple formula relating growth rate G and crystal size L is needed for statistical processing of scattered experimental crystal size distribution data. The new exponential formula

has been proposed which provides physically realizable values of G at extreme size values. The formula is simple enough to yield analytic solution of the number balance. Methods of estimation of three formula parameters and nucleation rate and examples of experimental data fitting have been presented as well.
Determination of individual rate constants of reaction and diffusion steps from over‐all crystal growth coefficient
Authors: Nývlt J. , Karpiński P.
Published: July 2007

A universal method, being a solution of the problem formulated independently by NÝVLT and GARSIDE in 1971 is proposed. The method makes it possible — having at one's disposal the experimental growth rate constant — to determine individual rate constants of the main steps of the process of crystal growth i.e., the diffusion step and the surface integration step and thus indicate the step controlling the whole process of crystal growth. Experimental data on crystal growth of MgSO4 and ZnSO4 were evaluated.
Impurity band conduction effects in liquid phase epitaxial Te‐doped GaP grown from tin solution
Authors: Neumann H. , Butter E. , Kramer P. , Kohl W. , Ernst H.‐G.
Published: July 2007

GaP layers were grown by liquid phase epitaxy from tin solution on semi‐insulating GaAs substrates with various amounts of Te added to the melt (xTe = 10−4 …︁ 3 · 10−2). The Sn and Te concentrations in the layers were determined by chemical analysis as function of x. An analysis of the electrical measurements shows that the carrier transport in the layers is essentially determined by impurity band conduction effects.
Über Glasbildung und Eigenschaften von Chalkogenidsystemen (XII). Das Phasendiagramm SnS‐GeS2
Authors: Feltz A. , Ludwig W. , Seiss R.
Published: July 2007

Im System SnS‐GeS2 tritt SnGeS3 als einzige ternäre Verbindung auf. Der inkongruente Schmelzpunkt beträgt 613°C. SnGeS3 bildet mit SnS im Molverhältnis 1 zu 1 eine eutektische Mischung, deren Schmelztemperatur bei 580°C liegt. Eutektische Schmelzen neigen relative stark zur Unterkühlung. Das Glasbildungsgebiet im System SnS–GeS–GeS2 hat in Richtung auf die eutektische Zusammensetzung seine größte Ausdehnung.
Reaktivität von mechanisch aktiviertem Quarz
Authors: Steinike U. , Ebert I. , Geissler H. , Hennig H.‐P. , Kretzschmar U.
Published: July 2007

Bei der mechanischen Aktivierung von Quarz in einer Schwingmühle in Luftatmosphäre wird u. a. eine Amorphisierung des Quarzes und das Entstehen von Sauerstoffdefektelektronenzentren beobachtet. Die Amorphisierung ist auf einen Primärteilcheneffekt zurückzuführen. Die Sauerstoffdefektelektronenzentren sind vorwiegend in den röntgenamorphen Bereichen konzentriert. Die röntgenamorphen Bereiche befinden sich an bevorzugten Stellen der Oberfläche, in Rissen und Vertiefungen. Diese amorphen Bereiche weisen eine erhöhte Reaktivität auf (Lösbarkeit bzw. Anfangslösegeschwindigkeit sowie Sorption).
Plastische Verformung von Silizium‐Einkristallen
Authors: Fischer A.
Published: July 2007

Es wird über Untersuchungen zur plastischen Verformung von Silizium‐Einkristallen und den sie bedingenden Elementarprozessen berichtet. Dabei wird gezeigt, daß die Abgleitung des Kristalls im Anfangsstadium durch die Bewegung von 60°‐Versetzungen in den Primärgleitebenen kontrolliert wird. Mit der Zunahme des Verformungsgrades wird das Quergleiten von Schraubenversetzungen unter der Wirkung innerer, durch elastische Versetzungswechselwirkung erzeugter Spannungen zum Mechanismus, der den Verformungsprozeß bestimmt.
Effects of growth rates on the defect generation in KCl crystals grown by the czochralski method
Authors: Inoue T. , Komatsu H.
Published: July 2007

The effects of the growth rates on the perfection of KCl crystals grown by the Czochralski method were investigated in the range of the pulling rate from 1 to 27.3 mm/hr using the etch pit method. It was found that the density of random dislocation within subgrains was almost independent on the pulling rate but the length of subboundaries in the unit area was decreased with an increase of the pulling rate. The shape of the solid‐liquid interface changed from convex towards the melt to flat with an increase of the pulling rates. It was found that the leading factor in producing subboundaries is the shape of the solid‐liquid interface, and that the pulling rate alone does not always determine the perfection.
Herstellung homogener CdxHg1−xTe‐Barren als Ausgangsmaterial für infrarotempfindliche Fotowiderstände
Authors: Schubert F. , Dittmar G. , Forbrig B.
Published: July 2007

