bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth, structure, and stoichiometry of epitaxial Cu‐III‐VI2 films on CaF2 substrates
Authors: Schumann B. , Kühn G. 
Published: January 2007

AbstractThin films of CuInTe2, CuInSe2, CuInS2, CuGaSe2 and CuGaS2 were deposited onto (111)‐and (100)‐oriented CaF2 substrates by flash evaporation technique. Epitaxial growth occurs at substrate temperatures in the range from 750 to 900 K, dependent on the kind of film material. Contrary to the case of GaAs, GaP and Ge substrates there are always polycrystalline parts. The layers were found to be single phase and crystallizing in the chalcopyrite structure only. The composition of the films varied in dependence on the substrate temperature. In the range of about 700 K a nearly stoichiometric composition was found.
On the microhardness of some organic molecular solids
Authors: Joshi Mihir J. , Shah B. S. 
Published: January 2007

AbstractMicrohardness measurements have been carried out on the (001) cleavage surfaces of anthracene, Phenanthrene and benzoic acid single crystals. The variation of the Vicker's Hardness Number (VHN) with load (P) shows a decrease in hardness with increasing load. Plots of load (P) vs the square of the diagonal (d2) and logarithm of load (log P) vs logarithm of diagonal (log d) are found to be linear. These observations are being explained in terms of the geometrical packing of molecules in these crystals which play an important role in causing slip.
Basic steps and layer homogeneity in CVD (I)
Authors: Arnold H. 
Published: January 2007

AbstractAs a first basic step in chemical vapor deposition (CVD), reactant depletion within batchtype reactors is treated. By introduction of a depletion resistance into the circuit representation of epitaxy and of LPCVD processes, the joint treatment of problems concerning layer thickness and doping homogeneity becomes more transparent. In the case of compensated depletion, this resistance increases linearly with the distance from the reactor input, and is independent on the kind of reactants if gas diffusion is negligible in the down stream direction. Without compensation it becomes nonlinear in the downstream local coordinate and depends on the resistance of the subsequent basic steps. Aspects of lowering the depletion are discussed.
Comments on the structure of copper (II) oxalate: Discussion of X‐ray powder diffraction and EXAFS results as a basis for the interpretation of magnetic properties
Authors: Fichtner‐Schmittler H. 
Published: January 2007

AbstractSome features of the crystal structure of Cu(II) oxalate, which are relevant for the interpretation of unusual magnetic properties of the substance, are discussed. EXAFS and X‐ray powder diffraction results described by different authors are compared. The results of both the analytical methods complement each other. The packing of the ribbon‐like structural units consisting of Cu2+ and (C2O4)2− ions is demonstrated. It is shown that the Cu ions are octahedrally coordinated by O atoms (four short and two long Cu‐O distances). The environment of a central Cu ion with other Cu ions is discussed in terms of intra‐ and inter‐ribbon distances. In view of the structural characteristics of Cu(II) oxalate it seems to be not justified to disregard the interaction between neighbouring ribbons in the discussion of the magnetic coupling, as done so far.
Basic steps and layer homogeneity in CVD [II]
Authors: Arnold H. 
Published: January 2007

AbstractTaking into account reactant depletion, gas diffusion, surface processes, and a fourth basic step that is connected with the influence of surface equilibria, the compensation of depletion is treated for both host material deposition and in‐situ doping. So, some aspects can be given for the realization of layer homogeneity in epitaxy, as well as in LPCVD. In conclusion, the terminology of border cases in CVD is discussed.
A study of some calcium dihalides and strontium fluoride halides systems
Authors: Hodorowicz S. A. , Hodorowicz E. , Eick H. A. 
Published: January 2007

AbstractThe CaX2‐CaY2 and SrF2‐SrX2 (where X and Y represent halides anions) systems were investigated by the Guinier powder X‐ray diffraction technique. In the calcium dihalides systems only solid solutions were found. In the strontium fluoride — strontium chloride and strontium fluoride — strontium bromide systems the dihalides and the PbFCl‐type SrFX phases were observed. The preparation, crystallographic data and atom distribution of the mixed fluoridhalides, SrFCl0.5Br0.5, Ca0.5Sr0.5FCl, Ca0.5Yb0.5FCl and Sr0.5Eu0.5FBr are presented and discussed.
High‐temperature X‐ray irradiation induced thermoluminescence and half‐life calculations in NaYF4 polycrystalline samples
Authors: Narasimha Reddy K. , Subba Rao U. V. 
Published: January 2007

