bluuebunny/crossref_metadata_2025 huggingface dataset:
Regularities of thermal deformations in Monoclinic Crystals
Authors: Filatov S. K. , Andrianova L. V. , Bubnova R. S.
Published: January 2007

The results of calculations of thermal deformation tensor and its analysis are given for eleven silicates and vanadates of clinopyroxenic structure. It is shown that the level of thermal deformation anisotropy in monoclinity plane is in stable correlation with velocity of monoclimity angle change. The correlation is explained by considerable contribution of shear component into deformations. Considering the shears it is possible to understand, to separate the thermal deformations in monoclinic crystals into components and to summarize them from those components. The given regularities permit generalisations for triclinic crystals as well as for pressure and chemical (compositional) deformations.
The structure of N‐Pyrid‐4‐yl‐iminotriphenylphosphorane, C23H19N2P
Authors: Kulpe S. , Seidel I. , Bödeker J. , Köckritz P.
Published: January 2007

Mr = 353.9, monoclinic, P 21/c, a = 11.248(2), b = 11.323(2), c = 14.845(4) Å, β = = 95.87(2)0, Z = 4, V = 1880.8(3) Å3, Dx = 1.28 Mgm−3, final R = 0.049 for 1995 independent reflections excluding those with |F0| < 5 σ(F0). Intensities were measured with an automatic diffractometer. The magnified imagePNC‐group of the molecule is nearly coplanar with the pyridine ring (dihedral angle 4.1°). The P atom and the C(2) atom of the pyridine ring overlap with their van der Waals spheres and have nearly the position with the maximum of steric hindrance. This conformation is the consequence of a conjugation between the Ph3PNgroup and the N‐standing pyridine ring as well as of an attraction between the P atom and the C(2) atom. A similar conformation has been observed in the molecule of N‐pyrid‐2‐yliminotriphenylphosphorane.
The structure of N‐Pyrid‐2‐yl‐iminotriphenylphosphorane, C23H19N2P
Authors: Kulpe S. , Seidel I. , Bödeker J. , Köckritz P.
Published: January 2007

Mr = 353.9, monoclinic, P 21/c, a = 11.371(4), b = 11.391(5), c = 14.699(11) Å, β = = 97.78(2)0, Z = 4, V = 1888.6(6) Å3, Dx = 1.28 Mgm−3, final R = 0.052 for 2360 independent reflections excluding those with |F0| < 5 σ(F0). Intensities were measured with an automatic diffractometer. The magnified imagePNC‐ part of the molecule is nearly coplanar with the pyridinring (torsion angle 6.4°). The P atom and the N(2) atom of the pyridinring overlap with their van der Waals spheres and have nearly the position with the maximum of steric hindrance.

This conformation of the molecule is the consequence of a conjugation between the Ph3P=N‐group and the N‐standing pyridine ring as well as of an attraction between the P atom and the N(2) atom.
The structure of Tetraphenyl Imidodiphosphate, C24H21NO6P2
Authors: Kulpe S. , Seidel I. , Herrmann E.
Published: January 2007

Mr= 481.24, monoclinic, P 21/c,a= 12.009(3),b= 12.305(5),c= 18.993(7) Å, β = = 122.1(1)0,V= 2377.2(6) Å3,Dx= 1.349 Mgm−3,Z= 4. FinalR= 0.051 for 2690 independent reflections excluding those with |F0| < 4 σ(F0). Intensities were measured with an automatic diffractometer. The two phosphoryl oxygen atoms are in trans position. The acidic hydrogen atom is bonded at the nittogen atom. The molecules form dimers connected by NH … O intermolecular hydrogen bonds. Results are compared with those of the structure of tris(tetraphenylimidodiphosphato)ytterbium (III).
The molecular and crystal structure of the Steroidal Alkaloid Aculeamine
Authors: Kutschabsky L. , Pfeiffer D. , Coll F. , Adam G.
Published: January 2007

A new solanocapsine‐type alkaloid named aculeamine has been isolated from roots of Solanum aculeatum and its structure has been established by X‐ray analysis as 22,26‐epimino‐23β‐methoxy‐16α,23‐epoxy‐5α,25αH,25βH‐chloestane‐3β‐ol. The compound crystallizes in the hexagonal space group P61 with the lattice parameters a = b = 16.706, c = 17.056 Å, α = β = 90°, γ = 120°. The final residual value was R = 0.079.
Vibrational properties of CdGa2S4
Authors: Neumann H. , Sobotta H. , Riede V. , Syrbu N. N. , Radautsan S. I.
Published: January 2007

Polarization‐dependent infrared reflectivity spectra of CdGa2S4 are measured at 300 K in the wavenumber range from 180 to 500 cm−1. The analysis of the spectra yields three E and four B modes in this frequency range. The results are compared with previously published data and a final identification of the infrared active modes in CdGa2S4 is proposed. It is shown that the two‐phonon absorption spectra of CdGa2S4 can be interpreted in terms of zone‐centre two‐phonon combination modes. The relation between the lattice vibrational properties of chalcopyrite and defect‐chalcopyrite compounds is discussed.
Dielectric properties of vacuum deposited Samarium Oxide sandwich structures
Authors: Chandra Shekar M. , Subba Rao U. V. , Hari Babu V.
Published: January 2007

