bluuebunny/crossref_metadata_2025 huggingface dataset:
Inclined Dislocations in Synthetic Calcite Crystals
Authors: Desai C. C. , George K. V.
Published: January 2007

A large number of perfect (100) cleavages were obtained by cleaving the laboratory grown synthetic calcite crystals. By etching such cleavages in 20% ammonium chloride solution, it is established that the pits indicate the sites of dislocations in the crystals. This is further confirmed by comparing the etch patterns on matched cleavage surfaces. Eccentricity of the pits has been attributed to the inclined nature of dislocations. Existence of parallel dislocations seems to be due to the purity of the crystal. These observations are verified by comparing etch patterns produced on opposite faces of a thin flake (0.048 mm thick) and also by successive etching and polishing a cleavage surface. It is conjectured that curl‐bottomed pits nucleate at the sites of screw dislocations in the crystal. The implications are discussed.
On the Determination of the Size Distribution Functions of Spherical Precipitations in Al–Zn Alloys by Neutron Small‐angle Scattering
Authors: Schülbe R. , Schmidt U. , Schild L. , Eichhorn F.
Published: January 2007

The size distribution of approximately spherical incoherent precipitations of Zn in AlZn‐alloys is calculated and experimentally tested by means of neutron small angle scattering (NSAS) at a double‐crystal diffractometer (DCD). The scattering curves can be approximated by a Gaussian function, so that the size distribution is directly calculated for the experimentical scattering curves under application of a particular LAPLACE‐transformation. The size distributions of the α′m‐phase of AlZn(16)‐samples of different averaged radii of precipitations are calculated by means of FWHM which are determined by the fitting procedure of a computer programme and compared with TEM micrographs.
The Slow Precipitation of Sparingly‐soluble Metal Salt Powders from Aqueous Solution: Mathematical Relations for the Kinetics of the Crystal Growth Processes in Different Types of Precipitation
Authors: Packter A.
Published: January 2007

The following types of slow precipitation, of sparingly‐soluble metal salts from aqueous solution, have been analysed: precipitations without an induction period – (i) with very few microcrystallites or seeds, (ii) with microcrystallites and first/second order surface or diffusion rate‐controlled growth, (iii) with very many microcrystallites; precipitations with significant induction periods – (i) with very few microcrystallites or seeds, (ii) with microcrystallites and first/second order surface or diffusion rate‐controlled growth, (iii) with very many microcrystallites.

Generally, in the early stages of precipitation, growth rates depend on the rate of addition of metal salt ions to the system and on the rate constant for crystal growth; in this stage, rates increase from low values to optimum values: in the later stages of precipitation, the metal salt ions are used up as rapidly as they are added to the system and growth rates then depend only on the rate of addition and on the number of microcrystallites or seeds; in this range, rates gradually decrease to low values.

Mathematical relations, for the variation of crystal size with precipitation time at different stages of growth, have been derived for each of the above types of precipitation.
Calculation of the Suspension Volume of Crystallizers with Non‐ideally Mixed Suspension
Authors: Winter B. , Gramlich K.
Published: January 2007

For the calculation of the suspension volume of crystallizers with non‐ideally mixed suspension the material balance was derived. The model of complete segregation and the cell modell were used to describe the micro‐mixing of solid phase. Testing was carried out in a laboratory crystallizer. The residence time distribution and the weight increase of the crystals were measured. The results showed that the model of complete segregation is suitable for describing the flow behaviour of the solid phase in crystallizers.
Correlation between Light Microscopical and Electron Microscopical Images of Crystal Defects in GaP
Authors: Tempel A. , Löschke K. , Bartsch H.
Published: January 2007

Ultramicroscopy and dark‐field‐illumination basing on the scattering of photons are easily available, they are nondestructive light microscopical methods for real structure investigations of semiconducting materials. The observation of dislocations is possible because of photon scattering at precipitations adherent to the dislocation line. This work gives a direct correlation between light microscopical and electron microscopical images of dislocations and in this way some hints on the nature of scattering centres. The light scattering takes place at precipitations caused due to gettering of impurity atoms by the dislocation line. Besides elongated dislocations prismatic loops were observed. The loop density was found to be in the order of magnitude of about 1012 cm−3 which corresponds to a concentration of about 1017 atoms contained in the loops in good agreement with the concentration of impurities in the crystals.
Determination of the fermi level, fermi distribution and activity coefficient for p‐SiC(Al)
Authors: Lilov S. K.
Published: January 2007

A calculation was made of the Fermi level value and Fermi distribution at different temperatures, concentrations of impurities and degrees of compensation in acceptive silicon carbide, doped by aluminium. The dependence of the activity coefficient of aluminium in the silicon carbide on the concentration and the temperature was established.
The pAl0.7Ga0.3As‐pGaAs‐nGaAs concentrator cell with electrolytical contacts
Authors: Prutskij T. A. , Purón E. , Rodríguez J. A. , Romero R. , DeRoux S.
Published: January 2007

The technological procedure involved in making p‐Al0.7Ga0.3As‐p‐GaAs‐n‐GaAs concentrator solar cells by forced cooling LPE is discussed. Electrical contacts were electrochemically deposited from acid baths of Au and Ni, followed by annealing. 1.4 A/cm2 short current densities and 1 V open circuit voltages were measured under 7 W/cm2 incident radiation.
The incorporation of oxygen impurities in semiconductor silicon in chemical vapour deposition
Authors: Bartsch K. , Wolf E.
Published: January 2007