AbstractElevated irradiation temperature studies with NaYF4 samples reveal that the intensity of the two glow peaks observed around 120 and 180°C enhances. The effect of temperature of irradiation (Tirr) on the sensitisation of the both peaks are studied. The half lives of these glow peaks were calculated and concluded that the half lives of these peaks decreases with the increase in irradiation temperatures.
Microharness and dislocation mobility in ionic crystals
Authors: Grabko D. Z. , Boyarskaya Yu. S. , Pishkova D. S. 
Published: January 2007

AbstractThe correlation between microhardness and dislocation mobility was investigated for the series of ionic crystals in the wide temperature interval (77 – 400 K). It was shown that the dislocation mobility was not the main parameter responsible for the microharness change in the series of KCl—NaCl—NaF—LiF—MgO crystals or in temperature lowering from 293 to 77 K.A marked activation of the dislocation mobility can play a significant role in the range T > 293 K only. In the low temperature region the microhardness change may be connected with the parameters caracterising the dislocation multiplicatio and interaction.
On the distribution coefficient of sulphur during the crystallization of GaP from nonstoichiometric gallium melts
Authors: Koi H. , Hein K. , Siegel W. 
Published: January 2007

AbstractGaP grown by the SSD technique was doped by sulphur in a wide concentration range. Using chemical, electrical and radiochemical methods the concentration and temperature dependence of the distribution coefficient k during this crystallization from the nonstoichiometric melt was determined. With the crystallization temperature at 1000°C for k a value 6.9 ± 1.4 was found independent on the sulphur quantity added. The distribution coefficient decreases clearly with increasing temperature.
Crystal and molecular structure of Bis(N‐[pyrid‐2‐yl]‐1‐imino‐2‐carbethoxy‐3‐oxo‐butan‐2‐ido)‐palladium (II)
Authors: Reck G. , Bannier G. , Heyn B. , Jäger E.‐G. 
Published: January 2007

AbstractThe crystal and molecular structure of the title compound has been determined by X‐ray diffraction techniques. It crystallizes in the orthorhombic space group Pbca with 4 formula units C24H26N4O6Pd in the unit cell. The lattice constants are a = 17.259, b = 19.070, and c = 7.480 Å. The structure was solved by the heavy atom technique and refined by least‐squares calculations to the conventional R = 0.057. The coordination sphere of palladium as well as the molecular geometry of the ligands are discussed in the paper.
Horizontal bridgman growth of gaas single crystals
Authors: Moravec F. , Pelikán M. 
Published: January 2007

AbstractIn order to meet requirements for the preparation of low dislocation density GaAs single crystals a horizontal Bridgman type apparatus was designed. Construction of the apparatus allows the establishment of enhanced temperature stability of the arsenic source and hence better stability of the arsenic vapour pressure during the growth. This effect was achieved without application of heat pipes which are usually used for the improvement of thermal profile and temperature stability. The influence of different arsenic vapour pressures on the density of dislocations was confirmed in the course of this work.
Twinning in hydrothermally grown synthetic quartz as revealed by etch structures
Authors: Kotru P. N. , Kachroo S. K. , Raina K. K. 
Published: January 2007

AbstractEtch structures obtained by HF etching on habit and cleaved rhombohedral surfaces of synthetic quartz grown by hydrothermal crystallization technique, indicative of twinning in them are described, illustrated and discussed. The twin traces appear in the form of lines of dis‐continuity in [1121] and [1211] directions. Etch pits within the parallelogram‐shaped bound areas are oppositely oriented with respect to those on the rhombohedral surface of the main crystal. The form of twinning observed is found to be of parallel lattice type and the surface within and outside the bound areas are coplanar in most of the cases. The rhombohedral faces of the twinned crystals are found to be geometrically related to each other as if one part is derived from the other by a rotation of 180° about [1210] direction.Discontinuation in the crystal lattice along the twin trace is evidenced by obstructions in the normal development of an etch pit. Deep penetration of twin traces and parallelogram‐shaped regions, enclosing etch pits of opposite orientation (twinned areas), well within the crystal structure is demonstrated by comparison of etch patterns on matched rhombohedral cleavages and the results on their successive etching. The type of twinning displayed by the crystals is discussed in the light of models suggested. Causes for the generation of twinning in synthetic quartz are explained to lie in the availability of twinned nuclei in the seed plates used for hydrothermal crystallization of quartz.
Thermodynamic approach to the problem of A3B5 crystals with an optimum structural perfection
Authors: Barchuk A. B. , Ivashchenko A. I. , Kopanskaya F. Ya. 
Published: January 2007

