bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of kinetics of phase transitions in the CuMnAl alloys
Authors: Soltys J. , Kozubski R. , Meres K. , Holender J.
Published: January 2007

The alloys of the system CuMnAl have been extensively investigated. The results of systematic studies of phase equilibria in those alloys have been recapitulated by West, Thomas, and by Köster, Gödecke. However, the alloys of the composition approximating Cu2MnAl have been drawing special attention.

At high temperatures the alloys of such composition are comprised in a range of equilibrium of the β‐phase which has simple crystalline structure and is often called the Heusler phase. The properties of the above alloys are very interesting due to the simultaneous occurrence of two kinds of structural phase transitions: the “order‐disorder” transformations in the range of β‐phase and the decomposition of the β‐phase in the temperature range of its metastability. It was indicated that above 1050 K the β‐phase has cubic disordered structure of the type A2 while, when cooled, it transforms at 1050 K into partially ordered B2‐type structure and at about 950 K into completely ordered L21‐type one, Dubois (Lisse).

On the other hand, the β‐phase is metastable at temperatures below 970 K and decomposes into three phases of the types βMN, γ‐Cu9Al4 and T‐Cu3Mn2Al (West, Thomas; Köster, Gödecke).

The simultaneous occurrence of the ordering and decomposition processes may be an interesting subject of theoretical considerations (Nishizawa et al.). The processes may be considered either on microscopic level requiring various simplifying assumptions or through the study of processes of precipitation in real structure.

The aim of the presented work was the detailed research of the process of decomposition of β‐phase in the stoichiometric alloy Cu2MnAl (Kozubski et al. 1982, 1983a, b, c). During the investigations the methods of X‐ray diffraction and the measurement of electrical resistivity as well as electron microprobe were applied. The X‐ray diffraction and microprobe measurements were performed at room temperature and the specimens quenched in water after the desired annealing were examined. All samples of the alloy were at first homogenized at 1123 K and then annealed at various temperatures between 423 and 973 K.
A microstructural examination of ZnAlCu alloys
Authors: Terziev L. , Wegria J. , Greday T.
Published: January 2007

A microstructural examination of a Zn‐11 wt% Al‐1 wt% Cu alloy in dependence on the applied heat treatment was carried out by means of scanning electron, transmission electron and optical microscopy as well as X‐ray investigations.
Photoluminescence from deformed CaO crystals
Authors: Remón A. , Piqueras J.
Published: January 2007

The plastic deformation of CaO crystals produces the increase of luminescence band centered at 385 nm and 454 nm. The bands are excited with light of 350 nm and 275 nm respectively, and their relative increase depends on the kind of deformation applied to the crystal. The results are compared with previous cathodoluminescence observations.
Autodoping of epitaxial silicon layers (II) diffusion‐induced autodoping
Authors: Kühne H. , Gaworzewski P. , Malze W.
Published: January 2007

From discussing the influences of layer growth duration and deposition temperature on the slope of the steep autodoping profile branch adjacent to the substrate, it is concluded that there exists a special autodoping part, termed redistribution autodoping, which is independent on solid state diffusion effects, but should be restricted to the beginning of the layer growth.
Determination of the orthorhombic coincidence site lattice for bicrystals of any lattice system
Authors: An Nguyen , Rothkirch L. , Herrmann R.
Published: January 2007

The concept of the coincidence site lattice is generalized for bicrystals of any lattice system. Describing the formation of bicrystals by cutting the ideal lattice and rotating the partial lattices the conditions for the coincidence site lattice are presented. For the construction of the special case of orthorhombic coincidence site lattice an instruction is given.
Electrical properties of r. f. sputtered thin films of CuInSe2(II). Conduction mechanism and intrinsic doping effects
Authors: Neumann H. , Tomlinson R. D. , Hill A. E. , Abdul‐Hussein N. A. K. , Samaan A. N. Y.
Published: January 2007

An analysis of the conduction mechanism in p‐type polycrystalline films of CuInSe2 is given. It is shown that in the r.f. sputtered films the hole mobility is limited by tunneling through the grain boundary potential barrier. It is suggested that the charge carrier transport is governed by conduction through valence band states at high temperatures and by impurity band conduction at low temperatures. On the basis of the chemical composition data for the r.f. sputtered films no conclusions can be made regarding the type of the acceptor‐like intrinsic defect responsible for the p‐type conductivity of the films.
On the structural characterization of solid state reaction product of cadmium carbonate and 8‐hydroxyquinoline
Authors: Singh M. , Singh H. C.
Published: January 2007

The formation of coordination compound of cadmium carbonate and 8‐hydroxyquinoline has been studied in solid state. The light yellow coloured crystals of this compound have been grown in non‐aqueous media for X‐ray studies. The crystal system and lattice parameters have been determined by powder technique of X‐ray diffraction. Infrared spectral study of the complex was carried out in order to study the mode of linkage. Molecular distortion due to coordination has been discussed.
On the influence of nonstoichiometry on luminescent properties of CdGa2S4 single crystals
Authors: Derid Yu. O. , Georgobiani A. N. , Gruzintzev A. N. , Radautsan S. I. , Tiginyanu I. M.
Published: January 2007

Results of a study of photoluminescence and thermoluminescence of cadmium thiogallate single crystals grown from the melt are presented. Effect of nonstoichiometry on the properties of samples is studied. Some assumptions about the nature of centres in CdGa2S4 compound are made.
On the preparation of tungsten oxides by chemical transport with TeCl4
Authors: Oppermann H. , Srtöver G. , Wolf E.
Published: January 2007

