bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic emission analysis of the brittle fracture behaviour of intermetallic layers in multifilametary cu‐ga/v superconductors
Authors: Fischer G. , Krumphold R. , Pompe W.
Published: January 2007

Combinding mechanical acoustic and SEM investigations, the influence of various heat treatment on the mechanical stability of the intermetallic phase V3Ga of multifilamentary Cu—Ga/V composites is analyzed. The destruction process of the boundary phase consists in cumulative microcracking perpendicular to the fibre orientation. Depending on the mean strength of the boundary layer as well as on the position of the elastic‐plastic transition of the fibre of the boundary layer as well as on the position of the elastic‐plastic transition of th efibre of the matrix, different types of acoustic emission rates are observed. A theoretical model of this behaviour is derived. Under optimum conditions the microcracking of the intermetallic boundary phase can be suppressed nearly completely up to a strain of about 0.8%
Crystal growth of β‐Phthalocyanines from the vapour phase in closed ampoules
Authors: Simonyan M. V. , Grigoryan L. S. , Gasparyan A. G. , Sharoyan E. G.
Published: January 2007

An influence of temperature gradient, inert gas pressure and pulling rate on the growth parameters of β‐phthalocyanine single crystals grown in the closed ampoules is investigated. The morphology and structure — sensitive properties of β‐CuPc crystals grown under different conditions are compared.
Precipitation of Strontium Sulphate
Authors: Sühnel Otakar , Handlířová Marie
Published: January 2007

Precipitation of unseeded supersaturated aqueous solutions of SrSO4 and growth of SrSO4 crystals at the size of approximately 20 μm were studied. Within the examined range of supersaturations, i.e. Sa < 16, the nucleation in aqueous solutions is controlled by the heterogeneous nucleation mechanism. The induction period of precipitation depends on the rates of both the nucleation and growth of the formed nuclei. The growth of SrSO4 crystals in supersaturated solutions at S ⪅ 5.6 is of the 2nd order with respect to the concentration and at temperatures 25 ÷ 45°C the process is controlled by the surface reaction mechanism. The number of crystals in the precipitated slurry is decreasing rapidly as a result of the Ostwald maturing.
Investigations on the homogeneity of single crystals of materials with variable composition grown by chemical transport reactions
Authors: Krabbes G. , Klosowski J. , Oppermann H. , Mai H.
Published: January 2007

To investigate the problem of homogeneity in crystals grown by chemical transport reactions (CTR) solid solutions Fe1‐yCoyS, Fe1‐yNiyS, and Zn1‐yCoyO were choosen as model substances. Relative concentration profiles of Co and Ni, respectively, were measured by electron‐probe microanalysis and light absorption (in Zn1‐yCoyO only). No significant deviations from homogeneity were found for Fe1‐yMeyS, whereas in Zn1‐yCoyO the Co contents increase in the growth direction. A qualitative explanation due to different diffusivities in the solids can be given.
A positron study on the effect of As, Sb, W, and Ti on the annealing of defects in cold‐rolled Ni
Authors: Meyendorf N. , Dlubek G. , Brümmer O. , Baranowski A. , Rozenfeld B.
Published: January 2007

The peak height of the 2γ‐angular correlation curve is measured as a function of the sample temperature during time linear heating of cold‐rolled Ni dilute alloyed with Sb, As, W or Ti (0.03 to 1.4 at.%). The effect of these foreign elements on the annealing of defects is very different. In Ni alloyed with As or Sb the formation of a large number of three‐dimensional vacancy clusters is observed indicated by a strong increase of the peak height. Obviously As and Sb atoms act as nucleation centres for the vacancy clustering. The addition of W to Ni leads to a shift of the vacancy annealing to higher temperatures. In Ni alloyed with Ti relative smooth peak height recovery curves are observed. Positron lifetime measurements show that no vacancy clusters are formed. The effect of the impurities on the vacancy annealing correlates with their binding enthalpy for vacancies in Ni.
Thermoluminescence studies of Al2O3 crystals doped with Cobalt impurity
Authors: Pandaraiah N. , Narasimha Reddy K. , Subba Rao U. V. , Wanklyan B. M.
Published: January 2007

Thermoluminescence (TL) studies of cobalt‐doped Al2O3 crystals irradiated with X‐rays have shown that the TL glow curve consists of three peaks at 105, 195 and 260°C. Bleaching, annealing and quanching studies have been performed in order to understand the nature of colour centers responsible for the formation of the three peaks. The values of the fundamental parameters like trap depth and frequency factor are estimated from TL data and the results obtained are discussed.
Disclinations and ovals in the Smectic B and E phases
Authors: Demus D. , Schiller P. , Sharma N. K.
Published: January 2007

Near to the clearing temperature the formation of the texture of a B phase was investigated. The growth of the B phase is beginning with germs, in shape similar to 2π‐disclinations whic some tenths of a degree below the clearing temperature dissociate to a system of two π‐disclinations. At further lowering the temperature, the latter change to the ovals which contain a set of wedge like material with plane smectic layers. By a competition of surface free energy and elastic free energy the sequence of textures can be explained theoretically.
Liquid crystalline swallow‐tailed compounds I
Authors: Weissflog W. , Wiegeleben A. , Diele S. , Demus D.
Published: January 2007

By reaction of di‐n‐alkyl 4‐hydroxybenzylidene‐malonates with different acid chlorides three homologous series of swallow‐tailed compounds were synthesized. The products were characterized by microscopic and calorimetric investigations and show nematic and smectic behaviour. As X ray studies prove the relatively broad molecules are statistically antiparallel arranged within the smectic monolayers.
Determination of the bending radius and diffraction profile parameters for X‐Ray Analyzer Crystals with X‐ray parallel beam
Authors: Kogan M. T. , Shechtman V. M.
Published: January 2007

A technique is proposed based upon angular scanning of a bent crystal shifted from the rotation axis. The axis‐to‐crystal distance providing the maximum reflecting efficiency is used to determine the bending radius of reflecting planes, and the diffraction profile can be obtained using an efficiency variation with a crystal shift tangential to Rowland circle at front focus. A rocking curve plotted — a “topogram” of the crystal surface is used to measure its reflecting area and a regularity of bending.

