bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermodynamic functions of (InP)x(InAs)1‐x from 5 to 300 K
Authors: Sirota N. N. , Antyukhov A. M. , Novikov V. V. , Fyodorov V. A. 
Published: January 2007

AbstractTemperature dependence of the heat capacity of the solid solutions (InP)x(InAs)1‐x has been investigated over the temperature range from 5 to 300 K. Solid solution samples with x = 1; 0.8; 0.6; 0.4; 0.2; 0.1; 0 produced by means of crystallization from the melt the following annealing and diffusion in the powder at temperature close to solidus have been studied. The absolute values of enthalpy H, entropy S, Gibbs free energy Z as well as their deviations from the additive values have been obtained for the (InP)x(InAs)1‐x system from the analysis of the thermodynamic properties of the solid solutions of the III–V compounds at low temperatures. The curves for the characteristic temperatures (T) of the solid solutions studied show that the change of the character of the phonon spectrum is negligible, the thermodynamic functions are close to additive, the influence of the enthalpy and entropy of mixing on the deviations from the additive enthalpy and entropy of the alloys is insignificant.
Periodic crystallisation of magnesium hydroxide: effect of additives and gel
Authors: Ambrose S. , Kanniah N. , Gnanam F. D. , Ramasamy P. 
Published: January 2007

AbstractEffect of additives on the periodic crystallisation of magnesium hydroxide is investigated. The dependence of the concentration ageing and pH value of the gel on periodic crystallisation of magnesium hydroxide is also investigated. Velocity constant, spacing coefficient, and the flocculation value are reported. The experimental observations have been accounted.
Anomalous stratification of copper carbonate in agar Gel
Authors: Krishnan S. , Gnanam F. D. , Ramasamy P. , Laddha G. S. 
Published: January 2007

AbstractDuring the periodic precipitation of copper carbonate in agar gel it is observed that the spacing law of Jablczynski is not obeyed if the rings have to occupy all the positions of the series. Instead, if it is assumed that there may be discontinuities in the observed pattern which indicate that the rings of corresponding orders might not have been formed, the geometric law is faithfully obeyed. These discontinuities disappear if thiourea is added as an impurity along with the inner electrolyte. For different pH values of gel the pattern splits up into a number of groups, each exhihibits a revert type Liesegang phenomenon in which the last group contains revert followed by direct ring. The Liesegang phenomenon of this system has been explained on the basis of coagulation theory.
On the codeposition of silicon and boron (I)
Authors: Bartsch K. , Wolf E. 
Published: January 2007

AbstractThe influence of the conditions of deposition on the distribution of boron between gaseous and solid phase has been calculated thermodynamically. The results of the experimental investigations in a system for deposition on rods agree with the thermodynamically calculated dependences up to concentrations of boron in deposited silicon of nearly 5 × 1016 cm−3. At lower concentrations of boron a significant decrease of the incorporation of boron is found which cannot be explained by the thermodynamic model.
Generation of etch pits on sectional planes of unidirectionally solidified cd‐zn eutectic samples
Authors: Rost J. , Schneider H. G. 
Published: January 2007

AbstractA series of experiments were carried out for generating defined etch pits on various sectional planes of unidirectionally solidified Cd‐Zn eutectic samples. This was done as preliminaries of real structure investigations. For that purpose chemical, electrolytic, and ion beam procedures were tested.
Chemical etching of sapphire
Authors: Marasina L. A. , Malinovsky V. V. , Pichugin I. G. , Prentky P. 
Published: January 2007

AbstractThe results on etching of sapphire substrates with different orientation are discussed. High temperature etching in hydrogen stream and etching in the mixture of H3PO4 and H2SO4 were used in experiments. The relation of etching rates for different sapphire orientations were established in both cases. The conditions of nonselective etching were determined.
The crystallisation of alkaline‐earth metal tungstates from metal chloride melts: solubility – temperature phase diagram studies
Authors: Packter A. 
Published: January 2007

AbstractThe solubility vs temperature phase diagrams, for magnesium, calcium, strontium and barium tungstate solutions in lithium, sodium, potassium chloride melts and in the alkalineearth metal chloride melts, have been analysed. The solution in the alkali metal chloride melts are pseudo‐binary reciprocal ternary mixtures; the more soluble barium tungstate systems show small deviations from ideality, while the less solube magnesium tungstate systems show marked deviations from ideality, especially in sodium and potassium chloride melts. These deviations are related to electrostatic effects in solution, that depend on some function of reciprocal solute and solvent cation radii.The solutions in the alkaline‐earth metal chlorids melts are binary mixtures with no solvate formation; these systems show some from ideality at low mole fractions (x = 0.1 to 0.25) but they are practically ideal at mole fractions from 0.25 to 0.6.
Kinetic of potash alum crystallisation
Authors: Karpinaski P. , Nyavlt J. 
Published: January 2007

