bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffusion Phenomena during the heteroepitaxy of Ternary Compounds of the Type (AxB1–x)1–ΔC1+Δ
Authors: Schäfer P. , Bremser W. 
Published: January 2007

AbstractIn heteroepitaxy of ternary compound systems of the type (AxB1–x)1–ΔC1+Δ has to be taken into account the occurrence of complex diffusion phenomena independent on the epitaxial method applied which cannot be considered within a quasi‐binary system AC–BC. Based on the statements of thermodynamics of irreversible processes a model for the calculation of diffusion profiles, regarding the influence of the compound crystal composition x on the deviation from stoichiometry Δ, is presented. Concentration profiles calculated in accordance to this model show typical maxima and minima. – Tellurium distribution profiles determined on heterostructures of the type (Pb1–xSnx)1–ΔTe1+Δ /PbTe got by electron‐probe microanalysis may be explained qualitatively within the presented model. With the EBIC‐method additional p‐n junctions at the position of the extrema in the tellurium distribution were found.
Isothermal Ageing in the T Range from 0°C to 180°C of a Technical Al‐2.0 at.% Zn‐1.3 at.% Mg Alloy after Direct Quench
Authors: Gerlach R. , Löffler H. 
Published: January 2007

AbstractThe variations of the structure and the mechanical properties had been investigated by means of TEM investigations and determination of the microhardness number in the Ta range between 0 °C and 180 °C. The main results are the following: – At the starting period of the isothermal ageing an incubation time, tinc, occurs. tinc plotted versus Ta yields two intersecting C curves at about 100 °C. – At Ta = 70 °C the only decomposition product are G.P. zones. – At 70 °C <Ta <100 °C the G.P. zones formed in the first period of decomposition can be transformed into η‐phase or spherical hexagonal (S.H.) zones. – Above about 110 °C the precipitates present in the matrix are quasi‐homogeneously formed at nucleation sites delivered by clusters of impurity atoms.
Calculation of the P and as activity coefficients in in–p and in–as mixtures with the regular solution approaches and lattice models
Authors: Kühn G. , Sühnel K. , Rentsch H. 
Published: January 2007

AbstractThe activity coefficients of P and As in the mixtures of In–P and In–As are calculated along the liquidus curve in the concentration ranges 0.014 ≦ xP ≦ 0.45 and 0.019 ≦ xAs ≦ 0.87 using different versions of the regular solution theory and the lattice models of BARKER and TOMPA. – It is shown that the Simple Solution, the Subregular Solution, and the model of BARKER with temperature‐dependent interaction parameters give a satisfactory description of the experimental variation of the activity coefficients and liquidus temperatures for both systems.
Purification of ZnSiP2 and ZnSiAs2 by sublimation in a hermetically sealed system
Authors: Deus P. , Koi H. , Buhrig E. , Voland U. 
Published: January 2007

AbstractIn many cases the ternary compounds of the type ZnSiC2v are produced by gas phase transport or growth from solution. In this way prepared ternary substances contain binary compounds as a rule which are mixed or intergrown with the ternary compound. By sublimation of binary accompanying components in closed ampoules may be purified these ternary compounds. The separation of contaminants is complete and the loss of ternary substance is negligible. The inhibited decomposition of the ternary compounds during sublimation compared with binary compounds is probably caused by formation of an Si surface layer hindering diffusion of the highly‐volatile elements of group II and V to the surface and their sublimation.
Calorimetric investigations in liquid crystalline terephthalylidene‐bis‐[4‐n‐alkylanilines] (TBAA)
Authors: Wiegeleben A. , Demus D. 
Published: January 2007

AbstractBy means of the calorimeter DSC‐2 the temperatures and enthalpies of phase transitions were measured in the homologues of TBAA with the alkyl chain length n from 2 up to 10, in order to confirm the existence of nine types of liquid crystalline mesophases and of the polymorphism in the solid state within this series. Pre‐and posttransitional phenomena, hysteresis effects in low temperature smectics and relations between enthalpies and chain lenght resp. kind of concerning phases could be observed.
Total pressure dependence of doping element incorporation during the chemical vapour deposition of epitaxial silicon
Authors: Kühne H. 
Published: January 2007

