bluuebunny/crossref_metadata_2025 huggingface dataset:
Diffraction Elastic Constants for Textured Materials — Different Methods of Calculation
Authors: Baczmański A. , Wierzbanowski K. , Haije W. G. , Helmholdt R. B. , Ekambaranathan G. , Pathiraj B.
Published: January 2007

A systematic review of different types of traditional averages for diffraction elastic constants in textured materials is given. In addition a new type of average, which recently was suggested, is presented. These averages are of vital importance for a correct interpretation of internal (e.g. residual) stress measurements.

The theoretically predicted diffraction elastic constants are compared with the experimental ones for rolled steel samples; there exists good agreement between theory and experiment.
Electrical Properties of CuInSe2 Single Crystals Implanted with Xenon
Authors: Tomlinson R. D. , Yakushev M. V. , Neumann H.
Published: January 2007

Both p‐type and n‐type CuInSe2 single crystals were implanted with 40 keV 130Xe+ ions up to doses of 5 · 1016 cm−2. Implanted layers on p‐type substrates showed an initial increase of the resistivity followed by a continuous decrease of the resistivity at higher doses. Implanted layers on n‐type substrates gave also an increase of the resistivity at lower doses, but at higher doses a conductivity type conversion from n‐type to p‐type took place, followed by a decrease of the resistivity. To explain the experimental results it is supposed that the increase of the resistivity is mainly due to charge carrier scattering at extended defects while the decrease of the resistivity at high doses is due to the predominant creation of intrinsic acceptor states during implantation.
Peculiarities of Silicon Carbide Crystal Growth in Quasiclosed Volume
Authors: Lilov S. K.
Published: January 2007

On the basis of the accomplished investigation is has been shown that in the known schemes for growing of SiC epitaxial layers from the gas phase in quasiclosed volume it takes place an excretion of the redundant silicon upon the front of crystallization, its accumulation in the gas phase up to the state of the saturation and its deposition upon the growing surface as drops. In this case the growth of the epitaxial layer takes place by the vapour‐liquid‐solid (VLS) mechanisms.
Solidification Behaviour of Benzamide‐β‐Naphthol Eutectic System
Authors: Singh N. B. , Kumar P. , Singh N. P. , Giri D. P.
Published: January 2007

Phase diagram studies have revealed that benzamide forms a simple eutectic with β‐naphthol. Linear velocity of crystallization and heat of fusion measurements have shown that the eutectic does not follow the mixture law. Microstructural studies have shown that the microstructure of the mixtures depend on the composition, the degree of undercooling and the nature of impurities.
Crystal Structure of 14‐Deoxy‐11,12‐Didehydroandrographolide — A Diterpenoid
Authors: Gupta Vivek K. , Rajnikant  , Goswami K. N. , Mazumdar S. K. , Gupta B. D. , Banerjee S. K.
Published: January 2007

The crystal structure of 14‐deoxy‐11,12‐didehydroandrographolide has been determined by X‐ray structure analysis. The compound crystallizes in the trigonal space group P31 with cell parameters a = b 15.860(3), c = 6.437(2) Å. The structure has been solved by direct methods and refined to R = 0.048. The six‐membered rings are trans‐fused and both are in the chair conformation. The furan ring is planar with maximum deviation −0.011 (4) Å for C(14). Molecular are held together by hydrogen bonds.
Electronic Transport Properties of Thallium Sesquiselenide Single Crystals
Authors: Gamal G. A.
Published: January 2007

Electronic transport measurements were made on single crystal samples of Tl2Se3. The crystals were prepared by a special design based on Bridgman technique. The influence of temperature on the electrical conductivity, Hall effect, Hall mobility and the carrier concentration was investigated in the temperature range 200–400 K. The energy gap as well as the ionization energy were calculated. The scattering mechanism of the charge carrier was discussed in the same temperature range.
Influence of Impurities and Testing Atmosphere on High‐temperature Deformation of CsI Crystals
Authors: Demchenko V. V. , Urusovskaya A. A.
Published: January 2007

The influence of anion (bromine) and cation (cadmium and barium) impurities, as well as testing atmosphere (air, argon, vacuum) on high temperature deformation of CsI crystals is studied. This deformation in CsI has some peculiarities, which are the superplasticity signs and evidencing about instability of a lattice state. All the impurities studied caused the hardening, their effect in superplasticity depends on its solubility in the CsI lattice: the less the solubility, the stronger the effect. With testing in vacuum and argon, when the formation of point defect clusters occurs, enhanced the superplasticity evidence compared to that by testing in air, where clustering is prevented. These facts, as well as a quality resemblance of stress‐strain curves of single‐ and polycrystalline specimens give the basis for the conclusion, that superplasticity is the manifestation of a plastic instability of the crystal, the instability centers may be precipitates and point defect clusters.
Structure and Luminescence of Eu‐activated Zirconium Hydroxide and Dioxide at Relatively Low Temperatures
Authors: Gutzov S. , Kynev K. , Peneva S. K.
Published: January 2007

Luminescent materials with composition ZrO2:0.01 Eu were prepared by co‐precipitation of zirconium and europium hydroxides and subsequent thermal decomposition at relatively low temperature. A stabilization of tetragonal ZrO2 prepared on this way is found. The structure of the prepared samples was investigated. The luminescence spectra of tetragonal and of monoclinic ZrO2 · 0.01 Eu and of ZrO2 · n H2O:0.01 Eu by excitation at 254 nm and at 365 nm are presented.
The Growth of Silver Whiskers by Reduction of Silver Halogenides
Authors: Varleva Sv. , Nanev Kr. , Nanev Chr.
Published: January 2007

