bluuebunny/crossref_metadata_2025_split huggingface dataset:
Causes of the formation of etch pits of different size and morphology on {100} faces of CsI crystals
Authors: Sangwal K. , Sizova N. L. , Urusovskaya A. A. 
Published: July 2007

AbstractCauses of the formation of dislocation etch pits of different shape and size on {100} faces of cesium iodide crystals by an etchant composed from 25–35 mg/1 CuCl2 · 2 H2O in 96% ethanol are studied. It is shown that one of the reasons of the change in the morphology of etch pits is the segregation of excessive iodine at dislocations.
On the kinetic of crystallization of zinc oxalate (II). Determination of the specific surface energy at the crystal solution interface by kinetic studies
Authors: Kirkova E. , Djarova M. 
Published: July 2007

AbstractAn apparatus based on turbidimetry was constructed for studying the kinetics of crystallization of sparingly soluble salts. The kinetics of crystallization of zinc oxalate was investigated at various supersaturations and pHs of the medium. The specific surface energy at the crystal‐solution interface was determined from the induction periods of the S‐shaped curves by means of the classical theory of nucleation. The calculations were made using the slope of the logarithmic dependence of I or τ, respectively, on supersaturation (equations 1 and 2) and the critical supersaturation which was also determined on the basis of kinetic data. Various values of σ were found for the different supersaturations. Different values for this quantity were also obtained when supersaturation was presented by the concentration ratio (S = C/C0) or by the ratio of the product of the two ions concentrations in the supersaturated solution to that in the saturated one (S = ab/Lp). These σ values were lower than those obtained using the critical supersaturations at the two different solution pHs. For the present it is impossible to give a definite explanation of the results obtained. The experiments for determining the specific surface energy at the crystal‐solution interface will be continued.
Über die röntgenographische Analyse der mittleren quadratischen Atomverschiebungen in einigen Halbleiterkristallen
Authors: Bublik V. T. , Gorelik S. S. 
Published: July 2007

AbstractIm Temperaturgebiet 100 K — 1000 K wurden an Einkristallen des Ge und halbleitender Verbindungen des Typs AIIIBV, AIIBVI und AIVBVI röntgenographische Messungen des Debye‐Waller‐Faktors durchgeführt. Aus den Ergebnissen wurden die mittleren quadratischen Atomverschiebungen 〈u2〉 und die Debye‐Temperatur ΘM berechnet. Beide Parameter werden im Hinblick auf den Einfluß der Temperatur, den Einfluß von Punktdefekten und bei den Verbindungen auch von Stöchiometrieabweichungen auf die thermischen Gitterschwingungen diskutiert. Abschließend werden einige Betrachtungen zum Zusammenhang zwischen den Größen 〈u2〉 bzw. ΘM und den Aktivierungsenergien der Leerstellenbildung und der Diffusion in den untersuchten Materialien mitgeteilt.
Influence of the morphology of voids in lithium fluoride on the Kinetics of their disappearance
Authors: Nenow D. , Gueleva S. 
Published: July 2007

AbstractThe morphology of voids in LiF single crystals is investigated using optical and electron microscope methods. – A difference in the growth and disappearance morphology is shown – the initial sharp corners and edges get truncated during the disappearance. – Kinetic studies on the disappearance of isometric voids were performed at a high temperature. The results show susceptible difference with the theoretical results for a void with sharp corners and edges.
The growth of single crystals of langbeinites Rb2Cd2(SO4)3, Tl2Cd2(SO4)3, K2Co2(SO4)3, and their phase transitions
Authors: Březina B. , Fousková A. 
Published: July 2007

AbstractSingle crystals of dicadmium dirubidium sulphate and dicadmium dithallium sulphate have been grown from non‐stoichiometric aqueous solutions by various methods. Optical and thermal properties in the vicinity of their phase transitions have been studied. Polycrystalline samples of dicobalt dipotassium sulphate have been prepared using Bridgman method. Optical and specific heat measurements have shown a new phase transition at −148°C.
A study of phase equilibria and heterojunctions in Ga–In–As–Sb quaternary system
Authors: Dolginov L. M. , Eliseev P. G. , Lapshin A. N. , Milvidskii M. G. 
Published: July 2007

AbstractThe phase diagram of the Ga–In–As–Sb quaternary system has been determined experimentally and also has been treated on the base of thermodynamic calculations. The liquidus data were obtained by DTA and solidus data were determined using electron microprobe analysis on LPE‐layers of GaxIn1–xAsySb1–y on GaSb and InAs substrates. Isolattice‐parameter heterostructures prepared on these substrates were free of mismatch dislocations and suitable for application to light‐emitting diodes and semiconductor lasers.
Golddekoration von Silbereinkristallen, ermöglicht durch Ionenbeschuß
Authors: Marinov M. 
Published: July 2007