The technique is suitable for various types of analyzers in both the reflecting and transmitting arrangements. Instrumental conditions are defined and some experimental examples are given.
The effect of impurity complexes on the shape of PbTe and Bi2Te3 crystals
Authors: Smorodina T. A. , Sheftal N. N. , Tsuranov A. P.
Published: January 2007

The causes of strong dependences of the external shapes of lead and bismuth telluride crystals grown under conditions close to equilibrium on the deviation from stoichiometric composition have been investigated. Auger‐analysis of lead telluride and its solid solutions indicates the change in the character of bonding in the subsurface layers connected with appearence of smooth faces not belonging to the equilibrium shapes of pure substances. The surface phase existance has been explained on basis of statistical thermodynamics within the framework of the Guttman model and due to the formation of „the crystalline”︁ impurity complexes in a layer medium in contact with the growing crystal surface. Particles attachment to the crystal under these conditions proceeds in two stages, which facilitates crystal growth.
A position study on the effect of C, Cu, Ni and Sb on the defect annealing in cold‐rolled iron
Authors: Dlubek G. , Brümmer O. , Mikhalenkov V. S. , Yli‐Kauppila J. , Vehanen A. , Hautojärvi P.
Published: January 2007

Positron lifetime and angular correlation measurements are used to study the formation of defects and their annealing behaviour in cold‐rolled pure Fe and dilute Fe alloys with C, Cu, Ni, and Sb. The results show that positrons are trapped by dislocations and vacancy clusters. The effect of foreign atoms on the cluster formation and the annealing properties are discussed.
The crystal and molecular structure of the Nematogenic Compound 5,8‐Dihydro‐5,8‐methano‐1,4‐naphthalenediyl Bis(4‐ethoxybenzoate)
Authors: Baumeister U. , Hartung H. , Jaskólski M.
Published: January 2007

Single crystals of the title compound with the formula (C2H5OC6H4COO)2C11H8have been investigated by X‐ray analysis. The compound crystallizes in the monoclinic space group P21/n witha= 8.555(1),b= 15.280(2),c= 19.093(3) Å, β = 94.17(1)0,V= 2489.2(5) Å3, andZ= 4. The structure was solved by direct methods and refined to a finalRvalue of 0.062

The molecule adopts an almost stretched form. The norbornene skeleton within the central part of the molecule is disordered and occurs in two different conformations. The molecular packing is characterized by different lattice regions: the molecules in one region are parallel but their long axes are inclined by 49.5° to the molecules of the other region.
The Electrohydrodynamical Transient instability region in Smectic C liquid crystals
Authors: Petrov M. , Simova P.
Published: January 2007

The hydrodynamical instability transient region between conducting („initial”︁ domains) and dielectric („fundamental”︁ domains) regimes in smectic C is investigated. Two‐dimensional domain structure and two‐dimensional coherent light diffraction is observed in the transient region. A comparison with electrohydrodynamical instability transient region in nematics is presented.
Electrical conduction in organic polyiodide chain complexes
Authors: Oza Ajay
Published: January 2007

The electrical conductivities of three organic polyiodide chain complexes, α‐cyclodextrin‐KI‐I2 · 4 H2O amylose‐iodine and (coumarin)4‐KI‐I2 are observed to be decreased at high pressure upto 80 Kilobars along the direction of iodine chains. The lowering of conductivities at high pressures and the Arrhenius‐type temperature dependences are explained with disordered semiconductor model. The disordered environement of polyiodide chain which lead to weak or strong localization of the charge carriers is discussed. The charge carriers move by thermally‐activated hopping with the energies away from the Fermi energy level.
Glow curves and the emission of BaFCl:Eu2+
Authors: Somaiah K. , Hari Babu V.
Published: January 2007

Thermoluminescence and the emission of γ‐irradiated BaFCl:Eu2+ has been studied. A well defined glow peak at 400 K and a shoulder at 480 K are obtained in addition to those obtained as in undoped BaFCl. Thermoluminescence emission has shown a band at about 390 ∼ 400 nm. Additional glow peaks have been attributed to the luminescence centers as caused by europium impurity.
Deformation modes in plasticity and fracture
Authors: Indenbom V. L. , Orlov A. N.
Published: January 2007

The character of collective motion of the point defects and dislocations of various types determines the mode of plastic deformation and of fracture as its final stage. The concepts of the translational and rotational modes appeared at an early stage in the study of the mechanisms of plastic deformation in crystals and have undergone substantial evolution in connection with the development of methods for the direct observation of lattice defects. As a rule, different modes, e.g. diffusion and dislocation plasticity, translations and rotations, slip and twinning, plasticity and fracture, etc. are interrelated. The conditions for the loss of stability in plastic deformation and fracture are discussed. The rotational modes of plastic deformation are shown to be a consequence of the translational ones. The disclination modes are demonstrated to result from a simplified description of the dislocation kinetics.
Effect of impurities on dynamic dragging of dislocations
Authors: Natsik V. D. , Chishko K. A.
Published: January 2007