By reduction of silver halogenides with hydrogen according to Brenner's method, silver whiskers were grown. Their investigation by contemporary techniques suggests that the driving force for their growth is the strongly enhanced capillary pressure in the silver halogenide droplets at the tip of the whiskers, leading to accelerated decomposition of this salt.
The Growth and Properties of K1‐yLiyTa1‐xNbxO3 Crystal
Authors: Wei J. Q. , Wang J. Y. , Guan Q. C. , Liu Y. G.
Published: January 2007

Potassium lithium tantalate niobate (K1‐yLiyTa1‐xNbxO3, KLTN) crystals with tetragonal phase at room temperature were grown by the flux pulling method. Two‐wave coupling energy transfer has been realized in this crystal. The two‐wave coupling gain coefficient measured is 0.46 cm−1, and the sign of the dominant carrier is positive. As compared with potassium tantalate niobate (KTN), the dielectric properties of KLTN changed significantly.
Application of a Novel Technique for Growing BTO and KTN Crystals
Authors: Wang J. , Ma X. , Zhang S. , Hu W. , Zhao Z. , Zhang X. , Xu J. , Guan Q.
Published: January 2007

The three thermal zone solute transport flux method is introduced for the first time. Application of this technique for the growth of BaTiO3 (BTO) and KTa1‐xNbxO3 (KTN) is satisfactory.
Liquid Phase Epitaxy of AlGaInP on GaAs Substrate Using AlGaAs Buffer Layer
Authors: Shibano E. , Fujiwara S. , Kohno K. , Takahashi N. S. , Kurita S.
Published: January 2007

Liquid phase epitaxial layers of AlGaInP were successfully grown on Al0.9Ga0.1 As buffer layer with varying aluminum melt composition. Epitaxial layers were characterised by using a scanning elelctron microscope, X‐ray diffraction, photoluminescence (PL) and Auger depth profile measurements. The shortest peak wavelength of PL spectra obtained in the samples was 630 nm at room temperature. It was found that the thickness of the AlGaInP layer is very small due to rapid change of aluminum in the melt composition.
Precipitation Rate of Calcium Sulphate Crystals
Authors: Nývlt J. , Maček J. , Zakrajšek S.
Published: January 2007

Results of experiments with continuous neutralisation of sulphuric acid with milk of lime have been used for the calculation of the nucleation and growth rates of calcium sulphate dihydrate. The treatment is based on experimental values of the mass of deposited crystals and of the supersaturation measured for varying experimental conditions. The data so obtained are compared with values published in the literature.
Thermodynamic analysis of the Gas Phase at the Dissociative Evaporation of Silicon Carbide
Authors: Lilov S. K.
Published: January 2007

The thermodynamic analysis of the gas phase at the dissociative evaporation of SiC in the temperature interval (1500–3150) K is carried out. On the basis of the obtained results of the thermodynamic analysis the composition of the equilibrium gas phase above silicon carbide and the “extents of development” of reactions of silicon carbide dissociation and evaporation are determined. The thermodynamic analysis shows that the composition and the stoichiometry of the gas phase above silicon carbide strongly depend on the temperature, and this dependence it is necessary to be taken into account in the analysis of the growth processes of silicon carbide monocrystals and epitaxial layers.
Energetic Band Location of Rhenium‐doped MoSe2 Single Crystals to Assess their Usefulness in PEC Solar Cell Fabrication
Authors: Agarwal M. K. , Gupta S. K.
Published: January 2007

Single crystals of MoSe2 and rhenium‐doped MoSe2 have been grown by direct vapour transport technique and characterized by optical and electrochemical studies. The transmission spectra show the crystals of MoSe2 and rhenium‐doped MoSe2 to be direct band gap semiconductors with band gap 1.6 eV and 1.2 eV, respectively. Mott‐Schottky plots have been drawn to determine the type of semiconductor and its parameters, Nd, EC and EV.
Growth Characteristics of GaAlAs Layers Obtained by Long Term Finite Melt Liquid Phase Epitaxy
Authors: Minkov D. , Nedev N. K.
Published: January 2007

The growth of GaAlAs layers by a long term finite melt liquid phase epitaxy is studied expermentally. The influence of the technological parameters of the process upon the growth characteristics of the layer is investigated for a wide range of the technological parameters. In some cases computations of the layer characteristics are made, based on a model of the process. The data for the layer growth characteristics are in agreement with the theory predictions. The comparison of the computed and the experimental results allows the Al and As diffusion coefficients in the melt to be determined, as well as to find when the effect of the homogeneous crystallisation and the convection in the melt can be neglected.
Role of Silver on Superconducting Properties of BPSCCO (2223) System
Authors: Muralidhar M. , Kishore K. Nanda , Nagabhushanam M. , Swaminathan G. , Babu V. Hari
Published: January 2007

The role of silver for the superconducting properties of the BiPbSrCaCuO (2223) system have been investigated systematically. Samples with various concentrations of Ag were prepared by the matrix method. D.C. resistance results showed that Tc(0) varied between 100–109 K for various compositions of Ag. Jc measured at LNT from I–V data shows an increase with silver addition. Jc decreased from 90 Amp/cm2 at zero field to 16 Amp/cm2 at 100 Oe. The Tc(0) obtained form the susceptibility data agreed with those obtained from resistance measurements. X‐ray diffraction results showed that the dominant phase in BPSCCO is the high‐temperature (2223) phase and the same is improved in silver added BPSCCO samples. The scanning electron micrographs indicated that silver is precipated along the grain boundaries, separating the superconducting grains. These results have showed that silver addition does not destroy the superconductivity and at the same time enhances the critical current density.
Studies of Nd(CH3CO2)3 · xH2O Complex Crystals
Authors: Yugeng Zhang , Qinde Su
Published: January 2007

