bluuebunny/crossref_metadata_2025 huggingface dataset:
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

The 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

In 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

By 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

Starting 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

The 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

The 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

YAG 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

GaN 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

The 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

Heteroepitaxial 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

The 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

The 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

New 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

The 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

The 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

The 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

Based 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

TiS1.7 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

Investigations 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

The 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

To 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

In 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

The 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

The 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

The 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

The 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.
Crystallization Rate Behaviour under Change of Czochralski Growth System Parameters
Authors: Nalbandyan H. G.
Published: January 2007

A comparative analysis of growth system parameters' (pulling rate, melt temperature and crucible position or melt level) change influence on crystallization rate in Czochralski growth system is represented.
Problems of Surface Morphology and Layer Deposition during Plasma Etching Processes (II) Si‐etching in CF4‐, CF4/O2‐and CF4/H2 Plasmas
Authors: Tiller H.‐J. , Krausse J. , Voigt R.
Published: January 2007

The plasma etching of Si in CF4‐, CF4/O2‐and CF4/H2 plasmas was investigated in dependence on the etching gas, the plasma conditions (pressure, power density) and etching time in different reactors. A roughening of the surface and the formation of a “semi‐amorphous” surface layer with a power‐like morphology was detected by TEM‐and RHEED methods. It is supposed that the surface layer has a fundamental consequence as an intermediate state in the etching mechanism.
Structural Characterization of Cut and Polished PbTe Surfaces
Authors: Engel A. , Berger H. , Roesler H.‐J.
Published: January 2007

The structural perfection of PbTe slices after spark‐erosive cutting and diamond polishing was investigated removing the damaged layers step by step by chemical lap polishing. Using X‐ray diffraction rocking‐curve measurements and chemical etching, it has been shown that there exist strongly disoriented crystallites aligned preferably into the straining directions. For diamond polishing this anisotropy is stronger, but the disorientations and the damage depth are smaller than for spark‐erosive cutting. The depth of significant damage amounts to 600 m̈m altogether. The damage caused by spark erosion and diamond polishing can be described by a model according to Cole and to Bucklow and Cole modified including machining anisotropy.

Die strukturelle Perfektion von PbTe‐Scheiben wurde nach dem Funkenerosionstrennen und Diamantpolieren durch schrittweises Abtragen der Deformationsschicht mit Hilfe des chemischen Wischpolierens untersucht. Durch Rockingkurven‐Messungen und chemisches Ätzen gelang der Nachweis streng disorientierter und bevorzugt in Bearbeitungsrichtung verschwenkter Kristallite. Bei der Diamantpolitur ist diese Anisotropie ausgeprägter, obwohl die Disorientierung und Schädigungstiefe kleiner als beim Funkenerosionstrennen sind. Die Tiefe der signifikanten Schädigung beträgt insgesamt etwa 600 m̈m. Die bearbeitungsinduzierten Schädigungen können durch ein Modell nach Cole und Bucklow et al. beschrieben werden, das entsprechend der verfahrensbedingten Anisotropie modifiziert wird.
Etching of Anthracene Cleavages in Sulphuric Acid — Formic Acid Solutions
Authors: Vaishnav R. M. , Mehta B. J. , Shah B. S.
Published: January 2007

Crystal etching, though a simple and widely adopted technique for the study of imperfections in a wide variety of materials, the process is not very well understood. The etch pit shapes are controlled by a number of factors, such as, the composition of etchant, the period of etching, the temperature of etching and the symmetry of plane under study. This communication reports observations of etching the (001) cleavage planes of anthracene in sulphuric acid — formic acid mixtures.
Growth of Li2CO3 Single Crystals by Zone Melting Technique
Authors: Palaniswamy M. , Gnanam F. D. , Ramasamy P. , Laddha G. S.
Published: January 2007

Li2CO3 single crystals have been grown by zone melting technique in carbondioxide atmosphere. The diameter of the grown crystal depends on the growth rate. The quality of the crystal depends on the growth rate, temperature of the molten zone, choice of the seed and the temperature of the auxiliary furnace. The crystal shows cleavage plane. The etch studies on cleavage planes show that the etch pits are always triangular in character.
The Crystallisation of Aluminium Trihydroxide (Gibbsite) from Sodium Hydroxide Solution Onto Fine Seeds: Physico‐chemical Studies on the Internal Structure and Agglomeration of Different Crystal Fractions
Authors: Packter A. , Daill H.
Published: January 2007

