bluuebunny/crossref_metadata_2025_split huggingface dataset:
An X‐ray Study of KBrxI1−x Mixed Crystals
Authors: Hussain K. A. , Subhadra K. G. , Sirdeshmukh D. B. 
Published: January 2007

AbstractKBrxI1−x mixed crystals have been prepared by melting and their X‐ray patterns have been recorded with a powder diffractometer. From measurements of the Bragg reflections, the lattice constants, grain size, lattice straian and mean Deby‐Waller factor have been determined. In the composition region × < 0.2 and × > 0.7, the lattice constant follows Vegard's law. However, in the region 0.2 < × < 0.7 where a miscibility gap has been reported, single phase mixed crystals are formed but the lattice constants have values larger than those expected from Vegard's law, indicating a strained lattice. The lattice strain directly determined from the half‐widths of the Bragg reflections also shows larger values in the same composition region. The mean Debye‐Waller factor shows a decrease with the degree of mixing, assuming a minimum value in the equimolar region.
Structure Charcterization of EDTA Transition Metal Complexes (I) Study on Sr[Co(HEDTA)H2O]2 · 4 H2O
Authors: Jianmin Li , Yugeng Zhang , Jifa Fan 
Published: January 2007

AbstractThe d‐d transition spectrum of Sr[Co(HEDTA)H2O]2 · 4 H2O crystal was recorded at room temperature and experimental results are discussed quantitatively. Using the ligand field theory and the radial wave function of non‐free Co(II), the d‐d transition energy levels of the title compound were calculated. And the results are seen to be in good agreement with the experimental values.
Electical, Magnetic, and Thermal Properties of Cadmium Hydrogen Phosphate Hydrate Crystals
Authors: Hebbar K. C. , Dharmaprakash S. M. , Mohan Rao P. 
Published: January 2007

AbstractThe d.c. electrical conductivity of pelletized samples of cadmium hydrogen phosphate hydrate (CHP) crystals have been studied in the temperature range 50 °C to 250 °C. It has been observed that CHP crystals exhibit ionic conductivity at 140 °C and possess semiconducting property. At room temperature CHP has stable crystal structure. From thermal analysis it is concluded that CHP crystals possess water of crystallization and the material to be diamagnetic.
Kinetics and Trapping Parameters of Thermoluminecence of Sr1−xEuxF2+x Mixed Crystrals
Authors: Sharma T. A. V. , Somaiah K. 
Published: January 2007

AbstractThe kinetics and trapping parameters of thermoluminescence of Sr1−xEuxF2+x mixed crystals have been calculated by using different methods. The trap depths, frequency factors, and order of kinetics of glow curve pattern in several compositions of the system revealed variations with composition.
Phase Transition Studies in Mixed Polymesomorphic Liquid Crystals with Cholesteric and Smectic A Phase
Authors: George A. K. 
Published: January 2007

AbstractCholesteric mesomorphism was induced in a polymesomorphic liquid crystal with nematic and smectic A phases by mixing it with a low pitch cholesteric. A variety of mixtures for a wide range of concentrations were studied. It was observed that the addition of cholesteric liquid crystal disrupts the smectic phase of the parent polymesomorphic liquid crystal. The measured valuses of ultrasound velocity and specific volume and their related parameters were found to exhibit anomalies near each of the phase transitions. The mean interaction parameter \documentclass{article}\pagestyle{empty}\begin{document}$ \bar \alpha $\end{document} was estimated for different mixtures and was found to decrease with increasing concentration of cholesteric liquid crystal in the mixture. It was observed that smectic A‐cholesteric transition becomes second‐order at a particular concentration in agreement with the theoretical predictions.
On the Intensity of Kossel Reflections
Authors: Nolze G. , Geist V. 
Published: January 2007