The incorporation of oxygen traces in chemical vapour deposited semiconductor silicon has been calculated for the temperature range of 1200–1500 K in dependence on the excess of hydrogen in the reaction gas. The results obtained correspond to the experimental data. With increasing temperatures of deposition and increasing excess of hydrogen the incorporation of oxygen decreases at a constant concentration of oxygen in the initial state.
DKDP Crystals for Electrooptic Devices
Authors: Ittu Zugrav M. , Dumitrica A. , Dumitras A. , Comaniciu N.
Published: January 2007

The deuterated homologue of potassium dihydrogen phosphate crystals (DKDP) was grown by a modified transport method. Experimental results concerning electrooptic characteristics of these single crystals used in construction of a Q‐switch and a four‐crystals modulator are presented. An infrared extension of KURTZ‐ROBINSON model electrooptic effect is also given.
Chemical Etching of Calcite Cleavages by Diluted Solutions
Authors: Mehta B.J.
Published: January 2007

Very low concentration of mineral acids and monocarboxylic acid (less then 0.001%) produces triangular etch pits on calcite cleavages at dislocations intersecting the surface. The orienation of triangular etch pits is opposite with respect to percussion mark on calcite cleavages. This may be due to opposite process of percussion and reaction at very low concentrations. When percentage of water is slightly decreased in both above acids, rhombic etch pits were formed. The non‐coincidence of depth points and geometerical centres of rhombic etch pits are explained. The similarity of shape cycle will not hold at higher concentrations.
Investigation of the Microstructure of Crystals Surfaces by the Method of Self‐decoration during Ion Bombardment
Authors: Marinov M. , Stoyanchev R.
Published: January 2007

A method is developed for self‐decoration with ion bombardment by which the surface structure of crystal samples is investigated. The existing surface structure of the objects, as well as the additionally developed structure after prolonged ion bombardment are visualized by this method. When using scanning electron microscopy the method allows multiple investigation of the sample or of one and the same parts of it respectively.

The mechanism of the method is revealed by the results obtained in the performed experiments. It is proved that the crystal surface and its decoration depend on the peculiarities of the crystal structure and on the conditions of bombardment. By varying the conditions of ion bombardment the sensitivity of the method is considerably changed.
Single Crystal Growth and Pyroelectric, Dielectric, Piezoelectric, Elastic, and Thermoelastic Properties of Orthorhombic Li2SiO3, Li2GeO3, and Na2GeO3
Authors: Haussühl S. , Liebertz J. , Stähr S.
Published: January 2007

Single crystals of optical quality of isotypic Li2SiO3, Li2GeO3, and Na2GeO3, space group Ccm21, with diameters of ca 16 mm and lengths of ca 20 mm (Li2SiO3) and ca 60 mm (Li2GeO3 and Na2GeO3) have been grown from the melt using the Czochralski technique. On Li2SiO3, Li2GeO3, and Na2GeO3 pyroelectric coefficients and complete dielectric, piezoelectric, elastic, and thermoelastic tensor properties have been determined; the latter from the temperature dependence of resonance frequencies. All crystals investigated exhibited only a small amount of 180° twins. They all possess large pyroelectric coefficients about‐five times that of tourmaline. The longitudinal piezoelectric constant d333 is about five times larger than d111 of alpha quartz. Qualitative measurements on Na2SiO3 revealed similar values of pyroelectric and piezoelectric effects. The technical application of these crystals encounters some difficulties: Li2SiO3 is excellently cleavable parallel (010). This face contains the polar direction [001]. Na2GeO3 suffers from chemical decomposition in humid atmosphere and is well cleavable too. Both happens to a much less extent in Li2GeO3. Na2SiO3 proved to be hardly suitable for any application of its polar properties due to its bad chemical stability against humid air and its excellent cleavage.
Applicability of the Method of VAN DER PAUW to Samples with Two‐dimensional Defects
Authors: Albers C. , Gertig H. , Reuter M.
Published: January 2007

The influence of cleavage steps and low angle boundaries on the results of conductivity and Hall measurements by Van der Pauw's method are investigated and some criterions for evidence of sample inhomogeneities by the assumption of symmetrical sample shape and contact arrangement formulated. Hall voltage is less influenced by cleavage steps, so that the determination of carrier concentration is nearly correct also in strongly disturbed samples. Conductivity and carrier mobility measurements in the usus usual calculation procedure will lead to considerable errors. By one pair of contacts only for conductivity as well as for Hall measurements, the influences of inhomogeneities cannot be distinguished from volume effects of the sample.
Rotational Striations and Diffusion in Barium Sodium Niobate Crystals
Authors: Aleksandrovskii A.L. , Naumova I.I. , Posmykiewicz P.
Published: January 2007

The possibility of inducing rotational growth striae with a small period in barium sodium niobate crystals (BSN) is examined. Crystals grown had a period stability up to 1 percent and were suitable material for anisotropic light diffraction by ferroelectric domains. However intense striae were produced only for periods λ > 5 m̈m. With the help of Bragg optical diffraction by growth striae the diffusion coefficient D in solid phase responsible for striae smoothing during annealing was measured. The magnitude D ≈ 10‐11 cm2 s‐1 at the melting point was obtained. Such D value leads to the vanishing of striae with λ < 5 m̈m in BSN crystals during growth.
A New Method for Powder Diffraction Phase Analysis
Authors: Fiala J.
Published: January 2007

A new method for quantitative X‐ray phase analysis is described. This universal procedure allows to analyse mixtures of components some of which are not known or partly known substances.

