bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical Properties of CuInSe2 Single Crystals Implanted with Xenon
Authors: Tomlinson R. D. , Yakushev M. V. , Neumann H. 
Published: January 2007

AbstractBoth 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

AbstractOn 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

AbstractPhase 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

AbstractThe 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

AbstractElectronic 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

AbstractThe 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

AbstractLuminescent 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

AbstractBy 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

AbstractPotassium 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

AbstractThe 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

AbstractLiquid 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

AbstractResults 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

AbstractThe 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

AbstractSingle 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

AbstractThe 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

AbstractThe 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

AbstractThree 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

AbstractThe 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

AbstractAfter 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

Abstract1‐(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

AbstractResults 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

AbstractThe 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

AbstractIn‐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

AbstractThe 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

AbstractThe 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

AbstractTin 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

AbstractIn 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

AbstractThe 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

AbstractIn 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractSingle 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

AbstractCompositions 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

AbstractGe1–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.