AbstractStarting from the literature on doping element incorporation at atmospheric and lower pressures the partial pressure of the dopants available within the deposition system is selected as a uniform basis of reference for the total pressure dependence of the doping element incorporation. It is shown that also at reduced pressures the incorporation equilibria of phosphor and arsenic, the author previously derived from the temperature dependence of the doping element incorporation may be used.
Influence of non‐uniformity of laser beam intensity on the surface layer structure of implanted silicon crystals
Authors: Wielunski M. , Auleytner J. , Czarnecki S. , Turos A. , Wielunska D. 
Published: January 2007

AbstractThe influence of the non‐uniformity of intensity distribution in a laser beam on the surface layer structure of As‐implanted silicon crystals as well as a method for homogenizing a pulsed laser beam is described.
Etch‐pit study of dislocation microstructure at the precipitates in NaCl:Ni crystals
Authors: Andreev G. A. , Klimov V. A. 
Published: January 2007

AbstractThe chemical etching technique was used to study the precipitation‐induced dislocation microstructures in NaCl:Ni crystals with 110 rod‐like precipitates. The comparison was made of the results obtained by the etch pit and decoration studies. The coincidence of the patterns suggests the prismatic dislocation loops and helices of the interstitial type to be only produced at elevated temperatures (above 300°C). The smallest size loops are removed by climb on slow cooling. These loops sometimes persist in quenched crystals.
Colour centre in YAG: Cr3+ crystals
Authors: Kvapil S. , Kvapil Jirí , Mánek B. , Perner B. , Sevastyanov B. K. , Orekhova V. P. 
Published: January 2007

AbstractYAG crystals doped with 0.01 wt% Cr were grown by Czochralski method using 98% Ar + 2% H2 protective atmosphere. Four colour varieties of the crystals were prepared in the dependence of the Al2O3 :Y2O3 ratio in the melt and the sign of electrical potential above the melt level. New absorption bands were attributed to the O− centre (400 to 480 nm), F centre (357, 500, and 833 nm) or Cr3+ at another site than octahedral (455, and 612 nm).
Investigation of GaN heteroepitaxial layers by means of the kossel effect technique
Authors: Geist V. , Ehrlich C. H. , Flagmeyer R. , Ullrich H. J. , Greiner W. , Rolle S. 
Published: January 2007

AbstractGaN heteroepitaxial layers grown on spinel substrates have been investigated by the Kossel effect technique. The excitation of GaKα X‐rays inside the crystal lattice was carried out either by means of 1.25 MeV protons or 40 KeV electrons. Both methods give similar results concerning the values of the lattice parameters and the sign of polarity. Following the proton irradiation a lattice expansion normal to the surface occurs. A comparison of our results with those of other authors shows that the growth direction is the same for {111} spinel and {0001} sapphire substrates.
Development of the microhardness of an al‐2.0 at.% zn‐1.3 at.% mg alloy with additions of technical impurities during a two‐step ageing treatment (ii)
Authors: Gerlach R. , Löffler H. 
Published: January 2007

AbstractThe alloy was preaged in the temperature range between Tpre = 50 °C and 160 °C for various times and afterwards postaged at R.T. The course of the microhardness and the related structure changes (TEM and SAXS investigations) were investigated. The main results are the following:– Preageing the samples times less than the incubation time no essential structure changes take place at least not in the sense that the further decomposition happening during the postageing at R.T. is remarkably influenced.– The samples preaged at Ta 110 °C for times somewhat longer than the incubation time show a distinct minimum after the end of the postageing period of 42 d at R.T. Most probably at Ta 110 °C in the starting period of the decomposition nuclei of the α‐phase or of spherical hexagonal zones were formed. These nuclei lessen considerably the amount of G.P. zones able to be nucleated during the R.T. postageing.
The heteroepitaxial growth of vacuum‐deposited GaP thin films on Si substrates
Authors: Malina V. , Kohout J. 
Published: January 2007

AbstractHeteroepitaxial GaP thin films were grown on (100) and (111)Si substrates by vacuum evaporation of the compound GaP and their structural characteristics were compared with homoepitaxial GaP films grown by the same technique on (100)GaP substrates. Nearly monocrystalline GaP thin films were deposited reproducibly on (100)Si substrates at the optimum substrate temperature of about 680–700°C and the deposition rate of 0.1 nms−1. The structure of such films was comparable in quality to homoepitaxial GaP/GaP films. No monocrystalline films could be deposited on (111)Si substrates.
Structural characterization of heteroepitaxial films of CdSe and ZnTe
Authors: Gagara L. S. , Gashin P. A. , Dvornik G. G. , Leondar V. V. , Paskal P. S. , Simashkevich A. V. 
Published: January 2007