Three neodymium acetate crystals Nd(Ac)3 · xH2O (x = 1.0, 1.5, 4.0) were synthesized in different pH values. According to the IR, thermal properties, and X‐ray diffraction data, we found that neodymium acetates may be a transition state in the lanthanide acetate system. The tetrahydrate neodymium acetate has two kinds of tendency of structure and properties.
X‐Ray Diffraction Studies on Point Defects in II–VI Compounds
Authors: Berger H.
Published: January 2007

The point defect concentration in Te‐rich CdTe and Hg1‐xCdxTe annealed at various temperatures has been estimated from precision lattice parameters using a simple continuum inclusion model and compared with densities of electrically charged defects determined by high‐temperature Hall and conductivity measurements. The nonstoichiometry is realized by cation vacancies. Dependent on the CdTe content, the ratio of total to charged defect concentrations varies between about unity for HgTe‐rich composition and 75 for CdTe. Therefore, it is necessary to distinct between “electrical” and “chemical” stability regions.
Atomic Processes during Crystal Growth Studied by Reflection High‐Energy Electron Diffraction
Authors: Däweritz L.
Published: January 2007

After a short retrospect on the development of the electron diffraction techniques it is shown that the atomic‐scale morphology of the crystal surface and growth processes on it can be studied in detail during molecular beam epitaxy (MBE) by reflection high‐energy electron diffraction (RHEED). This is demonstrated for the evolution of the terrace‐step‐structure of the singular GaAs (001) surface during growth and after growth interruption and for the attachment of Si atoms at misorientation steps on vicinal GaAs (001) surfaces.
Crystal Structure of 1‐(4‐Pyridylmethyl)‐2,4,6‐Triphenyl Pyridinium Perchlorate
Authors: Farag I. S. Ahmed , El‐Shora A. I. , Abdel‐Megeed M. F. , Rybakov V. B.
Published: January 2007

1‐(4‐pyridylmethyl)‐2,4,6‐triphenyl pyridinium perchlorate crystallizes in space groups P1 with 3 molecules per asymmetric unit. The cell parameters obtained are: a = 12.142(3), b = 16.972(4), c = 20.229(7) Å, α = 83.66(4), β = 74.83(3), and γ = 69.47(2)°. The crystal structure was determined using the direct methods technique. Anisotropic refinement was undertaken using block diagonal least squares. In the final cycle of the refinement the reliability factor was found to be R0 = 0.084 for 3982 reflections with I ≧ 3σ (I). All rings are planar within experimental errors. Rings B, C, D, and E are twisted with respect to the central plane.
Batch Precipitation of Calcium Sulphate
Authors: Maček J. , Zakrajšek S. , Nývlt Jaroslav
Published: January 2007

Results of the experiments with batch neutralisation of sulphuric acid with milk of lime have been used for calculation of the nucleation and growth rates and of the product crystal sizes of the calcium sulphate dihydrate. The procedure is based on the experimental values of calcium concentration in solution measured at various time intervals.
Photoacoustic Spectra of Pr3+, Nd3+, Gd3+ Acetate Complexes
Authors: Yugeng Zhang , Qinde Su , Guiwen Zhao
Published: January 2007

The crystals of the complexes Pr(Ac)3 · 4 H2O, Nd(Ac)3 · 4 H2O, Gd(Ac)3 · 4 H2O were synthesized and their Pa spectra determined firstly. Their PA spectra and absorption are interpreted. The fluorescence properties of Pr3+, Nd3+, Gd3+ and the relaxation process models were studied by their PA spectra.
Study on the Isomorphous Substitution of Silicon by Indium in the MFI Framework
Authors: Kosslick H. , Tuan V. A. , Walther G. , Storek W.
Published: January 2007

In‐ZSM‐5 zeolites were prepared by hydrothermal synthesis and characterized by XRD, MAS NMR, IR, thermoanalysis, TPD of ammonia and catalytically tested. The data reveal the isomorphous substitution of silicon by indium in the framework, however, in comparison with other elements the substitution degree is low: Al > Ga > Fe > B > In. In‐ZSM‐5 shows a low catalytic activity.
Crystal Structure of Deoxy‐Vasicine Zinc Complex
Authors: Sharma S. D. , Gupta Vivek K. , Goswami K. N. , Padmanabhan V. M.
Published: January 2007

The crystal structure of deoxy‐vasicine zinc complex has been determined by X‐ray structure analysis. The compound crystallizes in the monoclinic space group P21/c with cell parameters a = 9.24(4), b = 14.74(2), c = 19.84(10) Å, β = 115.6°. The structure has been solved by Patterson and successive Fourier methods and refined by full matrix least‐squares methods to an R‐index of 0.084. The molecular structure is found to be in ionic form, with ZnCl4 as a divalent anion and two moieties of deoxy‐vasicine (C11H12N2H) as independent monovalent cations. The dihedral angle between the mean planes of two cationic moieties is of the order of 50°. The crystal structure seems to be stabilized by ionic and van der Waals interactions as no hydrogen bonds have been observed.
Photoacoustic Spectroscopical Studies on L‐Tyrosine and Pd(Tyr)2Cl · H2O Complex Crystal
Authors: Yugeng Zhang , Jianmin Li
Published: January 2007

The complex crystal of Pd(Tyr)2Cl · H2O was synthesized and its PA spectra (with L‐tyrosine) were determined and explained. A method used to resolve the PA amplitude spectrum was suggested. With the phase spectrum of the complex, the PA absorption peaks were resolved by this method, and the non‐radiative relaxation time of all absorption bands were calculated.
Electrooptic Properties of SnSe Thin Films Synthesized by Solid State Reaction
Authors: Siddiqui S. S. , Desai C. F.
Published: January 2007