AbstractDie Oberflächenstruktur von Silbereinkristallen wurde mit Hilfe der Golddekorationsmethode unter gleichzeitigem Ionenbeschuß untersucht. Es wurde festgestellt, daß die Dichte des dekorierenden Stoffes bei einer bestimmten Intensität des Ionenbombardements stark von der Dichte der aktiven Stellen und von der kristallographischen Orientierung der Kristalloberfläche abhängt. Dadurch entsteht eine zusätzliche Möglichkeit zur selektiven Dekoration von aktiven Stellen. Bei der Dekoration unter starkem Ionenbeschuß und einer größeren Aufdampfrate des dekorierenden Stoffes erhält man eine „negative”︁ Dekoration, d. h. es werden Bereiche und Stellen der Kristalloberfläche sichtbar gemacht, auf welcher die Prozesse der Keimbildung und des weiteren Wachstums der Kriställchen gehemmt oder vollständig verhindert sind.
EPR‐spectrum of irradiated potassium dichromate single crystals
Authors: Alybakov A. A. , Gubanova V. A. , Tojchiev N. 
Published: July 2007

AbstractEPR‐spectra of X‐irradiated potassium dichromate crystals are studied at various temperatures from RT to LNT. The most intensive lines are interpreted as due to radicals CrO43− (A‐lines) and CrO3− (C‐lines), resulting from Cr2O7 owing to X‐irradiation. Hyperfine structure of C‐line, due to interaction of unpaired electron with Cr53 nucleus, occurs at low temperatures, and new unobserved earlier Q‐lines appear near‐by C‐line. The spectrum may be described by usual spin Hamiltonian for S = 1/2 with following parameters: for A‐line gz = 1.9841, gy = 1.9685, gx = 1.9592; for C‐line gz = 1.9148, gy = 1.9671, gx = 1.9886, |Az| = 30.53 · 10−4 cm−1, |Ax| = 10.62 · 10−4 cm−1, |Ay| = 6.62 · 10−4 cm−1.
Solid solution with fluorite structure in the CaF2 ‐ LaF3 system
Authors: Švantner M. , Mariani E. , Fedorov P. P. , Sobolev B. P. 
Published: July 2007

AbstractThe phase equilibrium of fluorite Ca1−xLaxF2+x solid solutions in the CaF2 ‐ LaF3 system is investigated by means of DTA and X‐ray analysis. The phase diagram of his system is of eutectic type with limited solid solutions with the structure of components. The eutectic coordinates are 1311°C and 58 mole% of LaF3. The saturation line of fluorite solid solution has an anomalous S‐shape. The elementary cell parameter of this solution has been approximated by the parabolic equation a = ao + 0.597x + + 0.134x2, where ao = 5.46295 Å denotes the parameter of CaF2 elementary cell.Both dc/from 20 to 450°C/and ac/from 450 to 600°C/electrical conductivities were measured at concentrations covering almost whole region of the Ca1−xLaxF2+x solid solution formation. They are characterized by increasing conductivity and decreasing activation energy with increasing LaF3 concentrations. In samples with x > 0, 11 an increase of electrical conductivity due to aging was observed.
On the significance of surface tension driven flow in floating zone melting experiments
Authors: Barthel J. , Eichler K. , Jurisch M. , Löser W. 
Published: July 2007

AbstractThe predominance of the surface tension driven (Marangoni) flow over the buoyancy driven free convection for small zone lengths in electron beam floating zone melting of doped molybdenum rods is pointed out. The observed different patterns of microsegregation and the critical conditions of their occurrence, i.e. B‐cores below a critical zone length of lc = 3.5 mm and B‐striations above this value, are shown to be in qualitative agreements with theoretical predictions made from convection models.
Kerr Effect Studies in Liquid Crystalline Substances
Authors: Hauser A. , Schädler U. , Demus D. 
Published: July 2007

AbstractThe static and dynamic pretransitional behaviour was investigated by the electric Kerr effect in three nematic substances above the clearing point. The measured Kerr constants exceed that of nitrobenzene by more than a factor of 50…︁ 80 which are due mainly to pretransition phenomena and the strong dipole moments of the compounds. A formula is given for the calculation of the Kerr constant. The latent heat at the nematic‐isotropic phase transition calculated from the temperature dependence of the Kerr constant by means of the Landau theory is in good agreement with the experimental values. Size and relaxation behaviour of pseudonematic domains are determined by Kerr effect measurements.
On the Description of Symmetry of OD Structures (I) OD Groupoid Family, Parameters, Stacking
Authors: Fichtner K. 
Published: July 2007