The rearrangement of the force of dynamic dragging of a dislocation due to its elastic interactio in with impurity atoms is analysed. The collisions of a moving dislocation with impurities excite additional vibrations of a dislocation line. Such vibrations lead to the appearance of extra parts to dissipative function and effective friction force of a dislocation which depend on location and concentration of impurities. This effect is one of the reasons of the influence of impurities observed in the experiments on the dynamic branch of the moving dislocation curve.
Formation of dislocation structure in shaped single crystals during their growth from the melt by Stepanov's Method
Authors: Antonov P. I. , Bakholdin S. I. , Krymov V. M. , Nikanorov S. P.
Published: January 2007

The paper is concerned with the formation of a dislocation structure due the thermal stresses in shaped single crystals with different degree of anisotropy grown by Stepanov's method. The calculation of root‐mean‐square tangential stresses allows to determine the regions in which the plastic deformation may occur. Analysis of thermal stresses in separate slip systems permits to explaine the slipe band distribution in shaped single crystals.
LPE growth of p(n)InAs1‐ySby‐n(p)GaSb(AlxGa1‐xSb) Heterostructures
Authors: Pramatarova L. D.
Published: January 2007

This paper presents the results of LPE–growth of p(n)InAs1‐ySby‐n(p)GaSb(AlxGa1‐xSb) heterostructures. It is shown the optimum technological regimes for growth of heterostructures p(n)InAs1‐ySby‐n(p)GaSb(AlxGa1‐xSb) with a decreased lattice matching of the materials forming the heterojunction.
Some crystallographic trends into the Na1+xZr2SixP3‐xO12 System
Authors: Krajewski A. , Valmori R. , Fiegna A.
Published: January 2007

This paper gives a contribution to the crystallographic characterization of the Na1+xZr2SixP3‐xO12 system, useful e.g. to analyze the right stoichiometric composition of a synthesized sample concerning this family of compounds, by powders X‐ray diffraction analysis. In the paper relations are in fact displayed to exist among dhkl, unit cell parameters and the stoichiometric parameter x. Such relations show to be linear for dhkl and a0, while the relation trend involving c0 let one think the system is isostructural in the atomic arrangement for the ranges x < 2 and x<2, respectively, to the end terms with x=0 and x=3.
Effect of Flux on thermoluminescence in Flux‐grown BaFCl crystals
Authors: Somaiah K. , Hari Babu V.
Published: January 2007

BaFCl crystals have been grown using BaF2 and BaCl2 by flux technique. Glow curves, optical absorption, and TL emission spectra of x/r — irradiated crystals are studied. The results have been compared with those BaFCl crystals grown from NaF flux so as to study the effects of flux on these properties. It is found that crystals grown from BaF2 flux are relatively purer. An additional TL glow peak at 460 K, an optical absorption band at 775 nm and TL emission band at 485 nm have been obtained in the presently grown crystals. The additional glow peak, optical absorption band have been attributed to F(¯F) aggregate centers, whereas the 485 nm TL emission band to impurity centers.
The effect of iron on the precipitation in an Al‐Mg‐Si alloy
Authors: Schmidt U. , Joachimi M. , Petzold L. , Eichhorn F.
Published: January 2007

The effect of iron on the precipitation of a technical Al‐Mg‐Si alloy was studied by macroand microhardness, Y‐modulus and SANS with DKD and was compared with a pure alloy. The iron phases of the technical alloy were preferentially considered by the SANS. In addition the damping by the elastomat of FÖRSTER and the variance of the microhardness were measured. It was found that iron essentially influences the kinetics of the precipitate, particularly the mechanism of nucleation and precipitation sequence.
Effect of the magnetic flux trapping upon the temperature dependence of the flow stress change at the superconducting transition
Authors: Dotsenko V. I. , Pustovalov V. V. , Sirenko V. A. , Fomenko V. S.
Published: January 2007

The effect of the superconducting transition on the flow stress in single and polycrystals of Pb‐In and Pb‐Sn alloys has been studied in the temperature range 1.8 K toTe. Unlike earlier efforts, these experiments involved investigation of the magnetic flux trapping. Two types of temperature dependences of the magnetic flux trapping,B0(T), were revealed. In Pb‐1.9 at.% In and Pb‐6 at.% Sn alloys (subjected to various thermal treatment),B0monotonically rises with lowering temperature. In Pb‐1.8, 3 at.% Sn single crystals the flux trapping arises at high strains (> 50%) and low temperatures (<2.5 K). In this caseB0magnitude depends on the strain rate. The difference in theB0(T) behaviour is associated with dissimilar flux pinnig by pinning centres. The date onB0(T) obtained give an insight into the two types of the Δσ(T) dependences; taking into account of the flux trapping allowed the Δσ values to be corrected, so that as a result, a single ΔσSN(T) curve was obtained for all the alloys and structures studied.
Coherent spinodal decomposition of equimolar mixed crystals of NaCl‐KCl
Authors: Andreev G. A. , Buritskova L. G.
Published: January 2007

Bulk density changes have been observed in equimolar mixed crystals of NaCl‐KCl by flotation technique at RT. The results are accounted for on the basis of the theory of coherent spinodal transformation. The interdiffusion coefficient has been estimated from the kinetics of the transformation in the crystals.
Plastic deformation and fracture in LiF Bicrystals with asymmetric tilt boundary
Authors: Smirnov B. I. , Snezhkova T. N. , Volkova O. L.
Published: January 2007