A batch of Bayer gibbsite crystals (particle size range 3 to 70 μm) was prepared by crystal growth onto fine seeds (1 to 3 μm) from sodium hydroxoaluminate/sodium hydroxid‐solution. The internal structures and seed agglomeration of different fractions were examined by optical microscopy, infra‐red spectrophotometry, thermal analysis and chemical dissolution analysis. These physico‐chemical studies confirmed that crystal growth occurs with some seed agglomeration in the early stages, followed by growth onto the ‘agglomerates’. The agglomerated seeds contents (X) were as follows: for fraction DiD (l0 = 6.3 μm), X = 0.44; for fraction Gi C (l0 = 20 μm), X = 0.41; for fraction Gi B (l0 = 38 μm), X = 0.31 and for fraction Gi A (l0 = 55 μm), X = 0.24.
Free Enthalpy of Ternary Alloy Superlattice
Authors: Šrobár F.
Published: January 2007

Increments due to superlattice structure are formulated for the free enthalpy and some other thermodynamic entities as functions of composition, geometry parameters and temperature. Physical contents of the general expressions, derived for simple (quasi‐regular) pseudobinary solutions, are illustrated by numerical data valid for the InxGa1–xAs/GaAs system. It is suggested that the free enthalpy of superlattice, is, at least at higher temperatures, largely dominated by the configuration entropy term. Corrections due to nonideality appear to be quite sizeable for the selected ternary alloy.
Connection of the Thermocapillary Flow Characteristics and the Impurity Distribution Pattern in Floating Zone Molten Molybdenum Single Crystals
Authors: Jurisch M. , Löser W. , Lyumkis E. , Martuzāne E. , Martuzāns B.
Published: January 2007

The results of the impurity distribution in W‐doped Molybdenum single crystals grown by electron beam floating zone melting are related to the characteristics of computed steady thermocapillary flow and impurity distribution within the molten zone. Particularly the influence of the number and the strength of eddies in the molten zone on the impurity distribution pattern in the grown crystal for different aspect ratios is considered.
Proposals for the Optimization of Crystal Growth in Gels
Authors: Wunderlich W.
Published: January 2007

Crystal growth in gels is viewed under the aspect of diffusion and factors governing this. From simple diffusion experiments proposals for the modification of growth apparatus and growth regime are made to minimize quality decreasing effects. The application of diffusion measurement results on crystal growth in gels is shown by optaining NaHC2O4 × × H2O crystals in silica gel (sodium metasilica gel respectively).
Improved Spatial Resolution in Electron Probe Microanalysis of Multilayer Structures
Authors: Sasama F. , Geselle B.
Published: January 2007

A method is described to measure composition profiles of layer systems on substrates by electron probe microanalysis with an improved effective spatial resolution down to 0.1 μm. The resolution problem in microanalysis of angle lapped layers and the related experimental problems are discussed and examples of composition profile measurements at GaAs‐AlxGa1–xAs double‐heterostructures are presented.
Determination of Two Donor (Majority) Levels in Semiconductors from Hall Effect Measurements
Authors: Ziegler E. , Siegel W.
Published: January 2007

Temperature dependence of the carrier concentration n0 is calculated for different impurity parameters under the assumption that two donor (majority) levels are present in a semiconductor. A nonlinear least squares fit using an equation cubic in n0 yields the impurity parameters of both impurities with relatively small errors. This determination of impurity parameters is suitable also in the case of donor (majority) levels with similar ionization energies. Through that it is possible semiconductors with two majority levels to analyse by Hall effect measurements. In the case of clearly different donor (majority) activation energies the cubic equation can be approximated by two quadratic relations in n0 valid in the high and low temperature region, respectively.
Crystallography of the Martensitic transformation in Indium‐Thallium Alloys
Authors: Schumann H.
Published: January 2007

On cooling a single crystal of Indium containing 20.75 atomic per cent Thallium may transform martensitically by the migration of a single interface, covering the whole cross‐section, from the high temperature face‐centred cubic β‐structure to the facecentred tetragonal α‐structure. Applied external mechanical stress is able to reverse the direction of interface motion during transformation. The α‐martensite consists of a stack of fine parallel twins which are suficiently wide to be visible under an optical microscope. There are no longrange stresses, provided the twins have mean thickness ratio 1.6:1. By extension or compression the whole specimen may undergo a conversion into one or the other orientation by movement of the twin boundaries, leading to ferroplasticity or ferroelasticity.