AbstractThe line intensity of Kossel reflections of various single crystals (A1, A2, B3, B4 and C16 type of structure) has been studied experimentally as well as theoretically. In contrast to earlier results high excess intensity of experimental Kossel lines can be explained solely by dynamical diffraction effects without an additional consideration of real structure effects. It has been shown that the different maxima of intensities of Kossel lines found above all result from the different line width. depending strongly on the X‐ray wavelength used (λ = 0.47−8.34 Å): Sole convolution of the theoretical profiles partly transforms the differences in the line width into variation of height.
Computer Simulation of Electron Diffraction Studies of Various Microcrystalline Bodies
Authors: Rajendran K. 
Published: January 2007

AbstractElectron diffraction of various microcrystalline bodies has been studied and examined by using computer simulation. Diffracted intensity studies indicated that the peak height increases with the scattering factor. First peak of FCC packed and crystalline observed at S = 6.01 Å and for HCP S = 5.0 Å. The amplitude of waves is most probably the same in the distribution function and providing a spectrum of interatomic distances in the crystalline bodies.
Thermal Expansion and Superconductivity in Alkali Metal‐ and Silver‐doped BiSrCaCuO System
Authors: Krishna B. Gopala , Chandra G. Ravi , Suryanarayana S. V. 
Published: January 2007

AbstractSamples with the nominal composition Bi2Sr2CaCu2Oy with na doped at the Ca site and K doped at the Sr site are prepared by solid state reaction method. From the X‐ray diffraction data it is found that all the the samples have exhibited a single phase 2212. The D.C. electrical resistivity data show that for Na‐doped samples the Tc (zero) varies from 80 K to 85 K and for K‐doped samples it is from 79 K to 82 K. The loss of oxygen from these samples around 400°C was confirmed by high temperature dilatometry. The variation of the thermal expansion coefficient (“α”) with temperature for different alkali dopings are discussed. Also the samples with the nominal composition Bi4Sr3Ca3Cu4−xAgxOy (with x = 0, 0.1, 0.2, 0.3) were studied.
A Study of the Metastable Zone in Nylon 12‐Toluene Solution
Authors: Renjun Feng 
Published: January 2007

AbstractThe metastable zone for a nylon 12‐toluene solution was determined in an established constant cooling rate apparatus. Supersaturation solubility curves and the equilibrium solubility curve are unparallel one to another. The metastable zone width under seeded conditions is dependent on the cooling rate, the retention time and the saturation temperature. And the metastable zone width under unseeded conditions is dependent on the cooling rate, the agitation rate and the saturation temperature. Through constant cooling rate crystallization experiments, two empirical correlations pertaining to the metastable zone of the solution have been found.
Shape Transformation of Plastic Crystals under the Effect of Surface Energy. Adamantane in Temperature Gradient Conditions
Authors: Iwanov D. , Nenow D. 
Published: January 2007

AbstractThe spontaneous transformation of a polycrystal into a single crystal at high temperatures is observed with adamantane samples. Since the plastic crystal phase at such temperatures is not elastically strained it is concluded that the process is due to the surplus of surface energy in the system. The spontaneous transformation to the equilibrium form of crystals under temperature gradient conditions is investigated. The effect is established both of the surface energy and the shape of the isothermic surfaces.
Thermally Stimulated Discharge Current Studies in Thin Films of Polyacrylamide
Authors: Rao K. V. Satyanarayana , Rao S. Sreepathi , Rao U. V. Subba 
Published: January 2007

AbstractTSDC of pure polyacrylamide films of thickness 22 μ grown by isothermal solution growth technique has been studied as a function of polarizing field and polarizing temperature at a constant heating rate of 0.09 K s1 In these studies only one TSDC peak was observed and the temperature corresponding to this peak was found to be independent of polarizing field strength but dependent on polarizing temperature. The activation energies, relaxation parameters and charge associated with the peak were evaluated. The origin of TSDC is discussed.
X‐ray and RHEED Characterization of Ge Ions‐Implanted Si Crystals Subjected to Pulsed‐Laser Annealing
Authors: Auleytner J. , Fiedorowicz H. , Furmanik Z. , Patron Z. , Regiński K. 
Published: January 2007