AbstractThermodynamics of A3B5 semiconductor crystal, containing impurity and native point defects is considered. The main limit of the present analysis is the absence of a significant interaction between point defects at thermal equilibrium. It is shown that the difference of the chemical potentials of A3 and B5 components may serve as a structural sensitive thermodynamic function of a crystal. The optimization of the crystal perfection may be obtained when this function becomes zero. In the case of undoped A3B5 crystal such a situation corresponds to the ideal lattice perfection. In the case of doped crystal the effects of native point defects and their interaction with the impurity on the electronic properties of the crystal have to be reduced.The developed thermodynamic approach has been applied to the quantitative analysis of the available experimental data (GaAs, GaP, GaAs:Si and GaP:In). The results of the calculation are in reasonable agreement with the experiment.
The size effect on the ice nucleating behaviour of PbI2 thin films
Authors: Gobinathan R. , Palanisamy M. , Ramasamy P. 
Published: January 2007

AbstractA relationship exists between the size of the particle and nucleation temperature. There exists an optimum particle size below which nucleation is inhibited. The behaviour of lead iodide thin films as a substrate for ice nucleation is reported in this study. It is found that the supercooling increases with increase in the thickness of the film. But the change in nucleation temperature above 1250 Å is negligible.
Nucleation of struvite (MgNH4PO4 · 6 H2O) single crystals and aggregates
Authors: Boistelle R. , Abbona F. 
Published: January 2007

AbstractThe conditions (concentration and pH) for preparation of single crystals of struvite at 25 °C from ammoniacal solutions equimolar with respect to magnesium and phosphate ions are given. The limits are found above which crystal aggregates (twins or dendrites) precipitate as dominant morphology. The mechanisms of nucleation are discussed and the interfacial tension between crystals and solution is evaluated.
Some observations on forms of NaA and NaX zeolites growing in the presence of triethanolamine
Authors: Gutsze A. , Kornatowski J. , Neels H. , Schmitz W. , Finger G. 
Published: January 2007

AbstractUsing modified preparation conditions for silicate and aluminate solutions some differences in the result of large A‐ and X‐type zeolites crystallization utilizing Charnell's procedure have been obtained. A‐type zeolite crystals show clearly {110} faces. X‐type zeolite occurs in mixed phase together with A‐type zeolite as separate as well as overgrown crystals. These observations can be explained by structure defects in A‐type crystals and by presence of polysilicate or/and too high aluminium content in the gel.
Dislocations of salol crystals grown by the Czochralski method
Authors: Inoue T. , Komatsu H. , Jim W. Q. 
Published: January 2007

AbstractCrystals of salol were grown by the Czochralski method in three different pulling directions to examine the crystallographic orientation effect of the seed. They were characterized by the etch pit method and X‐ray projection topography.It was found that the dislocation density was 2 × 103−1 × 104/cm2 and that the configuration of dislocations was straight. The running directions of dislocations strongly depend on the pulling directions; i.e., [110] and [110] for the crystal grown in [100] axis, [110], [110] and [110] for the crystal pulled along [112] axis and [010] for [010] axis crystal.
Problems on the mechanically induced polymorphic transformation
Authors: Senna M. 
Published: January 2007

AbstractSome typical experimental results are presented and discussed phenomenologically on the topics; (i) the transformations which are readily carried out with the aid of mechanical stimulation but hardly by simple heating (PbO, ZnS); (ii) formation of metastable phases under the influence of mechanical stresses from the phase which is stable at room temperature under the atmospheric pressure (CdS, CdSe); (iii) pseudo‐equilibrium between polymorphs during grinding (CaCO3).
Infrared reflection spectra of selected modifications of SiO2 and Al2O3
Authors: Pechar František 
Published: January 2007