The peculiarities of plastic deformation and fracture in isoaxial LiF bicrystals with misorientation angle α = 10° and tilt boundary of various asymmetry were experimentally studied by the single slip method. It was found that a number of effects at the boundary, attacked by mixed dislocations, is possible: retardation of dislocations near the boundary and pile‐ups formation, dislocation multiplication, accumulation of grain boundary dislocations with differential Burgers vector. Predominance of each or that effect in the process of crack initiation at the definite misorientation angle depends on the mutual orientation of slip planes in the neighbouring grains and on the edge and screw component part in the dislocations, attacking the boundary. The main role, apparently, belongs to dislocation pile‐ups. Cracks are always nucleated in the boundary, but in the case of strong asymmetry they stretch along cubic planes.
Investigations on mechanical properties and chemical composition of thermally treated TiCx coatings on steel (CVD technique)
Authors: Fischer W. , Wetzig K. , Seidler M.
Published: January 2007

The described technology allows the production of dense TiCx coatings onto steel at standard pressure. The residual stress in the coatings is a compressive one with a level of some GPa. It is lowered with an increase of the coating thickness and/or a substrate hardening. Both the residual stress level and the constitution of the contact region substrate/coating mainly influence the mechanical behaviour under external load. An occasional formation of cementite islands on the substrate surface in the initial stage of the deposition process reduces the adhesion of the coating. The coating failure of substratehardened samples has not to occur as a necessity at the contact region, but is possible also by breaking out inside the coating. Besides, the existence of voids along the contact region was observed in this case.
Apparent threshold characteristics of pretilted nematic layers
Authors: Hauck G. , Koswig H. D.
Published: January 2007

The influence of pretilt angles on the voltage dependence of the transmission of nematic liquid crystal cells has been investigated. A conception of an apparent threshold voltage and voltages of other selected deformation states characterized by a parameter A has been introduced. The dependence of the apparent threshold voltage on the pretilt angle is shown in experimental curves. An analytical expression of this dependence could be derived starting from a mean deformation angle.
A contribution to the kinetics of crystallisation of GaP by SSD process
Authors: Weinert B. , Buhrig E. , Hein K.
Published: January 2007

The influence of some important factors which appear during the synthesis of GaP by the SSD‐Process have been comprehended, and their mathematical relationships determined. The model for the growth of crystallisation is valid only for some definite and selected moments. For long‐time experiments the computation of the speed of crystallisation should be carried out step‐by‐step.
Photoelectron spectroscopic studies of anodic potentiostatic oxidation on various platinum surfaces
Authors: Wagner N. , Brümmer O.
Published: January 2007

Using XPS method it is shown that the anodic charge transfer supported oxidation of platinum single crystal electrodes in aqueous 0.1 M HClO4 solution is influenced by the atomic surface arrangements. The best electrode stability is received for the (111) surface with the largest atomic density in the case reported here.
The precipitation of magnesium hydroxoaluminate hydrate powders from sodium hydroxoaluminate solutions: Precipitate phases and precipitation mechanisms
Authors: Packter A. , Slaughter R. A.
Published: January 2007

Magnesium hydroxoaluminate hydrates were precipitated from different sodium hydroxoaluminate and hydroxoaluminate‐hydroxide solutions at ambient temperature, at CAl = 0.1 M, OH/Al ratios = 4–9 and XS OH/Al ratios = 1–6. The precipitations were monitored by potentiometric (pH) measurements while the final precipitate compositions were examined by chemical analysis, infra‐red spectrophotometry and thermal analysis.

At solution OH/Al ratio = 4, the main precipitate phase at 20°C was Mg(H2O)n[Al(OH)4]2 admixed with some Al(OH)3; at solution OH/Al ratio = 5, the main phase was Mg2(H2O)4[Al2(OH)10]; at solution OH/Al ratio = 7, the main phase was Mg4(H2O)n(OH)4[Al2(OH)10] while at solution OH/Al ratio = 9, the main phase was Mg6(H2O)n(OH)8[Al2(OH)10] admixed with some Mg(OH)2.

These hydrates were dehydrated at 60–100°C probably to the compounds Mg2[Al2O3(OH)4], Mg4(OH)4[Al2O3(OH)4] and Mg6(OH)8[Al2O3(OH)4], respectively.
The investigation of P‐ and As diffusion in liquid Gallium
Authors: Gorokhov V. A. , Dedegkaev T. T. , Ilyin Yu. L. , Moshnikov V. A. , Petrov A. S. , Sosov Yu. M. , Yaskov D. A.
Published: January 2007

The results on the As‐ and P‐diffusion in gallium melt are discussed. The definition method of P‐ and As‐diffusion coefficients in liquid gallium was stated. This method was based on the analysis of concentration profile formed during the diffusion annealing with following tempering. The diffusion coefficients were measured on temperature region 1113 to 1383 K. The expression for temperature dependence of diffusion coefficients was obtained.
Unstable internal friction in Bismuth and Antimony single crystals
Authors: Medrano Atencio E. , Pal‐Val P. P. , Ya. Platkov V.
Published: January 2007

In the temperature range of 6 to 300 K an effect of the high amplitude ultrasound waves on amplitudedependences of decrement and modulus defects in the antimony and bismuth single crystals of different orientation is studied. The character of changes of the decrement and modulus defect amplitude dependences under the influence of the high amplitude ultrasound indicates that dislocation multiplication, obstacle break‐through by dislocation pile‐ups or deformation twinning may be observed in crystals depending on the ultrasound propagation direction and the temperature interval investigated.
Growth and morphology of the CuGaS2, CuAlSe2, CuGaSe2 and CuInS2 ternary compounds
Authors: Bodnar I. V. , Bodnar I. T. , Vaipolin A. A.
Published: January 2007