Tin monoselinide thin films were obtained by solid state reaction in vacuum. They were characterised by X‐ray diffraction and subjected to resistivity and optical absorbance measurements. The data were analysed for obtaining activation energy and band gap. The effects of varying deposition parameters were studied. These films are concluded to be superior to those obtained directly from the compound semiconductor.
Silicon Epitaxial layers with non‐uniform doping profiles (II). The non‐uniform doping profile realization
Authors: Halaj J.
Published: January 2007

In Part I of the paper the epitaxial doping profile simulation program was described based on the Wong‐Reif trapping model for the SiCl4H2PH3 system. This model is used in Part II to design the non‐uniform profile epilayer processing procedure accounting also for the parasitic effect of autodoping. Several epilayers with exponential doping profiles are realized. The resulting profiles exhibit very close agreement with the target profiles.
Tribochemical synthesis of halogen‐phosphate luminophores
Authors: Gospodinov G. G. , Marchev V. M. , Stoeva V. , Yordanov G.
Published: January 2007

The possibility of tribochemical synthesis of Ca10(PO4)6 · (F, Cl)2SbMn is shown. It was proved that the synthesis with the initial compounds CaHPO4 · 2H2O or β‐Ca3(PO4)2 is realized 1–2 hours faster than the synthesis when CaHPO4 is used.
Investigation of the thermal conditions during silicon carbide crystal growth
Authors: Lilov S. K.
Published: January 2007

In the present work an analysis of the thermal conditions during silicon carbide crystal growth from the vapour phase by the sublimation method is carried out. On the basis of the obtained results from the calculation of the temperature distribution along the length of the growing crystal it was drawn a conclusion that in order to decrease the density of dislocations in the growing crystals it is necessary to decrease the temperature gradients in the crucible for growing.
Investigation of the role of crystal growth zone during silicon carbide growth by the sublimation method
Authors: Lilov S. K.
Published: January 2007

The dependence of the growth rate of SiC crystals on the diameter of the graphite crystallization sleeve (GCS) forming the crystal growth zone has been investigated. It has been established that at a given crucible construction there is an exactly determined diameter of (GCS) for growing of SiC crystals with maximum sizes.
X‐ray structure analysis of 4‐pregnen‐11α‐ol‐3,20‐dione—A steroid
Authors: Gupta Vivek K. , Rajnikant  , Goswami K. N. , Bhutani K. K.
Published: January 2007

The crystal structure of 4‐Pregnen‐11α‐ol‐3,20‐dione has been determined by X‐ray structure analysis. The compound crystallizes in the orthorhombic space group P212121 with cell parameters a = 8.4415(4), b = 10.6884(3), c = 20.1273(5) Å. The structure has been solved by direct methods and refined to R = 0.050. Ring A exists in half‐chair conformation. Rings B and C adopt a chair conformation, and ring D is a 13α‐envelope. The A/B ring junction is quasi‐trans, whilst ring systems B/C and C/D are trans fused about the bonds C(8)–C(9) and C(13)–C(14). Molecules are held together by hydrogen bonds.
Hydrogen in CuTi and NiTi Metallic Glasses
Authors: Spassov Tony , Tzolova Genka
Published: January 2007

The hydrogen solubility and its effect on the crystallization of CuTi and NiTi glasses were studied by differential scanning calorimetry, thermogravimetry, and X‐ray diffraction. Dependence of the crystallization products of the hydrogenated Ti‐based alloys on the hydrogen content was found. Whereas in Cu‐Ti alloys hydrogenation leads to drastic decreasing in the thermal stability due to phase separation in the amorphous state and to formation of microcrystalline structure during crystallization, in NiTi system hydrogen produces hydrides with Ni as well with Ti, which after heat treatment decompose, and finally the same crystalline phases as in unhydrogenated alloy are formed. The isothermal crystallization kinetics of the maximum hydrogenated Cu50Ti50 amorphous alloy was also investigated to obtain additional information about this transformation leading to nano‐crystalline material.
Stoichiometric dependence of electrical characteristics in WSSe single crystals grown by direct and chemical vapour transport techniques
Authors: Joshi Sanjay , Lakshminarayana D. , Garg P. K. , Agarwal M. K.
Published: January 2007

Single crystals of tungsten sulphoselenide (WSSe) have been grown by both direct and chemical vapour transport techniques. The crystals have been subjected to Hall effect and resistivity measurements for their electrical characterization. The observed differences in the electrical resistivity, type of conduction, and activation energy have been attributed to the stoichiometric differences between the crystals grown by the two techniques. The crystals grown by chemical vapour transport technique with iodine as the transport agent have been found to be more stoichiometric.
Kinetics and mechanism of corundum formation in the thermal decomposition of basic aluminium chloride gels
Authors: Brand P. , Ziegenbalg G. , Köhnkem K.
Published: January 2007

Compositions and corundum contents in products, formed by thermal decomposition of a basic aluminium chloride gel at temperatures up to 600 °C, were determined at variable temperatures and times of decomposition. For the kinetics of α‐alumina crystallization a model is proposed, valid for diffusion‐controlled two‐dimensional growth. A mechanistic interpretation of these results and of those from previous examinations is based on the essential influence of the gel structure and of the atmosphere in thermal decomposition. As the rate‐controlling step of corundum formation the transportation of HCl and H2O molecules is discussed.
Bridgman and Czochralski growth of GeSi alloy crystals
Authors: Dahlen A. , Fattah A. , Hanke G. , Karthaus E.
Published: January 2007