Es wird ein neues Verfahren der quantitativen rötgenographischen Phasenanalyse beschrieben. Dieses universelle Verfahren ermöglicht, Gemische von Komponenten, die unbekannt oder teilweise unbekannt sind, zu analysieren.
Influence of Additives and Surface Topography on the Alignment of Nematic Liquid Crystals
Authors: Hauck G. , Komitov L. , Derzhanski A. , Koswig H. D.
Published: January 2007

Observations of the influence of a simultaneous action of different surface topographies and polar or nonpolar additives in small concentration on the alignment properties of liquid crystal molecules are reported. The additive dependence of the threshold behaviour of planar aligned liquid crystal cells is also studied.
On the Influence of the Distortion Distribution on the Determination of Roentgenographic Particle Sizes and Distortions (II) Distortion Distributions and Evaluation Procedure
Authors: Röll H. , Schulz H.
Published: January 2007

It is shown that a Gaussian distribution of the distortion not enables in each case an exact evaluation of experimentally measured Debye‐Scherrer lines. – After a discussion of simple possibilities for set up of simple and more common distortion distributions with more than one free parameter is given a procedure independent on the distortion distributions for the determination of roentgenographic particle sizes and distortions.
Hydrothermal Synthesis and Characterization of VSZ‐3 Zeolite Crystals
Authors: Joshi M. S. , Mohan Rao P. , Choudhari A. L. , Kanitar Ravindra
Published: January 2007

Zeolite crystals (named here VSZ‐3) synthesized at 350°C by hydrothermal method are illustrated and described. These crystals are shown to be analcime type zeolites. It is established that their size is the largest among the zeolite crystals ever reported, and are stable upto 1000°C. The VSZ‐3 crystals are prismatic pyramidal and needle‐like. They are characterized by X‐rays, SEM, TGA, DTA and IR. Their chemical composition is shown to be 5.95 SiO2 ṁ Al2O3 ṁ 0.91 Na2O ṁ 0.17 H2O. Mechanism of growth of these crystals is explained.
Etch Pit Morphology on Calcite Cleavages by Glacial Acetic Acid
Authors: Mehta B. J.
Published: January 2007

Etch pit morphology has been studied on calcite cleavages by different concentration of glacial acetic acid. Lateral reaction rates are very less at high concentration as well as low concentration of glacial acetic Acid. Etch pit morphology changes due to formation of finite or infinite lateral reaction rates at some particular concentration called transition concentration. The underlying chemical equations are given for different etch pit morphology.
Ihnomogeneous Distribution of Doping Elements in Polycrystalline GaP
Authors: Moravec F. , Štrajblová J.
Published: January 2007

The distribution of Te and Zn in polycrystalline GaP ingots grown by SSD method was studied by means of the contact resistance measurements between a tungsten carbide probe and a lapped sample surface. The differencies in carrier concentrations measured in differently oriented GaP :Te crystal grains were found as high as one order of magnitude. In GaP: Zn crystals the constant Zn concentration throughout the sample was observed.
The Extrapolation Method in the Electron Probe Microanalysis
Authors: Christ B. , Oelgart G.
Published: January 2007

From the energy dependance of the k‐ratio measured for the SbLα and BiLα‐lines in the alloy system Bi1–xSbx the k‐ratio at the critical energy Ec is determined by extrapolation. The stopping power correction is discussed for the system investigated here on the basis of the known composition of the specimens. The mean ionization potentials J for Sb and Bi are estimated from the experiments.
Revelation of microtwinning in hydrothermally grown synthetic quartz by growth structures
Authors: Kotru P. N. , Raina K. K.
Published: January 2007

Growth structuress on prism surfaces of synthetic quartz grown by hydrothermal crystallization technique, indicative of microtwinning in them are described, illustrated and discussed. The microtwins are revealed by the misorientation of the growth structures, and it is observed that microtwinning is manifested in different forms. Twinned domains appear in the form of strictly oriented, square striated (stepped) structures with inclined surfaces, seemingly overlapping square striated structures, square and irregular regions demarcated by black line‐like boundaries, patch‐like structures enveloping irregularily bound domains, tongue‐like terraces bordered by irregular line of discontinuity of varying height and the regions with both differently shaped as differently oriented growth structures. From the orientations of the square shaped growth structures, it is shown that crystals consist of domains which are in twin relationship to the main crystal. Twins by rotation around an axis perpendicular to (10ī0) with rotation angles of 60°, 90°, and 180° have been observed. Critical examination of some twin boundaries delineated by black line‐like matter, with the application of multiple beam interferometry and FECO reveal that the black boundary is a ridge (line‐elevation). The line elevation along such a twin boundary is explained to be as a result of preferential adsorption of impurity atoms along the trace of the boundary. It is further observed that discontinuity in crystalline structure along the twin boundary leads to growth forms with distorted morphology thus establishing strong dependence of growth forms on the underlying crystalline structure. Causes for generation of the microtwins (twinning on a microscale) in synthetic quartz are discussed.
The effect of divalent impurity state on the microhardness of NaCl crystals
Authors: Andreev G. A. , Klimov V. A.
Published: January 2007