The Tungsten oxides WO3, W20O59, W18O49 and WO2 have been transported by TeCl4 in monocrystalline Form. W3O is not a equilibrium phase of the system, and therefore it is impossible to obtain this phase by CTR. The value of the lower phase boundary of tungsten trioxide is 2.96.
Growth of single crystals of potassium chloride from gels
Authors: Desai C. C. , Hanchinal A. N.
Published: January 2007

The growth of single crystals of potassium chloride (KCl) in silica gels upto 3 × 3 × 3 mm3 in size is described. To crystallize KCl incorporated in the gel, hydrochloric acid has been used to crystallize the KCl in the gel media. The crystalline perfection has been studied by the chemical etch pit technique.
X‐ray topographic study of quartz crystals with induced growth striations
Authors: Alter U. , Härtwig J.
Published: January 2007

The method of “induced growth striations” was applied to the hydrothermal growth of quartz crystals. Striations were due to a periodical modulation of the growth temperature induced and investigated by means of the X‐ray Lang topography and plane wave reflection topography. The results show that the X‐ray topographic methods are a sensitive tool for the characterization of the growth striations, which are produced generally by Al impurities. The application of the method of induced growth striations to quartz crystals and the characterization of these crystals with optical and X‐ray topographical methods allow a deeper understanding of the crystal growth behaviour.
Homogeneous nucleation in cooling crystallization
Authors: Liszi Ilona , Blickle Tibor , Liszi János
Published: January 2007

Nielsen's equation has been applied for cooling crystallization of KCl from watery solutions. In the calculations activities are used instead of concentrations, the temperature and concentration dependence of both the activity and diffusion coefficients are considered. It is found that

A) the interfacial tension between the crystal and its saturated solution is < 2.5 erg/cm2, which is less by two orders of magnitude than that of between crystal and vacuum;

B) homogeneous nucleation can take place even at very small supersaturations (ln S < < 0.01), which is unusual in precipitation.
Problems and results of diffusion length investigations by energy‐dependent EBIC measurements
Authors: Kittler M. , Seifert W. , Schröder K.‐W. , Susi E.
Published: January 2007

The fundamentals of the method are described. From applications of this measuring method the following results were obtained: The determination of the diffusion length on glass‐plate bevels with evaporated Schottky contacts is frequently quite difficult and sometimes even impossible. Besides a reduction of the diffusion length with increasing microdefect density surprisingly also the opposite behaviour can be found. Comparative PEM and EBIC investigations yield differences between both diffusion lengths (LEBIC < < LPEM) depending on the sample pre‐history.
On the formation and technical importance of the microsegregation in austenitic chromium‐nickel alloyed steels
Authors: Siegel Ulrich
Published: January 2007

The austenitic chromiumnickel alloyed steels are showing different types of concentration‐distributions of the elements chromium and nickel in the austenite in dependance on the content of alloys. As a consequence of the crystallization of the heat to austenite the “equal directed” type of segregation forms. The ferritic solidification of a heat and the following ferrite to austenite transformation leads to “unequal directed” segregation in the austenite. Heats having both the types of segregation solidify by way a 3‐phase reaction. For heats ferritically solidified better hot plasticity, lower susceptibility to hot cracking in the weld and better polishability is observed compared with heats solidified austenitically. The advantages are accounted to the lower separation during the ferritic solidification as consequence of the higher diffusivity of the alloying and accompanying elements in the ferrite compared with the austenite.
Lattice thermal expansion of potassium lithium sulphate
Authors: Venudhar Y. C. , Iyengar Leela , Krishna Rao K. V.
Published: January 2007

Unit‐cell parameters and coefficients of thermal expansion of potassium lithium sulphate have been determined accurately, as a function of temperature, by the X‐ray powder diffraction method. Both the parameters ‘a’ and ‘c’ increase non‐linearly with increasing temperature, the change in the ‘a’ parameter being more than that in the ‘c’ parameter. As a result, the average expansion coefficient along the c‐axis is found to be very small when compared to that along the a‐axis. The lattice thermal behaviour of this compound is explained in terms of the strength of the bonds along the respective directions. The diffraction pattern obtained at 435 °C was completely different from those taken at other lower temperatures, suggesting a structural change contrary to the earlier reports.
Evidence of VLS growth in CdTe film preparation by NH4Cl closed‐tube CVD
Authors: Paorici C. , Pessina V. , Zecchina L. , Mancini A. , Rizzo A.
Published: January 2007

By thermodynamical calculations of the vapour phase composition expected to occur in the closed — tube CVD of CdTe films on CdTe substrates, it is shown that a VLS growth mechanism should be active in the growth process when use is made of the thermal decomposition of NH4Cl for producing the proper amount of HCl as a transport agent. Responsible of this VLS mechanism is the liquid tellurium, which is always present when the NH4Cl concentration reaches values sufficiently high for the epitaxial deposition of CdTe films.
Investigation of convection in the solution zone at the growth of CdTe by THM
Authors: Schwenkenbecher K. , Rudolph P.
Published: January 2007

An investigation of the axial temperature distribution in the solution zone at THM growth of CdTe is presented. The results support the assumption, that density differences coused by concentration differences there are a substantial contribution to convection in the zone. The concentration Rayleigh‐number and the needed concentration expansion coefficient of the real experimental condition are estimated.
Crystal and molecular structure of 1,21‐diacetoxy‐11β,17‐dihydroxy‐4‐methyl‐19‐norpregna‐1,3,5(10),8(14)‐tetraen‐20‐one, C25H30O7
Authors: Reck G. , Langbein G.
Published: January 2007