AbstractMetastable zone width of potash alum in aqueous solutions has been measured as function of the cooling rate in absence as well as in presence of seed crystals. From these data, the effective nucleation rate was calculated. Growth rate of potash alum crystals has been measured in a fluidized bed. Overall growth rate coefficient, kG, was then used for determination of the mass transfer coefficient, kD, and the rate constant of the intergration step kr. The dependence of kD on hydrodynamic conditions is discussed.
A p‐AlxGa1‐xAs‐p‐GaAs‐n‐GaAs concentrator solar cell design without a collection grid
Authors: Romero R. 
Published: January 2007

AbstractA concentrator solar cell is designed without a front contact collact collection grid. Its p‐AlxGa1–xAs‐p‐GaAs‐n‐GaAs epitaxial structure on a p‐GaAs substrate allows for collection of the carriers generated in the p region through the substrate while carriers generated in the n region are collected through an edge ring contact.Although cell efficiency depends on specific cell design, it has been found that such a device may work efficiently at over 100 sun incident radiation levels.
On the Binding Energy of Clusters with a Small Number of Lithium Atoms and Varying Scope of Interaction Between the Atoms. Hückel Molecular Orbital Approximation
Authors: Delineshev S.V.P. 
Published: January 2007

AbstractThe effect of the scope of interaction between the atoms in two‐dimensional and threedimensional clusters containing 6, 7, 9, 10, 15 and 16 lithium atoms, upon the binding energy (BE) of the clusters has been investigated. BE of the clusters was calcuated by the HÜCKEL Molecular Orbital (HMO) method.It has been established that for clusters with the same number of atoms BE has its maximum value when the interaction of each atom of the cluster with the atoms of its first and second coordination spheres in the lithium lattice are taken into account. After the maximum BE decreases and tends to a constant value which is attained when the interaction of each atom of the cluster with the atoms of its six coordination spheres is taken into account.The reasons for the above result should be looked for in the limits of applicability of the calculation procedure based on the HMO method to the study of properties of various models of clusters containing a small number of metal (e.g. lithium) atoms.
Apparatus for Selfcontrolled Growth of Hg2Cl2 Single Crystals
Authors: Barta Č. , Koštál E. , Tříska A. 
Published: January 2007

AbstractThe device for growth process and quality of the growing calomel (Hg2Cl2) single crystals studying is described. The function of the apparatus is based on the analysis of the information modulated on the poychromic light beam passed through the growing crystal. By means of this method the device determinates the temperature and the quality of the growing crystal. In the second part of this paper the special TV equipment is described. By means of that an information about the temperature and quality distribution in the whole growing crystal is obtained.
Electron Optical Investigation of Growth‐Induced Inhomogeneities of Synthetic Hg2Cl2 Monocrystals
Authors: Ramlau R. , Reiche M. , Heydenreich J. 
Published: January 2007

AbstractThe submicroscopic structure of synthetic Hg2Cl2 monocrystals was investigated by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), indirect imaging of surfaces (Pt/C replica technique) as well as by application of supplementary methods. As already reported by NEUMANN et al., TEM‐images show a periodic stripelike contrast whose period varies from 0.1 m̈m to 0.2 m̈m. It proved that the stripelike contrast arises from a periodic chemical inhomogeneity of the synthetic crystals. The chemical inhomogeneity probably consists in periodic deviations from the stoichiometric composition of Hg2Cl2. By reason of the orientation on {110}‐, (001)‐, and {114} faces a reconstruction of arrangement of the structures in the crystals is carried out. According to that, the stripes have to be interpreted as intersection lines of 2‐dimensional formations with the corresponding faces.
New Types of Polarizers Made from Crystals of the Calomel Group
Authors: Barta Č. , Trnka J. 
Published: January 2007