The microhardness and bulk density variations with annealing temperature have been measured in NaCl crystals doped with Ca2+, Cd2+, Ni2+, and Pb2+. Both characteristics are not affected by coherent metastable precipitation while incoherent precipitation produces either hardening or softening depending on the impurity phase type (stable or metastable). The results support the suggestion that aggregates and coherent precipitates are cut through by dislocations whereas incoherent precipitates are by‐passed via the Orowan looping mechanism.
Dehydration of Selenite Cleavage Faces
Authors: Mehta B. J.
Published: January 2007

Initial dehydration of selenite cleavage surfaces start at temperature 86 °C. The dislocations are revealed by distilled water. Dislocations are mobile at dehydration temperature. Impurity centres may act as obstacles for dislocation movement. Dehydration figures are in probability formed at impurity centres.
Mikrohärteuntersuchungen an Einkristallen der Verbindungen Tl3BX4, (B = V, Nb, Ta; X=S, Se)
Authors: Wacker K. , Buck P.
Published: January 2007

Vickers microhardness measurements were performed on single crystals of compounds Tl3BX4 (B = V, Nb, Ta; X = S, Se). The anisotropy of the hardness on the (111)‐plane was beyond the standard deviation. Besides the load‐dependent Vickers hardness HV, the corrected, load‐independent hardness HVc was determined. Tl3VS4 showed the highest value of hardness (HV = 66 kp/mm2 at 15 p load), the othe compounds differ only slightly in hardness.
A Model Study of the Growth of Crystals Consisting of a Small Number of Metal Atoms by the Hückel Molecular Orbital Method (II) Addition of One Atom to (N + 1)‐atomic Clusters
Authors: Delineshev S. P. , Bliznakov G. M.
Published: January 2007

The regularities of the formation of (N + 2)‐atomic clusters obtained by the growth of (N + 1)‐atomic clusters and the distribution of the (N + 2)‐atomic clusters according to their stability are studied. The most stable (N + 2)‐atomic cluster is not always obtained from the most stable (N + 1)‐atomic cluster. Sometimes it is formed by the least stable (N + 1)‐atomic cluster.

A necessary condition for the appearance of the most stable (N + 2)‐atomic cluster is the formation of a bond between the N + 2nd and the N + 1st atoms. This means that the most stable (N + 2)‐atomic cluster may be considered as obtained directly from the N‐atomic crystal by jumping over the stage of the (N + 1)‐atomic cluster and adding a dimer suitably oriented with respect to the N‐atomic crystal.

The least stable (N + 2)‐atomic cluster is always obtained from the least stable (N + 1)‐atomic cluster.
Structure Changes in an Al‐4.5 at.% Zn‐2.0 at.% Mg Alloy during Continuous Heating in Dependence on the Starting Conditions
Authors: Oettel‐Gueffroy B. , Löffler H.
Published: January 2007

The structure changes proceeding during continuous heating of an Al–Zn(4.5 at.%)–Mg(2.0 at.%) alloy were investigated by DSC and SAXS in dependence of the start radius, rS, of the metastable phases (G.P. zones and/or η'‐phase) ranging from rS = 0.7 nm to 2.7 nm grown at Tpre = R.T. or 100°C. The stability of the metastable phases grown at Tpre is increasing with the ris e of rS, whilst the Tpre applied does not remarkably affect their stability. Starting with rS > 1.6 nm the minima in the DSC‐curve caused by the formation of η'‐phase on the expense of the dissolved part of the zones (1. minimum) or from overcritical G.P. zones (2. minimum) become more and more undistinct with the rise of rS.
The MORIN Transition – a Sensitive Criterion for Testing the Quality of α‐Fe2O3
Authors: Fritzsch E. , Pietzsch C. , Heegn H. , Huhn H.‐J.
Published: January 2007

The MORIN transition of α‐Fe2O3 is quite sensitive to impurities, lattice imperfections and particle size and, therefore, can be used to test the quality of α‐Fe2O3. If in the material under consideration the MORIN transition has completely taken place at 250 K, the material is pure, undistorted bulk α‐Fe2O3. For testing this only one Mössbauer spectrum has to be taken at 250 K.
Growth of Heterostructures Based on InAs–AlxGa1–xSb
Authors: Pramatarova L. D. , Tret'Yakov D. N.
Published: January 2007

It is reported on the liquid phase epitaxial (LPE) growth of heterostructures on the base of InAs–AlxGa1–xSb. The paper includes the investigation of epitaxial layers of AlxGa1–xSb alloys on InAs substrates and results of experiments for the determination of optimum growth regimes.
Laser Annealing of Chemical Bath Deposited CdS Films
Authors: Martinez G. , Martínez J. L. , Zehe A.
Published: January 2007

Chemical Bath Deposited (CBD) CdS films have been exposed to a cw Ar+ laser annealing. Measurementes on the dark electrical resistivity have shown a two decade decrement in the resistivity. A trend of improving this resistivity is shown upon atmospheric pressure increase. The annealing mechanisms of the samples show a threshold laser power density of 50 W/cm2. This power threshold accounts for some heating mechanisms and Cd ion evaporation from the samples; thus a gaseous Cd atmosphere annealing process is suggested. This laser annealing mechanism parallels thermal annealing of polycrystalline CdS films. Assessment of this mechanisms is supported by the fact that the mobility ratio, b = μn/μp, (greatly influenced by crystallite size and intergranular potential barrier in thin film semiconductors) does not show major changes to account for a two decade decrement of CBD laser annealed samples.
Zinc Oxide with High Luminescence in the Ultraviolet Region
Authors: Klikorka J. , Lošťák P. , Horák J. , Fojtík L.
Published: January 2007