Ge1–xSix crystals were grown with the Bridgman and the Czochralski method over a wide concentration range. With the Bridgman process single crystals up to 40 at.% Si were possible. The reasons for polycrystalline growth were the permanent contact of the interface with the crucible wall in combination with curvature towards the crystal and inclusions of high Si concentration. Analysis of striations in Czochralski grown material showed that in this process the crystal does not continuously grow in one direction but consists of piece‐wise grown crystals in which the composition permanently changes. According to that fact the main reason for polycrystalline growth in the Czochralski process is common due to lattice mismatch between the seed and equilibrium concentration transients in the crystal corresponding to the microscopic growth rates.
Effects of growth rate dispersion in industrial crystallizers–A classical approach
Authors: Dey Avijit , Gupta Bhaskar Sen
Published: January 2007

The present work concerns itself with the study of the effects of Growth Rate Dispersion (GRD) in industrial crystallizers. The GRD in crystallizers is described by a model similar to the one describes axial dispersion in near plug flow reactors. From it differential and cumulative equations are developed for crystal population, crystal length, crystal area, and crystal mass. The model results have been compared with the available experimental data of sucrose crystallizer.
Thermal cycling, DLTS, and PEC studies on LEC gallium arsenide
Authors: Santhanaraghavan P. , Sankaranarayanan K. , Arokiaraj J. , Anbukumar S. , Kumar J. , Ramasamy P.
Published: January 2007

This paper discusses the growth of gallium arsenide single crystals using the LEC technique. The Semi‐insulating gallium arsenide was studied. The defect investigations were made by DLTS and etching studies. The variation of deep level concentration along the wafer was estimated using DLTS. The fabrication and efficiency of the PEC Solar cells are also reported.
Mass transport effect within the boundary layers in solution crystal growth: Holographic study of KTP and KDP crystal growth
Authors: Xiling Yu , Youchen Liu , Xuefeng Yue , Yi Sun
Published: January 2007

Using holographic phase‐contrast interferometric microphotography, we have carried out real‐time investigations of the mass transport processes taking place during the high temperature solution growth of KTiOPO4 (KTP) crystal and low‐temperature solution growth of KH2PO4 (KDP) crystal. Our experiments demonstrate that a mere diffusion boundary layer is not existing. The mass transport process within the boundary layers is a result of the coupled effect of diffusion and convection actions, no matter whether it is high‐temperature or low‐temperature solution growth. Under free convection state, the influence of bulk supersaturation on the thickness of solute boundary layer exists in the two different regions. The solute concentration distribution within the layer is an exponential function of the position.
Thermoelectric properties of indium sesquiselenide single crystals
Authors: Nassary M. M. , Nagat A. T. , Hussein S. A.
Published: January 2007

Single crystals of δ‐In2Se3 were prepared in the solid state laboratory at Qena‐Egypt, by means of Bridgman technique. The temperature dependence of the thermal e.m.f. α in the temperature range from 205 K up to 360 K of In2Se3 was studied. The δ‐phase In2Se3 sample appeared to be n‐type. The ratio of the electron and hole mobilities are found to be μn/μp = 1.378. The effective masses of charge carriers are m = 1.3 × 10−30, m = 8.27 × 10−31 kg for holes and electrons, respectively. The diffusion coefficient was estimated to be Dn = 3.37 cm2/s and Dp = 2.45 cm2/s for both electrons and holes, respectively. The mean free time between collision can be deduced to be τn = 70 × 10−16 s and τp = 8 × 10−14 s for both electrons and holes. The diffusion length of the electrons and holes are found to be Ln = 1.5 × 10−7 cm and Lp = 4.4 × 10−7 cm.
Phase diagrams and mixing enthalpies of binary liquid‐crystalline systems exhibiting a semectic A phase
Authors: Ernst S. , Churjusova T. , Sokolova E. , Wiegeleben A. , Hauser A. , Demus D.
Published: January 2007

The induced smectic A phase which appears in binary liquid crystalline systems has been investigated. Phase diagrams, clearing enthalpies, heat capacities and mixing enthalpies of two binary mixtures of a terminal polar component and of a weakly polar one are presented. The influence of the alkyl chain length, steric and EDA‐type interactions on the formation of induced smectic A phase are discussed.
Second neighbours velocities and size of faces in crystal habit
Authors: Prywer Jolanta
Published: January 2007

Influence of growth velocities of first and second neighbours on the presence and size of the face in the crystal habit has been studied. It was established and confirmed that the consecutive neighbour affects the face size only after the disappearance of the previous neighbour. The formula for critical growth velocity governing disappearance of faces has been discussed.
A model for the calculation of the purification efficiency of a solid layer melt crystallization process
Authors: Wangnick K. , Ulrich J.
Published: January 2007

Melt crystallization processes are in use as suspension or as solid layer processes. The purification efficiency of such melt crystallization processes can be improved by further purification steps such as sweating and washing. Here a mathematical description of experimental results which come from a solid layer type of crystallization process is considered. The experimental results of the purification efficiencies of each step are described by dimensionless numbers which result from a dimension analysis of the influencing parameters.
Stacking fault formation in NiZn f.c.c. alloys
Authors: Vladkova E. D. , Vassilev G. P.
Published: January 2007

X‐ray diffraction study of the fault formation in NiZn alloys is carried out. Approximative analyses are performed in order to distinguish the influences of the dispersity and the microdeformations. Correlation between the X‐ray diffraction data and the free molar Gibbs energy is looked for.
Homometric polytypes
Authors: Zobetz Erich
Published: January 2007

A new theorem on homometric polytypes is presented. Examples of homometric close‐packed structures and MX2‐polytypes are given. The method derived may be used to construct homometric n‐tuplets by means of decomposition procedures.
Effect of plasma hydrogenation on the defect properties of CuInSe2single crystals
Authors: Yakushev M. V. , Zegadi A. , Neumann H. , Jones P. A. , Hill A. E. , Pilkington R. D. , Slifkin M. A. , Tomlinson R. D.
Published: January 2007