Samarium oxide films were prepared by vacuum thermal evaporation using tantalum boats. The effect of aging, frequency and annealing on capacitance and tan δ were studied for AlSm2O3Al capacitor structures. The variation in capacitance with frequency at low frequency region is quite considerable. The existence of oxygen vacancies were confirmed from the thermoluminescence studies of these oxide films. The results were discussed on the basis of oxygen vacancies existing in these films.
The influence of elastic anisotropy on interaction of dislocations with point defects in BCC metals
Authors: Chernov V. M. , Ivanov V. V.
Published: January 2007

With the use of the anisotropic theory of elasticity the energies and the force‐distance profiles for the interaction of various types of straight dislocations with point defects of intrusion (atoms of N, C or O) and of replacement in BCC metals with a different degree of elastic anisotropy (Nb, V, Ta, α‐Fe) have been calculated. The calculated force‐distance profiles in most cases are not centrally symmetric, that leads up to a gliding asymmetry at the direct and reverse directions of dislocation motion. The crystal elastic anisotropy can change the relative mobility of dislocations of various types and accounts for a number of experimentally observed peculiarities of BCC metals stress‐strain properties.
Effects of the dislocation collective behaviour in plasticity of single crystals
Authors: Bengus V. Z.
Published: January 2007

An analysis has been carried out of the motion of a pair of sign‐similar edge dislocations under a constant shear stress in a simplest nonuniform field of internal stresses τi with a constant gradient. The influence is shown of the dislocation interaction and τi on the activation „volume”︁ of the average velocity of a dislocation pair, which is measured by the flow stress relaxation. The experimentally revealed anomalies of the activation „volume”︁ measured by the flow stress relaxation are regarded as corroborating the analysis and as manifestations of the collective effects of the elastic interaction of sign‐similar mobile dislocations.
Stationary creep and dislocation structure of Rhenium Single Crystals tested at moderate temperatures
Authors: Aristov V. V. , Myshlyaev M. M. , Romanov Y. U. A. , Shmytko I. M.
Published: January 2007

Creep of rhenium single crystals is studied in tension along <11¯23> in the range of moderate temperatures (1233–1593 K). The kinetic equation is obtained to describe stationary creep rate as a function of temperature and stress, the parameters of this equation are determined. The activation energy is shown to be constant and independent of the stress applied. The X‐ray divergent beam technique (DB) is employed to show that glide occurs mainly in a basal plane, the preferential bending axis of its lattice lying along the tensile direction, and that the internal regions of the crystal comprise unstressed areas misoriented with respect to each other by an angle ≈ 10÷15'. The electron microscope studies of the dislocation structure suggest that hexagonal networks of dislocations located in basal glide planes are typical elements of the structural state.
The electron‐dislocation interaction and electronic effects at low‐temperature deformation
Authors: Ossipyan Y. U. A. , Bobrov V. S.
Published: January 2007

The effect of the electronic state of crystals on the processes of their plastic flow is considered. Presented are the results of the observation and study of the effects of the electrondislocation interaction at a low‐temperature deformation of metals.
Thermal effects in low‐temperature deformation: The response to strain rate changes
Authors: Kubin L. P. , Estrin Y.
Published: January 2007

The response of a deforming crystal to an abrupt strain rate change has been considered in the framework of the thermal model for low temperature anomalies of plastic deformation. Various modes of the deformation behaviour following strain rate changes have been predicted depending on the location of the point representing the state of the specimen in the plane of control parameters. A quantitive analysis of two characteristic modes of the deformation behaviour experimentally observed by KOMNIK and DEMIRSKI has been carried out with the aid of computer calculations and a good agreement with their data has been found.
Design of a continuous crystallizer by evaporation as unit operation
Authors: Chianese A. , Fasoli U. , Prati Gaglia M. P.
Published: January 2007

We have examined the continuous crystallization by evaporation as a unit operation, a process which is normally empirically designed and dimensioned. Through the mass balances and process equations (concerning the crystal growth, the secondary nucleation, the crystals dimensional and numeric balances) six equations were obtained upon which the calculation of the operating variables depends. The resulting mathematical system offers two degrees of freedom, and by defining the two independent variables it was possible to calculate — as shown in the graphics — the trends of the other six variables. One of the chosen independent variables was the diameter of the formed nuclei (as this is basically an experimental date), whereas the other was the variable τ which defines the residence time.
Morphology and characterization of ammonium bichromate crystals grown from aqueous solutions
Authors: Nowaczyk Z. , Sangwal K.
Published: January 2007

The morphology of ammonium bichromate single crystals grown from aqueous solutions by solvent evaporation method at temperatures between 22 and 56 °C is investigated. It is found that the crystal morphology changes monotonically with an increase in growth temperature. Chemical etching is used to characterize the as‐grown crystals.
Effect of stress field on spiral step patterns on n‐octacosane crystals
Authors: Prasad P. B. V. , Bhagavan Raju I. V. K.
Published: January 2007

Modifications in spiral step patterns on n‐octosane crystals resulting from stress fields is considered. Stress field seems to impede the propagation of growth fronts across it and leads to the formation of bunched step patterns. Effect of cylindrical stress fields with axes parallel and perpendicular to the direction of step motion is considered in altering the shapes of the bunched steps. Shear modulus of n‐octacosane crystals is estimated from the microtopographical features.
Kinetics of the gas bubble formation in liquids with chemical reactions under microgravitation. Open system
Authors: Cherepanova T. A. , Ushkans A. L.
Published: January 2007

A method of description for the nucleation kinetics in multicomponent systems with chemical reactions is proposed. Approximated expressions for the steady state nucleation rate of the gas bubbles in liquid phase and the nuclei size distribution function by composition and size for open systems have been obtained. Description for the gravitation effect on the nucleation process is given.
On the shape of the phase boundary of melt‐grown ribbon‐shaped crystals
Authors: Ch. Locharu E.
Published: January 2007