In the present work a preparation of ZnO showing high luminescence in the region of the interband transitions at about 385 nm is described, while luminescence in the green region is practically suppressed. The preparation consists of increasing the free carrier concentration by incorporation of Ga3+ ions into the ZnO lattice and decreasing further the concentration of oxygen atoms by annealing in a reducing in a reducing atmosphere. It has been shown experimentally that by using lead‐doped ZnO, the ration of band intensities in the UV and green regions is substantially higher than when ‘pure’ ZnO is used. We present finally a possible explanation of the role of Pb atoms bringing about this phenomenon.
Orientation relationships of aluminium nitride on sapphire
Authors: Sokolov E. B. , Malyukov B. A. , Kudakov U. D. , Naida G. A.
Published: January 2007

Orientation relationships of aluminium nitride on sapphire (1126) AlN/(0112) Al2O3 have been defined more exactly by X‐ray diffractometry techniques. It has been found that, depending on the substrate misorientation from the surface plane (0112), there can exist two kinds of azimuthal orientation of the epitaxial layer of AlN, namely, the projection of [0001] AlN on plane (0112) Al2O3 can coincide either with [2110] Al2O3 or with [2110] Al2O3 direction.

The vector field of the epitaxial layer inclination relative to the substrate misorientation has been drawn. The symmetry of this field obeys Neumann's rule. The epitaxial layer orientation has been found to depend on the sapphire substrate misorientation in direction [2110].
Investigations of flash evaporated cubIIIC2VI semiconductor thin films by Rutherford backscattering spectroscopy
Authors: Höbler H.‐J. , Flagmeyer R. , Schumann B.
Published: January 2007

The chemical composition of CuBIIIC2VI thin films grown by flash evaporation technique was analysed using Rutherford backscattering spectroscopy. The composition of the samples changes with variation of the substrate temperature. In certain temperature ranges nearly stoichiometric layers were obtained.
The influence of the lattice misfit on the growth of CuGaSe2 Epitaxial Films on {100}‐oriented GaAs and GaP Substrates
Authors: Schumann B. , Tempel A. , Kühn G.
Published: January 2007

CuGaSe2 epitaxial layers were prepared on GaAs and GaP {100}‐oriented substrates by flash evaporation technique and characterized by RHEED. Different epitaxial relationships have been found for growth on the different types of substrate material. The orientation is determined by the minimum misfit.
A New polytype notation for CdI2 type structures. The thr symbols
Authors: Fichtner K.
Published: January 2007

The thr notation is introduced to describe any stacking variant as a mixture of fractions of the three simplest or regular polytypes: 2H (trigonal), 4H (hexagonal), and 6R (rhombohedral). The new notation is compared with existing ones and applied to pairs of homometric structures and to the characterization of stacking faults.
Peculiarities of reoriented bands formation in crystals
Authors: Berezhkova G. V. , Perstnev P. P. , Romanov A. E. , Vladimirov V. I.
Published: January 2007

The peculiarities of the formation and the development of reorientated bands in crystals are considered. Reorientated bands are investigated experimentally in MgO single crystals under the compression testing. It is shown that the misorientation between the material in the band interior and the surrounding volume can reach some degrees. The data of electron microscopy investigations of dislocation structure of such bands are performed. The disclination model is proposed for the propogation of the reorientated bands. This model permits to explain the laws of the band development, for example, the formation of discrete areas with reoriented crystal lattice ahead the terminated band.
Elastic debye temperature of compounds with sphalerite structure
Authors: Deus P. , Schneider H. A.
Published: January 2007

Elastic Debye temperatures θEL of the semiconducting compounds AIIIBV, AIIBVI and CuCl are evaluated from second order elastic constants Cik available from the literature. The dependence of θEL on temperature is given. The results at 0 K are compared with those calculated from low temperature measurements of specific heat. Generally, the agreement between these values is better than found in the literature up to now.
A combination of oscillating slit and oscillating film techniques for the investigation of lattice defects
Authors: Auleytner J. , Furmanik Z.
Published: January 2007

A combination of oscillating slit and oscillating film techniques is described. This X‐ray topographical method allows reflections due to the same places on the crystal surface to be recorded first in form of a topogramme registrated on the oscillating film set in the parallel position to the crystal surface. Second on the stationary film set parallel to the crystal surface in the form of an interference line Kα1 or Kß outgoing from the investigated area and registrated on the first topogramme at the fixed angular position of the crystal and slit and next, recorded separate on the oscillating film and on the stationary film set in the distance of 50 mm from the crystal (oscillation axis). As an example a serie of photographs corresponding to four types of pattern obtained in the case of a PbSnTe crystal with small angle boundaries are presented.
On iodine behaviour in bulk crystals of PbTe and SnTe synthesized by the iodide method
Authors: Trifonova E. P. , Karagiozov L.
Published: January 2007

In order to explain the peculiar characteristics of iodidely synthesized PbTe and SnTe crystals a model for their interaction with iodine is suggested. It is based on the assumption that PbI and I, respectively SnI and I, resulting from the PbI2 (SnI2) dissociations, are incorporated independently and specifically in the crystals: in PbTe prevails the PbI‐incorporation; in SnTe — the incorporation of I + VSn. This difference is connected with the thermodynamic stability of the PbTe and SnTe crystal lattices.
Anisotropy of temperature factors and interatomic forces in II‐IV‐V2 semiconductors
Authors: Vaipolin A. A.
Published: January 2007