AbstractThe relations between the groupoid of partial symmetry operations of an OD structure and the description of the symmetry of this structure by an OD groupoid family as well as parameters and the stacking of layers are discussed. Proposals are suggested for some changes in the symbols of the OD groupoid families in order to simplify and unify these symbols.
In‐situ Study on the Fatigue Process of Metals by HVEM
Authors: Yamamoto A. , Saka H. , Imura T. 
Published: July 2007

AbstractIn‐situ fatigue test on pre‐fatigued aluminum single crystals and also in‐situ tensile test of pre‐fatigued copper‐2 at.% aluminum alloy single crystals were carried out in an HVEM. In the Al crystals, forward and backward motion of dislocations, change of cell structures, formation of voids and crack propagation were directly observed in‐situ by an HVEM under alternating stress. In the Cu‐Al crystals, it was observed that slip occurred only in the part of the persistent slip bands during in‐situ tensile deformation in an HVEM.
In‐situ HVEM Observations of Dislocation Processes during High Temperature Deformation of Silicon Crystals
Authors: Sumino K. , Sato M. 
Published: July 2007

AbstractThe characteristics in the plastic deformation of silicon crystals are first reviewed. Such characteristics have been interpreted quantitatively on the basis of some models on the velocity and the multiplication of dislocations during deformation. The results of the in‐situ observations of silicon crystals deformed at elevated temperatures in a HVEM are presented. The slowness and the smoothness in the dislocation motion, the dynamic pile‐up as a general mode of the collective motion of dislocations, the formation processes of multiplication centers of dislocations observed during the deformation all support the validity of the models adopted. Dislocation dipoles and Lomer‐Cottrell sessiles are observed not to act as strong obstacles which play important roles in the work hardening of the crystals.
In‐situ Observations on Dynamic Processes Associated with Stacking Faults and Deformation Twins in Silicon Crystals
Authors: Sato M. , Sumino K. 
Published: July 2007

AbstractStacking faults and thin deformation twins are observed to develop during the in‐situ deformation of silicon crystals at elevated temperatures in a HVEM. Both the nucleation and the motion of partial dislocations take place under the applied stress in the regions of the stress concentration. Twinning dislocations moving on twin boundaries are extremely flexible. The spontaneous nucleation of loops of twinning dislocation on twin boundaries is observed rather frequently. No pole mechanism is observed to be operating. Stacking faults and deformation twins interact with glide dislocations moving along the intersecting planes by various ways.
Growth of crystals of ferroelectrics Ln2Ti2O7 (LnLaNd) with layer‐type structure
Authors: Zakharov N. A. , Stefanovich S. Yu , Kustov E. F. , Venevtsev Yu. N. 
Published: July 2007

AbstractSingle crystals of rare‐earth (La‐Nd, Sm, Gd) and Y dititanates have been grown either by the method of direct high frequency heating in cold container or/and floating zone optical technique. The crystals Ce2Ti2O7 and Pr2Ti2O7 belong to the structural type of Ca2Nb2O7 and possess dielectric and optic characteristics which are very similar to that of known ferroelectrics La2Ti2O7 and Nd2Ti2O7.
Structure investigation on liquid gallium
Authors: Hoyer W. , Thomas E. , Wobst M. 
Published: July 2007

AbstractA brief description of the experimental arrangement to get the structure factor of liquid gallium at 50°C, 200°C, 300°C and 500°C is given. The evaluated structure factors and pair correlation functions are presented. A comparison of the nearest neighbour values and the radii of the first coordination shell of various authors is made. Some structure models are compared with the experimental data.
Change in dislocation distribution of KCl single crystals during thermal cyclic annealing
Authors: Inoue T. , Komatsu H. 
Published: July 2007