Approximated analytical solution of the stationary Stefan problem for the ribbon crystals pulled from the melt are obtained. The results of calculation of the crystallization front are compared with the numerical solution obtained by finite elements method. The good coincidance is demonstrated.
Structure of N‐5‐Anilino‐pentadien‐(2,4)‐ylidenaniliniumperchlorate, C17H17N2O4Cl
Authors: Kulpe S. , Seidel I.
Published: January 2007

Mr=348.65, monoclinic, P21/n,a=11.088(2),b=17.521(3),c=8.845(2) Å, β=98.87(3)0,Z=4,V=1697.8(8) Å3,Dx=1.368(1) Mgm−3, μ(MoKα)=0.256 mm−1, λ(MoKα)=0.71069 Å,T=296 K. FinalR=0.040 for 2454 independent reflections excluding those with |F0|<4σ(|F0|). Intensities were measured with an automatic diffractometer. The structure belongs to the openchained cyanines. Characteristic for this class of compounds is their nearly ideal polymethinic electron structure with its main geometrical features: equalisation of bond lengths, alternation of bond angles, planarity of the polymethinic chain. All three features are significantly to be observed in the structure. The bond angle alternation determines essentially the shape of the molecules and the molecular packing.
Dislocation behaviour in annealed and aged LiF crystals
Authors: Ostapchuk E. I.
Published: January 2007

Parallel investigation of the magnitude of the critical strear stress τ0 and dynamic characteristics of individual screw dislocations at temperatures 4.2, 77, and 300 K has been carried out in LiF crystals after annealing and after long aging at room temperature. It has been established that in impure LiF crystals, even at such low temperatures as room temperature (0.25Tmelt), diffusion processes take place which lead to quantitative and qualitative changes of the structure of obstacles determining macroscopic and microscopic mechanical properties.
High amplitude dislocation damping in superconducting Pb and In
Authors: Lomakin V. V. , Pal‐Val L. N. , Ya. Platkov V. , Roshchupkin A. M.
Published: January 2007

The amplitude dependence of ultrasound absorption due to dislocations, α, has been studied for single crystals of pure lead and indium as well as for lead doped with Tl, Sn or Bi, both in the superconducting and normal state and for a wide range of ultrasound amplitudes, ε0. Pure and Tl‐doped superconducting lead at large ε0displayed a maximum on the α(ε0) dependence which became a plateau upon transition to the n‐state. This is direct evidence for a change from static to dynamic dislocation hysteresis as a result of the increase in the electron drag constant. Limit values for the dislocation loop lengths have been estimated, viz. 2.4 × 10−4cm <LN< 10.4 × 10−4cm. In other single crystals the dynamic hysteresis occurred both in the n‐ and s‐state. In all the single crystals, α increased with the increase of ε0above the maximum amplitude and onset of the plateau which was observed in both states. The effect is associated with non‐linear phenomena arising at significant loop flexures. The amplitude dependence of the losses due to this effect has been analysed, the results of the analysis being in good agreement with the experimental data.
Acoustic study of elastic properties, dislocation damping and plasticity of crystals
Authors: Kardashev B. K. , Lebedev A. B. , Nikanorov S. P.
Published: January 2007

The results of acoustic studies of elasticity and dislocation inelasticity of crystals are presented. Regularities of elastic anisotropy variation with ionicity of bonds in ANB8‐N crystals have been considered. Amplitude dependences of ultrasound damping supply the information on dislocation structure and dislocation — to point defect interaction. Oscillation of dislocations during internal friction measurements are compared to their translation motion at the onset of plastic flow.
Influence of magnetic flux trapping on softening effect during superconducting transition in alloys Pb‐Ni and Pb‐Sn
Authors: Abraimov V. V. , Kalugin M. M. , Soldatov V. P.
Published: January 2007

The value of the trapped magnetic flux in strained superconducting alloys Pb‐Ni and Pb‐Sn during n‐s transitions is measured and the correction is made of the obtained earlier on these alloys temperature and deformation dependences of the softening effect, stimulated by the superconducting transition. The peculiarities of the behaviour of the true softening effect on the mentioned dependences and physical nature of these peculiarities are discussed.
Investigations of the process of crystal growth from a liquid zone by Seebeck measurements
Authors: Rudolph P. , Gille P. , Genzel C. H. , Boeck T.
Published: January 2007

An arrangement for measuring the thermoelectric voltage (Seebeck signal) during the crystal growth from a liquid zone is described. Using the example of growing PbTe single crystals by THM it is shown that different equilibrium temperatures at both phase boundaries provide a differential Seekeck voltage depending on the crystal growth rate. Relaxation times which are needed to reach steady‐state conditions with respect to the concentration difference between the growing and solving interface in the case of a start or sudden stop of the heater motion can be obtained.
Growth, structure, and stoichiometry of epitaxial Cu‐III‐VI2 films on CaF2 substrates
Authors: Schumann B. , Kühn G.
Published: January 2007

Thin films of CuInTe2, CuInSe2, CuInS2, CuGaSe2 and CuGaS2 were deposited onto (111)‐and (100)‐oriented CaF2 substrates by flash evaporation technique. Epitaxial growth occurs at substrate temperatures in the range from 750 to 900 K, dependent on the kind of film material. Contrary to the case of GaAs, GaP and Ge substrates there are always polycrystalline parts. The layers were found to be single phase and crystallizing in the chalcopyrite structure only. The composition of the films varied in dependence on the substrate temperature. In the range of about 700 K a nearly stoichiometric composition was found.
On the microhardness of some organic molecular solids
Authors: Joshi Mihir J. , Shah B. S.
Published: January 2007