The geometry and crystallography of and the effects of external stresses on the β → α transformation have been calculated on the basis of the phenomenological crystallographic martensite theory.
Study on the possibility of native oxide removal from GaP and GaAs surface by etching, using model experiments
Authors: Somogyi M.
Published: January 2007

Crystallites of α‐Ga2O3, β‐Ga2O3, GaOOH, GaPO4 and an amorphous phase have been detected previously on chemically etched GaP‐ and GaAs surfaces. The same compounds were prepared separately and submitted to solubility study, applying several etchants used in etching practice. It could be observed that the solubility of gallium oxides decreases as the chemically bound water is diminished, the anhydrous β‐Ga2O3 being almost insoluble. As the same poorly soluble oxide forms were found on etched GaP and GaAs surfaces, the difficulties occurring in etching practice can be connected with their presence.
Photoemission studies of Titanium Oxides
Authors: Wagner N. , Brümmer O. , Sauer N.
Published: January 2007

Titanium exposed to dry air at varying temperatures are studied by X‐ray photoelectron spectroscopy (XPS) in combination with low energy Ar ion sputtering. The 2 nm deposit formed at room temperature in 30dis an oxide mixture with chiefly Ti2O3. This result is indicated by the Ti(2p) level binding energy, FWHM and asymmetry. The dry air exposures at high temperatures resulted in oxide species of nonstoichiometric TiO2–x. As proposed from sputtering effects to XP‐spectra the oxygen deficient TiO2–xsurface region includes Ti3+‐interstitials. These interstitials act as donors (emission to (3d)‐states) and hinder the oxygen diffusion via interstitials (temperature: ≦ 550 °C). It is to be noted that electron emission from donor states is favoured in deeper lying (2p)‐states by decreasing concentration of oxygen vacancies.
Lattice Parameter Study in the Bi1–xSbx Solid‐solution System
Authors: Berger H. , Christ B. , Troschke J.
Published: January 2007

The lattice parameters of Bi1–xSbx single crystals were measured for 0 ≦ x ≦ 1 by a special X‐ray diffractometer technique using reflections chosen so that minimum errors were achieved. Corrections for thermal expansion and refraction were applied. The antimony concentration was determined by means of electron microprobe analysis. The dependences of the lattice parameters on x (in nm) can be described with good approximation by a = 0.45469 – 0.02398x and c = 1.186294 – 0.058632 [1 + 1.26 (x−1 – 1)]−1, resp. The behaviour of the parameter a is in agreement with the earlier study by CUCKA and BARRETT, whereas their linear expression for c(x) (0 ≦ x ≦ 0.3) was not confirmed.
Investigation of Crystalline Polymeric Solids at Reduced Beam Damage in the High Voltage Electron Microscope
Authors: Michler G. H. , Dietzsch Ch.
Published: January 2007

A special technique was used for investigating polymers in the electron microscope at essentially reduced radiation damage. The method is based on a high voltage electron microscope (accelerating voltage of 1 MV) and the use of highly sensitive X‐ray films. Compared with the conventional transmission electron microscopy this technique reduces the specimen damage by a factor of 50 … 100. Diffraction contrast can therefore be used to investigate the structure of semi‐crystalline polymers. Using samples of polyethylene, the arrangement of the lamellae was determined by bright field and dark field images and diffraction patterns.