AbstractThe present work deals with the applicability of the mercurous halide crystals to the production of polarizers of light. The wide transmission region of these crystals mainly in the infrared region allows to use them for wavelenghts up to about 20 m̈m for mercurous chloride and 30 m̈m for mecrurous bromide. Especially high double refraction allows a construction of classical polarizer types having very advantageous parameters, i.e. small thickness of the element and large angle of splitting of the ordinary and extraordinary ray. Besides, high double refraction allows an original design of single‐piece (monolithic) polarizers which are characterized by relatively simple treatment, high quality and low losses.
Properties of Surface Layers in Single Crystals of Calomel
Authors: Barta Č. , Brožek V. , H´jek B. , Barta Č. 
Published: January 2007

AbstractWithin the framework of the systematic study of differences in physical properties of the calomel (Hg2Cl2) single crystals before and after surface treatment, the differences in the microhardness, the residual stress in the surface layer, and the chemical etching rate were investigated on the (110) and (001) crystal faces. It has turned out that Beilby layer (B‐layer) formed during surface treatment is softer, and, on the cleavage surface is harder than the underlying bulk material. The thickness of the B‐layer in these samples ranged between 5 anf 7 m̈m. Further it has been found that a tensile residual stress s̀ = 14 Nm‐2 prevails in the surface layer of a polished (110) face to a depth of 70 m̈m and, after grinding, to a depth from 90 to 200 m̈m. On the other hand, a compressive stress has been found in the natural cleavage plane. Experiments on etching the Hg2Cl2 crystals with HCl + HNO3 etching solution have shown that the rate of chemical etching is 2 to 4 times larger on the (110) face than on the (001) face. Differences are very strongly dependent on the experimental conditions and on the real structure of a given surface.
The Morphology of Hydrothermally Grown Plagioclase
Authors: Franke W. , Ghobarkar H. 
Published: January 2007

AbstractPlagioclase crystals Ab20An00 and nearly pure anorthite were grown on the surface of artificial melts by hydrothermal treatment at 2 kb. The average crystal size was 0.002 to 0.008 mm. In the temperature range of 400° to 600°C a pseudohexagonal habit was observed for anorthite while a lath‐like habit due to the prevalence of {010} was found for the Ab20An80 composition. Dominating faces are {010} {130} {110} {100} {110} {130} in the zone [001] and {021} {111} {111} {021} {111} {111} together with {001}.
Melt‐Growth of Single Crystals of Cadmium Iodide and Study of Their Polytypsim by X‐ray Diffraction
Authors: Chaudhary S.K. , Trigunayat G.C. 
Published: January 2007

AbstractSingle crystals of cadmium iodide have been grown from melt using Bridgman‐Stockbarger system and their polytypism studied by X‐ray diffraction. The initially grown crystals were found to stick to the walls of the ampoule and had black specks of impurity suspended in them. A systematic study has been carried out to determine the effect of degree of vacuum, material of the ampoule and quality of raw material on crystal growth. It has been concluded and later verified using zone‐refined material that the observed sticking essentially stems from the presence of impurities in the raw material. From X‐ray diffraction it is found that all crystals belong to the most common polytype 4H alone.
Crystalloluminescence and Mechanoluminescence Spectra of Ba(ClO3)2 · H2O and 2 K2SO4 · Na2SO4 Crystals
Authors: Chandra B.P. 
Published: January 2007

AbstractCrystalloluminescence and mechanoluminescence of Ba(ClO3)2 · H2O and 2 K2SO4 · Na2SO4 crystals are investigated. The crystalloluminescence spectra are almost similar to the photoluminescence spectra; however, they differ completely from the mechanoluminescence spectra. The crystalloluminescence excitations may take place due to the various processes: (i) the recombination of ions, (ii) from amorphous to crystalline transition, (iii) from the phase change during the crystallization, and (iv) from the dielectric breakdown by the electric field produced due to the creation of microfracture during the crystal growth. It is concluded that the crystalloluminescence excitation in Ba(ClO3)2 · H2O and 2K2SO4 · Na2SO4 crystals may be chemical in origin.
Morphological Lattice and Reciprocal Crystal. Remarks on Morphology of Barite and Cerussite
Authors: Follner H. 
Published: January 2007

AbstractThe relationship between partitions of the three‐dimensional space into Dirichlet domains of morphological points and the face forms observed on crystals will here be examined. Dirichlet domains, the central points of which are to be found on the exterior net plane, can be connected two or one‐dimensionally through face‐sharing or they occur as isolated groups. If the crystal faces are arranged according to the proportion of these surface polyeder on the total surface of the net plane, the order of rank of barite and cerussite agree excellently with the experimental observations. The packings of space filling polyeder allow conclusions on growth mechanisms.
Morphological Stability of Vapour Grown Metal Single Crystals
Authors: Nanev Ch R. , Iwanov D. 
Published: January 2007