Microhardness measurements have been carried out on the (001) cleavage surfaces of anthracene, Phenanthrene and benzoic acid single crystals. The variation of the Vicker's Hardness Number (VHN) with load (P) shows a decrease in hardness with increasing load. Plots of load (P) vs the square of the diagonal (d2) and logarithm of load (log P) vs logarithm of diagonal (log d) are found to be linear. These observations are being explained in terms of the geometrical packing of molecules in these crystals which play an important role in causing slip.
Basic steps and layer homogeneity in CVD (I)
Authors: Arnold H.
Published: January 2007

As a first basic step in chemical vapor deposition (CVD), reactant depletion within batchtype reactors is treated. By introduction of a depletion resistance into the circuit representation of epitaxy and of LPCVD processes, the joint treatment of problems concerning layer thickness and doping homogeneity becomes more transparent. In the case of compensated depletion, this resistance increases linearly with the distance from the reactor input, and is independent on the kind of reactants if gas diffusion is negligible in the down stream direction. Without compensation it becomes nonlinear in the downstream local coordinate and depends on the resistance of the subsequent basic steps. Aspects of lowering the depletion are discussed.
Comments on the structure of copper (II) oxalate: Discussion of X‐ray powder diffraction and EXAFS results as a basis for the interpretation of magnetic properties
Authors: Fichtner‐Schmittler H.
Published: January 2007

Some features of the crystal structure of Cu(II) oxalate, which are relevant for the interpretation of unusual magnetic properties of the substance, are discussed. EXAFS and X‐ray powder diffraction results described by different authors are compared. The results of both the analytical methods complement each other. The packing of the ribbon‐like structural units consisting of Cu2+ and (C2O4)2− ions is demonstrated. It is shown that the Cu ions are octahedrally coordinated by O atoms (four short and two long Cu‐O distances). The environment of a central Cu ion with other Cu ions is discussed in terms of intra‐ and inter‐ribbon distances. In view of the structural characteristics of Cu(II) oxalate it seems to be not justified to disregard the interaction between neighbouring ribbons in the discussion of the magnetic coupling, as done so far.
Basic steps and layer homogeneity in CVD [II]
Authors: Arnold H.
Published: January 2007

Taking into account reactant depletion, gas diffusion, surface processes, and a fourth basic step that is connected with the influence of surface equilibria, the compensation of depletion is treated for both host material deposition and in‐situ doping. So, some aspects can be given for the realization of layer homogeneity in epitaxy, as well as in LPCVD. In conclusion, the terminology of border cases in CVD is discussed.
A study of some calcium dihalides and strontium fluoride halides systems
Authors: Hodorowicz S. A. , Hodorowicz E. , Eick H. A.
Published: January 2007

The CaX2‐CaY2 and SrF2‐SrX2 (where X and Y represent halides anions) systems were investigated by the Guinier powder X‐ray diffraction technique. In the calcium dihalides systems only solid solutions were found. In the strontium fluoride — strontium chloride and strontium fluoride — strontium bromide systems the dihalides and the PbFCl‐type SrFX phases were observed. The preparation, crystallographic data and atom distribution of the mixed fluoridhalides, SrFCl0.5Br0.5, Ca0.5Sr0.5FCl, Ca0.5Yb0.5FCl and Sr0.5Eu0.5FBr are presented and discussed.
High‐temperature X‐ray irradiation induced thermoluminescence and half‐life calculations in NaYF4 polycrystalline samples
Authors: Narasimha Reddy K. , Subba Rao U. V.
Published: January 2007

Elevated irradiation temperature studies with NaYF4 samples reveal that the intensity of the two glow peaks observed around 120 and 180°C enhances. The effect of temperature of irradiation (Tirr) on the sensitisation of the both peaks are studied. The half lives of these glow peaks were calculated and concluded that the half lives of these peaks decreases with the increase in irradiation temperatures.
Microharness and dislocation mobility in ionic crystals
Authors: Grabko D. Z. , Boyarskaya Yu. S. , Pishkova D. S.
Published: January 2007

The correlation between microhardness and dislocation mobility was investigated for the series of ionic crystals in the wide temperature interval (77 – 400 K). It was shown that the dislocation mobility was not the main parameter responsible for the microharness change in the series of KCl—NaCl—NaF—LiF—MgO crystals or in temperature lowering from 293 to 77 K.

A marked activation of the dislocation mobility can play a significant role in the range T > 293 K only. In the low temperature region the microhardness change may be connected with the parameters caracterising the dislocation multiplicatio and interaction.
Crystal growth of fatty acids from melt: CH3(CH2)14COOH and CH3(CH2)16COOH
Authors: Prasad P. B. V.
Published: January 2007

Crystalllization of palmitic acid and stearic acid from melt, held between glass plates, is discussed.
On the distribution coefficient of sulphur during the crystallization of GaP from nonstoichiometric gallium melts
Authors: Koi H. , Hein K. , Siegel W.
Published: January 2007