The structure of the title compound has been determined by X‐ray diffraction techniques. It crystallizes in the monoclinic space group P 21 with 2 formula units C25H30O7 in the unit cell. The lattice constants are a = 10.194, b = 11.790, c = 9.515 Å, and β = 100.69°. The structure was solved by direct methods using MULTAN‐78 and refined by least‐squares calculations to R = 0.061. The molecular configuration and conformation are discussed. The influence of the acetoxy groups and the 11‐hydroxyl group on the steroid backbone is of special interest. There are two symmetry independent intermolecular but no intramolecular hydrogen bridges.
The Polymorphism of 5‐n‐Hexyl‐2‐[4‐n‐pentyloxyphenyl]‐pyridine
Authors: Mädicke A. , Demus D. , Pavluchenko A. I. , Titov V. V. , Smirnova N. I.
Published: January 2007

The phase transitions of 5‐n‐hexyl‐2‐[4‐n‐pentyloxyphenyl]‐pyridine were determined by miroscopic and calorimetric investigations. The classification of the smectic modifications was done by investigation of the miscibility relations. Besides the nematic phase smectic phases C, F, G and H were identified.
Field‐Induced Orientation Transition in Ferroelectric Liquid Crystals
Authors: Schiller P.
Published: January 2007

Static and dynamic effects of a fast bistable device containing a ferroelectric liquid crystal are investigated theoretically. The switching mechanisms are different at low and high electric fields. There is a critical voltage which separates a bulk switching regime from the regime of domain wall motion. This threshold is determined as a function of physical device parameters.
Calculation of the Suspension Volumes of MSMPR Cascade Crystallizers
Authors: Kodura J. , Gramlich K.
Published: January 2007

A new algorithm for the design of cascade crystallizers with and without pure solution removal for the individual crystallizers has been described. The algorithm enables the calculation of active suspension volumes and mean retention times, as well as mean size of product crystals and kinetic quantities for the individual stages for the both variants: — presumption of the mean product sizes in each stage, or — presumption of the mean retention times in each stage.

Results have been shown and discussed for a two stage cascade of KCl‐vacuum crystallizers as example.
X‐Ray Radiography Investigations of Solid Solutions with Limited Miscibility in K2SO4‐(NH4)2SO4‐H2O System
Authors: Dejewska B. , Sedzimir A.
Published: January 2007

The measurements of crystal lattice parameters (a, b, c) were conducted and the volumes (v) and densities (∂) of solid solutions of (K, NH4)2SO4 were calculated. It was established that in the system K2SO4‐(NH4)2SO4‐H2O at 25 °C mixed crystals with limited miscibility were formed. The gap in the continuity of solid solutions occurred in a very narrow range of concentrations of (NH4)2SO4 in mixed crystals, namely from 69.5 to 72.5%.

In order to get the confirmation of the above, the detailed equilibrium investigations nearby the peritonic point (the concentration of K2SO4 −3.32%, the concentration of (NH4)2SO4 −38.66%) were carried out.
Study of Dislocation Distribution in NaClNaBr and NaClCaCl2 Crystals Grown from Melt
Authors: Sankaram T. Bhima , Raju I. V. K. Bhagavan
Published: January 2007

Dislocation distribution and content have been studied using etch pit method in the single crystals of mixed solids NaClNaBr and NaClCaCl2. In both the solid solutions the dislocation content is higher as compared to that in pure crystals of NaCl and NaBr grown under similar conditions. In mixed crystals of NaClNaBr the block structure of subgrain boundaries is not observed. The subgrain boundaries are highly fragmentary and the dislocations form arrays running randomly to short distances. In NaCl crystals doped with CaCl2 dislocation loops and impurity‐decorated dislocations are observed. The dislocation content is higher in impurity segregated regions. The impurity decorates both isolated dislocations and subgrain boundaries in calcium‐doped crystals. The results are discussed.
Optical, Electrical and Morphological Studies of SnSe2 Crystals Grown by Physical Vapour Transport Method
Authors: George Joy , Kumari C. K. Valsala
Published: January 2007

Tin diselenide single crystals have been grown by the physical vapour transport (PVT) method. Optical absorption studies give an indirect allowed transition at 1.03 eV at room temperature. The electrical resistivity parallel and perpendicular to c‐axis, mobility and carrier concentration have been determined. Dependence of resistivity parallel to c‐axis on temperature gives an activation energy of 0.072 eV. Growth spirals observed for the first time on the as grown faces of these crystals are also presented here.
Gaseous Bubble Formation in Bi2Te3Bi2Se3 Melt
Authors: Nghi Nguyen Thanh , Ushkans A. L. , Cherepanova T. A.
Published: January 2007

In this paper the mechanism of the formation of gaseous inclusions in the liquid phase on the example of Bi2Te3‐Bi2Se3 system is considered. The thermodynamic analysis for the model scheme of melting has been carried out. It is shown that the time dependence of the pressure and composition of gaseous phase is determined by establishment of equilibrium between liquid and gaseous phases in the system. The results of numerical computation give a quantitative evolution of the size of critical gaseous nucleus in the Bi2Te3‐Bi2Se3 melt with the time and its dependence on the height of melt column.
LPE of Isolated Pb0,85Sn0.15Te Islands on PbTe
Authors: Deppert K. , Schikora D. , Parthiek L. , Ickert L.
Published: January 2007

In recent years the importance of selective epitaxy has continuously increased. It is a tool for controlling the production of semiconductor structures as required. This method has been demonstrated and investigated by LPE as well as VPE and MBE.