AbstractIn the experiment a (111) oriented silicon plate was subjected to implantation by 80 keV Ge ions. Then the pulsed‐laser annealing of this sample was carried out by using neodymium laser to form several areas irradiated with different light power. The effectiveness of the annealing has been analyzed by means of transmission X‐ray topography, double crystal X‐ray spectrometry, and reflection high energy electron diffraction. These three methods have appeared to be complementary and very effective in studying the spatial homogeneity of annealed areas, their state of annealing, and the damage in the surface layers.
Compressibility in the Tetragonal Phase of AgInS2 From the X‐ray Diffraction Data under High Pressure
Authors: Orlova N. S. , Turtsevich G. A. , Kochkarik O. E. , Bodnar I. V. 
Published: January 2007

AbstractThe lattice parameters a and c as well as the compressibilities for different directions in the AgInS2 chalopyrite‐type compound are determined as a function of pressure up to 5 GPa using a powder X‐ray technique under high pressure. It is found that the compressibility is anisotropic, with compressibility along the tetragonal c‐axis (𝓏c) being smaller than that along the a‐axis (𝓏a). It is shown that as pressure rises the axial ratio c/a increases and as a result the tetragonal distortion δ = 2 ‐ c/a reduces.
Contribution to High‐temperature Modifications of the Anhydrous Alkaline Earth Metal Sulfates
Authors: Bimberg R. , Illner N. , Puhlmann P. W. 
Published: January 2007

AbstractLarge synthetic crystals of alkaline earth metal fluorides, especially fluorite crystals, contain sometimes unknown small inclusions of hexagonal form. Samples of these crystals were investigated by microscope, X‐ray, and microprobe analysis to identify the included small crystals. Optical behaviour of these inclusions, morphology, chemical composition, and the reaction with water allow their interpretation as high‐temperature modifications of the anhydrous water soluble alkaline earth metal sulfates, partly transformed to the corresponding sulfides.
Size Distribution Analysis of Needle‐Shaped Crystals
Authors: Nývlt Jaroslav , Žáček Stanislav 
Published: January 2007

AbstractTwo methods of measurement of the crystal size distribution of needle‐shaped carystals are compared: direct measurement of a number of crystals on a microphotograph, which is rather tedious and time consuming, and the photosedimetric method which is quicker, easy to perform but not so suitable for not isometric crystals. A methods is described that brings results of both of these methods into agreement. The method has been verified on strongly anisometric particles of calcium sulphate.
Defect Structure in Te‐doped GaAs single Crystals after Plastic Deformation (I). Twins and Stacking Faults
Authors: Paufler Peter , Wagner Gerald , Grosse Katrin 
Published: January 2007

AbstractAt temperatures above the brittle‐to‐ductile transition (490 °C) in Te‐doped GaAs three types of predominant defect configurations have been observed after uniaxial compression along a [001] direction: (i) twins and stacking faults (500 … 520 °C), (ii) slip zones of dislocations (≈ 550 °C) and (iii) dislocation cells (580 … 590 °C). In Part I quantitative details of the appearance of twins and stacking faults are given. Most frequently found were 30° partials in twins and stacking faults.
X‐ray Molecular and Crystal Structure Study of the Fe(II) Complex Containing 1,10‐Phenanthroline and Saccharin: [Fe(C12H8N2)3] (C6H4COSO2N)2 · 4 H2O
Authors: Jianmin Li , Jing Wei , Xingtao Wu , Nianyong Zhu , Yifan Zheng 
Published: January 2007

AbstractX‐ray molecular and crystal structure of the [Fe(C12H8N2)3] (C6H4COSO2N)2 · 4 H2O is reported. In the complex, the Fe atom is bonded to the six nitrogen atoms with a distorted octahedral stereochemistry.
Crystallization Kinetics of Silicalite‐1: Use of Tetrapropylammonium Bromide and Chloride as Templates
Authors: Çulfaz A. , Gündüz U. , Orbey H. 
Published: January 2007