The defect properties of p‐type CuInSe2single crystals hydrogenated by diffusion from a plasma source are investigated using the Rutherford backscattering/channeling technique and photoacoustic spectroscopy. Plasma hydrogenation is found to produce severe lattice damage, to affect the intrinsic defect equilibrium in the near surface region of the crystals and to create an additional donor. A defect formation model including both defect passivation by hydrogen and damage induced defect creation is proposed to explain the experimental data. The thermal stability of the property modifications is limited to temperatures below about 100 °C.
Extention of the “three partial rates” model to layer growth and composition of the ternary Si1–(x+y)GexBy system
Authors: Kühne H.
Published: January 2007

The previously published “three‐partial rates” model of Si1–xGex layer growth (Kühne 1992) has been extended for describing Si1–(x+y)GexBy ternary systems by taking additionally into account a partial rate of boron and a partial rate of boron‐originated silicon deposition. Silicon deposition from a silane‐germane‐diborane‐helium gas mixture at T = 500°C and Ptotal = 0.2 Torr is clearly enhanced by the presence of germane though to a low degree only, but not by diborane. Germanium partial rate as well as boron partial rate depends linearly on the partial pressure of the respective source gas. For illustration the data published by Murase have been used.
Tribologic properties and crystallization behaviour of filled poly(tetrafluoroethylene) resins
Authors: Dobreva A. , Kopchev P. , Veleva M.
Published: January 2007

The coefficient of friction and wear rate of poly(tetrafluoroethylene) filled with molybdenum disulphide, graphite, lead oxide, and basalt are determined. It is found that basalt decreases the wear rate 2000 times. The degree of crystallinity and other nucleation characteristics are also studied. It is estimated that the nucleation activity of basalt is 0.9. The specific surface energy at the melt/crystal interface is found to be 9 · 10−3 J/m2 and the adhesion energy between poly(tetrafluoroethylene) and basalt is 2 · 103 J/m2.
Zn1−xCdx polytype single crystals with various degree of order
Authors: Gosk J. , Kozielski M. J.
Published: January 2007

The results of X‐ray investigations of the polytype structures formed in solid solutions of Zn1–xCdxSe are presented. For compositions of 0.22 < x < 0.35 polytypes 8H, 6H, 4H, and DS (disordered structure) are present. The Zn1–xCdxS single crystals of 0 ≦ x ≦ 0 were obtained by Bridgman's method under high protective argon pressure from the melt. The structures are characterised by FARKASZ‐JAHNKE statistical parameters π(m,p), and by parameters PLH of the polytype unit cell formation probability.
Study of the evaporation mechanism in silicon carbide crystals growth from vapour phase
Authors: Lilov S. K.
Published: January 2007

Investigation of the thermal etching (evaporation) of the source material in the process of silicon carbide crystal growth from the vapour phase by the sublimation method has been carried out. It has been established that silicon carbide etching in the temperature interval (2200–2600) °C takes place with the formation of whiskers of evaporation. The mechanism of their formation has been examined and the character of the whisker distribution in the charge of the source silicon carbide has been studied.
Remarks on the separation of a solid solution transported by evaporation‐condensation at a small temperature difference
Authors: Szczerbakow Andrzej
Published: January 2007

The nearly congruent transport of a solid solution by incongruent solid‐vapour and vapour‐solid phase transitions in a closed, almost isothermal system is considered–in particular referring to the crystal growth of pseudobinary AIVBVI solid solutions. The fact is interpreted that the small temperature difference required for the creation of the mass driving force of the process causes composition variations smaller than often assumed.
Thermal expansion in the AgGa(S1−xSex)2solid solutions from X‐ray diffraction data
Authors: Orlova N. S. , Kochkarik O. E. , Bodnar I. V.
Published: January 2007

The lattice parametersaandcas well as the axial thermal expansion coefficients in the AgGa(S1‐xSex)2solid solutions with chalcopyrite‐type structure were determined as a function of temperature in the range from 80 to 700 K and compositionxusing an X‐ray powder diffractometry technique. It is found that the thermal expansion coefficients were anisotropic and for all the solid solutions the thermal expansion coefficients along the tetragonalc‐axis were negative whereas those along thea‐axis and the volume coefficients were positive. The directions in which the crystal thickness does not change as temperature varies, were found. The composition dependences of these coefficients were non‐linear.
Physical properties of single crystals of KTiPO4, KxRb1−xTiOPO4 (x = 0.85; 0.75), KGeOPO4 and KTiOAsO4
Authors: Haussühl S. , Luping Shi , Baolin Wang , Jiyang Wang , Liebertz J. , Wostrack A. , Fink Ch.
Published: January 2007

Single crystals of the title compounds of optical quality and dimensions up to 30 × 25 × 25 mm were grown by the flux method. During the growth process the formation of twins consisting of bicrystals was observed, even in the case of single‐crystalline seeds.

The twinning boundaries could be detected by etching with hot KOH solutions.

The following physical properties were investigated: refractive indices, dielectric constants, thermal expansion, piezoelectric, and electrooptic effects, elastic and thermoelastic constants. The crystals exhibit a quite similar behaviour. The anisotropy of all properties is quasi‐tetragonal.

