bluuebunny/crossref_metadata_2025_split huggingface dataset:
Possibilities of the quantitative characterization of intermetallic phases in the cast structure of aluminium alloys
Authors: Griger Á. , Lendvai A. , Stefániay V. , Turmezey T. , Hidvégi É. 
Published: January 2007

AbstractThe quality and quantity of intermetallic compounds in a commercial aluminium alloy based on 99.5% Al purity are responsible for the final properties of products. Compositional and spatial distribution of intermetallics in the matrix are determined besides the chemical composition by the circumstances of solidification fixed with casting conditions. Therefore in order to get a cast structure, corresponding to the quality favourable in further processing, the casting process should be controlled in accordance with the formation of intermetallic compounds.The main and unavoidable impurities in aluminium alloys are iron and silicon. Quality demand requires, however, iron and silicon to be considered as alloying elements. Methods used in the investigations of AlFe and AlFeSi phases in function of crystallization are reported in this paper.
Study of kinetics of phase transitions in the CuMnAl alloys
Authors: Soltys J. , Kozubski R. , Meres K. , Holender J. 
Published: January 2007

AbstractThe alloys of the system CuMnAl have been extensively investigated. The results of systematic studies of phase equilibria in those alloys have been recapitulated by West, Thomas, and by Köster, Gödecke. However, the alloys of the composition approximating Cu2MnAl have been drawing special attention.At high temperatures the alloys of such composition are comprised in a range of equilibrium of the β‐phase which has simple crystalline structure and is often called the Heusler phase. The properties of the above alloys are very interesting due to the simultaneous occurrence of two kinds of structural phase transitions: the “order‐disorder” transformations in the range of β‐phase and the decomposition of the β‐phase in the temperature range of its metastability. It was indicated that above 1050 K the β‐phase has cubic disordered structure of the type A2 while, when cooled, it transforms at 1050 K into partially ordered B2‐type structure and at about 950 K into completely ordered L21‐type one, Dubois (Lisse).On the other hand, the β‐phase is metastable at temperatures below 970 K and decomposes into three phases of the types βMN, γ‐Cu9Al4 and T‐Cu3Mn2Al (West, Thomas; Köster, Gödecke).The simultaneous occurrence of the ordering and decomposition processes may be an interesting subject of theoretical considerations (Nishizawa et al.). The processes may be considered either on microscopic level requiring various simplifying assumptions or through the study of processes of precipitation in real structure.The aim of the presented work was the detailed research of the process of decomposition of β‐phase in the stoichiometric alloy Cu2MnAl (Kozubski et al. 1982, 1983a, b, c). During the investigations the methods of X‐ray diffraction and the measurement of electrical resistivity as well as electron microprobe were applied. The X‐ray diffraction and microprobe measurements were performed at room temperature and the specimens quenched in water after the desired annealing were examined. All samples of the alloy were at first homogenized at 1123 K and then annealed at various temperatures between 423 and 973 K.
A microstructural examination of ZnAlCu alloys
Authors: Terziev L. , Wegria J. , Greday T. 
Published: January 2007

AbstractA microstructural examination of a Zn‐11 wt% Al‐1 wt% Cu alloy in dependence on the applied heat treatment was carried out by means of scanning electron, transmission electron and optical microscopy as well as X‐ray investigations.
Photoluminescence from deformed CaO crystals
Authors: Remón A. , Piqueras J. 
Published: January 2007

AbstractThe plastic deformation of CaO crystals produces the increase of luminescence band centered at 385 nm and 454 nm. The bands are excited with light of 350 nm and 275 nm respectively, and their relative increase depends on the kind of deformation applied to the crystal. The results are compared with previous cathodoluminescence observations.
Autodoping of epitaxial silicon layers (II) diffusion‐induced autodoping
Authors: Kühne H. , Gaworzewski P. , Malze W. 
Published: January 2007

AbstractFrom discussing the influences of layer growth duration and deposition temperature on the slope of the steep autodoping profile branch adjacent to the substrate, it is concluded that there exists a special autodoping part, termed redistribution autodoping, which is independent on solid state diffusion effects, but should be restricted to the beginning of the layer growth.
Determination of the orthorhombic coincidence site lattice for bicrystals of any lattice system
Authors: An Nguyen , Rothkirch L. , Herrmann R. 
Published: January 2007