There are further advantages concerning the improved possibility of investigating very thick specimens (thicknesses above 5 μm). Thus, a better stereoscopic analysis of extended structures is possible, and in‐situ deformation tests of polymers can be performed in the electron microscope.
Investigation of the Interaction of Quartz with Hydrogen under Supply of Mechanical Energy (II) Investigation by IR Spectroscopy
Authors: Geissler H. , Hennig H.‐P. , Kunath D. , Ebert I. , Hopfe V. , Steinike U.
Published: January 2007

Infrared investigations demonstrate a chemical interaction of quartz in hydrogen atmosphere during mechanical activation:

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By means of the SiH stretching band the number of formed SiH‐groups is estimated as a function of the period of activation. of activation. This number is more than one order of magnitude less than the total number of adsorbed molecules.
Microanalytical Characterization of Mineral Impurities and their Effect to Graphitizability of Brown Coal Pitch Cokes
Authors: Preiss H. , Adam K.
Published: January 2007

The main impurities in brown coal pitch cokes are Si, S, Ca, Fe, Al and Mg. Microanalysis exhibits that these elements besides sulphur are localized in non‐carbonaceous particles which are identical with the mineral impurities in the pitch precursors. Sulphur is present both in sulphate particles and as “organic” sulphur in the carbonaceous phase. The impurities reduce optical anisotropy and graphitizability of electrode cokes. Crystallite size and xylene density were measured to characterize the graphitizability.
Studies on Induced Smectic Phases (II) Transition Enthalpies, X‐ray Patterns and Layer Spacings of Orthogonal Phases of Binary Mixtures of Nematogens with Contrasting Dielectric Anisotropies
Authors: Szabon J. , Diele S.
Published: January 2007

Binary mixtures of two nematogens, 4,4′‐di‐n‐heptyl‐azobenzene with 4‐n‐pentyl‐4′ ‐cyano biphenyl were studied by optical, calorimetric and X‐ray measurements. At a given concentration induced phases with a sequence SA, SB, SE were detected, the properties of which were discussed.
Electron microscopic study of precipitates in oxidized BaF2 Single Crystals
Authors: Aronova A. M. , Berezhkova G. V. , Perstnev P. P.
Published: January 2007

Precipitates structure in oxidized BaF2 single crystals was studied by high voltage electron microscopy. By the analysis of microdiffraction patterns from precipitates it was shown that the precipitate are BaO phase. It was established that the {112} plane of BaO precipitate coincides with the {111} plane of BaF2 matrix, and the 〈111〉 and 〈110〉 directions of BaO precipitate coincide with the 〈112〉 and 〈110〉 directions of BaF2 matrix. Precipitates observation in different diffraction conditions did not reveal dislocations neither within precipitates, nor on their boundaries.
Effect of electrode annealing on the aging characteristics of thin metal films
Authors: Patel A. R. , Pandya N. C. , Chourasia N. C. , Shivakumar G. K.
Published: January 2007

The resistance of thin films of silver, copper, indium and aluminium deposited onto clean glass substrates were measured using annealed and unannealed films of chromium‐copper alloy as electrodes. The percentage variation in resistance for different metal films differ with annealed and unannealed electrodes. Formation of oxide and alloying at the electrodefilm junction are discussed taking into account the observed variations in resistance. Microscopic observations are also made of the film‐electrode junctions.
Phase Equilibrium of the Ga–Al–Sb system
Authors: Yordanova I. , Tret'Yakov D. N.
Published: January 2007

Employing the method of liquid‐phase epitaxy (LPE) solid‐solutions of Ga1–xAlxAlxSb (0 ≦ x ≦ 0.8) have been obtained. The dependence of Sb solubility on Al concentration in the liquid phase at 403°C, 452°C, 500°C has been established. The dependence of AlSb concentration in the solid phase on the composition of the liquid phase has been investigated at 452°C.

Using the chemical constants equilibrium method, the phase equilibrium of the Ga–Al–Sb system in the region of liquid phase composition near the Ga‐rich corner of the phase diagram has been calculated. The comparison of experimental and calculated data for the liquid and solid phases shows their agreement within the limits of experimental error.
Characteristics of Growing of Heterostructures in the System GaSb–AlSb
Authors: Yordanova I.
Published: January 2007

In the present work, some factors are pointed out hindering the growing of good‐quality epitaxial layers and heterostructures in the system GaSb–AlSb. Their influence is studied on the morphology of the surface and the cleavage of the epitaxial structures GaSb–Ga1–xAlxSb. The characteristics of the optimal technological regime are shown.
Study of InxGa1–xP/GaAs Films Formation on the Basis of In–Ga–P Liquidus Precised Investigation
Authors: Bolkhovityanov Yu. B.
Published: January 2007