Monocrystals of the ternary compounds CuGaS2, CuAlSe2, CuGaSe2, and CuInS2 were grown from their elements by transport reactions; their cell parameters and melting temperature were determined. The character of the phase transition in these compounds was found out and also the boundary conditions of growing the monocrystals as well as their dislocation structure (by etching).
The morphology of hydrothermally grown epistilbite
Authors: Ghobarkar H.
Published: January 2007

Epistilbite crystals were grown on the surface of an artifical glass by hydrothermal treatment at 1 kb in the range of 250° to 400°C. Laminar twinned crystals were observed at low temperatures, with increasing temperature twinning decreases and the thickness with respect to [010] increases.
Configuration of grain boundaries
Authors: Herrmann R. , An Nguyen , Worm G.
Published: January 2007

In the present paper a model of the configuration of grain boundaries from a general point of view in the framework of the CSL concept has been developed. Rotations and rotations with translations were taken under consideration. The main result is the determination of the coincidence conditions for symmetrical and asymmetrical grain boundary facets between two and three grains. The facet angles of grain boundaries in any crystal surface are determined.
Influence of impurities, irradiation and temperature on the mechanical and electrical properties of LiF crystals
Authors: Urusovskaya A. A. , Knab G. G. , Regel V. R. , Alekseeva L. I. , Shchepina L. I.
Published: January 2007

On the basis of study of the temperature dependence of mechanical and electrical properties of LiF crystals with different impurities an evident interaction between radiation defects and impurities is revealed. As a result of trapping of radiation defects (F‐ and H‐aggregate colour centres) by impurity centres the reconstruction of impurity centres takes place, causing a change of mechanical and electrical properties.
The study of the influence of γ‐irradiation on LiF crystals by optical, electrical and mechanical characteristics
Authors: Shchepina L. I. , Alekseeva L. I. , Lobanov B. D. , Shuraleva E. I. , Parfianovich I. A. , Knab G. G. , Urusovskaya A. A. , Regel V. R.
Published: January 2007

The influence of the dose of γ‐irradiation on some physical properties (storage of colour centres, ionic conductivity, microhardness) in LiF crystals differing in oxygen content is studied. It is found out that optical, electrical and mechanical characteristics change nonmonotonously with an increase in dose of γ‐irradiation in the range from 104 to 107 J per kg. Maxima and minima are revealed on all the three dependencies, indicating a periodie construction and redistribution of radiation defects during the change of the absorbed dose. Oxygen impurity enhanced the colouring of LiF crystals, significantly reduced the conductivity, caused mechanical softening and intensified the secondary radiation processes having qualitatively changed the behaviour of electrical and mechanical properties with an increase in irradiation dose.
Synthesis and characterization of ferrierite
Authors: Çulfaz Ali , Yilmaz A. Kürşat
Published: January 2007

Ferrierite, a medium‐port molecular sieve zeolite, was synthesized as the only crystalline phase from an aqueous gel of composition 1.6 Na2O · 1.6 K2O · Al2O3 · 13.5 SiO2 · 130 H2O · 0.8 CO2 · 2.4 (HCO2)2 at 250 °C in reaction periods ranging from 40 to 95 hours. The crystallization time was reduced with seeding. Ferrierite was a metastable phase in this system and it transformed into tridymite, high sanidine and orthoclase at longer reaction periods. At 200 °C, chabazite was crystallized from the same batch composition at a very slow rate. At temperatures higher than 250 °C and in the absence of carbonates and bicarbonates in the batch mixture, tridymite, high sanidine and orthoclase crystallized directly without the formation of ferrierite. The synthetic ferrierite sorbs benzene, toluene and cyclohexane and behaves as a medium port molecular sieve. The sorption capacity of ferrierite was improved by acid treatments with no deterioration of the crystal structure.
Solvent effect on the polytype structure of CdI2 crystals
Authors: Gierlotka S. , Pałosz B.
Published: January 2007

Single crystal platelets of cadmium iodide have been grown from alcohols: n‐propyl, isobutyl and isoamyl and from their aqueous solutions. The structures of 880 crystals has been identified and the effect of solvent on the polytype structure of CdI2 has been discussed regarding: the stability of the basic structures 2H and 4H, the structure of complex polytypes, the effect of the solvent on the structure of faults, the period of polytypes. Some relations indicating the role of the solvent in the formation of polytype structure of CdI2 have been found.
Preparation and electrical conductivity of Pb2Ru2O6.5 crystals
Authors: Řehák B. , Frumar M. , Koudelka L.
Published: January 2007

Single crystals of Pb2Ru2O6.5 have been grown by flux method from a mixture of lead oxides. The electrical conductivity of the crystals is of a metallic type, major current carriers being holes.
Vacancy migration energy in aluminium as determined from exoelectron emission measurements
Authors: Górecki Cz. , Górecki T.
Published: January 2007

After almost forty years of investigations the phenomenon of exoelectron emission (EEE) is still poorly understood. Nevertheless, the phenomenon is seriously considered as a research tool in radiation dosimetry, solid state and surface physics as well as in physical metallurgy. One of the most heatedly discussed problems is the role of the crystal lattice defects in EEE from metals (Górecki, Górecki). In the present note the possibility of determining the vacancy migration energy in cold rolled and quenched metals will be demonstrated.