Als Ausgangsmaterial für hochempfindliche Infrarot‐Fotowiderstände wird heute oft Kadmium‐Quecksilbertellurid (CdxHg1−xTe) verwendet. Um daraus CdxHg1−xTe‐Infrarotdetektoren mit annähernd gleichen elektrischen Eigenschaften herstellen zu können, ist eine gute Homogenität des Materials erforderlich. Diese kann mit den konventionellen Kristallzüchtungsmethoden (z. B. Bridgmanverfahren) nicht erreicht werden. Dagegen liefert das Verfahren der schnellen Abkühlung der Schmelze gute Ergebnisse.
Elastic interaction of point defects and volume defects near interfaces
Authors: Michel B.
Published: July 2007

The paper contains a generalization of previous works of the author dealing with the calculation of the interaction energy of point defects and more or less extended volume defects near a solid surface. Formulae for the interaction energy of two defects between each other and with an interface are derived. For special cases the well‐known results of BACON for dilatation centres have been generalized to extended defects with arbitrary shape and size.
Luminescence during release of pressure in X‐ray irradiated alkali halide crystals
Authors: Chandra B. P. , Elyas M.
Published: July 2007

Emission of light is found during application as well as release of uniaxial pressure in X‐ray irradiated alkali halide crystals. As unpinning of dislocations can not take place, however, dislocations can move in backward directions during release of the pressure; the emission of light during release of pressure gives a direct support that the interaction of moving dislocations with F‐centers is responsible for the emission of light during deformation of colored alkali halide crystals.
Study of temperature distribution in high‐temperature furnaces for silicon carbide monocrystal and epitaxial layer growing
Authors: Lilov S. K. , Tairov Yu. M. , Tsvetkov V. F.
Published: July 2007

A method to determine temperature gradient and distribution in high‐temperature furnaces for silicon carbide monocrystal and epitaxial layer growing is suggested on the basis of the results obtained from the experiments on silicon carbide epitaxial layer growing kinetics in gas using 2 „sandwiches”︁.
Influence of oxygen on electrical properties of CaF2 crystals
Authors: Švantner M. , Mariani E.
Published: July 2007

The O2− ions appear as an unwanted impurity that contaminates the crystals of alkaline and rare earth fluorides during their preparation. The easy incorporation into the lattice and difficulties with their detection make the measurement of electrical properties problematical. In order to elucidate the influences of oxygen on CaF2 crystals we have measured electrical conductivity. The crystals were prepared from a raw material of various moisture content, or they were doped by CaO, respectively. The measured courses exhibit equal activation energy E = 0.64 eV in the middle range. We thus conclude that synthetizing the crystal contaminated by moisture yields incorporation of O2− ions only. We proved that even a two hours delay of melted raw material in gaseous products of Teflon pyrolysis does not suffice to remove oxygen. The method is effective only when applied after drying of raw material in vacuum.
Polarization of Mo Kα ‐radiation of the bragg diffraction in real silicon crystals
Authors: Olekhnovich N. M. , Karpei A. L. , Markovich V. L.
Published: July 2007

The results are given for the experimental investigation of the polarization ratio (ϱ∥/ϱ⊥) and the integrated intensity (ϱ⊥) for the Bragg reflections 111, 333, 444 of silicon crystals with different dislocations density (Nd). The measured polarization ratio as a function of Nd and ϱ⊥ is found to have a maximum which is greater than that for the perfect crystal. Attention is drawn to the fact that the polarization ratio maximum for the reflection 111 exceeds unity. The obtained results are analyzed in terms of the mosaic model taking into account the primary extinction for a finite mosaic block and the secondary one between the blocks. The approximation of the mosaic model does not appear to account for the observed polarization ratio maximum.
Kinetics of etching of dislocations in magnesium orthosilicate single crystals
Authors: Desai C. C. , John V.
Published: July 2007

Cleavages of undoped, doped and natural magnesium orthosilicate crystals have been simultaneously etched in concentrated hydrochloric acid solution. The lateral and normal velocities of the growth of pits were then measured at different temperatures for the varieties of crystals. The time dependence of the growth of pit dimensions is found to be linear, while the temperature dependence of the growth of pits is found to be exponential, viz. V = A exp (− E/kT). The dissolution parameters, e. g. the activation energy (E) and the pre‐exponential factor (A) for dissolution along the surface and along the dislocation lines have been computed. It is observed that: (1) the activation energy (E1) of dissolution along [001] direction is found to be greater than the activation energy (Eb) along [100] direction, irrespective of whether the crystals are doped, undoped or natural, and (2) the doping of the crystal with manganese has lowered down the activation energy (Ed) to such an extent that it is less than E1 and Eb. The implications are discussed.
Investigations of surface of glasses by nematic and cholesteric liquid crystals
Authors: Boden G. , Küchler R.
Published: July 2007

The relatively strong interaction between the surface of the glass and the nematic liquid crystals is demonstrated. The same texture of liquid crystals is observed after every renewed cycle of warming and cooling. Defects, which are invisible without an electrical field, become visible by the dynamic scattering effect. The thermografic results, which are received by cholesteric liquid crystals, are able to demonstrate only strong defects.
Kinetics of nucleation for non‐spherical nuclei and the effect of high pressures
Authors: Vasudevan S. , Nagalingam S. , Ramasamy P. , Laddha G. S.
Published: July 2007