AbstractThe change in dislocation distribution of KCl single crystals during thermal cyclic annealing was studied by etch pit method. The results obtained are summarized as follows.(1) In contrast to the case in Cu (KITAJIMA et al.; HASEGAWA et al.), the dislocation distribution in KCl crystals became non‐uniform with an increase in the cyclic annealing time, i.e., in the region near the surface, many sub‐boundaries were formed, but in the interior, the density of dislocations and sub‐boundaries decreased. The cyclic annealing is more effective in reducing the dislocation density than the isothermal annealing.(2) The longer the period of thermal cycle, the more effective in reducing the dislocation density.(3) The larger the temperature difference between the maximum and minimum during one cycle, the more effective in reducing the dislocation density.(4) In the Sr‐doped crystals, the thermal cyclic annealing was also effective in reducing the dislocation density within subgrains but sub‐boundary length per unit area slightly increased by the cyclic annealing.(5) When the samples were annealed under the atmosphere of Cl2, the dislocation density remarkably increased against our expectation, although the scattering centres had disappeared by this treatment.
Purity and doping possibilities of Al2O3 and YAG molten in Mo crucibles and crystals grown from this melt
Authors: Kvapil Jiří , Perner Bohumil , Kvapil Josef , Blažek Karel 
Published: July 2007

AbstractDoping possibilities of Al2O3 and YAG crystals grown from the melt alternatively doped with alkali earth, silicon, iron group or molybdenum ions under 98% Ar – 2% H2 or 98% He – 2% H2 protective atmosphere are described. Alkali earth and particularly Si ions evaporate slowly from the melt. Reduction of iron group ions was observed. Mo may enter YAG phase using a wet protective atmosphere. Al2O3 phase contains Mo ions if grown from the electrolyzed melt.
A positron annihilation study of vacancies and their clusters in diluted aluminium alloys quenched or neutron‐irradiated
Authors: Dlubek G. , Gerber W. , Vehanen A. , Yli‐Kauppila J. 
Published: July 2007

AbstractPure Al and Al alloyed with Mg, Zn, Ge, and Si was quenched from 600°C in water at room temperature or irradiated with fast neutrons. With the help of positron lifetime and angular correlation peak height measurements vacancies, their clustering and their annealing behaviour were studied.
X‐ray and X‐ray photoelectron spectra of vanadium oxides
Authors: Werfel F. , Dräger G. , Berg U. 
Published: July 2007

AbstractX‐ray (XS) and X‐ray photoelectron (XPS) spectra are reported for vanadium oxides. Because of the multivalent character of vanadium in the oxide system high quality measurements can be used for chemical shift investigation. Both inner level and valence band spectroscopy give information on the electronic structure and their systematic change with increasing oxidation state. The experimental results are discussed favourable in terms of molecular orbital theory (MO‐theory). The complete set of XS and XPS data reported here for V‐oxides allows the identification of unknown vanadium oxidation states too.
Defect Investigations in CdTe Crystals by RXT, SCL, and EBIC(V) Techniques
Authors: Klimkiewics M. , Auleytner J. , Warmiński T. 
Published: July 2007

AbstractThe paper covers results of investigations on the defect structure of CdTe crystals. Several techniques have been involved, namely RXT supplied with CL‐IR, EBIC(V), and SACP using Electron Probe Micro‐Analyzer (EPMA): EBIC(V) measurements were performed on Schottky diodes with CdTe‐Au contacts. It has to be emphasized that microscopic images at small magnification (45 ×) had successfully been obtained which were next correlated with X‐ray topographs. The observed due to grain boundaries, twins, “as grown” dislocations as well as those introduced either during high‐temperature plastic deformation or by pyramidal diamond indenter are discussed.
Extended defects in III‐V semiconductor compounds
Authors: Ferenczi G. , Dózsa L. 
Published: July 2007

AbstractA new class of defects characterized by inherent non‐exponential capture and emission processes was observed. A theory – based on the potential barrier model – is proposed to describe the measured DLTS and capacitance transient data. It is argued that these defects are related to dislocations or dislocation generated lattice defects.
Kinetics of FCC‐ and diamond type binary crystal growth (II). Peculiarities of Si‐Ge and Cu‐Ni alloy crystallization
Authors: Cherepanova T. A. , Dzelme J. B. 
Published: July 2007

AbstractKinetic equations have been used to study how crystal growth rate and component concentration in the solid phase depend on temperature for different crystallographic orientations of the growing faces of binary crystals silicon‐germanium and copper‐nickel. The shape of kinetic phase diagram has been calculated. Compared are the main characteristics of the process obtained in a model “with overhangs” of the atomic relief of the interphase with those obtained in a model “without overhangs”. The kinetic equation solutions are compared with the results of Monte Carlo computer simulations. Their quantitative agreement has been shown.
Precipitation‐induced Dislocations in Crystals of NaCl:Ni
Authors: Andreev G. A. , Hartmanovà M. , Klimov V. A. 
Published: July 2007

