bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractThe 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

AbstractCrystal 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

AbstractLi2CO3 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

AbstractA 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

AbstractIncrements 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

AbstractThe 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

AbstractCrystal 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

AbstractA 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

AbstractTemperature 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

AbstractOn 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

AbstractCrystallites 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

AbstractTitanium 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

AbstractThe 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

AbstractA 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

AbstractInfrared investigations demonstrate a chemical interaction of quartz in hydrogen atmosphere during mechanical activation:magnified imageBy 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

AbstractThe 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

AbstractBinary 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

AbstractPrecipitates 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

AbstractThe 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

AbstractEmploying 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

AbstractIn 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

AbstractIt 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

AbstractIn 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

AbstractThe 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

AbstractEtch 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

AbstractWe 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

AbstractThe 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

AbstractA 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

AbstractThe 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.