Formulae are derived for the excess free energy of cylindrical and pill‐box nuclei under homogeneous and heterogeneous conditions. The surface free energy is taken to be different for lateral and end surfaces of the nucleus in deriving the critical dimensions. The effect of pressure on the formation of a nucleus is studied theoretically first for the appearance of a new phase from a gas and then for a condensed phase.
Textures forming in some steels machined by abrasives
Authors: Savchuk V. I. , Moroz I. A. , Ivaniji V. S. , Grishkevich A. V.
Published: July 2007

The texture formation, at each machining stage, in the CT45, CT50 and CT40X steels machined via two technological alternative ways has been investigated, these being as follows: (1) turning — grinding — superfinishing, (2) turning — hardening — grinding — superfinishing. Presented are the (110) pole figures obtained by the reflection method. It was shown that the grinding and superfinishing of the specimens in compliance with the alternative way 1 led to formation of the texture, the basal ideal orientations of which resemble that of rolling one for the [Russian Text Ignored].‐metals. The recrystallization (110) [001] component is therewith also contained in the grinding texture. No texture was recognized in specimens machined by the procedure according to the alternative way 2. These facts being accounted for by the pressure and temperature factors operating in the course of grinding and superfinishing, as well as by the dependence of the deformation mechanism of the steels under study on a preliminary machining of the latter.
Oriented inclusions in single crystals of potassium dihydrogen phosphate
Authors: Joshi M. S. , Antony A. V.
Published: July 2007

Different forms of oriented inclusions in single crystals of potassium dihydrogen phosphate (KDP) grown by gel method and from aqueous solutions are reported. Small rod like chain and channel types of liquid inclusions are illustrated. These inclusions are oriented along 〈001〉, 〈011〉 and 〈010〉 directions and are attributed to mother liquor trapped in the body of the crystal during growth.
Epitaxial growth of silicon carbide layers by sublimation „sandwich method”︁ (I) growth kinetics in vacuum
Authors: Vodakov Yu. A. , Mokhov E. N. , Ramm M. G. , Roenkov A. D.
Published: July 2007

The growth kinetics of SiC epitaxial layers has been investigated by sublimation sandwich‐method in vacuum at temperature range from 1600 to 2100°C. The limiting stages of the crystallization process have been determined. Silicon deficit in the growth cell was shown to result in the great retarding of SiC epitaxial layers growth due to the decreasing of evaporation coefficient by a factor of 101–102 and more. The impurities introduced into the system at low supersaturations and temperatures, especially rare‐earth elements, Al, B, Cr reduce as a rule evaporation and condensation coefficients and therefore the growth rate of epitaxial layers.
Field‐induced Colour Change of Liquid Crystalline Dyes
Authors: Pelzl G. , Schubert H. , Zaschke H. , Demus D.
Published: July 2007

Planar oriented nematic layers and also partially oriented smectic C phases of certain diphenyl‐1,2,4,5‐tetrazine compounds due to their positive dielectric anisotropy can be oriented by an electric field (Freedericksz‐transition). The orientation is connected with a distinct change of absorption respectively colour. The mechanism of the effect is discussed. For both liquid crystalline phases the response times and decay times were measured.
Investigation of II—IV—V Systems by the Method of Differential Thermal Analysis
Authors: John M. , Hein K. , Buhrig E.
Published: July 2007

It is reported on experiences with the investigation of II—IV—V systems by DTA. Two different arrangements with different sensibility were used. Because of the high volatility of the component V, i.e. phosphorus, samples generally were put in sealed quartz ampoules. Because of the danger of ampoule bursting a special heating procedure was necessary. The results on various II—IV—V systems confirm and precise most of the data of the literature.
Zur Bestimmung von Aktivierungsparametern für die Stoffübergangs‐ und Stofftransportprozesse an AgCl‐ und AgBr‐Kristallen mittels radioaktiver Nuklide
Authors: Winzer A.
Published: July 2007

Es wird über die mit Hilfe der Nuklide110mAg+,82Br−und36Cl−durchgeführten radiochemischen Messungen zur Bestimmung der Aktivierungsparameter für die Stoffübergangsprozesse beim AgCl und AgBr im Verlauf der Ostwald‐Reifung berichtet. Dazu wurde vorwiegend der Einfluß der thermischen Vorbehandlung sowie der Alterung des AgCl und AgBr auf die Aktivierungsparameter geprüft. Vergleichende Untersuchungen an den Systemen AgCl−(s)‐110mAg+(aq)und110mAgCl(s)‐Ag+(aq)ergaben, daß sowohl die Stoffübergangsprozesse am Kristall (Einbau der Ionen in das Kristallgitter bzw. Ablösung der Ionen von den Gitterplätzen) als auch die Stofftransportprozesse im Kristallgitter (Diffusion der Ag+‐Ionen über Zwischengitterplätze) geschwindigkeitsbestimmend sein können; die Dehydratation der Ag+‐Ionen sollte dagegen nicht dominieren, was auch durch Messungen in gemischten Lösungsmitteln bestätigt werden konnte.
OD Structures, — a Game and a Bit More
Authors: Dornberger‐Schiff K.
Published: July 2007

The notion of OD structures consisting of layers is explained, and visualization of its main features facilitated by a simple game: the player is asked to stack prefabricated layers periodic in 2 dimensions, which are all of the same kind or of a small number of different kinds, in accordance with some rules which correspond to the vicinity condition (VC).