AbstractInfrared reflection spectra were measured within the wave number range of 1400 – −400 cm−1 for following SiO2 and Al2O3 modifications: quartz, opal, quartz glass, cristobalite, tridymite, corundum, sapphire, ruby, gibbsite, boehmite, and diaspore. The spectral bands were attributed, according to literature quotations, to individual vibrations of bonds SiO, OSiO, SiOSi, AlO, OAlO, and AlOAl. The evaluation of infrared reflection spectra has shown that they are very sensitive to internal vibrations of SiO, AlO, which are affected by the symmetry of the surrounding crystal field. They are therefore selective for individual minerals and thus suitable for quick identifying purposes.
Stability of growth conditions and α‐HgI2 crystal habit during growing by temperature oscillation method
Authors: Zaletin V. M. , Lyakh N. V. , Ragozina N. V. 
Published: January 2007

AbstractOn the basis of analysis of the experimental data, it is shown that:

the crystal growth rate is mainly determined by diffusion in vapour phase;
the limitation of the growth process by transport leads to an unremitting change of the growth conditions, being the cause of slowing down the growth and the change of the growth rates ratio of the crystallographically different facets, the latter evokes refaceting;
the limitation of the growth by the transport process is the factor reducing the perfection of the structure and the maximum sizes of single crystals.
The rapid precipitation of magnesium hydroxide from aqueous solutions: Analysis of nucleation and crystal growth kinetics, final nucleus numbers and primary crystal sizes
Authors: Packter A. 
Published: January 2007

AbstractThe studies of the rapid precipitation of magnesium hydroxide, from aqueous solutions of different concentrations by sodium, calcium and ammonium hydroxides, are analysed. The kinetics of nucleation and microcrystallite formation during the induction periods and the kinetics of crystal growth (onto the microcrystallites) to the final primary crystals are examined; the high final nucleus numbers and the sub‐microscopic sizes of the final primary crystals are discussed according to Nielsen's theories.
EDA complex stability constants and formation enthalpies in a binary liquid crystalline system with induced smectic phase
Authors: Demus D. , Hauser A. , Pelzl G. , Böttger U. , Schönburg S. 
Published: January 2007

AbstractIn the binary system 4,4′‐bis‐[n‐butylamino]‐biphenyl/‐(2,2‐dicyano‐ethenyl)‐phenyl 4‐n‐nonyloxybenzoate which due to EDA complex formation exhibits an induced SA phase, measurements of the charge transfer band, the molar volumina and transition enthalpies were done. By the concentration and temperature dependence, resp., of the charge transfer absorption and the strongly negative excess volumina we estimated the stability constant and the formation enthalpy of the complex.The data obtained by the two independent methods agree sufficiently.
Study of fatigue properties of AlZnMg alloy
Authors: Ptáček L. , Míšek B. 
Published: January 2007

AbstractThe present work is part of the comprehensive research of relations between the structure and mechanical properties of the AlZn4Mg1 alloy. Chemical composition of this alloy is Zn 4.97, Mg 1.21, Mn 0.25, Cr 0.13, Ti 0.05, Cu 0.015, Fe 0.28, Si 0.17, Al. The aim of the study of fatigue properties of the alloy is to provide information on the relations between fatigue properties, fracture structure and the heat treatment applied.The structure of the AlZn4Mg1 alloy is comparatively complex. The matrix is formed by solid solution with f.c.c. lattice. Dissolved in the solid solution are accompanying elements (Zn, Mg, Si, Fe). Also found in the matrix is the secondary phase (precipitates), both on grain and subgrain boundaries and dispersed within the grain. The dispersion degree of the secondary phase depends on the manner of aging.Due to high impurity content in raw materials (Fe, Si), large inclusions are formed in the structure with quite different mechanical properties.On the basis of earlier experience two types of heat treatment were used in testing the fatigue properties.Fatigue tests were made in alternating symmetrical cycle on a Wolpert‐Amsler 10 HFP 1478 pulsator. The stress amplitude for individual specimens was altered such that the Wöhler curve could be drawn up to 108 cycles. The cycling loading frequency did not differ considerably from the value of 125 Hz. Used in fatigue tests were cylindrical specimens that had been heat treated together whith reference specimens for tensile tests.Subsequent to destruction, the specimens were examined metallographically and fractographically, the substructure in fracture vicinity was investigated by SEM.Fractographic specimens were obtained by cutting away parts of the rod with fracture. For TEM, thin foils were taken from regions right under the fracture surface. The foils were cut with a diamond disk and subsequently thinned electrochemically. The JET method was used to prepare the foils.The values of mechanical properties for all the material states studied are tabulated below.
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Mass transfer during growth of GaInPAs solid solution in the equilibrium cooling growth technique
Authors: Kuznetsov V. V. , Moskvin P. P. , Sorokin V. S. 
Published: January 2007