AbstractSilicalite‐1, the aluminum‐free end number of the ZSM‐5 zeolites, was synthesized from a batch composition of 3.25 Na2O · 40.0 SiO2 · 552 H2O · 2.00 TPA by using tetrapropylammonium bromide (TPA‐Br) or chloride (TPA‐Cl) as templates in the temperature range of 100 to 175 °C in a batch system. Conversion of silica in the starting batch composition into silicalite‐1 in the product was followed quantitatively. The activation energies of nucleation and crystallization were determined as 37.2 and 66.5 kJ/mol, respectively. The use of TPA‐Cl as the template instead of TPA‐Br results in longer induction period for crystallization to start and a larger crystal size in product.
Crystal and Molecular Structure of 1‐Cyano, 4(Trans‐1′, N‐Pentyl‐Cyclohexyl‐4′‐Carboxy)‐Benzene, ECH‐5
Authors: Ibrahim I. H. , El‐Shora A. I. , Abdeen A. M. , Aly N. F. 
Published: January 2007

AbstractThe crystals of ECH‐5 belong to the triclinic system, the space group is P1 with two molecules in the unit cell. The lattice dimensions are a = 9.153(2), b = 16.848(3), c = 5.770(4) Å, α = 97.26(5), β = 93.68(4), γ = 93.07(2)°. The structure was solved by direct methods and was refined using block diagonal least squares method to a final value of R0 = 0.083 for 1787 observed reflections. The cyclohexane ring is chair. Torsion angles calculations showed that the middle part of the molecule is bent. The molecules are packed in head to tail manner, and they are arranged nearly parallel to each other.
A Metastable Mg11Sm Phase Obtained by Rapid Solidification
Authors: Budurov Stojan 
Published: January 2007

AbstractMolten Mg‐Sm alloys with a Sm concentration of 4.93, 6.86, and 8.35 at. % were rapidly soldified with the aid of a shock wave gun device. Investigations of the obtained splats were performed with the aid of DSC, X‐ray analysis, and metallography. Rapid soldification of the eutectic MgSm8.35 alloy forms a new Im3m‐ type phase.
Anomalous Up‐and‐Down Variation of Positron Lifetime Near Tc in High‐temperature Superconductors
Authors: Zhang D. M. , Tang C. Q. , Gen T. , Li G. Y. 
Published: January 2007

AbstractThe temperature dependence of the positron lifetimes in the polycrystalline high Tc superconducting YBaCuO and BiSrCaCuO and the non‐superconducting YBaCuO have been investigated by using the position lifetime technique. It is found from the experiments that there is an evident temperature dependence for the two kinds of superconducting samples but no temperature dependence for non‐superconducting sample. It is important that the anomalous up‐and‐down variation of positron lifetime near Tc has been observed in the measured superconducting samples. We suggest that this strange temperature dependence of the positron lifetimes near TC may result from some changes induced by the phase transition.
Resistance and Current Density Studies on Plasma Sprayed Coatings of Bi(Pb)CaSrCuO Superconducting Materials
Authors: Rao D. Mangapathi , Mishra D. , Venudhar Y. C. 
Published: January 2007

AbstractPlasma spraying is a potential technique for forming flexible tapes from brittle high Tc oxides. It is possible to obtain superconducting Bi(Pb)CaSrCuO coating by suitable heat treatment schedule after spraying. In an effort to get maximum transport current densities (Jc) of the coating, the content of lead and sintering time have been optimised. A Jc value of 200 Amp/cm2 is obtained in Bi1.4Pb0.6 · Ca2Sr1.9Cu3Oy specimen coated on silver sprayed Fe[(Ag)/Fe] substrate. Remarkable improvement in Jc values up to 694 Amp/cm2 is obtained in the same specimen coated on Ca2Sr1.9Cu3Oy sprayed Fe[Ca2Sr1.9Cu3Oy)/Fe] substrate. The observed decrease in Jc(B) curves with increase in magnetic field shows the presence of weak coupling between the grains.
Thermally Stimulated Discharge Currents in Pure and Doped Sodium Yttrium Fluoride
Authors: Shareefuddin Md. , Chary M. Narasimha 
Published: January 2007