AbstractUsing the decoration technique, the dislocation structure has been observed in regions localized near precipitates in nickel‐doped NaCl crystals. The results are interpreted in terms of the stress‐operated mechanism for the generation of prismatic dislocations by the precipitates. Normally only two of twelve possible slip directions operate for 〈110〉 rods. This is accounted for in terms of the climb and disappearance of dislocation loops corresponding to the other directions. {100} plates produce loops spreading along for 〈110〉 directions.
Dislocation Etching Behaviour of Hydrothermal and Organic Acid Etchants on Natrolite Crystals
Authors: Gupta N. K. , Kotru P. N. 
Published: July 2007

AbstractStudies on etching of (110) cleavages of natrolite crystals in organic acids (viz., succinic acid, formic acid, and phthalic acid) and stream under high hydrostatic pressures have been made. It is observed that on successive etching of matched cleavages in any of these organic etchants, the pits get bigger both in regard to depth as well as lateral dimensions. Study of matched cleavages etched in any of these etchants indicates 1:1 correspondence of point bottomed pits. Similar results are obtained when matched cleavages are etched by the hydrothermal method. In contrast to such results, it is observed that the etch pit density on a cleavage etched by the hydrothermal method is always higher when compared with its matched cleavage etched in any of the given organic acids. Through a series of experiments, it is found that while corresponding to every etch pit due to any of these organic acids there is a pit due to hydrothermal etching, the converse is not true. It is suggested that the hydrothermal etching is more reliable so far as dislocation density estimation on (101) cleavages of natrolite is concerned.
Microstructures on gel‐grown KClO4 single crystals
Authors: Patel A. R. , Rao A. Venkateswara , Narayana D. L. 
Published: July 2007

AbstractThe present paper reports the observations made on the microstructures of gel grown KClO4 single crystals. Various observations such as growth spirals, growth layers, liquid inclusions and growth of microcrystallites are discussed in relation to the mechanism and conditions of crystal growth.
Frequency dependence of the threshold voltage of the Freedericksz effect in nematic and nematic reentrant phases
Authors: Hauser A. , Kresse H. , Pelzl G. , Demus D. 
Published: July 2007

AbstractIn four substances exhibiting reentrant nematic phases the threshold voltage of the Freedericksz transition was measured as function of the frequency in the nematic and reentrant nematic phases. The isotropy frequency and the relaxation frequency were calculated using the experimental data. We found that extrapolated to the same temperature the relaxation frequency of the reentrant nematic phase is larger than that of the nematic phase.
The role of iron ions in laser ruby
Authors: Kvapil Jiří , Perner B. , Kubelka J. , Kvapil Jos. 
Published: July 2007

AbstractDoping possibility of long ruby crystals grown by Czochralski method under reducing protective atmosphere by iron ions in described. Using the admixture of hydrocarbons to the protective atmosphere this dopage may be realized. Iron ions increases damage threshold of the Q‐switched laser ruby rods.
Study of growth and doping of semiconductor films by the method of computer simulation
Authors: Aleksandrov L. N. 
Published: July 2007

AbstractThe possibility of Computer Simulation Monte‐Carlo Method for the study of growth and doping regularities of semiconductor films with diamond type lattice and for control of their parameters is considered. The events probabilities of isolation attachment and diffusion displacements of atoms on the growing surface of the basic material and doping impurities are compared. The periodic regional conditions on the boundary of the considered area are presented. It is shown the limitations of the computer simulation methods because of growth processes knowing level and computer possibility. The modeling calculations are made for growth and doping of one‐component material films and for growth of two‐component compounds. It can be noticed the connection between supersaturation, deposition temperature, time growth rate, surface film roughness (impurity atoms), capture coefficient, doping level, critical thickness of continuous films, defects density. Computer experimental results are compared with experimental data on growth and doping of Si, Ge, GaAs film with the various orientations from vapour or molecular beams in vacuum. The ways of further development of computer simulation method are discussed.
Optimized growth conditions of GaN epitaxial layers
Authors: Fremunt R. , Černý P. , Kohout J. , Rosická V. , Bürger A. 
Published: July 2007

AbstractOptimized growth conditions of the epitaxial GaN layers on the (0001) oriented sapphire substrates in the Ga/HCl/NH3/H2 system have been proposed. The corresponding growth rate varied about the value 0.5 μm · min−1. The study of surface morphology and X‐ray diffraction have confirmed the single crystalline character of the layers even though the surface shows a faceted structure. The c/a ratio calculated from our measured data of the lattice parameters was found 1.624 which is relatively close to the ideal close‐packed wurtzite structure value. The cathodoluminescent spectra of the layers with a sufficient thickness were characterized by a peak at 3.35 eV having a halfwidth of about 0.2 eV.