The measurements were performed in atmospheric air using the apparatus described by Sujak et al. The electrons were detected with the aid of an open air point counter with ethanol quenching vapour. Through the measurements the samples were illuminated with unfiltered UV radiation of a quartz lamp. The samples were prepared from industrial Al sheets of the purity of 99.75%.
Digitalapparatur für hochtemperaturwiderstandsstudium der ausscheidungskinetik in aluminiumlegierungen
Authors: Lašek J.
Published: January 2007

Genaue Messungen des elektrischen Widerstandes ermöglichen es, Strukturänderungen in Legierungen direkt bei hohen Temperaturen isotherm oder bei Temperaturänderungen empfindlich und kontinuierlich zu verfolgen.

Zur Messung und Registrierung der einzelnen experimentellen Werte wird eine Meßzentrale mit Datenausgabe auf Lochstreifen (Lašek, Hykel) verwendet. Die gleichzeitige Datenvorverarbeitung auf dem Mikrorechner ermöglicht auch die Durchführung verschiedener unerläßlicher Korrekturen. Für die berichtigten Werte Rb des elektrischen Widerstandes erhält man unter Voraussetzung eines konstanten Probenvolumens und einer homogenen Deformation den Ausdruck Rb = )2, wo R, Δl die direkt gemessenen Größen (Widerstand, Verlängerung) sind, l die ursprüngliche Probenlänge.
Phase lead determined growth of 〈100〉 — textured germanium crystallites in eutectic AgGe alloys
Authors: Vetter J. , Frühauf J. , Schneider H. G.
Published: January 2007

AlSi type eutectics (AlSi, AgSi, AgGe, ZnGe) form 〈100〉 — textured eutectic dendrites of the semiconductor phase when a certain growth rate R and liquid temperature gradient G are held. The spacings of these eutectic dendrites λ follow the relationship: λ = (rλ ≈︁ 0.2; g ≈︁ 0.5). The exponents of this relationship can be explained by the model of phase lead determined growth. This model is based on the consideration of the analogy to dendrite growth. The AlSi type eutectics have geometrically similar morphologies for determined Gx/R‐relations (x = 1.25 in the case of AgGe) and the relation λ2R = const. is valid. In this paper the AgGe eutectic will be discussed in close detail.
Crystal agglomeration
Authors: Nývlt Jaroslav , Karel Miloslav
Published: January 2007

Three different methods have been proposed for quantitative description of agglomeration: visual determination of the percentage of agglomeration, numerical correction of crystal size distribution leading to the degree of agglomeration and the method of decomposition of the two‐peak crystal size distribution. The effect of neglecting the agglomeration on kinetic data of crystallization calculated from crystal size distribution may be very significant.
LEED‐AES investigation on the influence of thermally segregated chromium on the oxidation of an iron‐chromium alloy
Authors: Müssig H.‐J. , Allmer F.
Published: January 2007

When heating a (111)‐oriented Fe1‐xCrx single‐crystal sample (0.05 ≦ x ≦ 0.10) for 15 minutes at 550 °C an unarranged surface layer rich in chromium and nitrogen, simultaneously, with x = 0.40 will ermerge. The low‐energy Auger signals of iron and chromium were involved for characterizing the chemical bond and the high‐energy ones used for quantitative analysis. The shape and the energy position of the transitions were exactly determined by integration, background subtraction and approximate deconvolution of the Auger electron spectra measured differentiatedly. Chromium nitride layers were detected which retard probably the formation of the FeO layer compared to Leygraf et al.

While the adsorption isotherm at room temperature for the surface poor in chromium and crystallographically perfect shows two erratic changes of the sticking probability, the adsorption isotherm for the surface rich in chromium is a continuous curve with a higher increase in the lower dose‐region typical for random surfaces.
The structure of the “influenced grain boundary region” of an Al‐12at.% Zn alloy in dependence on quenching conditions
Authors: Siebert P. , Kroggel R.
Published: January 2007

It is known that in the AlZn alloys the nucleation and growth of the G.P. zones during isothermal ageing in the RT‐range considerably depend on the applied quenching treatment and often certain “irregularities”, e.g. an inversion of the decomposition rate with increasing homogenization temperature (Tq), are observed. Various conceptions were developed in order to explain these inversions, but none of them can consistently interpret the observed main features. For more details see Siebert and Kroggel et al. It is of interest for the present work to mention that various models were developed to explain the structure of the precipitation free zone (PFZ). They are mainly based on suggesting that the profile of the vacancies or that of the solute atoms or both in the GB‐region determine the width and the structure of the PFZ (see e.g. Synecek et al.).

It was the idea of the authors to gain more information on the effect of the GB on the structure changes proceeding in its vicinity on investigating not only the width and structure of the PFZ, but the details of the structure changes occurring from the regions very close to the GB up to the midgrain in dependence on various quenching conditions (Tq and quenching rate, vq).

For this reason we selected an Al‐12at.%Zn alloy produced from materials of purity 4N and aged the samples of thickness 0.12 mm, after various quenching treatments, at 100 °C for 1 h in order to attain precipitates suitable to be determined in size sufficiently accurately. The samples were annealed at Tq = 300 °C or 490 °C for 0.5 h, quenched to RT into water, fluid W250, or oil, stored at RT for 10 s, and finally aged at 100 °C for 1 h. The foils investigated in the TEM of type TESLA BS 540 operating at 120 kV were electrolytically thinned by the well‐known window method.
Mass transport during growing mercuric iodide by static sublimation method
Authors: Zaletin V. M. , Lyakh N. V. , Nozhkina I. N.
Published: January 2007