AbstractThe thermally stimulated discharge currents (TSDC) of pure NaYF4, and NaYF4 doped with 0.5 mole% Sm (in the form of SmF3) have been studied as function of polarizing temperature and polarizing field strength at a constant heating rate (β) = 0.05 Ks−1. The activation energies, relaxation parameters and charge were evaluated. The origin of TSDC spectra in NaYF4: Sm is attributed to space charge polarization. Whereas both dipolar and space charge process are found to operate in NaYF4 sample.
Mathematical Description of Strongly Nonlinear Pressure Dependence of Phase Transition Temperatures
Authors: Rein C. , Demus D. 
Published: January 2007

AbstractIn order to describe mathematically the pressure dependence of phase transition temperatures we have derived an equation using the following assumption:
i. The transition enthalpy ΔtH = const.
ii. The transition volume ΔtV depends on the pressure p according to:

The modified Simon‐Glatzel‐equation
T = T0(1 + p/b)a exp (cp)
allows to calculate the transition temperatures T also in cases of strongly non‐linear relations.
Calcium Oxalate Monohydrate Crystal Growth
Authors: Costa‐Bauzá A. , Grases F. , Söhnel O. 
Published: January 2007

AbstractThe growth rate of calcium oxalate monohydrate seed representing aggregates of highly irregular crystals from solutions of the stoichiometric composition with I = 100 mol m−3 in the range of supersaturation Δc = 0.056 to 0.353 mol m−3 was measured at 37 °C by the constant composition method. The crystal growth rate decreased during the initial period of experiment, then reached a value constant over a considerable time and later increased again. The initial decrease of the growth rate resulted from crystal perfection whereas the later increase was caused by formation of new crystals by secondary nucleation. The supersaturation dependence of the kinetic growth rate satisfied the power law with the growth order equal to 2 and 4 at supersaturations lower and higher than about Δc = 0.150 mol m−3, respectively.
Optical Phonons and Chemical Bonding in TlSbS2, TlSbSe2, and Tl3SbS3 Crystals
Authors: Syrbu N. N. , Krasovsky V. T. , Grincheshen I. N. 
Published: January 2007

AbstractThe optical phonons at k = 0 of TlSbS2, TlSbSe2, and Tl3SbS3 have been investigated by infrared reflectivity measurements from 50 to 4000 cm−1 at 300 K. The factor group analysis of vibrational modes of TlSbS2 and Tl3SbS3 crystal lattices has been made. The dielectric constant dispersion for E ‖ a and E ‖ b has been determined by classical dispersion relations. The Szigeti effective charges, the Born dynamic effective charge, and the Tl, Sb, S (Se) relative ion charges were calculated in dependence on the polarization of the incident light.
Etch Pit Density Distributions in Undoped and Doped GaAs Single Crystals
Authors: Moravec F. , Štěpánek B. , Šestáková V. 
Published: January 2007

AbstractThe undoped and doped (Si, N, In) GaAs single crystals are grown by horizontal Bridgman technique. The etch pit density (EPD) profiles were measured in transverse direction for each crystal. It was found that the shape of EPD profiles differs in dependence on the used dopant.
Thermoelectric Power of Polycrystalline Sb2Te3 Films
Authors: Patel N. G. , Patel P. G. 
Published: January 2007