AbstractThe concept of the coincidence site lattice is generalized for bicrystals of any lattice system. Describing the formation of bicrystals by cutting the ideal lattice and rotating the partial lattices the conditions for the coincidence site lattice are presented. For the construction of the special case of orthorhombic coincidence site lattice an instruction is given.
Electrical properties of r. f. sputtered thin films of CuInSe2(II). Conduction mechanism and intrinsic doping effects
Authors: Neumann H. , Tomlinson R. D. , Hill A. E. , Abdul‐Hussein N. A. K. , Samaan A. N. Y. 
Published: January 2007

AbstractAn analysis of the conduction mechanism in p‐type polycrystalline films of CuInSe2 is given. It is shown that in the r.f. sputtered films the hole mobility is limited by tunneling through the grain boundary potential barrier. It is suggested that the charge carrier transport is governed by conduction through valence band states at high temperatures and by impurity band conduction at low temperatures. On the basis of the chemical composition data for the r.f. sputtered films no conclusions can be made regarding the type of the acceptor‐like intrinsic defect responsible for the p‐type conductivity of the films.
On the structural characterization of solid state reaction product of cadmium carbonate and 8‐hydroxyquinoline
Authors: Singh M. , Singh H. C. 
Published: January 2007

AbstractThe formation of coordination compound of cadmium carbonate and 8‐hydroxyquinoline has been studied in solid state. The light yellow coloured crystals of this compound have been grown in non‐aqueous media for X‐ray studies. The crystal system and lattice parameters have been determined by powder technique of X‐ray diffraction. Infrared spectral study of the complex was carried out in order to study the mode of linkage. Molecular distortion due to coordination has been discussed.
On the influence of nonstoichiometry on luminescent properties of CdGa2S4 single crystals
Authors: Derid Yu. O. , Georgobiani A. N. , Gruzintzev A. N. , Radautsan S. I. , Tiginyanu I. M. 
Published: January 2007

AbstractResults of a study of photoluminescence and thermoluminescence of cadmium thiogallate single crystals grown from the melt are presented. Effect of nonstoichiometry on the properties of samples is studied. Some assumptions about the nature of centres in CdGa2S4 compound are made.
On the preparation of tungsten oxides by chemical transport with TeCl4
Authors: Oppermann H. , Srtöver G. , Wolf E. 
Published: January 2007

AbstractThe Tungsten oxides WO3, W20O59, W18O49 and WO2 have been transported by TeCl4 in monocrystalline Form. W3O is not a equilibrium phase of the system, and therefore it is impossible to obtain this phase by CTR. The value of the lower phase boundary of tungsten trioxide is 2.96.
Growth of single crystals of potassium chloride from gels
Authors: Desai C. C. , Hanchinal A. N. 
Published: January 2007

AbstractThe growth of single crystals of potassium chloride (KCl) in silica gels upto 3 × 3 × 3 mm3 in size is described. To crystallize KCl incorporated in the gel, hydrochloric acid has been used to crystallize the KCl in the gel media. The crystalline perfection has been studied by the chemical etch pit technique.
X‐ray topographic study of quartz crystals with induced growth striations
Authors: Alter U. , Härtwig J. 
Published: January 2007

AbstractThe method of “induced growth striations” was applied to the hydrothermal growth of quartz crystals. Striations were due to a periodical modulation of the growth temperature induced and investigated by means of the X‐ray Lang topography and plane wave reflection topography. The results show that the X‐ray topographic methods are a sensitive tool for the characterization of the growth striations, which are produced generally by Al impurities. The application of the method of induced growth striations to quartz crystals and the characterization of these crystals with optical and X‐ray topographical methods allow a deeper understanding of the crystal growth behaviour.
Homogeneous nucleation in cooling crystallization
Authors: Liszi Ilona , Blickle Tibor , Liszi János 
Published: January 2007

AbstractNielsen's equation has been applied for cooling crystallization of KCl from watery solutions. In the calculations activities are used instead of concentrations, the temperature and concentration dependence of both the activity and diffusion coefficients are considered. It is found thatA) the interfacial tension between the crystal and its saturated solution is < 2.5 erg/cm2, which is less by two orders of magnitude than that of between crystal and vacuum;B) homogeneous nucleation can take place even at very small supersaturations (ln S < < 0.01), which is unusual in precipitation.
Problems and results of diffusion length investigations by energy‐dependent EBIC measurements
Authors: Kittler M. , Seifert W. , Schröder K.‐W. , Susi E. 
Published: January 2007