GaP grown by the SSD technique was doped by sulphur in a wide concentration range. Using chemical, electrical and radiochemical methods the concentration and temperature dependence of the distribution coefficient k during this crystallization from the nonstoichiometric melt was determined. With the crystallization temperature at 1000°C for k a value 6.9 ± 1.4 was found independent on the sulphur quantity added. The distribution coefficient decreases clearly with increasing temperature.
Crystal and molecular structure of Bis(N‐[pyrid‐2‐yl]‐1‐imino‐2‐carbethoxy‐3‐oxo‐butan‐2‐ido)‐palladium (II)
Authors: Reck G. , Bannier G. , Heyn B. , Jäger E.‐G.
Published: January 2007

The crystal and molecular structure of the title compound has been determined by X‐ray diffraction techniques. It crystallizes in the orthorhombic space group Pbca with 4 formula units C24H26N4O6Pd in the unit cell. The lattice constants are a = 17.259, b = 19.070, and c = 7.480 Å. The structure was solved by the heavy atom technique and refined by least‐squares calculations to the conventional R = 0.057. The coordination sphere of palladium as well as the molecular geometry of the ligands are discussed in the paper.
Horizontal bridgman growth of gaas single crystals
Authors: Moravec F. , Pelikán M.
Published: January 2007

In order to meet requirements for the preparation of low dislocation density GaAs single crystals a horizontal Bridgman type apparatus was designed. Construction of the apparatus allows the establishment of enhanced temperature stability of the arsenic source and hence better stability of the arsenic vapour pressure during the growth. This effect was achieved without application of heat pipes which are usually used for the improvement of thermal profile and temperature stability. The influence of different arsenic vapour pressures on the density of dislocations was confirmed in the course of this work.
Twinning in hydrothermally grown synthetic quartz as revealed by etch structures
Authors: Kotru P. N. , Kachroo S. K. , Raina K. K.
Published: January 2007

Etch structures obtained by HF etching on habit and cleaved rhombohedral surfaces of synthetic quartz grown by hydrothermal crystallization technique, indicative of twinning in them are described, illustrated and discussed. The twin traces appear in the form of lines of dis‐continuity in [1121] and [1211] directions. Etch pits within the parallelogram‐shaped bound areas are oppositely oriented with respect to those on the rhombohedral surface of the main crystal. The form of twinning observed is found to be of parallel lattice type and the surface within and outside the bound areas are coplanar in most of the cases. The rhombohedral faces of the twinned crystals are found to be geometrically related to each other as if one part is derived from the other by a rotation of 180° about [1210] direction.

Discontinuation in the crystal lattice along the twin trace is evidenced by obstructions in the normal development of an etch pit. Deep penetration of twin traces and parallelogram‐shaped regions, enclosing etch pits of opposite orientation (twinned areas), well within the crystal structure is demonstrated by comparison of etch patterns on matched rhombohedral cleavages and the results on their successive etching. The type of twinning displayed by the crystals is discussed in the light of models suggested. Causes for the generation of twinning in synthetic quartz are explained to lie in the availability of twinned nuclei in the seed plates used for hydrothermal crystallization of quartz.
Thermodynamic approach to the problem of A3B5 crystals with an optimum structural perfection
Authors: Barchuk A. B. , Ivashchenko A. I. , Kopanskaya F. Ya.
Published: January 2007

Thermodynamics of A3B5 semiconductor crystal, containing impurity and native point defects is considered. The main limit of the present analysis is the absence of a significant interaction between point defects at thermal equilibrium. It is shown that the difference of the chemical potentials of A3 and B5 components may serve as a structural sensitive thermodynamic function of a crystal. The optimization of the crystal perfection may be obtained when this function becomes zero. In the case of undoped A3B5 crystal such a situation corresponds to the ideal lattice perfection. In the case of doped crystal the effects of native point defects and their interaction with the impurity on the electronic properties of the crystal have to be reduced.

The developed thermodynamic approach has been applied to the quantitative analysis of the available experimental data (GaAs, GaP, GaAs:Si and GaP:In). The results of the calculation are in reasonable agreement with the experiment.
The size effect on the ice nucleating behaviour of PbI2 thin films
Authors: Gobinathan R. , Palanisamy M. , Ramasamy P.
Published: January 2007

A relationship exists between the size of the particle and nucleation temperature. There exists an optimum particle size below which nucleation is inhibited. The behaviour of lead iodide thin films as a substrate for ice nucleation is reported in this study. It is found that the supercooling increases with increase in the thickness of the film. But the change in nucleation temperature above 1250 Å is negligible.
Nucleation of struvite (MgNH4PO4 · 6 H2O) single crystals and aggregates
Authors: Boistelle R. , Abbona F.
Published: January 2007

The conditions (concentration and pH) for preparation of single crystals of struvite at 25 °C from ammoniacal solutions equimolar with respect to magnesium and phosphate ions are given. The limits are found above which crystal aggregates (twins or dendrites) precipitate as dominant morphology. The mechanisms of nucleation are discussed and the interfacial tension between crystals and solution is evaluated.
Some observations on forms of NaA and NaX zeolites growing in the presence of triethanolamine
Authors: Gutsze A. , Kornatowski J. , Neels H. , Schmitz W. , Finger G.
Published: January 2007

Using modified preparation conditions for silicate and aluminate solutions some differences in the result of large A‐ and X‐type zeolites crystallization utilizing Charnell's procedure have been obtained. A‐type zeolite crystals show clearly {110} faces. X‐type zeolite occurs in mixed phase together with A‐type zeolite as separate as well as overgrown crystals. These observations can be explained by structure defects in A‐type crystals and by presence of polysilicate or/and too high aluminium content in the gel.
Dislocations of salol crystals grown by the Czochralski method
Authors: Inoue T. , Komatsu H. , Jim W. Q.
Published: January 2007

Crystals of salol were grown by the Czochralski method in three different pulling directions to examine the crystallographic orientation effect of the seed. They were characterized by the etch pit method and X‐ray projection topography.