AbstractThe formation of shallow cavities on the faces of zinc (and cadmium) single crystals after reaching some critical size during growth from vapours in inert gas (Ar, H2) atmosphere has been discussed. New experimental facts concerning cavity form and the diffusion origin cause of the phenomenon have been reported. A satisfactory good semi‐quantitative agreement with the theoretically predicted critical sizes (CHERNOV, CAHN) has been found as a result of the precise discussion of the experimental results. The conclusion has been drawn that the diffusion in the parent phase plays unambigously a decisive role by the formation of the morphological peculiarities during vapour growth in inert gas atmosphere.
Crystallization of Sulphides in KSCN Melts
Authors: Bohac P. , Tanner V. , Gaeumann A. 
Published: January 2007

AbstractThe melt of potassium thiocyanate can be used as solvent and as supplier of sulphur for the preparation of crystals of sulphides and complex sulphosalts. The solubilities of some sulphides in the KSCN melt were determined at 250°C. Small crystals of sulphides of Cu, Ag, Tl, Hg, Pb, Ni and of ternary As‐ and Sb‐sulphosalts of these metals could be obtained from this flux in a temperature gradient. Moreover, crystals of sulphides were formed by a direct slow reaction of metals with molten KSCN.
Changes of the Surface Structure of Quartz Monocrystals as a Result of the Influence of Sodium Salts at High Temperature
Authors: Sokoll R. 
Published: January 2007

AbstractIn Ergänzung zu der früher beschriebenen Überstrukturbildung auf Quarzeinkristall‐Oberflächen infolge ihrer Wechselwirkung mit einfachen Gasen, wird über Strukturveränderungen berichtet, welche bei der Einwirkung von Natriumsalzen auf die große Rhomboederfläche (1011) und die Prismenfläche (1010) von Quarz ablaufen, Neben schon bekannten Erscheinungen bildet sich auf der Prismenfläche infolge der Einwirkung von NaNO3 eine bisher noch nicht beobachtete Überstruktur aus. Als Untersuchungsmethode dient die streifende Beugung hochenergeitischer Elektronen (RHEED).
Crystal Growth in Magnetic Fields (II) Crystallization of Co(NH4)2(SO4)2 · 6 H2O from Aqueous Solutions in High Magnetic Fields
Authors: Kuschel F. , König AN 
Published: January 2007

AbstractThe displacement rate of (110) single crystal faces of Co(NH4)2(SO4)2 · 6 H2O has been measured in dependence on the supersaturation of aqueous solutions in the zero field and at magnetic flux densities of 7 T. The results show that in a given external field measurable effects near the equilibrium don't occur (thermostatic field effect). On the contrary a marked influence at extreme relative supersaturations can be observed (kinetic field effect).
Growth and Characterization of GaP Substrates for Liquid Phase Epitaxy
Authors: Moravec F. , Novotný J. , Kirsten P. , Siegel W. , Koi H. 
Published: January 2007

AbstractGaP light‐emitting diodes were prepared by a single LPE process on LEC and SSD substrates. Red LEDs with a maximal efficiency of 5% could be grown reproducibly on SSD substrates with grains. The effciency of the best LEDs on substrates grown by the conventional LEC method is essentially lower (0.5%) but it can be improved considerably by a modification of the growth conditions. The substrates were characterized by structural, chemical, electrical and optical measurements and the observed differences in the luminescence efficiency between the LEDs grown on LEC and SSD subtrates, respectively, were discussed under consideration of these investigations.
The Growth Kinetics and Surface Morphology of GaN Epitaxial Layers on Sapphire
Authors: Malinovsky V. V. , Marasina L. A. , Pichugin I. G. , Tlaczala M. 
Published: January 2007

AbstractThe growth kinetics of GaN on Sapphire was analyed on the base of some experimental data such as: the growth rate temperature depandence, on the base of some experimental data such as: the growth rate temperature dependence, the grwoth rate dependence on the gas flow velocity, the growth rate depandence on the crystallographic and spatial orientation of the substrate. The limiting stage of the epitaxy process was established at different growth conditions. The morphology of GaN epitaxial layers obtained at these conditions is described.
Germanium Incorporation in Ga1–xInxAs LPE Layers and GaAs Bulk Crystals
Authors: Müller K. , Mothes W. , Jacobs B. , Butter E. 
Published: January 2007