It is shown that the In–Ga–P melt which is prepared by contacting with the GaP seed becomes supersaturated in reality. Some peculiarities of InxGa1–xP/GaAs films formation at quasi‐equilibrium conditions are described. It is observed that the saturated In–Ga–P melt dissolves the GaAs substrate when isothermally contacting if the InxGa1–xP equilibrium solid has the lattice parameter less than that of GaAs. As a result some InGaAsp deposit arises on the substrate. This phenomenon takes place if the In–Ga–P melt is just supercooled. This instability of the liquid‐solid interface is explained on the basis of the relaxation theory of non‐equilibrium liquid‐solid contact which has been created by the author in previous papers.
The Development of the Dislocation Structures during the Fatigue Process of F.C.C. Single Crystals
Authors: Mecke K. , Blochwítz C. , Kremling V.
Published: January 2007

In recent years the dislocation arrangements in the mechanical saturation stage have been studied to a great extent. In the present work the development of the dislocation arrangements in the range of cyclic hardening are dealt with in relation to the mechanical behaviour, giving special attention to the development of persistent slip bands (PSBs). The description of the dislocation structure development is related to the shape changes of the mechanical hysteresis loops.

Above a cycle number Nn a set of about 1 μm long dislocation dense regions (“rungs”) aligned along the primary slip direction can be discerned. From these first rungs the ladder‐like structures of PSBs develop until the saturation. Beside the PSB structure the matrix structure changes markedly between Nn and mechanical saturation.

In amplitude changing tests another mechanism of PSB nucleation is observed, namely the breaking up of the existing matrix dislocation structure by “cords”.
Defect structure in nickel single crystals in dependence on the cyclic deformation prehistory
Authors: Hoffmann E. , Kleinert W. , Schmidt W.
Published: January 2007

The development of the dislocation structure in nickel single crystals push‐pull fatigued at room temperature is investigated for different deformation types using electrical resistivity measurements and results of TEM observations. The dislocation density in the bundles of the matrix is higher after changing the strain amplitude from region A to region B (CDAB‐type) of the cyclic stress‐strain curve (NdB ≈︁ 1.6 ≈︁ 1015 m−2) than after virginal deformation in region B (VDB‐type) especially at higher strain amplitudes (NdB ≈︁ 0.75 ≈︁ 1015 m−2). Increasing the strain amplitude within region B (CDBB‐type) does not change NdB. The farther development of the matrix structure after reaching the vH‐minimum during the VDB‐type of deformation suggests the action of the „formation and dissolution”︁ – mechanism, whereas the CDBB‐type causes the „cord”︁‐mechanism of the PSB nucleation.
Etch pit morphology on calcite cleavages by hydrochloric acid
Authors: Mehta B. J.
Published: January 2007

Etch pit morphology has been studied on calcite cleavages by different concentrations of hydrochloric acid. Magnitudes of lateral reaction rates are very high concentration while they are decreasing as concentration decreases. Due to formation of finite or infinite lateral reaction rates at some particular concentration etch pit morphology changes. It is shown that the morphology changes are systematic. The underlying chemical equations are given for different etch pit morphology.
Proton NMR studies of smectic‐C phases
Authors: Limmer St. , Findeisen M.
Published: January 2007

We present proton NMR second moments studies of some compounds exhibiting smectic‐C phases. From the comparison of experimental and theoretical angular dependences of the second moments the tilt angles δ are derived. The ratio f of the second moments of samples with statistical distribution of domain orientations and of perfectly aligned samples is calculated and compared with experimental data. For certain substances with constant tilt here are significant deviations from the theoretically expected values suggesting that the underlying theoretical model has still to be modified.
EPD investigation in LEC‐grown silicon‐doped gallium arsenide
Authors: Fornari R. , Paorici C. , Zanotti L.
Published: January 2007