It was found that the dislocation density was 2 × 103−1 × 104/cm2 and that the configuration of dislocations was straight. The running directions of dislocations strongly depend on the pulling directions; i.e., [110] and [110] for the crystal grown in [100] axis, [110], [110] and [110] for the crystal pulled along [112] axis and [010] for [010] axis crystal.
Problems on the mechanically induced polymorphic transformation
Authors: Senna M.
Published: January 2007

Some typical experimental results are presented and discussed phenomenologically on the topics; (i) the transformations which are readily carried out with the aid of mechanical stimulation but hardly by simple heating (PbO, ZnS); (ii) formation of metastable phases under the influence of mechanical stresses from the phase which is stable at room temperature under the atmospheric pressure (CdS, CdSe); (iii) pseudo‐equilibrium between polymorphs during grinding (CaCO3).
Infrared reflection spectra of selected modifications of SiO2 and Al2O3
Authors: Pechar František
Published: January 2007

Infrared reflection spectra were measured within the wave number range of 1400 – −400 cm−1 for following SiO2 and Al2O3 modifications: quartz, opal, quartz glass, cristobalite, tridymite, corundum, sapphire, ruby, gibbsite, boehmite, and diaspore. The spectral bands were attributed, according to literature quotations, to individual vibrations of bonds SiO, OSiO, SiOSi, AlO, OAlO, and AlOAl. The evaluation of infrared reflection spectra has shown that they are very sensitive to internal vibrations of SiO, AlO, which are affected by the symmetry of the surrounding crystal field. They are therefore selective for individual minerals and thus suitable for quick identifying purposes.
Stability of growth conditions and α‐HgI2 crystal habit during growing by temperature oscillation method
Authors: Zaletin V. M. , Lyakh N. V. , Ragozina N. V.
Published: January 2007

On the basis of analysis of the experimental data, it is shown that:

the crystal growth rate is mainly determined by diffusion in vapour phase;

the limitation of the growth process by transport leads to an unremitting change of the growth conditions, being the cause of slowing down the growth and the change of the growth rates ratio of the crystallographically different facets, the latter evokes refaceting;

the limitation of the growth by the transport process is the factor reducing the perfection of the structure and the maximum sizes of single crystals.
The rapid precipitation of magnesium hydroxide from aqueous solutions: Analysis of nucleation and crystal growth kinetics, final nucleus numbers and primary crystal sizes
Authors: Packter A.
Published: January 2007

The studies of the rapid precipitation of magnesium hydroxide, from aqueous solutions of different concentrations by sodium, calcium and ammonium hydroxides, are analysed. The kinetics of nucleation and microcrystallite formation during the induction periods and the kinetics of crystal growth (onto the microcrystallites) to the final primary crystals are examined; the high final nucleus numbers and the sub‐microscopic sizes of the final primary crystals are discussed according to Nielsen's theories.
EDA complex stability constants and formation enthalpies in a binary liquid crystalline system with induced smectic phase
Authors: Demus D. , Hauser A. , Pelzl G. , Böttger U. , Schönburg S.
Published: January 2007

In the binary system 4,4′‐bis‐[n‐butylamino]‐biphenyl/‐(2,2‐dicyano‐ethenyl)‐phenyl 4‐n‐nonyloxybenzoate which due to EDA complex formation exhibits an induced SA phase, measurements of the charge transfer band, the molar volumina and transition enthalpies were done. By the concentration and temperature dependence, resp., of the charge transfer absorption and the strongly negative excess volumina we estimated the stability constant and the formation enthalpy of the complex.

The data obtained by the two independent methods agree sufficiently.
Study of fatigue properties of AlZnMg alloy
Authors: Ptáček L. , Míšek B.
Published: January 2007

The present work is part of the comprehensive research of relations between the structure and mechanical properties of the AlZn4Mg1 alloy. Chemical composition of this alloy is Zn 4.97, Mg 1.21, Mn 0.25, Cr 0.13, Ti 0.05, Cu 0.015, Fe 0.28, Si 0.17, Al. The aim of the study of fatigue properties of the alloy is to provide information on the relations between fatigue properties, fracture structure and the heat treatment applied.

The structure of the AlZn4Mg1 alloy is comparatively complex. The matrix is formed by solid solution with f.c.c. lattice. Dissolved in the solid solution are accompanying elements (Zn, Mg, Si, Fe). Also found in the matrix is the secondary phase (precipitates), both on grain and subgrain boundaries and dispersed within the grain. The dispersion degree of the secondary phase depends on the manner of aging.

Due to high impurity content in raw materials (Fe, Si), large inclusions are formed in the structure with quite different mechanical properties.

On the basis of earlier experience two types of heat treatment were used in testing the fatigue properties.

Fatigue tests were made in alternating symmetrical cycle on a Wolpert‐Amsler 10 HFP 1478 pulsator. The stress amplitude for individual specimens was altered such that the Wöhler curve could be drawn up to 108 cycles. The cycling loading frequency did not differ considerably from the value of 125 Hz. Used in fatigue tests were cylindrical specimens that had been heat treated together whith reference specimens for tensile tests.

Subsequent to destruction, the specimens were examined metallographically and fractographically, the substructure in fracture vicinity was investigated by SEM.

Fractographic specimens were obtained by cutting away parts of the rod with fracture. For TEM, thin foils were taken from regions right under the fracture surface. The foils were cut with a diamond disk and subsequently thinned electrochemically. The JET method was used to prepare the foils.