As shown, important features of the sequences of layers depend only on their symmetry (i.e. layer groups) and on geometrical features of any of the kinds of pairs, especially the layer group of any of the pairs.

Table 1 shows that OD crystals consisting of layers occur amongst the most diverse chemical substances. In Tables 2 and 3 some examples of OD crystals with a variety of relations between crystallochemical entities and OD layers are listed.

In the Appendix and Table 4 new and simplified formulae for the numberZv'(v)of possible positions of a certain layerLv′relative to the fixed position of its predecessor (or successor)Lvare given.
On Some Features of X‐Ray Powder Patterns of OD Structures
Authors: Fichtner‐Schmittler H.
Published: July 2007

X‐ray powder data of OD crystals may be misinterpreted, if the OD character of the substance is not taken into account. For some typical OD structures, problems in connection with their identification and the determination of lattice parameters are discussed. Some features of X‐ray powder patterns, which — on principle — are relevant to all OD crystals are summarized.
HVEM Investigation of the Structure Change during Work Softening of Molybdenum
Authors: Luft A. , Brenner B. , Ritschel Ch.
Published: July 2007

The change of the dislocation structure of cold worked Mo single and polycrystals during reloading at T2 ⪆ 350 K has been studied by HVEM. The structure change was found to proceed in three discernible stages: i. formation of obstacle‐free zones by local annihilation of existing dislocations, ii. appearence of large scale slip in these zones, iii. blocking of slip zones by the formation of dislocation cell structure.
Electron Beam Induced Changes of the Real Structure of Semiconductors
Authors: Aseev A. L. , Astakhov V. M. , Pchelyakov O. P. , Heydenreich J. , Kästner G. , Hoehl D.
Published: July 2007

The formation of irradiation defects produced in a high voltage electron microscope (HVEM) has been studied in Ge and other semiconductor crystals in dependence on various thermal treatments and on covering of the specimen surface. It has been concluded that the defect formation depends — besides general features known for pure metals — also on the state of electrically neutral impurities. Besides, various interactions between dislocations and irradiation defects were observed.
Dislocation arrangements in cyclically deformed polycrystalline molybdenum
Authors: Mecke K. , Holste C. , Terentjev W. F.
Published: July 2007

The present paper deals with the cyclic stress‐strain behaviour of polycrystalline molybdenum at room temperature and the dislocation structures built up within this material during the fatigue process. A cyclic stress‐strain curve of molybdenum deformed in a strain‐controlled and symmetrical push‐pull test is shown. At strain amplitudes ea < 3 × 10−3 arrangements of relatively homogeneously distributed dislocations are observed in the stage of the stabilization of mechanical properties. The characteristics of these dislocation arrangements are similar to those of dislocation structures of unidirectionally deformed molybdenum single crystals. At strain amplitudes ea > 3 × 10−3 dislocation structures are developed with an inhomogeneous dislocation distribution (bundles structures). The dislocation density in the surface layers of fatigued specimens shows larger values than within the material. The cyclic deformation after a change from a small deformation amplitude to a larger one, or vice versa, is connected with characteristic changes of dislocation density.
On the description of symmetry of OD structures (III). Short symbols for OD groupoid families
Authors: Fichtner K.
Published: July 2007

Two kinds of short symbols are proposed: 1. The short symbol of any OD groupoid‐family consists of two parts: the symbol for the point group of the groupoid of partial symmetry operations and the symbol for the layer group. No information on the parameters is given. 2. The short symbol of any OD groupoid‐family consists of those parts that correspond to the lines of the full symbol. There is, however, only one of the partial symmetry operations given, which transform a layer into an adjacent layer. These short symbols are suitable for storage of the symmetry data of OD structures in computer operated data banks.
The polymorphism of some liquid crystalline 4′‐n‐alkyloxy‐3′‐nitro‐biphenylcarboxylic acids
Authors: Demus D. , Marzotko D. , Sharma N. K. , Wiegeleben A.
Published: July 2007

The substances of the homologous series
magnified image
with n = 6, 12, 14, 15, 16, 18 were investigated by calorimetry and microscopy. In the lower members exist nematic, smectic A and smectic C phases, in the homologs with n = 16 and 18 appear phases of the type smectic D with cubic structure. The kinetics of these phase transitions, in which smectic D is participating shows a strong dependence upon the experimental conditions. Supercooling, as well as, overheating effects were found. In the supercooled state we could detect for the first time smectic phases, which are metastable with respect to another liquid crystalline phase (SD).
Crystal growth from a calcium nitrate tetrahydrate melt
Authors: Pacák P.
Published: July 2007

The kinetics of growth of calcium nitrate tetrahydrate crystals from its melt were studied in the supercooling region ΔT = 0 — 65 K. The experimental results were compared with the theoretical equations, and it was found that the growth proceeds according to a dislocation mechanism at low supercooling values and changes to continuous growth governed by the melt viscosity at higher values of supercooling.
Surface topographic studies of MoSe2 single crystals
Authors: Agarwal M. K. , Patel H. B. , Patel J. V.
Published: July 2007