AbstractThe fundamentals of the method are described. From applications of this measuring method the following results were obtained: The determination of the diffusion length on glass‐plate bevels with evaporated Schottky contacts is frequently quite difficult and sometimes even impossible. Besides a reduction of the diffusion length with increasing microdefect density surprisingly also the opposite behaviour can be found. Comparative PEM and EBIC investigations yield differences between both diffusion lengths (LEBIC < < LPEM) depending on the sample pre‐history.
On the formation and technical importance of the microsegregation in austenitic chromium‐nickel alloyed steels
Authors: Siegel Ulrich 
Published: January 2007

AbstractThe austenitic chromiumnickel alloyed steels are showing different types of concentration‐distributions of the elements chromium and nickel in the austenite in dependance on the content of alloys. As a consequence of the crystallization of the heat to austenite the “equal directed” type of segregation forms. The ferritic solidification of a heat and the following ferrite to austenite transformation leads to “unequal directed” segregation in the austenite. Heats having both the types of segregation solidify by way a 3‐phase reaction. For heats ferritically solidified better hot plasticity, lower susceptibility to hot cracking in the weld and better polishability is observed compared with heats solidified austenitically. The advantages are accounted to the lower separation during the ferritic solidification as consequence of the higher diffusivity of the alloying and accompanying elements in the ferrite compared with the austenite.
Lattice thermal expansion of potassium lithium sulphate
Authors: Venudhar Y. C. , Iyengar Leela , Krishna Rao K. V. 
Published: January 2007

AbstractUnit‐cell parameters and coefficients of thermal expansion of potassium lithium sulphate have been determined accurately, as a function of temperature, by the X‐ray powder diffraction method. Both the parameters ‘a’ and ‘c’ increase non‐linearly with increasing temperature, the change in the ‘a’ parameter being more than that in the ‘c’ parameter. As a result, the average expansion coefficient along the c‐axis is found to be very small when compared to that along the a‐axis. The lattice thermal behaviour of this compound is explained in terms of the strength of the bonds along the respective directions. The diffraction pattern obtained at 435 °C was completely different from those taken at other lower temperatures, suggesting a structural change contrary to the earlier reports.
Evidence of VLS growth in CdTe film preparation by NH4Cl closed‐tube CVD
Authors: Paorici C. , Pessina V. , Zecchina L. , Mancini A. , Rizzo A. 
Published: January 2007

AbstractBy thermodynamical calculations of the vapour phase composition expected to occur in the closed — tube CVD of CdTe films on CdTe substrates, it is shown that a VLS growth mechanism should be active in the growth process when use is made of the thermal decomposition of NH4Cl for producing the proper amount of HCl as a transport agent. Responsible of this VLS mechanism is the liquid tellurium, which is always present when the NH4Cl concentration reaches values sufficiently high for the epitaxial deposition of CdTe films.
Investigation of convection in the solution zone at the growth of CdTe by THM
Authors: Schwenkenbecher K. , Rudolph P. 
Published: January 2007

AbstractAn investigation of the axial temperature distribution in the solution zone at THM growth of CdTe is presented. The results support the assumption, that density differences coused by concentration differences there are a substantial contribution to convection in the zone. The concentration Rayleigh‐number and the needed concentration expansion coefficient of the real experimental condition are estimated.
Crystal and molecular structure of 1,21‐diacetoxy‐11β,17‐dihydroxy‐4‐methyl‐19‐norpregna‐1,3,5(10),8(14)‐tetraen‐20‐one, C25H30O7
Authors: Reck G. , Langbein G. 
Published: January 2007

AbstractThe structure of the title compound has been determined by X‐ray diffraction techniques. It crystallizes in the monoclinic space group P 21 with 2 formula units C25H30O7 in the unit cell. The lattice constants are a = 10.194, b = 11.790, c = 9.515 Å, and β = 100.69°. The structure was solved by direct methods using MULTAN‐78 and refined by least‐squares calculations to R = 0.061. The molecular configuration and conformation are discussed. The influence of the acetoxy groups and the 11‐hydroxyl group on the steroid backbone is of special interest. There are two symmetry independent intermolecular but no intramolecular hydrogen bridges.
The Polymorphism of 5‐n‐Hexyl‐2‐[4‐n‐pentyloxyphenyl]‐pyridine
Authors: Mädicke A. , Demus D. , Pavluchenko A. I. , Titov V. V. , Smirnova N. I. 
Published: January 2007