AbstractAtomic absorption spectroscopy (AAS) is used to determine the Ge concentration in Ga1–xInxAs and GaAs. The orientation dependence of Ge incorporation in (111)A‐and (111)B oriented samples has been studied. The distribution coefficients for both the orientations were determined to be kGe(111)A = 2.6 · 10−2 and kGe(111B = 1.4 · 10−2 for Ga1–xInxAs with 0 ≦ x ≦ 0.13. The differences between the two orientations are explained with the aid of the band bending model. Doping gradients in thick epitaxial layers and along crystal length of polycristalline TGS‐grown GaAs ingots have been investigated too. In Ga1–xInxAs layers any Ge concentration gradient couldn't be observed, but in TGS compact crystals Ge concentration increases with crystal length because the melt composition changes significantly during solidification. The results are compared with those of electrical measurements.
On the Density of Synthetic Glasses in the System Soda Melilite – Gehlenite/Ákermanite
Authors: Teichert G. , Strohmann R. , Paufler P. , Schreiter P. 
Published: January 2007

AbstractThe solid density has been determined at 25°C by hydrostatic weighing along the binary systems Sm–Ge50Åk50 and Sm–Ge70Åk30. The molar volume V decreases linearly with increasing mole fraction of GemÅkn, xB, according to δV/δxB = −5.08 cm3 mol−1 and −4.40 cm3 mol−1 for Ge50Åk50 and Ge70Åk30, respectively. The results enable the molar fraction xB to be determined from density measurements with an absolute error of ±5 mol%.
Dielectric Relaxation in Low Temperature Smectic Phases of 4‐n‐Alkyloxy‐benzylidene‐amino‐4′‐cyanobiphenyls
Authors: Gajewska B. , Kresse H. , Weissflog W. 
Published: January 2007

AbstractThe dielectric behaviour of five homologous 4‐n‐alkyloxy‐benzylidene‐amino‐4′‐cyanobiphenyls was investigated. Especially, we were interested in the dielectric relaxation frequencies of the smectic low temperature phases SB and SE as well as the dielectric behaviour in the solid state. We have found in all liquid crystalline phases a low frequency relaxation region explained by a hindered rotation of the molecules around their short axes. By supercooling of the hexyl and heptyl derivatives a new liquid crystalline phase can be obtained. A dielectric relaxation in the solid phase could not be found.
Time‐varying Temperature Profile CVD Methods for Growing CuInS2 and CdIn2S4 Crystals
Authors: Paorici C. , Zanotti L. , Curti M. 
Published: January 2007

AbstractA time‐varying temperature profile method is reported for growing crystals in horizontal closed‐tube arrangements by vapour phase iodine transport. After an initial stage, during which the temperature is linearly raised with time in the source region of the container, in such a way as to control the primary nucleation (a limited number of seed crystals can thus be produced), a second stage follows during which the source temperature is allowed to oscillate in order to favour the secondary nucleation (only the first grown seed crystals are then allowed to grow). A proper choice of the frequency and amplitude of the temperature cycle is shown to control the growth up to the obtainement of solitary crystals per run of CuInS2 and CdIn2S4. The role of the slow growing faces in favouring good performances of the method is emphasized.
The recovery of Quenched‐in Vacancies in Fe–Al (6.3 to 28.3 at.%) Alloys studied by Positron Annihilation
Authors: Dlubek G. , Brümmer O. , Möser B. 
Published: January 2007

AbstractMeasurements of the peak height of the 2γ‐angular correlation curve were carried out during constant rate heating of Fe–Al alloys with an Al‐content between 6.3 and 28.3 at.%. The samples had been quenched form 1000°C into water at room temperature. Two recovery stages are observed. The first stage at 100 to 200°C shows a small decrease of the peak height. The main stage at 300 to 400°C is attributed to the migration and disappearance of monovacancies. From isothermal measurements the migration enthalpy of vacancies is estimated to (1.15 ± 0.1) eV in Fe–Al (19.9 at.%) and to (1.31 ± 0.1) eV in Fe–Al (24.4 at.%). – In samples with an Al‐content between 13.8 and 28.3 at.% a minimum in the peak height at 400°C is found. Obviously a particular stage is formed in these samples during migration of quenched‐in vacancies. Possible causes of the effect are discussed.