AbstractThe effects of composition, orientation and temperature of substrate on the structure and morphology of epitaxial CdSe and ZnTe films are analyzed. Single crystal wafers of zinc telluride and zinc selenide oriented along (110) and natural cleaved mica were used as substrates. This paper presents a complex investigation of the growth mechanism and crystal perfection of the films by optical microscopy, X‐ray and electron diffraction, and by electron microscopy. The structure of the transient region of the film substrate interface was studied by X‐ray microanalyzer and by scanning electron microscope.Cadmium selenide layers grown on mica had hexagonal structure and were oriented in the (0001) plane, those grown on zinc telluride crystals had cubic structure and orientation along (110). Zinc telluride layers were cubic and were oriented parallel the (111) plane when deposited on mica, and parallel to (110) when deposited on zinc selenide substrates. It is shown that the layers grew by a layer mechanism.Epitaxial growth of cubic cadmium selenide layers on zinc telluride single crystals, as well as of ZnTe layers on ZnSe substrates, made it possible to grow heterojunctions with a low density of misfit dislocations at the interface; this gave rise to intensive injection electroluminescence and effective separation of non‐equilibrium charge carriers in such structures.
The influence of silicon on the crystallographic phases of the niobium‐gallium system studied by x‐ray diffraction methods
Authors: Herold A. , Försterling G. , Kleinstück K. , Savitski E. M. , Yefimov Y. V. , Bytschkova M. J. , Sumarokov B. N. 
Published: January 2007

AbstractThe influence of silicon on the crystallographic phases of the binary niobium‐gallium system is studied by X‐ray diffraction methods. The samples were prepared by rapid quenching. Silicon substituted gallium in all phases of the binary system. It exists a complete pseudobinary solid solution Nb5Ga3‐Nb5Si3. The maximum degree of substitution in the A 15 phase Nb3Ga1–xSix is x = 0.5. The presence of two A 15 phases with different cell parameters indicates the existence of a miscibility gap.Contrary to the expections the supercondusting transition temperatures decreases with an increasing degree of substitution.
Dislocation etch pits in anhydrous diglycine sulfate
Authors: Pandya G. R. , Vyas D. D. 
Published: January 2007

AbstractNew dislocation etchants for anhydrous diglycine sulfate single crystals have been developed and the etching results are reported. Dichloroacetic acid, glacitel acetic acid and their mixtures work as dislocation etchants on the cleavage plane of the crystal. Morphology of the etch pits was found to vary with the etchant composition.
Ultraviolet Absorption of Hg2Cl2‐and Hg2Br2 Single Crystals
Authors: Bryknar Z. , Hersel W. , Barta Č. 
Published: January 2007

AbstractThe optical unpolarized absorption spectra of Hg2Cl2 and Hg2Br2 single crystals were measured in the spectral range 230–400 nm. A sharp exciton peak and other absorption bands of both halides were observed near the fundamental absorption edge. The absorption peaks due to the splitting of the halogen doublet were also observed. Positions of the exciton peaks are characteristic for the Frenkel (localized) type of excitons. Possible interpretations of the other observed bands are discussed.
Study of a Surface Layer of Calomel Monocrystals by the Method of Plastmatic Etching
Authors: Barta Č. , Barta Č. , Bartov´ A. , Brožek V. , H´jek B. , Hoŕček V. 
Published: January 2007

AbstractThe method of plasma (ionic) etching provides information on both the degree of damage and the real structure of a treated surface of a cleavage crystallographic plane (110). The altered surface structure of this plane, which is due to cutting, grinding and polishing, is a cause of a rapid loss of calomel at the beginning of the etching process. The minimum loss rate is directly proportional to the thickness of the damaged surface. The ensuring rapid loss of calomel is due to an increased ruggedness of the surface. The ionic etching of calomel on the crystallographic plane (110) proceeds in six phases which are documented in photographs. The method of ionic etching is promissing for a high‐quality treatment of surfaces of calomel acousto‐optical functional elements designed for connections with ultrasound transducers.
Optical Properties of CuInSe2 Thin Films Prepared by R.F. Sputtering
Authors: Neumann H. , Perlt B. , Abdul‐Hussein N.A.K. , Tomlinson R.D. , Hill A.E. 
Published: January 2007