AbstractThe phase transitions of 5‐n‐hexyl‐2‐[4‐n‐pentyloxyphenyl]‐pyridine were determined by miroscopic and calorimetric investigations. The classification of the smectic modifications was done by investigation of the miscibility relations. Besides the nematic phase smectic phases C, F, G and H were identified.
Field‐Induced Orientation Transition in Ferroelectric Liquid Crystals
Authors: Schiller P. 
Published: January 2007

AbstractStatic and dynamic effects of a fast bistable device containing a ferroelectric liquid crystal are investigated theoretically. The switching mechanisms are different at low and high electric fields. There is a critical voltage which separates a bulk switching regime from the regime of domain wall motion. This threshold is determined as a function of physical device parameters.
Calculation of the Suspension Volumes of MSMPR Cascade Crystallizers
Authors: Kodura J. , Gramlich K. 
Published: January 2007

AbstractA new algorithm for the design of cascade crystallizers with and without pure solution removal for the individual crystallizers has been described. The algorithm enables the calculation of active suspension volumes and mean retention times, as well as mean size of product crystals and kinetic quantities for the individual stages for the both variants: — presumption of the mean product sizes in each stage, or — presumption of the mean retention times in each stage.Results have been shown and discussed for a two stage cascade of KCl‐vacuum crystallizers as example.
X‐Ray Radiography Investigations of Solid Solutions with Limited Miscibility in K2SO4‐(NH4)2SO4‐H2O System
Authors: Dejewska B. , Sedzimir A. 
Published: January 2007

AbstractThe measurements of crystal lattice parameters (a, b, c) were conducted and the volumes (v) and densities (∂) of solid solutions of (K, NH4)2SO4 were calculated. It was established that in the system K2SO4‐(NH4)2SO4‐H2O at 25 °C mixed crystals with limited miscibility were formed. The gap in the continuity of solid solutions occurred in a very narrow range of concentrations of (NH4)2SO4 in mixed crystals, namely from 69.5 to 72.5%.In order to get the confirmation of the above, the detailed equilibrium investigations nearby the peritonic point (the concentration of K2SO4 −3.32%, the concentration of (NH4)2SO4 −38.66%) were carried out.
Study of Dislocation Distribution in NaClNaBr and NaClCaCl2 Crystals Grown from Melt
Authors: Sankaram T. Bhima , Raju I. V. K. Bhagavan 
Published: January 2007

AbstractDislocation distribution and content have been studied using etch pit method in the single crystals of mixed solids NaClNaBr and NaClCaCl2. In both the solid solutions the dislocation content is higher as compared to that in pure crystals of NaCl and NaBr grown under similar conditions. In mixed crystals of NaClNaBr the block structure of subgrain boundaries is not observed. The subgrain boundaries are highly fragmentary and the dislocations form arrays running randomly to short distances. In NaCl crystals doped with CaCl2 dislocation loops and impurity‐decorated dislocations are observed. The dislocation content is higher in impurity segregated regions. The impurity decorates both isolated dislocations and subgrain boundaries in calcium‐doped crystals. The results are discussed.
Optical, Electrical and Morphological Studies of SnSe2 Crystals Grown by Physical Vapour Transport Method
Authors: George Joy , Kumari C. K. Valsala 
Published: January 2007

AbstractTin diselenide single crystals have been grown by the physical vapour transport (PVT) method. Optical absorption studies give an indirect allowed transition at 1.03 eV at room temperature. The electrical resistivity parallel and perpendicular to c‐axis, mobility and carrier concentration have been determined. Dependence of resistivity parallel to c‐axis on temperature gives an activation energy of 0.072 eV. Growth spirals observed for the first time on the as grown faces of these crystals are also presented here.
Gaseous Bubble Formation in Bi2Te3Bi2Se3 Melt
Authors: Nghi Nguyen Thanh , Ushkans A. L. , Cherepanova T. A. 
Published: January 2007