Usually substrates are used having either preferentially etched channels or windows in masks to predetermine the site. In the present paper epitaxy of Pb0.85Sn0.15 Te deposits growing in isolated islands on PbTe substrates by means of LPE is investigated.
Crystal Growth and Physico‐Chemical Properties of Lead Molybdate in the Homogeneity Region
Authors: Gabrielian V. T. , Fedorova L. M. , Tkachenko E. B. , Neiman A. Y. , Nikogosian N. S.
Published: January 2007

From data of both X‐ray phase analysis and differential thermal analysis, as well from measurements of the crystal lattice parameters, electric conductivity and diffusion coefficients of cations in ceramics and single crystals the width of the homogeneity region of the lead molybdate phase which lies in the composition range of 49.85–50.50 mole% MoO3, has been determined. It was also established that the compound was a daltonide phase. The results obtained explain the Pb/Mo ratio changes along the crystal.
The Structure of Metastable Phases in AlZn Alloys (II). HREM Investigations on α‐Precipitates
Authors: Ramlau R. , Löffler H.
Published: January 2007

Precipitates of the metastable ‐phase grown in an Al‐(6.8 at.%)Zn alloy are investigated by means of a technique of high resolution electron microscopy, namely by two‐beam lattice fringe imaging with tilted illumination. It is demonstrated by this direct method that the ‐precipitates are in fact semicoherent. The transition of fully coherent Guinier‐Preston zones into semicoherent precipitates of the ‐phase takes place by formation of additional (III)rh and { III }rh planes inside the zones.
Transformation of Light Wave in Absorbing Crystals with Low Symmetry and Determination of their Own Waves Parameters (I)
Authors: Shamburov V. A. , Evdishchenko E. A.
Published: January 2007

The decision of the direct and reverse problems in the optics of the low symmetry absorbing crystals are obtained and graphically represented by the specific drawing on the Poincare sphere. The direct problem is connected with the transmission and reflection of the normally incident light wave and reverse problem — with the determination of the own waves parameters. Instead of the usually used boundary conditions the equations of Fresnel and Airy are applied to each of the own waves separately, as the incident, reflected and transmitted waves are represented by the vector sum of the own waves. On the basis of the comparatively simple decision of the direct problem the simpliest method of the reverse problem decision, i.e. for the determination of the own waves parameters in the crystal plate is proposed. In the capacity of the experimental data for this purpose the measured polarization parameters, the reflection‐ and transmission coefficients of the reflected and transmitted waves must be used as well as the right and left circular polarized incident waves and also two different, but close thicknesses of the crystal plate.
Effect of Ambient Atmosphere on Defect Generation in MgO during Mechanical Activation
Authors: Spitsyn V. I. , Steinike U. , Barsova L. I. , Hennig H.‐P. , Jurik T. K. , Kretzschmar U.
Published: January 2007

As previous studies have shown (Spitsyn et al.; Henderson, Wertz; Steinike et al. 1981, 1984; Hennig et al.), mechanical activation of MgO in air results in the generation of anion and cation vacancies in the lattice, thus causing heterogeneous lattice distortions. These anion and cation vacancies are identified as F+‐ and V−‐centres, respectively, by EPR spectroscopy. F+‐centres are anion vacancies filled with electrons, V−‐centres are cation vacancies filled with holes. The electrons and defect electrons filling the vacancies are generated essentially during γ‐irradiation. Since the effect of the ambient atmosphere on the generation of electronic and structural defects upon mechanical activation is known (Bystrikov et al.), the studies of mechanical MgO activation in air were extended to the generation of above defects in an argon atmosphere. The results are compared with those obtained in air.
Studies on Epitaxial Growth of Organic Compounds on Sucrose by the Fourier Transform Method (II). Iso‐ and Heteroepitaxy
Authors: Adler H.‐J. , Follner H.
Published: January 2007

Iso‐epitaxial growth (twinning, parallel growth) of sucrose, β‐succinic acid, anthraquinone and isatin can be explained by a good fit of the energetic structures of both partners. The symmetry operations result from the pseudo‐symmetries of the reciprocal crystals. In all cases possible planes favoured for the formation of twins or parallel grown individuals can be predicted. Heteroepitaxial growth of β‐succinic acid, hexachlorobenzene, anthraquinone and isatin on (100)‐oriented sucrose has been observed. It is possible to explain the growth mechanisms by symmetry considerations of the energetic structures.
The Interaction Process between Crystallization and Solubility Interfaces in the Temperature Gradient Zone Melting Method
Authors: Tairov Ju. M. , Peev N. S. , Smirnova N. A. , Kalnin A. A. , Miropolski M.
Published: January 2007

In the present work the problem of the interaction process between crystallization and solubility interfaces in case of the temperature gradient zone melting method is discussed. Wellknown assumptions are considered. It is shown that an interaction between the both interfaces exists and the change of the form of the one interface leads to the corresponding change of the other interface.
The Precipitation of Sparingly‐soluble Alkaline‐earth Metal and Transition Metal Oxyanion Salts from Aqueous Solution at Ambient Temperatures to 100 °C: Anhydrous and Hydrated Precipitate Phases
Authors: Packter A.
Published: January 2007

The anhydrous and hydrated phases of the sparingly‐soluble barium, strontium, calcium, magnesium, lead(II), mercury(II), cadmium, zinc, copper(II), nickel(II), cobalt(II), iron(II) and manganese(II) salts of series of inorganic and organic oxyanions, precipitated from aqueous solution at ambient temperatures to 100 °C, have been tabulated and classified. The alkaline‐earth and transition metal chromates, molybdates and tungstates are mainly anhydrous.