A description of a simple model for calculations of diffusion mass transport rates for growing α‐HgI2 crystals by sublimation in iodine vapour is presented. A satisfactory agreement with experiment was obtained. Incorporation of iodine into red mercuric iodide is estimated (2 · 10−7 mole/cm3).
Development of scale formed on cooling surface towards equilibrium state
Authors: Veverka František , Söhnel Otakar , Kolařík Stanislav
Published: January 2007

Changes in the morphology of scale deposited on the surface of a submerged cooling element during its prolonged contact with a saturated solution of oxalic acid were studied. Needle‐like crystals formed during the initial stage of oxalic acid scale depositing bring about a markedly rough surface. During a longer contact with the solution, however, the needle‐like crystals are gradually dissolved and the scale surface is becoming smooth. After a steady state has been established, i.e. when mass transfer between the solution and scale does not take place any longer, the scale recrystallises completely forming a smooth crystalline coating on the cooling wall and neither its morphology nor weight are changing any further.
On crystal growth of orthorhombic alkali acid phthalates. An application of fourier transform of crystal morphology to tracht and habitus
Authors: Schwarz H. , Fiedler R. , Follner H.
Published: January 2007

The orthorhombic alkali acid phthalates crystallize in three different structure types. The structure of potassium acid phthalate (P21ab) can be regarded as a basic structure. The elementary cells of ammonium (Pcab) and sodium crystals (B2ab) contain two potassium structure units which are connected to each other along [001] by a symmetry centre in the first case and by a twofold rotation axis in the second case. It will be shown that close morphological relations between the crystals also can be observed. The morphological lattices of the substances agree fairly well with the centres of gravity of the phthalate ions (HP). The reciprocal crystals have mmm (KHP, NH4HP) and mm2 symmetry (NaHP), respectively. The growth rates of the faces are proportional to the areas of the net plane meshes, divided by the number of the morphological units per growth layer. The thickness of the growth layer is determined by the morphological extinction rules. The specific surface energies are proportional to the surfaces of the reciprocal crystals parallel to the crystal faces, divided by the areas of the net plane meshes. The theoretical growth and equilibrium forms of the hydrogen phthalates are in good agreement with the experimental observations.
The crystal and molecular structure of the steroidal alkaloid 20‐epi‐kibataline
Authors: Kutschabsky L. , Pfeiffer D. , Kretschmer R.‐G. , Adam G.
Published: January 2007

The major constituent of the alkaloid fraction of the leaves of Paravallaris macrophylla Pierre has found to be the new paravallarine‐type steroidal alkaloid 20‐epi‐kibataline. The structure of this steroidal alkaloid has been determined by X‐ray analysis. The compound crystallizes in the monoclinic space group P21 with the lattice parameters a = 11.286, b = 14.250, c = 6.206 Å, β = 97.88°. The final R value was 0.067.
Precipitation processes in AlZn5Mg2CuX alloys
Authors: Nagy P. , Kovács‐Csetényi E. , Turmezey T. , Honyek G. Y. , Kovács I.
Published: January 2007

AlZnMgCu alloys are important structural materials because of their high strengths and good stress corrosion resistance (Speidel Archambault, Chevier, Beck). The relationship between the properties and structure, as well as the formation of different phases in the ternary alloys are well known (Ungar et al.; Löffler et al.). However, the decomposition and transformation processes in the quaternary AlZnNgCu alloys are not well known at present and there are several contradictions in the literature. Only a few systematical investigations have been made on the role of Cu in the decomposition processes in the quaternary alloys (Bryant Soeno, Chigasaki).

The aim of this work is to determine the effect of Cu addition on the precipitation processes in the AlZn5Mg2 alloys.
Effect of Zr and Mo in AlZn5Mg2 alloy
Authors: Turmezey T. , Kovács‐Csetényi E. , Nagy P. , Rajkovits Z. S. , Lendvai J.
Published: January 2007

Alloy properties can considerably be improved by the addition of small amount of alloying elements, which might cause the decrease of production cost, as well.

Transition metals are generally applied as addition elements in age‐hardenable aluminium alloys (Baba 1968, 1970; Groma, Kovács‐Csetenyi Lang, Vitális, Lakner). Most of the investigations are dealing with phase transition but the physical, mechanical and corrosion properties are thoroughly studied, too.

It is well known that transition metals are relatively less soluble in aluminium. The reactions in the binary systems of A‐transition metal are mostly of peritectic character and due to this fact the transition elements are acting as grain refiners, however, this effect is explained on basis of their electron structure, as well (Laminov, Samsonov).

Investigations were carried out on the AlZn5Mg2 with the addition of 0.2 m% Zr and 0.15 m% Mo, 0.1 m% Zr + 0.1 m% Mo and 0.2 m% Zr + 0.2 m% Mo samples, respectively. The alloys were prepared on high purity base aluminium (5N), cast in copper mould, homogenized, scrapped and finally cold rolled.
The effect of solid solution decomposition temperature on the structure, mechanical properties and stress‐corrosion resistance of AlZn5%Mg3% alloy
Authors: Szymanski J. , Karp J. , Klyszewski A.
Published: January 2007

The data obtained in recent years (Nicholson Klyszewski, Karp; Szymański et al. have revealed that the temperature of the first step in the precipitation treatment (e.g.) quenching, quench interruption and pre‐ageing) has a decisive effect on the stress‐corrosion resistance of commercial weldable wrought AlZnMg alloys.