AbstractPolycrystalline stochiometric films of Sb2Te3 with different thickness were prepared on glass substrates by a flash evaporation technique at constant substrate temperature of 423 K. The thermoelectric power of these films was determined by measuring integrally the developed thermo — e.m.f. at different temperature differences between the hot and cold ends. The thermoelectric power of Sb2Te3 films was determined as a function of the temperature and thickness of the films. It was found that the Fermi level becomes pinned at higher temperatures. The values of γ, E0, and A parameters were determined as functions of the thickness of the films. The dependence of the thermoelectric power on the reciprocal thickness of the films was explained on the basis of the grain size effect.
Positron Annihilation Study on the Thermal Fatigue in a Die Steel
Authors: Tang C. Q. , Li X. Z. , Shi Z. H. 
Published: January 2007

AbstractSamples of 5Cr2NiMoVSi die steel which underwent thermal fatigue with different fatigue cycles have been studied by using microhardness and positron lifetime measurements. It is found that the microhardness and the positron lifetime parameters increase and decrease alternatively with increasing the number of the fatigue cycles. The experimental results reveal that the fatigue strain, the dynamical recovery, and recrystallization and the precipitation are main causes of variation of the defects in the process of thermal fatigue.
Two‐Phonon Combination Mode Spectra of AgGaS2
Authors: Neumann H. , Sobotta H. , Moise E. , Treser E. , Krämer V. 
Published: January 2007

AbstractAbsorption spectra of (001)‐oriented AgGaS2 single crystals are measured in the wavenumber range from 400 to 900 cm−1. The spectra exhibit 12 structures due to two‐phonon combination modes which can be all interpreted as sum modes of zone‐centre phonons. Possible frequencies for the B1 and A2 modes are discussed. The results obtained are compared with second‐order Raman spectra of the compound.
Thermoelectric Behaviour of Some Phases in the InSe System
Authors: Nassary M. M. , Hussein S. A. , Nagat A. T. 
Published: January 2007

AbstractThe differential e.m.f. of In6Se7 single crystals as a function of temperature have been measured. The electron to hole mobility ratio is determined to be μn/μp = 3.62. The effective masses of electrons and holes are 4.21 × 10−33 kg and 9.01 × 10−29 kg, respectively. The diffusion coefficient for holes and electrons as well as the diffusion length of free charge carriers have been determined.
Kinetics of Long Term Finite Melt Liquid Phase Epitaxyal Growth of GaAs and GaAlAs Layers. I. Gallium Arsenide
Authors: Minkov D. , Nedev N. K. 
Published: January 2007

AbstractA model is proposed for a description of the growth kinetics of long term finite melt liquid phase epitaxy of GaAs and GaAlAs layers. The applicability region of the model is discussed. The correct liquidus, the temperature dependence of the diffusion coefficients, the precise concentration profiles of the components of the melt, and the non‐equilibrium construction of atoms in the layer are taken into account. The influence of the crystallisation reaction at the surface of the layer is considered, and different temperature regimes of the process can be treated. Temperature dependences of the Al and As diffusion coefficients in the melt are determined, based on comparison between theoretical and experimental results for the thicknesses and the concentration profile of GaAs and GaAlAs growon (etched) layers.
Infrared and Raman Spectra of ZnIn2Se4
Authors: Riede V. , Neumann H. , Schwer H. , Krämer V. , Gregora I. , Vorliček V. 
Published: January 2007

AbstractInfrared reflectivity and Raman spectra of polycrystalline ZnIn2Se4 revealed a total number of seven structures due to optical vibrational modes. Based on a comparison with previous measurements on other AIIB2IIIC4VI compounds a symmetry assignment of the modes is proposed.
Analysis of Transient Crystal Size Distribution in a Continuous Sodium Chloride Crystallizer
Authors: Dey Avijit , Gupta Bhaskar Sen 
Published: January 2007

AbstractThis work deals with the transient analysis of crystal size distribution (CSD) in a continuous sodium chloride crystallizer. The crystallization is assumed to take place under diffusion controlled conditions and the crystal growth models reported by Sen Gupta and Dutta elsewhere have been used. Monte Carlo (MC) scheme has been employed for simulation purposes. The simulation results have been compared with the available experimental data at steady state.