In respect to polar properties only small differences within the mixed crystals KxRb1–xTiOPO4 are found. Replacement of P by As does only slightly affect the polar properties, whereas the replacement of Ti by Ge leads to a drastic reduction of polar effects.
Growth of large doped Bi12SiO20 crystals
Authors: Gospodinov M. , Doshkova D.
Published: January 2007

The conditions for growing Cr‐, Mn‐, Fe‐, Co‐, Ni‐, and Cr + Al‐doped BSO crystals from a stoichiometric melt by the Czochralski method have been the subject of research. A decrease of the absorption coefficient along the growth axis was observed in undoped crystals of 50 mm diameter and 150 mm long, which is indicative of melt stoichiometry change in the course of the growth run. The transmission and reflection spectra of different crystals were measured and the absorption coefficients was determined in the range 0.38–0.70 μm. When Fe dopant concentration exceeds a limit value, the absorption spectrum is blue‐shifted relative to the undoped case and the absorption coefficient decreases. Co, Cr, Mn, and Cr + Al dopants produce a red shift and increase the absorption coefficient. Combined Cr + Al doping shift the absorption spectrum to the blue region as compared to Cr‐only doping with the same Cr concentration.
Aerosol particles from bubblers in metalorganic vapor phase epitaxy
Authors: Deppert K. , Wiedensohler A.
Published: January 2007

We report on aerosol particles generated by bubblers in metalorganic vapour phase epitaxy (MOVPE). A triethylgallium bubbler was investigated in a MOVPE set‐up regarding the generation of aerosol. Our measurements show that aerosol particles are produced, and the production depends on the carrier gas flow bubbling through. The distribution of the particle diameters was measured and was found to range from 10 to 600 nm, with the maximum at about 200 nm. While the number of particles is not negligible the precursor is almost only transported as gas molecules. However, particles could possibly reach the substrate and create defects on the surface.
Investigations of phase relations in the system CaONa2OK2OP2O5
Authors: Schneider M. , Gildenhaar R. , Berger G.
Published: January 2007

The lattice constants of the compound Ca2NaK(PO4)2 have been studied at room temperature using an X‐ray powder diffractometer and also in the temperature range from 20 up to 1000 °C by Guinier‐Lenné‐technology. A hexagonal lattice with the parameters a0 = 5.4367 Å and c0 = 7.3125 Å and a cell volume of 187.18 Å3 has been determined for the high temperature phase, existing from 670 °C upward. At temperatures below 670 °C a superlattice structure is formed by tripling the axis a, a′, and c so that it results in a hexagonal superlattice structure cell with the lattice constants of a0 = 16.311 Å and c0 = 21.939 Å and a cell volume of 5054 Å3.
Some peculiarities of the formation of thallium‐containing phases with perovskite‐like structures
Authors: Kuz'micheva G. M. , Khlybov E. P. , Kochetkov V. N. , Palewski T. , Warchulska J.
Published: January 2007

The authors systematize and analyse their own and described in literature experimental data on the composition and structure of high‐temperature superconductors with thallium‐containing phases. Some peculiarities of the isomorphic replacement and formation of thallium phases having single‐ and double‐layered‐type structure were found. Principles of crystallochemical formation of some phases, and chemical and thermal treatment allowing for their formation are described.
Comparative optical absorption and photoreflectance study of n‐type CuInSe2 single crystals
Authors: Neumann H. , Hörig W. , Jones P. A. , Lippold G. , Sobotta H. , Tomlinson R. D. , Yakushev M. V.
Published: January 2007

Optical absorption spectra in the photon energy range from 0.4 to 1.2 eV and photoreflectance spectra in the range of the fundamental edge are measured on n‐type CuInSe2 single crystals. Photoreflectance spectroscopy yields the true gap energy while the near‐edge absorption spectra are dominated by acceptor–to–conduction band transitions, the acceptor ionisation energy being about 80 meV. Based on intrinsic defect chemistry considerations this acceptor is ascribed to copper vacencies.
Application of the selected‐area channelling pattern technique to gypsum
Authors: Girlich I.
Published: January 2007

The applicability of the selected‐area channelling pattern (SACP) technique to gypsum single crystals and to polycrystalline gypsum samples is investigated. Suitable specimen preparation and choice of microscope parameters are proposed. In the case of gypsum single crystals it is observed that after some minutes of prolonged electron irradiation the structure is destroyed, and the pattern can no longer be detected. From a series of SACPs a monoclinic standard map for gypsum covering the pole triangles [100‐101‐311] and [010‐111‐210] is constructed and indexed. Practical problems of the technique occurring in polycrystalline samples are analysed.
Stabilization and destabilization of the SA phase in mixtures of 4‐nitrobenzyl‐2,5‐bis(4‐n‐alkyloxybenzoyloxy)benzoates
Authors: Haddawi S. , Diele S. , Kresse H. , Pelzl G. , Weissflog W.
Published: January 2007

4‐Nitrobenzyl‐2,5‐bis(4‐n‐alkyloxybenzoyloxy)benzoates exhibit SA phases which are characterized by an antiparallel packing of the molecules and a partial intercalation of the terminal alkyl chains. In binary systems of selected rod‐like components the SA mixed phase can be stabilized or destabilized depending on the molecular length of the rod‐like molecules. This unusual behaviour is mainly due to steric interaction and can be interpreted by a simple packing model.
The radial selectivity of in‐situ core‐doped crystal rods grown by the double die EFG method
Authors: Rudolph P. , Shimamura K. , Fukuda T.
Published: January 2007

The radial selectivity of in‐situ core‐doped Cr, Nd: LiNbO3 crystal rods, grown by the double die EFG (edge‐defined film fed growth) method, has been investigated. Two crucibles are combined with an outer and inner die for ascending of different doped melts. The critical growth parameters affected by the diffusion depended spreading effect of the dopant within the melt meniscus have been estimated. The first experimental tests show a good agreement with the theoretical prediction. Single crystalline LiNbO3 rods with a length of about 100 mm and an outer diameter of 5 mm consisting of sharp separated inner Cr‐ or Nd‐doped core region with diameters between 1.5 and 4 mm were grown successfully.
Study of the mechanism of low‐temperature DyBa2Cu3O7–x synthesis
Authors: Sokolowski J. , Lasocha W. , Hodorowicz S.
Published: January 2007