The paper gives an account of a study of the effect of variations in quenching interruption and pre‐ageing on structure, mechanical properties and resistance to stresscorrosion of an alloy of this group in sheet forms.
Growth mechanisms in GaAs‐VPE at low deposition temperature
Authors: Schwetlick S. , Seifert W. , Butter E.
Published: January 2007

The VPE growth of GaAs in the system GaAsAsCl3 with either H2 or He as the Carrier gas was studied in the range of low deposition temperatures. Down to about 670 °C the growth in the H2‐system is limited by the kinetics of chlorine desorption by molecular hydrogen. The increase in growth rate at lower temperatures results from the onset of GaCl3‐desorption (disproportionation mechanism). The addition of NH3 to the vapour phase enhances this effect. Below about 700 °C the growth rate in the GaAsAsCl3H2NH3 system becomes comparable to that in the GaAsAsCl3He‐system, where the GaCl3 desorption mechanism is the only possible growth mechanism.
Cleavage marks on the melt‐grown palmitic acid crystals
Authors: Prasad P. B. V.
Published: January 2007

Occurrence of cleavage marks along (110) planes of palmitic acid crystals, the relevence of cleavage to the polymorphism and habit changes are presented.
Doping of epitaxial CVD silicon with arsenic or phosphorus (i). Steady state conditions
Authors: Kühne H.
Published: January 2007

A modified theoretical model of dopant incorporation is discussed, while comparing it with the Reif‐Dutton model. In contrast to the Reif‐Dutton model, which has been based on the adsorption step of dopant substances, the modified model is related to the real dopant incorporation step and its backreaction as the rate controlling factors. By that a thermodynamical decomposition equilibrium of the dopant source material may be established without being influenced by the dopant incorporation. Each component of the decomposition equilibrium acts as a source for making dopant atoms available for incorporation. Equivalent to the Reif‐Dutton model the modified model describes the growth rate influence of the layer on the incorporation of dopants and additionally enables the temperature dependence, total pressure dependence and the specific features of dopant incorporation at high concentrations to be explained.
Ionicity of the chemical bond in Tl3XS4 compounds
Authors: Čermák K.
Published: January 2007

Levine's extension of the Phillips‐Van Vechten's dielectric theory to multibond crystals containing transition metals is used for estimating the bond ionicities in Tl3XS4 compounds (X = V, Nb, Ta).
Study of inclusions and growth bands in potassium bichromate crystals grown from aqueous solutions
Authors: Szurgot M. , Sangwal K. , Karniewicz J.
Published: January 2007

The nature of inclusions and growth bands in potassium bichromate crystals obtained from aqueous solutions and their formation in relation to growth temperature and supersaturation are investigated. It is observed that impurities present in solution, fluctuations in growth temperature and high growth rates are responsible for their formation.
On the ordering of Cr1‐xAlx alloys (x < 0.33) leading to microprecipitations of X‐ and β‐phases
Authors: Dłużewski Piotr
Published: January 2007

The analysis of electron diffraction patterns of Cr1‐xAlx alloys with 0.16 ≦ x ≦ 0.24 has been performed. The diffraction vectors describing the position of X‐phase spots were corrected to the new 0.769 < 0.004 〈111〉value. The ordering model of Cr1‐xAlx alloys with x < 0.33 is discussed in connection with physical properties. The new identification of the X‐phase as Cr4Al displacive modulation structure is proposed.
On the madelung constant of the nonstoichiometric tin dioxide crystal containing conducting electrons
Authors: Horodecki A. J. , Skowron A. , Precht W.
Published: January 2007

The nonstoichiometry of the conducting tin dioxide is assumed to be due to the doubly ionized oxygen vacancies. The use of a potential of the type e−r/λ/r for the nearest tin ions surrounding the vacancy results in a dependence of the Madelung constant on the defect concentration that exhibits a soft maximum. Various summation topologies are discussed.
On the elements of the dislocation structure of deformed corundum
Authors: Kirichfnko V. V. , Voinova N. N.
Published: January 2007

It is found by the method of transmission electron microscopy that the main elements of dislocation structure of deformed corundum are spatial triple dislocation nodes, recombination zones and dislocation network fragments. The structure of dislocation nodes is analyzed. It is shown that the nodes in corundum are the “rigid” constructions.
The effect of silica substitution on electrical conduction in nickel ferrite
Authors: Satyanarayana R. , Ramana Murthy S.
Published: January 2007

The electrical conductivity and Seebeck coefficient for nickel ferrite and nickel ferrite with 5% silica has been studied as a function of temperature. The lattice constant and the existence of a single phase are established from X‐ray studies. Both the ferrites exhibit a transition near the Curie temperature with a change in slope of the conductivity (log σT) versus temperature (103/T) curves. It is found that the activation energy in the paramagnetic region is higher than that in the ferrimagnetic region for both the ferrites.
Nucleation at changing density of monomers
Authors: Kashchiev Dimo
Published: January 2007

The kinetics of nucleation at constant supersaturation are analyzed when the process occurs at changing density of those monomers (atoms or molecules) that start the nucleation chain of consecutive bimolecular reactions. The Zeldovich kinetic equation is solved for arbitrary time variation of the monomer density and exact general expressions are obtained for the time dependence of the nonstationary nucleation rate J and the density N of nuclei formed in the system up to time t. Exponential decrease and increase of the monomer density are considered as examples, and the corresponding J(t) and N(t) dependences are analytically found.
The electrolytical coloration of synthetic quartz crystals with induced growth striations
Authors: Bernhardt Hj. , Woitzik B.
Published: January 2007

Electrolytical coloration of quartz crystals with induced smoky quartz striations has been investigated, and compared with the arrangement of smoky quartz stripes after X‐irradiation. Investigations have been made on z‐, s‐, −x‐ and +x‐regions of the crystal after application of an electrolytical current in z‐direction.