An imcomplete set of X‐ray reflections with high indices („back”︁ reflections by MoK‐radiation) was measured for six II‐IV‐V2 semiconducting compounds of the chalcopyrite structure. The site parameter of the V‐atom and the temperature parameters proportional to the components of mean square displacements of atoms () were determined. General peculiarities of the relation of temperature factor constants and its variation within this family of compounds are reported. A qualitative crystallochemical interpretation of this relation is proposed on the basis of the atomic interaction scheme taking into account the principal and auxiliary bonds in the first and the second coordination sphere, respectively.
The melt growth of semicircular crystals of the pure Pb and its dilute alloys
Authors: Hayashi S. , Fukui M. , Komatsu H.
Published: January 2007

Semicircular crystals of Pb were grown from the melt by a rotational operation so as to change the orientation of the solid‐liquid interface during crystallization. In pure Pb, specimens grew as polycrystals with grain boundaries developed transversely to the growth direction. According to the decrease in purity, the grown crystals consisted of several long grains along the circular arc. A competitive growth between grains was inhibited by a small amount of impurity and then the mode of growth approached to the complete adhesive one.
On the structure of α′m‐precipitates in Al‐Zn alloys
Authors: Werner M. , Löffler H.
Published: January 2007

The lattice parameter of the f.c.c. α′‐phase in an Al‐12at.% Zn alloy decomposed at ageing temperatures ranging between 170 °C and 210 °C was investigated by an analysis of Moiré fringe contrasts which appear inside the precipitates in the TEM‐micrographs. Additionally information was gained concerning the relationship between the corresponding lattice of the α′m‐precipitates and the matrix. The analysis proved that the misfit between the lattice of the α′m‐precipitates and the adjoining matrix is fairly small, namely less than 1.5% in lattice spacing and less than 1° in the angular rotation. From these results it was concluded that the major part of the matrix planes passes the precipitates without interruption.
SIMS‐AES investigations on water vapour adsorption on nickel (100) at room temperature
Authors: Uhlmann K. , Storbeck F. , Griessbach R.
Published: January 2007

By means of the methods SIMS and AES the adsorption of water vapour on the (100) surface of nickel was studied. We conclude from the results obtained that the adsorption has three stages: chemisorption of OH groups, formation of a surface hydroxide and finally, formation of an oxide layer containing O and OH. The quantity of oxygen detected corresponded maximally to about a monolayer coverage.
Influence of intrinsic defects on the electrical properties of AIBIIIC compounds
Authors: Neumann H.
Published: January 2007

The electrical parameters of undoped melt grown AIBIIICVI2 crystals are compared with predictions which can made considering the deviations from stoichiometry due to the incongruent evaporation of these compounds. It is shown that the electrical properties of all AIBIIIC compounds can be interpreted in a consistent manner if the electrical activity (donor or acceptor) of the intrinsic defects is considered in the covalent bonding model.
Defect levels in the energy gap of the PbI2 crystal evidenced by optical methods
Authors: Constantinescu M. , Ghit˘ L. , Baltog I. , Ghit˘ C.
Published: January 2007

A scheme of the localized levels in the energy gap of PbI2 single crystal is deduced on the base of our experimental studies of luminescence, photoconduction and thermo‐stimulated currents on crystals as grown or submitted to a specific thermal treatment and optical irradiation.
Textural properties of AISb films
Authors: Patel S. M. , Biradar A. M.
Published: January 2007

Textural studies have been carried out in AlSb films deposited by coevaporation method under high vacuum at different substrate temperatures between 450° to 625 °C. The films have been examined by X‐ray and electron diffraction techniques. It was observed that the films deposited around 550 °C were found to exhibit [110] and [111] textures and the films deposited at higher substrate temperatures (above 600 °C) were found to exhibit only [111] textures.
Mode of solidification and strength properties for lead‐tin binary system
Authors: Bassi P. S. , Sharma N. K. , Chawla J. S. , Sharma M. K.
Published: January 2007

Tensile strength and ductility of unidirectionally and randomly solidified Sn, Pb and Sn–Pb eutectic alloy are determined. Appreciable increase in the ductility from random to directional growth has been observed in case of Sn, Pb and Pb–Sn eutectic. Improvement in tensile strengths of pure metals and their eutectic composite by 15–20% and 15%, respectively, was evident in case of directionally solidified to randomly grown samples. The increase in tensile strength of the eutectic was 2–2.5 times to the strength of the pure metals. Tensile strength of directionally solidified Pb–Sn eutectic studied at different rates of solidification for constant temperature gradient was lower at higher and at lower rates of solidification than the value at medium rates of solidification.
Temperature distribution in growing semi‐transparent crystals (III). Conical liquid/solid interface
Authors: Kvapil Jiří , Kubelka J. , Kvapil Josef , Perner B.
Published: January 2007

Temperature distribution in Al2O3 and YAG crystals grown by Czochralski method and in the melt layer adjacent to the liquid/solid interface of the conical shape was computed. The results were compared with the quality of the crystals. Using a highly absorbing material, temperature difference near the deeply submerged sharp interface decreases from the edge to the centre of a crystal and it is relatively great and unalterable in the case of a shallowly submerged blunt interface. Sharp interface show the crystals grown from the melt of the same composition (Al2O3 or accurately “stoichiometric” YAG), whereas the blunt one is typical of YAG grown from the melt of the “non‐stoichiometric” composition, because its solidifying point is below the melting point of YAG phase.
Influence of the flow velocity, supersaturation and temperature on the crystal growth from solutions
Authors: Kirkova E. , Nikolaeva R.
Published: January 2007