The values of mechanical properties for all the material states studied are tabulated below.
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Mass transfer during growth of GaInPAs solid solution in the equilibrium cooling growth technique
Authors: Kuznetsov V. V. , Moskvin P. P. , Sorokin V. S.
Published: January 2007

Kinetical analysis of crystallization of GaInPAs solid solutions grown by equilibrium cooling growth technique was performed. Theoretical data were compared with experimental data on LPE of the material. The dependencies of layer thickness, lattice mismatch variation between the substrate and layer and energy gap in the layers lattice matched to InP were calculated for different growth temperatures.
Dislocation etch‐pits revealed in submicron (100) GaAs epilayers by selective dissolution in the saturated GaSb melt
Authors: Bolkhovityanov Yu. B. , Bolkhovityanova R. I. , Trukhanov E. M.
Published: January 2007

It has been showed that the saturated GaSb melt when contacting with a (100) GaAs substrate or a thin film selectively dissolves these solid phases. The dissolved thickness can be made so small as 500 Å and the revealed etch‐pits are corresponding to the entrances of dislocation lines on the examined surface.
Electrical properties of r.f. sputtered thin films of CuInSe2(I)
Authors: Abdul‐Hussein N. A. K. , Samaan A. N. Y. , Tomlinson D. , Hill A. E. , Neumann H.
Published: January 2007

Thin films of CuInSe2 are deposited by r.f. sputtering onto glass substrates at different r.f. voltages and substrate temperatures using pressed and powder targets. The films are polycrystalline and p‐type conducting. The temperature dependence of the conductivity and the chemical composition of the films are measured as a function of the deposition conditions.
Study of the temperature stability of chabasite
Authors: Rykl D. , Pechar F. , Chalupský V.
Published: January 2007

Isothermal decomposition of chabasite was carried out at temperatures of 20, 180, 400, 600, 735, 850 and 1000 °C with the aid of differential thermal analysis. The decomposition products were identified by X‐ray powder diffraction and infrared absorption spectroscopy. It was found that the crystal structure of chabasite was stable in the whole range of temperatures. Dehydration takes place at a single stage. A change in lattice parameters, in intensity and splitting of X‐ray diffraction lines takes places with increasing temperature. Dehydration corresponds to the decrease in intensities of valence vibrations of OH, and the vanishing of librations and deformation vibrations of H2O. The residual water is heterolytically decomposed and forms structural OH groups in the large cavities of the mineral, which partly survive up to 1000 °C.
Untersuchungen der entmischungsprodukte in AlZnMg‐Legierungen mit hilfe der elektronenmikroskopie
Authors: Degischer H. P. , Lacom W.
Published: January 2007

Die Charakterisierung und Trennung der mit unterschiedlicher Struktur, Kohärenz und Orientierung zur Al‐Matrix auftretenden metastabilen und stabilen Phasen in einer AlZnMg‐Legierung mittels verschiedener elektronenmetallographischer Methoden werden beschrieben, wobei besonders auf die Interpretation der Feinbereichsbeugungsbilder hingewiesen wird.

Der Unterschied zwischen den metastabilen Phasen η2 und R2 wird herausgestellt; für die wichtigsten η‐Orientierungen gemäß Löffler et al., Degischer et al., und Buerger werden Modelle der geometrischen Gestalt vorgeschlagen. Die Korrelation einzelner Wärmebehandlungsschritte zu identifizierten Entmischungsprodukten wird hergestellt.
A general treatment of X‐ray (residual) macro‐stress determination in textured cubic materials: General expressions, cubic invariancy and application to X‐ray strain pole figures
Authors: Brakman C. M.
Published: January 2007

An expression in terms of general hkl and orientation distribution functions for the relationship between the elastic lattice strain measured by means of X‐ray diffraction methods and the (residual) elastic stress is given for cubic textured materials. In practice the socalled sin2 Ψ‐method is often used to determine these macro stresses. Then, for the case of textured specimens the quasi‐isotropic X‐ray elastic constants (depending on hkl only) become complicated functions of the crystallographic texture (J. Appl. Crystallogr. 16, 325 (1983)).

Results are given for both orthorhombic and monoclinic specimen symmetry in terms of general (b.c.c. or f.c.c.) hkl and allow every permutation possible for a given hkl combination. From this cubic invariancy some new cubic invariant spherical surface harmonics are derived which are represented on a basis consisting of the 4‐fold symmetry axes of the cubic crystals.

Special textures and special stress‐states are discussed. For a given texture of a cold‐rolled production steel sheet values of the predicted elastic strains are given in terms of “X‐ray strain pole figures”.
A correlation between concentration of deep levels and growth conditions for VPEGaP
Authors: Seifert W. , Jacobs K. , Pickenhain R. , Biehne G.
Published: January 2007

A minimum in deep level concentration in VPE‐GaP is found which corresponds to exceptional growth conditions near a relative maximum of the growth rate r in dependence on the GaCl input pressure pG̊aCL. The minimum occurs at the cross‐over between mass flow controlled growth (at low pG̊aCL.) and surface reaction controlled growth (at high pG̊aCL.).
The precipitation of sparingly‐soluble alkaline‐earth metal phosphates in gelatine gels by diffusion of anion (i). the precipitation of calcium hydrogen phosphate dihydrate and basic calcium phosphates
Authors: Packter A. , Chatterjee A.
Published: January 2007

The precipitation of different calcium phosphates in gelatine gels was studied by diffusion of disodium hydrogen phosphate solutions into ten percent gels containing calcium cation at liquid gel pHs from 6 to 11. At pHs 6.0 to 7.5, calcium hydrogen phosphate dihydrate (CaHPO4 · 2 H2O) was deposited as a continuous precipitate and then as rings of precipitate (the Liesegang phenomenon): their spacing coefficients varied with the reciprocal initial anion concentrations according to the Packter‐Matalon relation.