AbstractKinetical analysis of crystallization of GaInPAs solid solutions grown by equilibrium cooling growth technique was performed. Theoretical data were compared with experimental data on LPE of the material. The dependencies of layer thickness, lattice mismatch variation between the substrate and layer and energy gap in the layers lattice matched to InP were calculated for different growth temperatures.
Dislocation etch‐pits revealed in submicron (100) GaAs epilayers by selective dissolution in the saturated GaSb melt
Authors: Bolkhovityanov Yu. B. , Bolkhovityanova R. I. , Trukhanov E. M. 
Published: January 2007

AbstractIt has been showed that the saturated GaSb melt when contacting with a (100) GaAs substrate or a thin film selectively dissolves these solid phases. The dissolved thickness can be made so small as 500 Å and the revealed etch‐pits are corresponding to the entrances of dislocation lines on the examined surface.
Electrical properties of r.f. sputtered thin films of CuInSe2(I)
Authors: Abdul‐Hussein N. A. K. , Samaan A. N. Y. , Tomlinson D. , Hill A. E. , Neumann H. 
Published: January 2007

AbstractThin films of CuInSe2 are deposited by r.f. sputtering onto glass substrates at different r.f. voltages and substrate temperatures using pressed and powder targets. The films are polycrystalline and p‐type conducting. The temperature dependence of the conductivity and the chemical composition of the films are measured as a function of the deposition conditions.
Study of the temperature stability of chabasite
Authors: Rykl D. , Pechar F. , Chalupský V. 
Published: January 2007

AbstractIsothermal decomposition of chabasite was carried out at temperatures of 20, 180, 400, 600, 735, 850 and 1000 °C with the aid of differential thermal analysis. The decomposition products were identified by X‐ray powder diffraction and infrared absorption spectroscopy. It was found that the crystal structure of chabasite was stable in the whole range of temperatures. Dehydration takes place at a single stage. A change in lattice parameters, in intensity and splitting of X‐ray diffraction lines takes places with increasing temperature. Dehydration corresponds to the decrease in intensities of valence vibrations of OH, and the vanishing of librations and deformation vibrations of H2O. The residual water is heterolytically decomposed and forms structural OH groups in the large cavities of the mineral, which partly survive up to 1000 °C.
Untersuchungen der entmischungsprodukte in AlZnMg‐Legierungen mit hilfe der elektronenmikroskopie
Authors: Degischer H. P. , Lacom W. 
Published: January 2007

AbstractDie Charakterisierung und Trennung der mit unterschiedlicher Struktur, Kohärenz und Orientierung zur Al‐Matrix auftretenden metastabilen und stabilen Phasen in einer AlZnMg‐Legierung mittels verschiedener elektronenmetallographischer Methoden werden beschrieben, wobei besonders auf die Interpretation der Feinbereichsbeugungsbilder hingewiesen wird.Der Unterschied zwischen den metastabilen Phasen η2 und R2 wird herausgestellt; für die wichtigsten η‐Orientierungen gemäß Löffler et al., Degischer et al., und Buerger werden Modelle der geometrischen Gestalt vorgeschlagen. Die Korrelation einzelner Wärmebehandlungsschritte zu identifizierten Entmischungsprodukten wird hergestellt.
A general treatment of X‐ray (residual) macro‐stress determination in textured cubic materials: General expressions, cubic invariancy and application to X‐ray strain pole figures
Authors: Brakman C. M. 
Published: January 2007

AbstractAn expression in terms of general hkl and orientation distribution functions for the relationship between the elastic lattice strain measured by means of X‐ray diffraction methods and the (residual) elastic stress is given for cubic textured materials. In practice the socalled sin2 Ψ‐method is often used to determine these macro stresses. Then, for the case of textured specimens the quasi‐isotropic X‐ray elastic constants (depending on hkl only) become complicated functions of the crystallographic texture (J. Appl. Crystallogr. 16, 325 (1983)).Results are given for both orthorhombic and monoclinic specimen symmetry in terms of general (b.c.c. or f.c.c.) hkl and allow every permutation possible for a given hkl combination. From this cubic invariancy some new cubic invariant spherical surface harmonics are derived which are represented on a basis consisting of the 4‐fold symmetry axes of the cubic crystals.Special textures and special stress‐states are discussed. For a given texture of a cold‐rolled production steel sheet values of the predicted elastic strains are given in terms of “X‐ray strain pole figures”.