The alkaline‐earth and transition metal carbonates, orthophosphates, orthoarsenates, sulphates, selenates, bromates and iodates show mixed character. The precipitated barium, some strontium, lead(II) and mercury(II) salts are anhydrous: many of the other salts are precipitated as hydrates and the hydration numbers generally increase from one‐half to three with decrease in the cation radius.

All the alkaline‐earth and transition metal oxalates (except lead oxalate) are precipitated as hydrates (below 100 °C). The hydration numbers at ambient temperatures generally increase from two to three‐four but there is no clear inverse variation with cation radius.

These results are explained by Johnson's thermodynamic treatment for the free energies of solution and precipitation (and crystallisation) of ionic salts.
Native Point Defects and Nonstoichiometry in GaAs (I). Homogeneity Region of Gallium Arsenide
Authors: Morozov A. N. , Bublik V. T. , Morozova O. Yu.
Published: January 2007

Homogeneity region and the concentration of dominant native point defects along its boundary are calculated by the method of quasichemical reactions with the use of experimental data on the structure type of solid solutions formed by the components in GaAs. The entropy and enthalpy of the formation of dominant native point defects in GaAs are obtained. Temperature ranges of the formation of microdefects‐finely dispersed Ga and As precipitates are considered.
Electrical Properties of Large‐grain Polycrystalline GaP
Authors: Siegel W. , Kühnel G.
Published: January 2007

I–U and I–T measurements have been performed on large‐grain polyerystalline p‐GaP grown by the SSD method or synthesized in a high‐pressure autoclave. There exists a clear correlation between these characteristics and those of corresponding bierystals from which it can be concluded on a strongly unequal division of the applied voltage on both depletion regions of the grain boundaries. On the other hand I–U characteristics of polysilicon mostly are described by a sinh‐behaviour which supposes an equal division of the voltage. These differences are discussed. The I–U characteristics of the polycrystalline GaP at room temperature are governed by thermionie emission and thermionic field emission whereas at low temperatures (and high voltages) tunneling dominates. At high temperatures the influence of grain boundaries disappears.
Growth Mechanism in Atomic Layer Epitaxy (I) Re‐evaporation of Cd and Te from CdTe(111) Surfaces Monitored by Auger Electron Spectroscopy
Authors: Herman M. A. , Jylhä O. , Pessa M.
Published: January 2007

The mechanism of atomic layer epitaxy (ALE) of cadmium telluride has been studied. Auger electron spectroscopy is used to measure the isothermal re‐evaporation rates of elemental Cd and Te deposits on the (111)A and (111)B surfaces of CdTe substrates. The results include an observation that the sticking coefficients of Cd and Te are smaller than unity at the growth temperatures typical of CdTe ALE. After desorption the substrates are left partially covered: 35% by a Cd overlayer on the (111)B surface and 72% by Te on the (111)A surface. The re‐evaporation rates of Cd and Te experience a drastic change near the substrate‐deposit interface. These rates appear two orders of magnitude smaller than those of bulk‐like amorphous Cd and Te solids. The activation energies for reevaporation of the near‐interface layer region are estimated to be: 1.5 eV for Te on the (111)A face, 1.0 eV for Te on (111)B and 0.5 eV for Cd on (111)B. It has also been shown that AES can be used to identify the polarity of the CdTe(111) surfaces. The relative difference in peak‐to‐peak intensity ratios of Cd MNN to Te MNN for (111)A and (111)B is (11 ± 2)%.
Effect of Particle Size on the Ice Nucleating Ability of AgIAgBrCuI System
Authors: Palanisamy M. , Thangaraj K. , Gobinathan R. , Ramasamy P.
Published: January 2007

The effect of particle size on the ice nucleating behaviour of AgI‐AgBr‐CuI system has been studied for the first time. Six samples of different molar ratios and five sizes in each sample are considered in the present study. It is found that the nucleation temperature is the highest for particle size in the range of 60 ± 5um.
Native Point Defects and Nonstoichiometry in GaAs (II) Mechanism of Formation and Degradation of Semiinsulating Properties of Undoped Gallium Arsenide Crystals
Authors: Morozov A. N. , Bublik V. T. , Yu. Morozova O.
Published: January 2007

The nature of the main electron trap, EL2, in undoped semiinsulating GaAs crystals have been studied both qualitatively and quantitatively. It has been shown that point defects which, most probably, are responsible for the EL2 level are antisite AsGa defects or (AsiVGs) complexes which are indistinguishable from the thermodynamic standpoint. The enthalpy and entropy of AsGa formation according to the reaction AsAs + VGa ⇄ AsGa + VAs are equal to 0.5 eV and −7k, respectively.
Polytypism of Pb‐doped Single Crystals of Cadmium Iodide
Authors: Tyagi U. P. , Trigunayat G. C.
Published: January 2007

The zone refining technique has been used both for the purification of cadmium iodide and for the growth of lead‐doped single crystals of cadmium iodide. The as‐grown crystals when studied by X‐ray diffraction show exclusive presence of the most common polytype 4H. The hexagonal plate‐shaped crystals of the doped material, grown from aqueous solution, show polytypism, but of a different nature than the crystals of pure cadmium iodide. The results have been discussed.
Investigation of the Influence of Grinding on Regions near the Surface of Steel by Ultrasonic Surface Waves
Authors: Schneider D. , Herrmann K. , Brenner B. , Schläfer D. , Winderlich B.
Published: January 2007