At liquid gel pHs 8.0, 8.5, tretacalcium phosphate (Ca4H(PO4)3) was deposited as a continuous precipitate.

At liquid gel pHs from 8.5 to 11, hydroxyapatite (Ca10(PO4)6(OH)2, Ca/P ratios = 1.50 to 1.67) was deposited as a continuous precipitate.

The mechanisms of precipitation of the different calcium phosphates (in gelatine gels) is briefly discussed.
Preparation and characterization of silver trimolybdate
Authors: Lasocha W. , Lasocha A. , Hodorowicz S. A.
Published: January 2007

Fibrillar crystals of silver trimolybdate have been obtained. The composition and structural characterization of the compound were determined by chemical analysis and derivatographic, proton magnetic resonance and X‐ray diffractometric studies.
On the bindings in the crystal phases of Mn
Authors: Schubert K.
Published: January 2007

The heterotypism of Mn may be interpreted energetically when a temperature dependent valence electron concentration is supposed which takes on values between 2.2 and 0.6 electrons per atom. The room temperature phase Mn.r (= αMn) belongs to a series of structural types: Cr3Si, U.h1 (= βU), Mn.r, which occur in alloy systems such as MoReM (M = undetermined mole number) at certain values of the averaged group number (AGN) of the perodic system of chemical elements (rule of Raub). An interpretation of the series by means of the plural‐correlations model becomes possible when instead of the (Ekmanian) AGN count another (non‐Ekmanian) electron count is used. The phase Mo3Re (Cr3Si‐type) yields a simple bonding type (binding) which undergoes moderate transformations to form the phases Mo2Re3(U.h1) and MoRe3(Mn.r) and the binding of MoRe3 may be taken to be valid also for Mn.r; it corresponds to the valence electron concentration N′Ab = 2.16. For the high temperature phases Mn.h1 (= βMn) and Mn.h2 (= γMn) the values N′Ab = 1.6 and 1.0 are probable and allow the brass‐like structures Mn.h1 (C20) and Cu(Fl). The binding of Mn.h2, incidentally, explains the occurrence of the tetragonal metastable phase Mn.m. finally Mn.h3 (= δMn) crystallizing in the W‐type is isodesmic to Fe.h2 (= δFe), i.e. of the same binding.
Study of the oriented overgrowth of sodium nitrate crystals
Authors: Anuradha P. , Bhagavan Raju I. V. K.
Published: January 2007

Formation of overgrowths of NaNO3 on crystalline and noncrystalline substrates has been investigated employing the solvent evaporation method. Calcite, Gypsum, Sodium chloride, Mica, Glass and Polystyrene films formed on glass have been employed as substrate materials. The solvents employed are water, liquid ammonia, methyl alcohol and n‐butyl alcohol. Random orientation of the overgrowths is observed on the substrates except in the case of calcite and mica. It is found that the morphology of the overgrowths manifests in the form of rhombic‐, triangular‐ and hexagonal platelets. The occurrence of (001), (110) and (111) twins is observed. The effect of supersaturation and nature of the substrate on the formation of overgrowths is considered.
Computation of the axial temperature distribution for the travelling heater method
Authors: Parthier L. , Schikora D. , Schäfer P.
Published: January 2007

A theoretical model for the computation of the axial temperature distribution for the THM arrangement is described considering the heat flow in radial direction. The calculated temperature distribution is compared with the measured one. The correspondence is sufficient. By means of this model, it is possible to estimate the effect of a change of important growth parameters prior to the experiment. The model also permits a calculation of temperature distributions of other crystal growth methods (e.g. Bridgman, zone levelling, zone melting) by changing the boundary conditions only.
The effect of crucible movement in Bridgman‐Stockbarger technique
Authors: Sabharwal S. C. , Mirza T. , Karandikar S. C. , Ghosh B.
Published: January 2007

The effect of the crucible movement on the growth of large size alkali halide crystals effected in a ceramic crucible by B‐S technique is investigated. From the studies carried out it follows that the crucible movement adversely affects the thermal conditions in the furnace resulting in a defective growth. To circumvent the problems faced suitable modification of the conventional B‐S technique yielding good crystals is suggested.
Photovoltaic effect in polycrystalline ZnTe films
Authors: Patel S. M. , Patel N. G.
Published: January 2007

Anomalous but weak photovoltaic effect has been observed in the case of thin polycrystalline ZnTe films obliquely deposited on glass substrate. Photovoltage of the order of a few hundred millivolt per centimeter have been observed at the ambient temperature. Optimized conditions for growing films to obtain maximum photovoltage have been found. In order to explain the observed photovoltaic effect, a model comprising of a long chain of aligned microcells in the form of pp+ homojunctions has been proposed. The implications are discussed.
Etch patterns on borax crystals
Authors: Takoo R. K.
Published: January 2007

Etch patterns obtained on habit as well as cleaved matched faces of borax crystals are described. Morphology of all the etch pits is discussed. It is found that all the pits are formed at the sites of dislocations. A report about various dislocation configurations is given. From the dislocation density measurements, it is established that the borax crystals grown are of very good quality.