This paper is a review of our experimental research on the influence of the supersaturation, flow velocity and temperature on the linear crystallization rate of different faces of model crystal systems. The obtained experimental results are discussed in the light of the new theoretical treatments on crystal growth from low temperature solutions.
On the mechanism of chemical polishing of GaAs crystals
Authors: Zach D. , Löwe H.
Published: January 2007

In order to establish reproducible conditions for chemical lap polishing of GaAs with NaOCl solutions, containing also OH−‐ and CO ‐ions, the mechanism of dissolution was investigated using the rotating disk arrangement. In solutions with excess OCl− concentrations likewise diffusion and a reaction of the first order with respect to OH− and CO, complexing agents for Ga‐ions, control the dissolution rate, and the surfaces of the wafers are polished. OH− and CO32– concentrations in excess with respect to OCl− lead to rate determining OCl− diffusion and to irregularly polished or film covered surfaces. Diffusion constants for OH−, CO and OCl− are given.
Determination of the phase ranges during cooling and heating of Al‐40wt.%—(0—3) wt.% Mg alloys
Authors: Major B. , Ciach R. , Wendrock G. , Löffler H.
Published: January 2007

The various phases and the respective ranges of their existence were determined during continuous cooling from temperatures close below the solidus line to R.T. with a rate of 2 K min−1 as well as during the subsequent heating in few AlZn(40 wt.%)–Mg(X) alloys (X = 0; 0.5; 1.0; and 3.0 wt.%) by means of X‐ray phase‐analysis, small angle X‐ray scattering, differential thermo‐analysis, optical microscopy, and X‐ray micro‐analysis.

The most striking features are that even addition of only 0.5 wt.% Mg cause the formation of precursors of the MgZn2 equilibrium phase few degrees below the solidus line.
Influence of the aggregation state of Sr2+ ions on glow curves behaviour of NaCl: Sr2+
Authors: Reddy K. Narasimha , Babu V. Hari
Published: January 2007

Glow curves were recorded for NaCl:Sr2+ crystals subjected to annealing and quenching from elevated temperatures. These specimens were irradiated with X‐rays at room temperature by tungsten target. Samples exhibit certain glow peaks which are observed only in the first thermal cycle. A marked difference in the glow curves pattern for first and subsequent thermal cycles has been observed. It is suggested that these changes may be due to the change in configurational coordinate system of F‐centre due to impurity existing different states. This idea is supported by optical microscopy studies.
Results of crystal growth of bismuth‐antimony alloys (Bi100–xSbx) in a microgravity environment
Authors: Schneider G. , Herrmann R. , Krüger H. , Rudolph P. , Kuhl R. , Röstel R.
Published: January 2007

Results of two experiments are presented for growth of crystals from (Bi100–xSbx) alloys in a microgravity environment. In the growth experiments different variants of the Bridgman technique were used.

It was shown that in crystal growth from the melt in closed ampoules under microgravity conditions convection can be prevented completely. Therefore it is possible to grow crystals from melts of some components under diffusion controlled conditions of mass transfer.

In microgravity a reduced interaction between the melt and the confining walls was observed even if they have large contact with each other. The investigation of surface morphology corroborated the importance of surface effects for crystal growth from the melt under microgravity conditions. Measurements of electronic properties of crystals grown in microgravity showed a good quality in comparison to earth grown crystals.

Because under microgravity conditions in closed ampoules the diffusion controlled mass transfer can be realized and the interaction between the melt and confining wall is reduced, homogeneous crystals with high perfection can be grown melts of some components.
Influence of additives on periodic crystallisation in Gel(I). theory
Authors: Ambrose S. , Gnanam F. D. , Ramasamy P.
Published: January 2007

A quantitative explanation is given for the influence of additives on periodic crystallisation in gel. The theory involves the diffusion of the outer, inner and the additive electrolytes. It is assumed that precipitation begins when the product of the concentrations of the reactants reaches a critical value. Expressions are found for the velocity constant and spacing coefficient incorporating the valency and concentration of the additive.
Influence of additives on periodic crystallisation in Gel(II). Experimental verification
Authors: Ambrose S. , Gnanam F. D. , Ramasamy P.
Published: January 2007

The theory proposed by the authors on the influence of additives on periodic crystallisation in gel is applied to magnesium hydroxide system. A close agreement between the theoretical and experimental results is observed.
On the incorporation mechanism and distribution mode of impurities in potassium acid phthalate crystals grown from aqueous solutions
Authors: Gerasimov Y. M. , Distler G. I. , Kanevsky V. M. , Kortukova E. I. , Suvorova E. I. , Okhrimenko T. M. , Belikova G. S.
Published: January 2007

Mechanism of impurity structure formation in crystals grown from aqueous solutions has been studied on the example of potassium acid phtalate (abbreviated hereafter as KAP) single crystals. Gold decoration technique at an electronmicroscopic scale has been applied to the study of the distribution of uncontrolled impurities on KAP cleavage face (010) after 10, 20 and 30 days of growth, taking into consideration different growth rates in 〈001〉 and 〈001〈 directions. A technique for visualization of impurities in water, based on the adsorption of these impurities by the surface of amorphous film of nitrocellulose (parlodion) and the vacuum decoration with gold of these impurities, has been developed.