Single crystals of MoSe2 of fairly large size have been grown by the sublimation method. A careful study of microstructures on the as‐grown faces has revealed a variety of surface patterns. All these features have been critically studied and the implications have been discussed.
Trends in the thermal expansion coefficients of the AIBIIIC2VIand AIIBIVC2Vchalcopyrite compounds
Authors: Neumann H.
Published: July 2007

Empirical relations are derived for the average linear thermal expansion coefficient αLand the linear thermal expansion coefficients αaand αcof the lattice parametersaandc, respectively, of the AIBIIIC2IVand AIIBIVC2Vcompounds. It is shown that the thermal expansion coefficients of all tetrahedrally coordinated compounds can be described within the same model. The anisotropy of the thermal expansion coefficients depends essentially on the lattice constant ratioc/a. There exists a criticalc/avalue below of which αcbecomes negative.
A method for the determination of the cyclic stress‐strain curve of presistent slip bands in fatigued single crystals
Authors: Blochwitz C. , Kahle E.
Published: July 2007

Single crystals of pure nickel oriented for single slip were fatigued at constant total strain amplitude (εat) at room temperature. The dependence of the saturation resolved shear stress amplitudes (τas) on the saturation plastic resolved shear strain amplitudes (γaps) (cyclic stress‐strain curve — CSSC) was determined. In the plateau range of the CSSC the volume fraction f of persistent slip bands (PSBs) was found to be linearly related to γaps. The reduction of the total strain amplitude after saturation in the plateau range of the CSSC leads to the so‐called secondary CSSC with a slope n > 0 in the log‐log plot. From the secondary CSSC the ”︁true”︁ cyclic stress‐strain curve of the PSB‐volume (PSB‐CSSC) can be determined. The method is based on the two assumptions that firstly the PSB‐groups (or ”︁macrobands”︁) penetrate the whole cross‐section of the specimen and secondly the volume fraction of PSBs in the secondary range of the CSSC remains constant.
Field‐induced phase transition in lead magnesium niobate
Authors: Schmidt G. , Arndt H. , Cieminski J. V. , Petzsche T. , Voigt H.‐J. , Krainik N. N.
Published: July 2007

The temperature dependence of the dielectric constant, polarization, and elastic compliance as well as the field dependence of the polarization and strain at different temperatures was measured at lead magnesium niobate single crystals for three different directions. From the results some conclusions with respect to the symmetry of the field‐induced ferroelectric phases can be drawn. Below −70°C and after complete poling, the spontaneous polarization is probably directed along [111].
On the Mechanism of the Copper‐induced Hexagonal‐Cubic Transformation of Zinc Sulphide
Authors: Grus M. , Horodecki A. J. , Jankowska A. , Skowron A.
Published: July 2007

The influence 2H → 3C transition on the lattice constants, electron paramagnetic resonance and electroluminescence of ZnS: Cu, Mn was investigated. The effect of the electron gasionized donors interaction on the lattice constants of crystal is discussed. It is concluded that 2H → 3C transition is the first‐order phase transition.
Dynamic deformation of silicon‐rich V3Si single crystals at elevated temperatures
Authors: Bertram M. , Paufler P. , Kleinstück K.
Published: July 2007

The plastic deformation behaviour of the intermetallic phase V3Si (Cr3Si type) was investigated under dynamic conditions. The experiments revealed that V3Si deforms plastically at a strain rate of about 4.7 × 10−5s−1 above 1200°. Flow stress depends strongly on deformation temperature and strain rate. An alloy hardening by deviation from stoichiometric composition within the range of homogeneity is observed.
Electron microscopic investigations of the recombination activity of dislocations in silicon
Authors: Heydenreich J. , Blumtritt H. , Gleichmann R. , Johansen H.
Published: July 2007

By combined application of scanning electron microscopy (EBIC technique) and transmission electron microscopy conclusions on the electrical activity (recombination efficiency) of individual dislocations in silicon are drawn.
Studies on two‐dimensional nucleation
Authors: Vasudevan S. , Nagalingam S. , Dhanasekaran R. , Ramasamy P.
Published: July 2007

Assuming a square shaped two‐dimensional nucleus, the expressions for critical size and critical free energy are derived. As an example of the relations derived, a system of ADP‐water at 300 K has been considered. Also a graph connecting the critical size and the supersaturation is drawn. Using the McDonald theory, the nucleation rate of two dimensional nucleus is derived.
Growth and etching of calcite crystals
Authors: Desai C. C. , George K. V.
Published: July 2007

Single crystals of calcite (CaCO3) have been grown by the method employed by GRUZENSKY, using an aquoeus solution of CaCl2 and a solid (NH4)2SO3, The chemical reaction takes place according to the following equation:
CaCl2 + (NH4)2SO3 CaCO3 + 2 NH4Cl
The crystals grown by this method are about 0.2 to 0.8 mm in edge dimensions.