The applicability of surface wave velocity measurements as a nondestructive test method to investigations of deformation layers with preferred orientations and residual stresses has been examined at steel C70W2. The residual stresses in various directions parallel to the surface have been detected from changes of velocity caused by a stress‐free annealing. From the anisotropy and the frequency dependence of velocity the existence of a surface layer with preferred orientations has been deduced and such characteristic parameters as preferred orientation and depth have been estimated. The results have been compared and completed with X‐ray texture investigations and data from Barkhausen noise.
Dislocation Etch Studies on Diammonium Hydrogen Citrate Single Crystals
Authors: George Joy , Peter George
Published: January 2007

Diammonium Hydrogen Citrate single crystals have been grown from aqueous solution. The etch technique for defect studies is applied to these crystals. Propionic acid is shown to be a reliable etchant capable of bringing out dislocations intersecting the (001) face. Various other interesting features observed during etching are also presented and discussed.
Growth Mechanism in Atomic Layer Epitaxy (II). A Model of the Growth Process of CdTe on CdTe (111) Substrates
Authors: Herman M. A. , Jylhä O. , Pessa M.
Published: January 2007

A realistic model of CdTe growth by atomic layer epitaxy (ALE) has been proposed. This model is based on experimental studies concerning the isothermal re‐evaporation rates of elemental Cd and Te deposits on the (lll)A and (lll)B surfaces of CdTe substrates, on a study of surface morphology and crystal structure of CdTe single crystal overlayers grown by ALE on CdTe(lll)B substrates under various crystallization conditions as well as on the existing theories related to the interaction of thermally activated atoms or molecules with hot solid surfaces.

This model includes: (i) an existence of transition layers of both Cd and Te2 species, intermediate between a chemisorbed and a bulk‐like film, which create reaction zones 3–4 monolayers thick near the substrate surface, and (ii) partial re‐evaporation of the first, chemisorbed monolayer of the deposited constituent elements.
The Stochastic Theory of the Solidification of Binary Systems
Authors: Chvoj Z.
Published: January 2007

The stochastic theory was applied to the description of the solidification of binary systems. This theory is suitable for the studying of the dependence of kinetic phase diagrams on the technological conditions. The general relations between the concentrations of the liquid and the solid phases and between the rate of the solidification and the thermodynamic potentials of both phases are presented. In the case the stationary solidification of the binary systems our results are compared with the results published in the previous papers. The dependences of the kinetic phase diagrams on the growth rate or on the diffusion are in a good agreement with the Monte‐Carlo calculations.
Influence of γ‐Irradiation on Some Properties of NaCl:Eu++ Crystals (II). Colourability
Authors: Suszyńska M. , Opyrchal H. , Nierzewski K. D. , Macalik B. , Gubański A.
Published: January 2007

The room temperature colouration process of NaCl:Eu++ crystals strongly depends on both the dopant concentration, represented by the absorption coefficient α(eg), and the dopant dispersion state as well.

It has been found that within the UV spectral range either some V‐type absorption bands appear or only the background absorption increases. For heavily irradiated crystals the clustering of halogen‐interstitial results in the formation of dislocation loops.

In dependence of the dopant concentration the colourability of as received crystals is either larger (α(eg) ⪅, or smaller (α(eg) ⪆ −1) of that characteristic of the solution treated ones. The difference in the effectiveness of the halogen‐interstitials trapping‐process has been explained in terms of the various structure and/or composition of the europium‐related aggregates and/or precipitates.
Intercalation and Graphitizability of Electrode Cokes
Authors: Preiss H. , Lunkenheimer Ch. , Nissel U.
Published: January 2007

Experimental results show in case of intercalation by SbCl5, CrO3 and Br2 the influence of the degree of perfection and size of graphite crystals on synthesis, intercalant distribution and stage disordering of intercalation compounds. High temperature treatment of electrode cokes improves steeply the ability of intercalation by SbCl5 and Br2 between 1900 and 2000 °C. A gradual increase of intercalated CrO3 with temperature have been found in cokes annealed between 2000 and 2800 °C. By means of CrO3‐intercalation a distinction of graphitized cokes is possible. Filling of galleries between carbon layers by CrO3 have been only completed in crystals of natural graphite with low flake diameter. EPMA showed CrO3‐intercalation in large crystals only in the prismatic edge area. SbCl5‐intercalation exhibits an increase in stage disordering with decreasing degree of crystallite perfection and increasing degree of grinding of original graphites.
Doping of PbTe with Ga during Growth from the Vapour Phase
Authors: Möllmann K.‐P. , Siche D. , Zajnudinov S.
Published: January 2007

In the present paper a method for doping of PbTe with Ga during crystal growth from the vapour phase is presented. The galvanomagnetic and photoelectric properties of the produced material are compared with results of other techniques and the equivalence of these physical properties is proved. Furthermore a defect model of the build‐in mechanism of Ga in PbTe is shown.
General Method of Formulation and Crystal Growth of Ornamental Garnets
Authors: Petrosyan A. G.
Published: January 2007

“Compositional” shift of spectral lines of Eu2+, Yb2+ and Zr3+ ions resulting from crystal field variation in e‐sites of the garnet lattice is considered with respect to the provision of a general method of formulation and crystal growth of ornamental material with colour smoothly changing from violet to red.
Autodoping of Epitaxial Silicon Layers (III). Theoretical Treatment of Lateral Autodoping
Authors: Kühne H.
Published: January 2007