The EPD distribution is investigated in silicon‐doped LEC‐grown gallium arsenide crystals, 30 ÷ 40 mm in mainbody diameter and weighing within 300 ÷ 500 grams. The silicon‐doping‐dependent hardening effect, previously observed in S‐doped and Bridgman grown silicon‐doped gallium arsenide is here confirmed. The EPD decreasing with silicon‐doping increase is observed to be less pronounced than in the case of S‐doped and Bridgman grown silicon‐doped samples and possible reasons for this different behaviour are discussed. In any case, a large microprecipitate density together with the EPD reduction appears as a clustering of shallow‐pits around dislocation pits.
Oxygen ion concentration in solvents for the growth of garnets
Authors: Linzen D. , Sinn E. , Fischer K. , Klupsch Th. , Bornmann S.
Published: January 2007

A concentration cell for the determination of the oxygen ion concentration by means of e. m. f. measurements is described which is suitable for oxidic melts with low viscosity and high attack on ceramic materials. Applying this concentration cell binary mixtures of oxides and fluorides used as solvents for the garnet preparation were investigated. The oxygen ion concentration is given in dependence on the composition of the mixtures. By comparison with simple models conclusions on the structure of the melt are made.
X‐ray and electron microscopy studies of arsenium implanted silicon crystals after a pulsed laser annealing
Authors: Bryza B. , Auleytner J. , Bartsch H. , Wieteska K.
Published: January 2007

The structural changes obtained due to laser annealing in the surface layer of As‐implanted silicon crystals were investigated by means of a triple crystal spectrometer. The rocking curves of implanted crystals do not show any changes compared with non‐implanted crystals. It was caused by the large dose of ions which amorphized the surface layer. Laser annealing process influenced on the broadening of rocking curve. The comparative studies were carried out by using the HTEM technique. They showed that the laser annealing caused formation of quasi‐mosaic structure, planar defects and dislocation clusters. These defected structure and local strains influence on the broadening of rocking curves.
Real domain structure in orthorhombic phase of NaNbO3 crystals
Authors: Dec Jan
Published: January 2007

Systematics and essential elements of real domain structures in antiferroelectric phases of NaNbO3 crystals is presented. Observed deviations from ideal model can be caused by crystal defects and conditions of the phase transition.
Investigation of shallow strain distributions in silicon single crystals with X‐ray bragg reflection
Authors: Zaumseil P. , Winter U.
Published: January 2007

The use of X‐ray double crystal diffractometry in Bragg case reflection for the determination of shallow strain distributions is investigated. Based on the theory of Takagi‐Taupin theoretical calculations of reflection curves of silicon crystals with diffusion induced strain profiles are carried out for different wave lengths and reflections. Possibilities for an optimal choise of reflections are discussed and the limits of detectibility are estimated. Experimental results of boron diffused silicon crystals confirm the theoretical results. Triple crystal diffractometry of (+n, –n, +n) setting is discussed as one possibility to increase the sensibility.
Polarization optics for X‐rays
Authors: Brümmer O. , Eisenschmidt Ch. , Höche H. R.
Published: January 2007

An experimental arrangement for X‐rays is described which is analogous to the optical bench for polarization investigations. Using this arrangement elliptically polarized X‐rays should be generated and proved. Although the dynamical theory of X‐ray diffraction is needed for X‐ray optics the polarization phenomena can be phenomenologically interpreted in analogy to visible light optics. The experimental results showed that with a wedge‐shaped crystal used as the phase shifter any polarization state of X‐rays can be generated.
Morphogenetic aspects of the LPE heterostructure growth: Time evolution of configuration entropy
Authors: Šrobár F.
Published: January 2007

The concept of the configuration entropy ΔSconf, introduced originally in the context of heterojunction superlattices, is extended to cover general one‐dimensional concentration profiles. Changes in ΔSconf as well as in its production rate Pconf = d ΔSconf/dt accompanying the growth of single and double AlxGa1–xAs based heterostructures are evaluated for a suitable set of relevant parameters. — ΔSconf is shown to increase monotonously during the growth process, while the — Pconf vs t dependences may exhibit sharp maxima and discontinuities in response to movements of the LPE apparatus slide. Given the fact that ΔSconf measures departure of the atomic population from the homogeneous (macroscopically structureless) equilibrium condition, such studies in effect monitor time distribution of the morphogenetic activity by the LPE growth processes.