Synthetic calcite crystals have been cleaved along (100) planes and the cleavage surfaces have been studied by multiple beam interferometry. The interferograms have revealed that the cleavages are quite flat. The cleavage faces have also been chemically etched and the etch patterns studied optically. By etching a cleavage successively for three different periods it was found that the bottoms of the point‐bottomed pits follow a linear etch path. By etching a cleavage pair, one face in one etchant and the other face in a different etchant and by comparing the etch patterns produced, before and after polishing a cleavage face it has been shown that the etch pits nucleate at the sites of dislocations in the crystal. The etch patterns have also been compared with those produced on the cleavage faces of natural crystals. The density of dislocations in the syntheitc calctie crystals was generally less than the density of dislocations in the natural calcite crystals. The implications have been discussed.
Structure and morphology of metal oxide depositions on SiO2(II). Structural aspects of the intergrowth of metal oxides on quartz
Authors: Bräer K. , Müller E.
Published: July 2007

The oxides (TiO2, SnO2, GeO2) were deposited on the surfaces of quartz crystals ((1010), (1010), (0111), (0001)) and investigated by RHEED. Anatase and rutile were found for TiO2, the quartzisomorphous structure for GeO2 and for SnO2 apart from cassiterite a structure which was hitherto unknown. The epitaxy relations were derived and discussed from the aspect of structural chemistry.
X‐ray topographic investigation of growth defects in natural calcium fluoride crystals
Authors: Desai C. C.
Published: July 2007

Calcium fluoride crystals have been cleaved along {111} faces and the freshly cleaved faces have been chemically etched in 2.6 N nitric acid solution. The etched faces have been optically studied. One‐to‐one correspondence of dislocation etch pits have been established on the matched cleavage faces and on the opposite sides of thin flakes. The same crystal has been studied using X‐ray topographic technique. By using 022‐ and 022 reflections, stereopair projection topographs were studied and compared with the optical micrographs. The close resemblance between dislocation etch pits and dislocation out‐crop images has been established. The orientation of the Burgers vectors of the dislocation lines has been identified using AgKα radiation with 111‐, 111‐ and 111 reflections. It has been confirmed that Burgers vectors of dislocation lines lie parallel to 〈110〉 directions. The implications are discussed.
Correlation between microhardness and dislocation mobility in crystals with a different type of bond
Authors: Boyarskaya Yu. S. , Grabko D. Z. , Dintu M. P.
Published: July 2007

The complex investigations of microhardness and dislocation mobility in temperature interval 77–873 K have been performed on ionic crystals, semimetals and covalent crystals. It is shown that the correlation between the microhardness and dislocation mobility exists as a whole only. The temperature change of microhardness is not often connected with the change of dislocation mobility. An “anomalous” behaviour of semimetals has been established – they have a small microhardness and a low dislocation mobility at a time.
Low‐angle grain boundaries in synthetic calcite crystals
Authors: Desai C. C.
Published: July 2007

Single crystals of calcite grown in this laboratory by the solution method have been cleaved along (100) planes and have been chemically etched in 20% NH4Cl and 5% citric acid solutions. Rows of equally spaced etch pits have been observed. By etching matched cleavage faces, correspondence has been established for low angle grain boundaries. Correspondence of grain boundaries has also been observed on the two sides of a thin plate 0.68 mm thick. It is observed that the density of pits in all the corresponding rows of matched cleavage faces and on the two sides of a thin plate is the same. Correspondence in the matching of four boundaries forming a node has also been observed on the matched faces and the relation na = nb = nc + nd (where n is the pit density along the boundary line) has also been established. The implications are discussed.
Epitaxial growth of silicon carbide layers by sublimation “Sandwich method” (II) structural defects and growth mechanism
Authors: Mokhov E. N. , Shulpina I. L. , Tregubova A. S. , Vodakov Yu. A.
Published: July 2007

Structural defects of α‐SiC epitaxial layers grown by sublimation “sandwich‐method” in vacuum at the temperatures ranging from 1600 to 2100 °C have been investigated by X‐ray topography and optical microscopy methods. It was shown, that perfect SiC layers with the homogeneous polytype structure and small dislocation density (≦ 102 cm−2) may be obtained on the substrates with any crystallographic orientation at the conditions close to quasi‐equilibrium one. The presence of impurities and silicon deficiency in the vapour phase, lead usually to the deterioration of morphological and structural perfection of SiC layers. There are the following structural defects: uncoherent polytype inclusions (mainly β‐SiC), pores, dislocations, specific stacking faults. Morphological peculiarities of the SiC epitaxial layers and possible growth mechanisms are discussed.
Growth spirals of gadolinium gallium garnet (GGG) crystals
Authors: Naumowicz P. , Wieteska K. , Szarras S. , Cinak J.
Published: July 2007

Slices cut from various locations in two GGG spirals grown by the Czochralski method have been studied using double crystal X‐ray topography. In selected regions of the slices the lattice parameter has been measured by a modified Bond method. An increase of lattice parameter has been found in the outer part of the crystal where growth bands have smaller periodicity than those in the central region of the spiral. An analysis of crystallization front changes allowed us to suppose that the asymmetry of the heat field around the growing crystal, and the forced convection of the melt, are responsible for the crystal's growing in the shape of a spiral.
A New Calcium Oxalate Monohydrate Produced by Thermal Dehydration of Weddellite
Authors: Schubert G. , Ziemer B.
Published: July 2007