Solving dopants from the silicon surface into the volume during epitaxial layer growth is commonly described as a solution equilibrium, which forms an essential part of modelling intentional silicon doping. Above buried layers a so‐called redistribution autodoping causes the inversely directed process within an initial layer growth period. When the layer begins to grow, the dopants are not totally buried by the silicon deposited, but are partially swept towards the surface to develop the redistribution equilibrium. Above that part of the layer surface located above buried layers, simultaneously a certain dopant partial pressure is established. It gives rise to a vertical and lateral dopant transport by means of gas diffusion. The flow in lateral direction is considered the source of lateral autodoping. In the present paper a theoretical model of autodoping is developed and the layer deposition parameters are discussed with regard to minimizing autodoping effects.
Distribution of Cations and the Proton Location in Kaersutite
Authors: Jirák Z. , Pechar F. , Vratislav S.
Published: January 2007

The crystal of Kaersutite, (Na0.63K0.37Ca1.99) (Mg3.10Fe0.98Al0.51Mn0.01Ti055) (Si6.07Al1.93) (O, OH)24 from lecality Vlčí Hora – Bohemia was studied by powder neutron diffraction.

The refinement of the crystal structure within space group C2/m gave cell dimensions a = 0.9863, b = 1.8040 and c = 0.5306 nm, β = 105° 28′, Z = 2. Protons were found to form bridges between two 03 ioxygens. (This location allows for the existence of proton per f.u. in maximum). The actual population was refined to 0.8. The occupation of the five eation sites was determined as follows: M 1 (0.60 Mg + 0.25 Ti + 0.10 Al + 0.05 Fe), M 2 (0.50 Mg + 0.35 Fe + 0.15 Al), M 3 (0.8 Mg + p.2 Fe), M 4 (Ca) and A (Na, K).
Micro Non‐Homogeneity Studies in Tin Telluride Synthesized by a Low‐Temperature Iodide Method
Authors: Assenov R. , Moshnikov V. A. , Yaskov D. A.
Published: January 2007

The micro non‐homogeneity of SnTe samples obtained by a low‐temperature iodide method was studied by means of an X‐ray spectral microanalyser Cameca MS‐46. The composition of the microprecipitates was studied, as well as the possible causes for their formation in the process of obtaining the material. The paper shows the favourable prospects of using a SnI2 solvent obtained in advance for synthesizing SnTe.
Investigation of Optical Properties of YAlO3Pr3+ Single Crystals
Authors: Butaeva T. I. , Kaminskii A. A. , Ovanesyan K. L. , Petrosyan A. G.
Published: January 2007

Colour centers in YAlO3:Pr3+ crystals originating under xenon lamp or y–radiation and oxidizing annealing are considered. The nature of colour centers under these treatments is similar in nominally pure and Pr3+ containing crystals but the intensity of induced absorption lines is higher in activated crystals which assumably is associated with valent transitions of Pr ions.
The Properties of Undoped InP and GaP Bulk Crystals Prepared by Floating Zone Melting
Authors: Popov A.
Published: January 2007

Undoped GaP and InP crystals which are produced by floating zone melting without a crucible were investigated. The background concentration was 1015cm−3 after several passages of the molten zone. The fundamental residual impurities are carbon and silicon penetrating into the crystals during the crystallization process. After purification, the electron mobility of GaP was 200 cm2/V. s, and for InP – 4000 cm2/Vs. The compensation decreased to 20%. A very effective purification was observed with respect to the carbon atoms, but for silicon this result is observed only after several passages of the molten zone.

GaP and InP are basic materials for optoelectronic devices and it is important to investigate the possibility for production of pure bulk crystals. A proper method for this aim is the floating zone melting, where the crucible effect is removed and the influence of residual impurities is observed. In this work the influence of the number of floating zone passages on the electrical and luminescence properties of InP and GAP bulk crystals has been investigated.
Application Fields of ANOF Layers and Composites
Authors: Kurze P. , Krysmann W. , Schneider H. G.
Published: January 2007

Anodic oxidation by spark discharge (ANOF) produces e.g. Al2O3 layers containing up to 25% α‐Al2O3 on the average if carried out on Al (Kurze et al. (1) and corresponding oxide layers with special outstanding properties on other barrier layer forming metals esp. Ta, Ti, Zr, Nb(Cb) (Kurze) et al. (2), (3), (4); Schneider (1), (2)). There is a wide field of application possibilities of such layers and composites of them with the bearing metals and other materials, e.g. in the fields of electrical engineering, electronics, medicine and vacuum engineering etc. This is the last one of three general ANOF papers published in this journal (Krysmann et al.; Dittrich et al.).
Elimination of Texture Influence in Quantitative Phase Analysis of Boron Nitride Samples
Authors: Černy R. , Šíichová H.
Published: January 2007

A simple method of texture influence elimination in quantitative phase analysis of boron nitride samples is presented. The method is applicable for the compounds with hexagonal symmetry. The range of validity is discussed and the application in study of phase transitions in boron nitride samples is demonstrated.
Gel growth and X‐ray studies of single crystals in the mixed system KDP:ADP
Authors: Mohanlal S. K. , Baskaran R.
Published: January 2007

Crystals of KDP and ADP and of the mixed system KDP:ADP are grown by gel technique resulting in good quality single crystals. The lattice parameters and densities of the mixed crystals show a linear dependence on composition in accordance to Vegard's Rule.
Coloured ANOF layers on aluminium
Authors: Kurze P. , Krysmann W. , Schreckenbach J. , Schwarz Th. , Rabending K.
Published: January 2007