AbstractIn this paper the mechanism of the formation of gaseous inclusions in the liquid phase on the example of Bi2Te3‐Bi2Se3 system is considered. The thermodynamic analysis for the model scheme of melting has been carried out. It is shown that the time dependence of the pressure and composition of gaseous phase is determined by establishment of equilibrium between liquid and gaseous phases in the system. The results of numerical computation give a quantitative evolution of the size of critical gaseous nucleus in the Bi2Te3‐Bi2Se3 melt with the time and its dependence on the height of melt column.
LPE of Isolated Pb0,85Sn0.15Te Islands on PbTe
Authors: Deppert K. , Schikora D. , Parthiek L. , Ickert L. 
Published: January 2007

AbstractIn recent years the importance of selective epitaxy has continuously increased. It is a tool for controlling the production of semiconductor structures as required. This method has been demonstrated and investigated by LPE as well as VPE and MBE.Usually substrates are used having either preferentially etched channels or windows in masks to predetermine the site. In the present paper epitaxy of Pb0.85Sn0.15 Te deposits growing in isolated islands on PbTe substrates by means of LPE is investigated.
Crystal Growth and Physico‐Chemical Properties of Lead Molybdate in the Homogeneity Region
Authors: Gabrielian V. T. , Fedorova L. M. , Tkachenko E. B. , Neiman A. Y. , Nikogosian N. S. 
Published: January 2007

AbstractFrom data of both X‐ray phase analysis and differential thermal analysis, as well from measurements of the crystal lattice parameters, electric conductivity and diffusion coefficients of cations in ceramics and single crystals the width of the homogeneity region of the lead molybdate phase which lies in the composition range of 49.85–50.50 mole% MoO3, has been determined. It was also established that the compound was a daltonide phase. The results obtained explain the Pb/Mo ratio changes along the crystal.
The Structure of Metastable Phases in AlZn Alloys (II). HREM Investigations on α‐Precipitates
Authors: Ramlau R. , Löffler H. 
Published: January 2007

AbstractPrecipitates of the metastable ‐phase grown in an Al‐(6.8 at.%)Zn alloy are investigated by means of a technique of high resolution electron microscopy, namely by two‐beam lattice fringe imaging with tilted illumination. It is demonstrated by this direct method that the ‐precipitates are in fact semicoherent. The transition of fully coherent Guinier‐Preston zones into semicoherent precipitates of the ‐phase takes place by formation of additional (III)rh and { III }rh planes inside the zones.
Transformation of Light Wave in Absorbing Crystals with Low Symmetry and Determination of their Own Waves Parameters (I)
Authors: Shamburov V. A. , Evdishchenko E. A. 
Published: January 2007

AbstractThe decision of the direct and reverse problems in the optics of the low symmetry absorbing crystals are obtained and graphically represented by the specific drawing on the Poincare sphere. The direct problem is connected with the transmission and reflection of the normally incident light wave and reverse problem — with the determination of the own waves parameters. Instead of the usually used boundary conditions the equations of Fresnel and Airy are applied to each of the own waves separately, as the incident, reflected and transmitted waves are represented by the vector sum of the own waves. On the basis of the comparatively simple decision of the direct problem the simpliest method of the reverse problem decision, i.e. for the determination of the own waves parameters in the crystal plate is proposed. In the capacity of the experimental data for this purpose the measured polarization parameters, the reflection‐ and transmission coefficients of the reflected and transmitted waves must be used as well as the right and left circular polarized incident waves and also two different, but close thicknesses of the crystal plate.
Effect of Ambient Atmosphere on Defect Generation in MgO during Mechanical Activation
Authors: Spitsyn V. I. , Steinike U. , Barsova L. I. , Hennig H.‐P. , Jurik T. K. , Kretzschmar U. 
Published: January 2007

AbstractAs previous studies have shown (Spitsyn et al.; Henderson, Wertz; Steinike et al. 1981, 1984; Hennig et al.), mechanical activation of MgO in air results in the generation of anion and cation vacancies in the lattice, thus causing heterogeneous lattice distortions. These anion and cation vacancies are identified as F+‐ and V−‐centres, respectively, by EPR spectroscopy. F+‐centres are anion vacancies filled with electrons, V−‐centres are cation vacancies filled with holes. The electrons and defect electrons filling the vacancies are generated essentially during γ‐irradiation. Since the effect of the ambient atmosphere on the generation of electronic and structural defects upon mechanical activation is known (Bystrikov et al.), the studies of mechanical MgO activation in air were extended to the generation of above defects in an argon atmosphere. The results are compared with those obtained in air.