A high temperature‐Guinier photograph of weddellite power showed at 118 °C a transition to a so far unknown phase which transformed to β‐Ca(COO)2 at 135 °C and during cooling down to whewellite at 103 °C. X‐ray diffraction studies on single crystals revealed the new phase to have an orthorhombic symmetry with the lattice constant a = 12.088 Å, b = 10.112 Å, c = 14.634 Å, α = β = γ = 90°. There are very simple orientation relations to weddellite: a1 (wed) ∥ a (new phase), a2 (wed) ∥ b (new phase), c (wed) ∥ c (new phase). DTA/TG studies showed that the new phase is a calcium oxalate monohydrate.
Precipitation of Alkaline‐earth Metal Hydroxoberyllate, Hydroxoaluminates and Allied Salts from Aqueous Solution: Ionic Equilibria, Crystalline Phases and Precipitation Mechanisms
Authors: Packter A.
Published: July 2007

The precipitations of alkaline‐earth metal hydroxoberyllates and zincates, hydroxochromates (III), ferrates (III), aluminates and gallates, hydroxotitanates, zirconates and stannates (IV) and hydroxoantimonates (V) from different aqueous solutions are surveyed. The relevant ionic equilibria (hydroxoanion formation, precipitation of hydroxosalts, amphoteric metal hydroxides and alkaline‐earth metal hydroxides) that may influence these precipitations are examined. The crystalline phases precipitated from different systems are tabulated and precipitation mechanisms are analysed.
The accuracy of extrapolation methods; an automatic box–jenkins package sift
Authors: Hill Gareth , Fildes Robert
Published: July 2007

Hill and Woodworth (1980) proposed an algorithm suitable for identifying Box–Jenkins models automatically without reliance on the investigator. This paper first reviews the method. It is then used on the 111 series analysed by Anderson in the Makridakis forecasting competition. The results show that the automatic method of Hill and Woodworth is comparable in terms of accuracy to the full Box–Jenkins identification procedure.
General exponential smoothing and the equivalent arma process
Authors: McKenzie Ed.
Published: July 2007

Although the basic principles of exponential smoothing and discounted least squares are easily understood, the full power of the technique is only rarely exploited. The reason for this failure lies in the complexity of the standard procedures. Often they require fairly complex mathematical models and use a variety of cumbersome algebraic manipulations. An alternative formulation for exponential smoothing is presented. It simplifies these procedures and allows an easier use of the full range of models. This new formulation is obtained by considering the relationship between general exponential smoothing (GES) and the well‐known ARMA process of Box and Jenkins. The three commonest seasonal models have only recently been considered for GES systems. They are discussed in some detail here. The computational requirements of the GES and equivalent ARMA procedures are reviewed and some recommendations for their application are made. The initialization of GES forecasting systems and the important problem of model selection is also discussed. A brief illustrative example is given.
An interpretation of the non‐symmetric responding logistic model in terms of price and experience effects
Authors: Sharp J. A.
Published: July 2007

This paper presents an alternative derivation and a generalization of the non‐symmetric responding logistic model of Easingwood, Mahajan and Muller (1981) based upon a combination of experience curve and price elasticity effects.
Forecasting the economic recession in the U.K. 1979‐1982: A comparison of model‐based ex ante Forecasts
Authors: Barker Terry
Published: July 2007

This paper compares the forecasts of recession and recovery made by five non‐government U.K. teams modelling the economy (Cambridge Econometrics, the London Business School, the National Institute of Economic and Social Research, the Cambridge Economic Policy Group and the Liverpool Research Group). The paper concentrates on annual ex ante projections as published over the period 1978‐1982, i.e. forecasts made, before the event, of the onset, length, depth and character of the economic recession in the U.K. which began in 1979. The comparison is in terms of year by year changes in production, unemployment, prices and other variables. It concludes that no group was systematically better or worse than other groups (confirming U.S. experience) and that the groups tended to perform better in their chosen areas of specialization, e.g. medium‐term groups did better at forecasting the medium‐term outcome.
Modelling the advertising‐sales relationship through use of multiple time series techniques
Authors: Heyse Joseph F. , Wei William W. S.
Published: July 2007

When time series data are available for both advertising and sales, it may be worth while to model the two series jointly. Such an analysis may contribute to our understanding of the dynamic relationships among the series and may improve the accuracy of forecasts. Multiple time series techniques are applied to the well‐known Lydia Pinkham data to illustrate their use in modelling the advertising‐sales relationship. In analysing the Lydia Pinkham data the need for a joint model is established and a bivariate model is identified, estimated and checked. Its forecasting properties are discussed and compared to other time series approaches.
Tourism forecasting: A review of empirical research
Authors: Sheldon Pauline J. , Var Turgut
Published: July 2007