By addition of metal salts to a basic electrolyte as colouring components coloured ANOF layers can be produced. The colour shades of such layers are dependent on concentration and deposition parameters. Two application examples of coloured ANOF layers are demonstrated.
Defect generation on mechanical surface defects before and after the oxidation (I). TEM investigations on the nucleation of oxidation stacking faults at mechanically induced weak surface defects
Authors: Morgenstern G. , Weidner G.
Published: January 2007

In order to obtain information on the nucleation mechanism of oxidation stacking faults, mechanically induced weak surface defects as simulated by low‐load scratches were investigated with TEM before and after a short‐time wet oxidation at 1050 °C. The experimental results could not confirm the existing models which explain stacking fault nucleation by the splitting of complete dislocations. Rather it was found that clusters of silicon interstitials are generated due to strong local compression during scratching, which then act as nuclei for stacking faults in the subsequent oxydation process.
Morphological features of synthetic crystals of As2Se3
Authors: Kothiyal G. P. , Ghosh B.
Published: January 2007

Scanning electron microscope (SEM) studies have been carried out on vapour grown arsenic triselenide platelet crystals and whiskers grown under argon and normal air ambients. The crystal morphology and microstructure were found similar in both types of crystals. While investigating the microstructure the layered structure of these crystals could be discerned under SEM. Layers with average thickness of 2–2.5 μm could be distinctly observed for the first time in As2Se3 crystals. This might be an important observation.
Crystallization of fatty acid (C16H32O2) from short‐chain hydrocarbon (C6H14)
Authors: Prasad P. B. V. , Sato K.
Published: January 2007

A strong evidence for the occurrence of palmitic acid in highly fibrous form, when crystallized in presence of linear chain hydrocarbon, is obtained by crystallizing palmitic acid from n‐hexane solutions, by the evaporation of solvent at high rate of evaporation.
Defect generation on mechanically surface defects before and after the oxidation (II). Dislocation generation at cracks
Authors: Weidner G. , Morgenstern G.
Published: January 2007

The generation of crystal defects at residual cracks due to a wet oxidation of chemically mechanically polished silicon wafers at 1100 °C was investigated. It was found that the nucleation of oxidation stacking faults at these elastic cracks is impeded as compared to the regions between the cracks. However, extended dislocations, dislocation dipoles, certain stacking faults, and precipitates are generated at such cracks. These crystal defects and the crack itself impede the nucleation of oxidation stacking faults at the crack, as they locally reduce the excess interstitials at the oxidation front.
The role of Mg2+‐V‐dipoles: In the thermoluminescence of LiF2:Mg single crystal
Authors: Opyrchal H. , Macalik B. , Watterich A.
Published: January 2007

The thermoluminescence and radiation or thermally induced changes of the concentration of magnesium dipoles have been studied in LiF:Mg2+ crystal grown in an inert atmosphere.

The evolution of the TL spectrum with γ‐radiation dose shows that the glow peaks observed at the beginning of irradiation decrease at high doses whereas new peaks, positioned at higher temperatures, appeare. Moreover, it has been found that the thermally induced recovery of the dopant dipoles, destroyed during the irradiation, strongly depends on the dose applied. The recovery curves obtained for a fixed irradiation dose dose not exhibit thermal annealing steps at temperatures, at which glow peaks occur. Further, the number of the recovered magnesium dipoles is not correlated with the quantity of light emitted during heating the irradiated crystal what is expected in respect to some of the previously proposed models.

On the basis of results obtained it is proposed that the decay of the magnesium dipoles is mainly due to the dopant aggregation induced by the γ‐radiation. The role of the magnesium ions in thermoluminescent processes is discussed.
METAL CVD: A thermodynamic model
Authors: Cebulla Horst , Erben Elke
Published: January 2007

This paper describes a thermodynamic model for the chemical vapour deposition of metal films. The values of the equilibrium mole fractions, the metal mole flux, and the deposition rate were calculated. This dependences are discussed for the normal pressure and low pressure tantalum deposition. Experimental values are reported and compared with theoretical results.
Crystal and molecular structure of (20R)‐19‐nor‐5β,14β‐pregnane‐3β,14,20‐triol 3,20‐diacetate
Authors: Pfeiffer D. , Weiland J. , Leibnitz P.
Published: January 2007

The title compound (20R)‐19‐nor‐5β,14β‐pregnane‐3β,14,20‐triol 3,20‐diacetate crystallizes in the monoclinic space group P21 with 4 formula units C24H38O5 in the unit cell. The lattice parameters are a = 14.324, b = 12.569, c = 12.685 Å, β = 90.21°. The crystal structure was determined by direct methods and refined by the least‐squares procedure to the discrepancy factor R = 0.042. Bond length, bond angles, ring conformations, as well as the absolute configuration at C20 were determined. In the crystal the molecules are linked to infinite chains by two hydrogen bonds.
The crystal and molecular structure of a dioxan photoadduct of 3‐dehydro‐gibberellin A1 methyl ester
Authors: Kutschabsky L. , Kretschmer R.‐G. , Adam G. , Sung T. V.
Published: January 2007

The three‐dimensional structure of a dioxan photoadduct of 3‐dehydro‐gibberellin A1 methyl ester has been established as (2′S)‐3‐[dioxanyl‐(2′)]‐3‐epi‐gibberellin A1 methyl ester (1) by X‐ray analysis. The compound crystallizes in the orthorhombic space group P212121 with four molecules in the unit cell of dimensions a = 9.751, b = 22.189, c = = 10.064 Å. The final R‐value is 0.103 for 1151 reflections.