Differences in the impurity structure of KAP regions located in 〈001〉 and 〈001〉 directions from the seed have been established. In 〈001〉 direction after 20 days of growth impurity assemblies 0.1—0.4 μm in size are revealed, and in 〈001〉 direction heterogeneous impurity structure is revealed only after 30 days of growth. The real (impurity) structure of KAP outside impurity assemblies is quite homogeneous and is the same throughout the whole crystal volume, the impurities incorporating mainly into complex active centres. From comparison of the changes in time of the impurity structure of water used for crystallization solutions and the impurity structure of KAP crystals a conclusion is made that the impurity structure of crystals is “programmed” in the impurity structure of crystallization solutions which regularly changes with time, i. e. impurities from different kinds of assemblies which are selectively adsorbed by the growing crystal faces. The role of the adjacent to the growing face interfacial layers which control the growth rate and have a complex impurity structure is stressed.
State of dispersion of impurity on formation of Z1‐centres in NaCl:Sr2+ crystals
Authors: Reddy K. Narasimha , Rao U. V. Subba , Babu V. Hari
Published: January 2007

Thermoluminescence (TL) and Optical absorption studies are carried out to study the bleaching kinetics of F‐centre and formation of Z1‐centres in X‐irradiated strontium doped NaCl crystals, both in as‐grown state and in quenched state. An additional TL peak is observed in this crystal system after F‐bleaching of irradiated samples which is attributed to thermal annealing of Z1‐centres. Various models proposed for Z1‐centres are reviewed in the light of these results and it is concluded that Z1‐centres are associated with impurity‐vacancy dipoles.
On the adsorption‐ and equilibrium‐referred interpretation of the doping element incorporation during the growth of CVD epitaxial silicon
Authors: Kühne H.
Published: January 2007

Für die Betrachtung der Teilschritte des Dotandeneinbaus: Gastransport, Adsorption‐Desorption, Einbau, erhält man nur dann eine den kinetischen Einfluß des Schichtwachstums befriedigend wiedergebende Lösung, wenn man für den Einbauschritt spezielle Hinund Rückreaktionsmechanismen in Ansatz bringt. Trotz der Annahme eines thermodynamischen Zerfallgleichgewichts für die Dotandenquellsubstanz und von Einbaugleichgewichten für die einzelnen Komponenten des Zerfallsgleichgewichts sind die Komponenten des Zerfallgleichgewichts als Quelle für die Bildung des Dotandeneinbaustroms nicht gleichberechtigt. Im Einbaugeschehen dominiert diejenige Komponente mit dem größten relativen Gleichgewichtspartialdruck.
On the scandium distribution in indium arsenide crystals grown by the Czochralski method
Authors: Lilov S. K. , Yakimova R. T.
Published: January 2007

In this paper the behaviour of scandium in n‐type monocrystalline indium arsenide grown by Czochralski method in sealed ampoule is studied. The crystals have been grown in [111] direction under different conditions: crystallization rate, As‐partial pressure and scandium initial concentration in the melt. The effect of the above factors on the scandium distribution along the crystals have been investigated. Using these results and by means of the equation of normal freezing the effective Sc distribution coefficient (k) in InAs under different technological conditions has been determined. It has been found that k < 1 in all experiments. In order to find the equilibrium coefficient (k0) at fixed growth conditions the Burton‐Prim‐Slichter model has been used. On the basis of Hall measurements and atomic absorption analysis of Sc‐doped InAs it is concluded that connected with Sc electrically active centers behave as shallow donors, most probably monovalent ones.
Increase of sensibility of X‐ray diffraction technique for investigation of quartz monocrystal perfection
Authors: Zargaryan Y. G. , Bezirganyan P. H. , Adamyan S. A.
Published: January 2007

It is shown that for the increase of sensibility of X‐ray topogram methods to investigate the slantwise cut quartz monocrystal, the external electrostatic field of a certain magnitude should be applied on the sample.
Calculation of the cyclic hardening curves of fatigued FCC monocrystals using a two‐phase model
Authors: Blochwitz C.
Published: January 2007

The cyclic hardening curve of fatigued fcc monocrystals shows a maximum of the stress amplitude if the plastic resolved shear strain amplitude γap exceeds the threshold value γM for the formation of persistent slip bands (PSBs). Using a simple two‐phase model the typical shape of the cyclic hardening curve will be calculated for lower γap values. The calculation takes into account the fact that the PSB formation starts already at a „nucleation stress”︁ amplitude τn below the maximum stress amplitude τam. Qualitatively the maximum of the cyclic hardening curve follows from the superposition of cyclic hardening of the matrix volume and of volume growth of the „soft”︁ PSB phase between the nucleation cycle number Nn and the saturation cycle number Ns.
Glow curves of flux‐grown NaMgF3 crystals
Authors: Reddy B. Kantha , Somaiah K. , Babu V. Hari
Published: January 2007

Glow curves and optical absorption spectra of X‐irradiated flux grown crystals are studied. Two glow peaks at 370, 585 K and three shoulders at 420, 540 and 610 K are obtained. Optical absorption studies reveal two absorption bands at 405 and 475 nm and a well defined peak at 295 nm. Room temperature annealing and bleaching studies have suggested that the glow peaks at 370 and 585 K may correspond to impurities and F‐centers of 295 nm band respectively. The other shoulders at 420, 540 and 610 K are attributed to other F‐aggregate centers. The glow peaks are analysed using first order kinetics.