AbstractThe optical absorption of r.f. sputtered CuInSe2 thin films was studied in the photon energy range from 1 to 3 eV. The gap energy and the spin‐orbit splitting are found to be (1.01 ± 0.01) eV and (0.24 ± 0.02) eV, respectively. From the photon energy dependence of the absorption coefficient it is concluded that the heavy and light hole bands are parabolic whilst the split‐off band contains terms linear in the wavevector. The optical transition probability for valence band‐ to‐ conduction band transitions is estimated to be (10.8 ± 1.0) eV which yields an admixture of copper d states to the valence band of (30 ± 8) %.
Redistribution of Heavy Metal Impurities in Silicon by Phosphorus Diffusion
Authors: Knoll D. , Fischer A. 
Published: January 2007

AbstractBased on a model for redistributing heavy metals in two‐phase‐silicon an expression is obtained, describing the intensity of redistribution, being determined by the segregation coefficient between intrinsic and phosphorus‐doped silicon and the spatial extension of the phosphorus phase. The P‐diffusion and heavy metal segregation representing two partial processes of heavy metal gettering are discussed as a one‐ and multiple‐temperature‐time‐procedure. The heavy metal gold is selected as an example, by means of which the different temperature‐time‐regimes are compared to each hother with a view to the redistribution intensity.
On the Structural and Electronic Characteristics of Titanium Sulphide (Tis1.7) Crystals
Authors: Pande Chitra , Prasad Neelam , Srivastava O.N. 
Published: January 2007

AbstractTiS1.7 crystals have been grown by vapour transport technique employing a two‐zone furnace with the temperatures of reaction and growth zone maintained at 1073 K and 973 K, respectively. We have measured the variation of electrical conductivity (s̀) with temperature (T) of TiS1.7 single crystals. It has been found that the conductivity increases at temperatures T > 433 K, which provides convincing evidence that the TiS1.7 crystal is a semiconductor. Another electronic characteristic of TiS1.7 crystals observed in the present investigation is the occurrence of voltage controlled negative resistance (VCNR) at a field of 32.1 V cm‐1 to 35.7 V cm‐1. All the polytypes of TiS1.7 were found to exhibit VCNR nearly at the same field which indicates that the VCNR is polytype independent property. The occurrence of VCNR has been explained on the intervally transfer of electrons in the conduction band.
Periodic Crystallisation of Magnesium Hydroxide in Agar‐Agar Gel
Authors: Ambrose S. , Kanniah N. , Gnanam F. D. , Ramasamy P. 
Published: January 2007

AbstractInvestigations are made to get the experimental conditions for obtaining periodic crystallisation of magnesium hydroxide in agar‐agar gel. A detailed study is made on the dependence of the velocity constant (K), the spacing coefficient \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {p = \frac{{x_{n + 1} }}{{x_n }}} \right)'$\end{document} the length of the continuous precipitate and the width of the rings on the concentrations of the inner and outer electrolytes. Using SHINOHARA's revised coagulation theory, the flocculation value F is calculated. F = Γ + C30, where Γ is the characteristic concentration of the outer electrolyte for which the flocculation starts and C30 is the reduced concentration of the reaction product. The value of the concentration of the outer electrolyte for which the flocculation stops (γ) is calculated. The dependence of F on the concentrations of the reactants is also discussed. Observation of a coneshaped precipitation is also reported.
Batch Precipitation of Potash Alum Crystals by Mixing Aqueous Solutions of the Component Salts
Authors: Mullin J.W. , Žáček S. , Nývlt J. 
Published: January 2007

AbstractThe effects of temperature, supersaturation, excess of reacting component salts and method of precipitation on the batchwise precipitation of potash alum crystals, by mixing aqueous solutions of potassium sulphate and aluminium sulphate, have been investigated. From the primary characteristics of the process (crystal size, size distribution and yield) relative crystal growth rates and relative nucleation rates are calculated and interrelation of these rates with the corresponding supersaturation leads to a value of the nucleation order. It is concluded that secondary nucleation plays an important role in the batch precipitation of potash alum crystals.
Quantitative Description of the Influence of the Inhibitor Concentration on the Growth Rate of Barium Sulfate Crystals in Suspension (III)
Authors: Van Rosmalen G.M. , Van Leeden M.C. Der 
Published: January 2007