Many publications on tourism forecasting have appeared during the past twenty years. The purpose of this article is to organize and summarize that scattered literature. General conclusions are also drawn from the studies to help those wishing to develop tourism forecasts of their own. The forecasting techniques discussed include time series models, econometric causal models, the gravity model and expert‐opinion techniques. The major conclusions are that time series models are the simplest and least costly (and therefore most appropriate for practitioners); the gravity model is best suited to handle international tourism flows (and will be most useful to governments and tourism agencies); and expert‐opinion methods are useful when data are unavailable. Further research is needed on the use of economic indicators in tourism forecasting, on the development of attractivity and emissiveness indexes for use in gravity and econometric models and on empirical comparisons among the different methods.
Diagnostic checks of non‐standard time series models
Authors: Smith J. Q.
Published: July 2007

Diagnostic checks have become a standard tool for helping to assess the adequacy of a forecasting system since Box and Jenkins' (1970) ARIMA modelling technique became popular. However, most of the research has developed checks for normal or second‐order stationary models. This paper gives various diagnostic checks that can be performed simply on nonnormal, non‐standard models such as the class of multiprocess models (Harrison and Stevens, 1976), where residuals are definitely not normal. The performance to date of these models can then be objectively scrutinized on‐line. Examples, including a generalized cusum technique, are given to illustrate the effectiveness of the techniques on specific series.
Inferential processes in the construction of scenarios
Authors: Jungermann Helmut
Published: July 2007

The process of scenario construction is not yet well understood. Procedures appeal to the ‘disciplined intuition’ of experts. From a psychological perspective, however, generating scenarios represents a most difficult cognitive task. Two cognitive functions involved in this task are discussed: forward inferences and backward inferences. Whereas forward inferences explore the implications of given options and help to identify potential consequences, backward inferences explore the implications of given goals and help identify potential options. The first process leads to an exploratory scenario, the second to an anticipatory scenario. It is argued that the two approaches, applied to the same problem, result in different scenarios, i.e. scenarios that differ in their elements, their structures, their ranges and their ‘holes’. A bi‐directional construction method is suggested that balances the drawbacks implied in using one cognitive strategy only (e.g. forward inference) by using complementarily the other strategy (e.g. backward inference). In contrast to other methods proposed in the literature, this method is theoretically derived and can be tested empirically.
Forecasting temporally aggregated vector ARMA processes
Authors: Lütkepohl Helmut
Published: July 2007

If interest centres on forecasting a temporally aggregated multiple time series and the generation process of the disaggregate series is aknownvector ARMA (autoregressive moving average) process then forecasting the disaggregate series and temporally aggregating the forecasts is at least as efficient, under a mean squared error measure, as forecasting the aggregated series directly. Necessary and sufficient conditions for equality of the two forecasts are given. In practice the data generation process is usually unknown and has to be determined from the available data. Using asymptotic theory it is shown that also in this case aggregated forecasts from the disaggregate process will usually be superior to forecasts obtained from the aggregated process.
Prediction in a duration model
Authors: Brännäs Kurt
Published: July 2007

Predictors of mean duration and an arbitrary quantile are given for the Weibull regression model for duration data. Associated prediction variances arising from maximum likelihood and least squares estimation are given. In an empirical example, based on duration of employment data, the uses of various model diagnostics and the predictors are illustrated.
Subjective confidence in forecasts: A response to fischhoff and MacGregor
Authors: Wright George , Ayton Peter
Published: July 2007

Here we evaluate the generalizability of calibration studies which have used general knowledge questions, and argue that on conceptual, methodological and empirical grounds the results have limited applicability to judgemental forecasting. We also review evidence which suggests that judgemental forecast probabilities are influenced by variables such as the desirability, imminence, time period and perceived controllability of the event to be forecast. As these variables do not apply to judgement in the domain of general knowledge, a need for research recognizing and exploring the psychological processes underlying uncertainty about the future is apparent.
A comparison of forecasts from least absolute value and least squares regression
Authors: Dielman Terry E.
Published: July 2007

A Monte Carlo simulation is used to compare forecasts from least absolute value and least squares estimated regression equations. When outliers are present, the least absolute value forecasts are shown to be superior to least squares forecasts. The results emphasize the importance of exercising caution when using forecasts from least squares estimated regressions. Use of least absolute value regression (or some other robust regression method) instead of, or as an adjunct to, least squares is recommended. The comparison of forecasts from the two methods provides one way of assessing whether the least squares forecasts have been adversely affected by outliers. If outliers are present, the least absolute value regression forecasts can be used.
Linear constraints and the efficiency of combined forecasts
Authors: Trenkler G. , Liski E. P.
Published: July 2007

This note extends some recent results, achieved by Clemen, on constraining the weights of a combined forecast. There is a great potential for improving the ordinary least squares forecast by imposing linear restrictions, and it will be shown how this potential can be exhausted by using anF‐test. The corresponding decision procedure leads to a pre‐test forecast with good statistical properties.
On tests for non‐linearity in time series analysis
Authors: Chan W. S. , Tong H.
Published: July 2007

We have developed a new test for non‐linearity in time series data in discrete time. A comparative study has been conducted on Subba Rao, Gabr and Hinich's test, Keenan's test, Petruccelli and Davies test, and the new test. Both simulated and real data are used in the study. The implication for forecasting is briefly discussed.