The formation of superconducting DyBa2Cu3O7–x was investigated by powder X‐ray method. It was found that when oxides and barium carbonate, or precursors were applied the temperature of formation of the ‘123’ phase is the same, only the reaction rates are different.
Growth studies of YVO4 crystals (II). Changes in YVO‐stoichiometry
Authors: Erdei S. , Johnson G. G. , Ainger F. W.
Published: January 2007

Incongruent vanadium oxide vaporization of yttrium orthovanadate (YVO4) melt generates changes in both oxygen and yttrium‐vanadium (YV) stoichiometry. Slightly modified YVO4 or YVO4 + Y8V2O17 phases are formed from continuously changing melt systems depending on their starting compositions. The occurrence of Y8V2O17 in yttrium orthovanadate crystal fibers grown by laser heated pedestal growth (LHPC) technique can be simply eliminated by utilization of suitable V2O5‐excess starting compositions. In contrast, the oxygen‐deficient YVO4–x black phase is an inherently oxygen deficient phase with limited solid solution in the YVO4YVO3 subsystem of Y2O3V2O5V2O3 complex ternary phase diagram close to the congruent YVO4 composition (49.3 mol% V2O5–50.7 mol% Y2O3). The greater oxygen deficiency YVO4–x specimens have smaller lattice parameters as determined from detailed XRD data. Ceramic feed rod and fiber crystal grown from the feed rod with slight yttrium oxide excess starting composition were characterized by electron microprobe analysis. Changes in both YV and oxygen stoichiometry were observed along the fiber, due to double limited solid solution system of three dimensional ternary phase diagram. Consequently, both the presence of Y8V2O17 phase and change of YV stoichiometry over oxygen deficiency cause difficulties for YVO4 crystal growth from yttrium oxide excess melt.
X‐ray study of debye‐waller factors and debye characteristic temperatures in AgGa(S1−xSex)2 solid solutions
Authors: Orlova N. S. , Kochkarik O. E. , Bodnar I. V.
Published: January 2007

The Debye‐Waller factors and Debye characteristic temperatures for two principal crystallographic directions in the AgGaS2–AgGaSe2 solid solutions with chalcopyrite structure were determined by an X‐ray powder diffractometry technique as a function of composition and temperature in the range from 80 to 700 K. The anisotropy of both the dynamical characteristics is shown to exist and the character of anisotropy changes with composition. The composition dependences of the Debye‐Waller factors and Debye temperatures are non‐linear. From the experimental data some thermodynamic properties were calculated and the variation of all investigated dynamical characteristics during anion substitution was analyzed.
Electrical and photoelectrical properties of chalcopyrite n‐AgInS2 crystals
Authors: Opanowicz A. , Kościelniak‐Mucha B. , Vassilev V.
Published: January 2007

The chalcopyrite n‐type crystals have been grown from AgInS2 material having stoichiomtric Ag excess. The temperature dependence of the Hall effect in these crystals have been studied. The ionization energies of donors have been determined. The dependence of the photoconduction on the photon energy, the light intensity and the temperature in the n‐AgInS2 crystals have been measured. The recombination model of photoconductor with one class of recombination centres has been proposed for explanation of the photoelectrical results.
Design of agitated crystallizers
Authors: Nýlvlt Jaroslav
Published: January 2007

The evaluation and/or design method for crystallization, based on the system constant BN, has been applied on crystallization data of various substances published in the literature. A correlation of the BN values with the relative kinetic exponent of crystallization, n/g, demonstrates that the applicability of the method is independent of the size of equipment, mode of crystallization and mode of supersaturation creation.
Porous solids and their characterization methods of investigation and application
Authors: Meyer K. , Lorenz P. , Böhl‐Kuhn B. , Klobes P.
Published: January 2007

Porous and finely divided solids are distinguished by a large surface to volume ratio. As a result, they have specific properties, such as enhanced reactivity, a high adsorption capacity, and a lowered sinter temperature.

This contribution gives a survey over selected aspects of porous solids, with the main emphasis on methods of characterization and their applications. We treat porous solids with a regular pore network (zeolites) and irregular pore structure (sintered compacts, rocks). After a short review of the possibilities of characterization, we will describe the methods of gas adsorption and Hg intrusion in detail. Furthermore, we will give a critical assessment of the measurement of typical characterization parameters, such as the specific surface area, the pore volume and the pore volume distribution. The fractal character of large‐surface and porous solids and the related uncertainty of the outcomes of measurements result in the necessity of standardization of experimental procedures and in the need for reference materials.

The section on applications treats examples of porous solids from different areas: densification of ceramic materials, porous ceramic carriers for flue gas desulfurization, technical catalysts (zeolite/binder), zeolites for the separation of substances, sedimentary and crystalline rocks.
Investigations on triallylthiourea mercury bromide (ATMB) crystal growth
Authors: Hou Wen‐Bo , Xu Dong , Yuan Duo‐Rong , Liu Ming‐Guo , Zhang Nan , Tao Xu‐Tang , Sun Suo‐Ying , Jiang Min‐Hua
Published: January 2007

This paper presents the growth process of a new organometallic nonlinear optical (NLO) crystal triallylthiourea mercury bromide (ATMB). The growth conditions are analyzed in terms of the pH value of solution, and also crack of the crystal is interpreted according to anisotropy of thermal expansion coefficients.