AbstractTo describe quantitatively the effect of a growth inhibitor on the growth rate of barium sulfate crystals, suspended in a supersaturated solution, the “strength of inhibition” has been introduced. The strength of inhibition is defined as the ratio of the mean linear growth rates without and with inhibitor at the same value of the growth affinity. It has been shown that the strength of inhibition, exerted by 1‐hydroxyethylidene‐1, 1‐bisphosphonic acid (HEDP) and aminomethylene‐bisphosphonic acid (AMDP) on the growth process, not only depends on its concentration, but also on the growth affinity, or probably even on both the growth affinity and the changes in the geometry of the crystals due to their growth in the presence of an inhibitor.
Influence of Gravitation on the Processes of Heat and Mass Transfer in Solution Crystal Growth by the Travelling Heater Method (THM) (I)
Authors: Cherepanova T.A. 
Published: January 2007

AbstractIn axially symmetric and planar cases the formulation is given of a two‐dimensional hydrodynamic thermodiffusive problem on the crystal PbTe growth from solution by the travelling heater method. The analysis of the one‐dimensional thermo‐diffusive problem solution is presented. The dependences were obtained of the growing and dissolving interface positions relative to the heater on the heater travel rate for different lengths of solvent zone.
Saturation Dislocation Structures in Cyclically Deformed Nickel Single Crystals of Different Orientations
Authors: Mecke K. , Blochwitz C. 
Published: January 2007

AbstractThe major aim of this paper is to describe and characterize qualitatively the saturation dislocation structures in fatigued nickel single crystals with different orientations and to relate them to the mechanical properties. Within the investigated plastic strain amplitude region all measured cyclic stress strain curves exhibit two ranges with a sharp transition. In the first range of the cyclic stress strain curve the dislocation arrangement of the nickel single crystals oriented for single slip is significantly dependent on the plastic strain amplitude, that is the volume of the dislocation‐poor regions decreases at increasing amplitude. In the second range ladder‐like structures of the persistent slip bands and vein‐like structures of the matrix are observed in agreement with the results of copper single crystals. Beside, at great amplitude, but within the second range, there is a steady increase of parquet‐like matrix structures. On [001] single crystals the spatial dislocation structure is characterized by condensed and uncondensed {100} dislocation walls. The limited regions with condensed walls are supposed to be regions of high plastic strain amplitude (“mesoscopic” strain localizations). Amplitude changing tests are suitable to obtain results on the stability of the dislocation structures to increasing amplitude and decreasing amplitude, respectively.
Effect of an External Magnetic Field on Polytypism of CdI2 Crystals Grown from Solutions
Authors: Palosz B. , Przedmojski J. 
Published: January 2007

AbstractThe effect of growth conditions on the polytypic structure of crystals of CdI2 was analyzed for crystallization from solutions. Three solvents were used: H2O, 3 H2O + 1 C2H5OH and 1 H2O + 1.C2H5OH. Crystals were grown at two temperatures: 5 and 25°C with low and high growth rates; an external magnetic field of about 0.25 tesla was used. The effect of the above three parameters on the formation of the basic polytypes 2H and 4H and on the ordering of faults in disordered structures and polytype cells was studied by X‐ray analysis of crystal surfaces. Some distinct relations between the polytypic structure of crystals of CdI2 and the magnetic field were found.
On the Solubility of Garnets in PbO/B2O3 High Temperature Solvents
Authors: Fischer K. , Görnert P. 
Published: January 2007

AbstractThe paper is concerned with solubility models for Y3Fe5O12 (YIG) and Gd3Ga5O12 (GGG) solved in PbO/B2O3 high temperature solutions containing Fe2O3 or Ga2O3 in excess. It is shown that a new extended eight‐particle model Interprets well the literature data of the solubility of YIG as well as the DTA data of the solubility of GGG. Comparisons of solution enthalpies determined in terms of the single‐molecule, eight‐particle, and extended eight‐particle model are carried out in dependence on the excess concentration of species containing iron or gallium, respectively.
Influence of Gravitation on the Processes of Heat and Mass Transfer in Solution Crystal Growth by the Travelling Heater Method (THM) (II)
Authors: Cherepanova T. A. , Cherepanov V. Y. , Iljukhin V. V. 
Published: January 2007

AbstractThe two‐dimensional quasi‐stationary thermodiffusive hydrodynamic problem of the crystal PbTe growth from solution by the travelling heater method has been solved. Computation is given for the temperature field distribution in crystal and solution. The picture of fluxes in solution was obtained under free convection for different lengths of solvent zone. It is shown that in the absence of absence of gravitation at the growing interface in solution there occurs a constitutional supercooling, whereas the free convection removes it, which leads to greater morphological stability of a growing crystal face.