bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dependence of Energy Band Gap and Lattice Constant of III‐V Semiconductors on Electronegativity Difference of the Constituent Elements
Authors: Xiuying Gong , Fengsheng Gao , Yamaguchi Tomuo , Kan Hirofumi , Kumagawa Masashi 
Published: January 2007

AbstractThe dependence of the energy bandgap and lattice constant of III‐V semiconductors on the electronegativity difference of the constituent elements were investigated. Some empirical expressions for estimating the energy bandgap and lattice constant with respect to solid compositions for mixed crystals were obtained. The results for some material systems predicted by electronegativity difference approach (ENDA) are compared with those obtained experimentally and those calculated by classical interpolation techniques (IT). The agreement between them is quite good, and it is demonstrated that ENDA is a simple and useful method for designing III‐V mixed crystals.
Chrial Smectic Side‐chain Copolymers and their Properties
Authors: Kozlovsky M. V. , Bata L. , Fodor‐Csorba K. , Shibaev V. P. 
Published: January 2007

AbstractCopolymers have been synthesized in which chiral monomer units are combined with those of a tilted smetic homopolymer. The copolymers with the proportion of chiral units not exceeding 37% form a S phase and have therefore ferroelectric properties. Temperature dependences of the pyroelectric coefficient, spontaneous polarization and relaxation time have been mesured for a series of ferroelectric LC copolymers.
X‐Ray Study of Strained CdTe Powders
Authors: Sirdeshmukh D. B. , Subhadra K. G. , Hussain K. A. , Krishna N. Gopi , Rao B. Raghavendra 
Published: January 2007

AbstractLattice strains have been produced in cadmium telluride by grinding for different durations. X‐ray diffractograms have been obtained at different stages of grinding. The lattice constants, particle size, lattice strain and Debye‐Waller factors have been determined. From the correlation between the strain and the effective Debye‐Waller factor, the Debye‐Waller factor for zero strain has been estimated.
Assessment of the Equilibrium between Solid and Liquid Cobalt‐Zinc Solutions
Authors: Vassilev G. P. 
Published: January 2007

AbstractExperimental and literature informations on the phase equilibria f.c.c. solid/liquid CoZn solutions, and about the thermodynamic properties of these alloys have been combined for the evaluation of two sets of polynomial coefficients serving to calculate thermodynamic or phase boundary values.
Effect of Halide Ions on the Electronic Conductivity in Calcium Borate Glasses
Authors: Gohar I. A. , Assem E. E. , Abuel‐ela A. 
Published: January 2007

AbstractSome halogen‐doped calcium borate glasses containing iron have been prepared according to the percentage molar composition [(30 – x) CaO · x CaX2 · 10 Fe2O3 · 60 B2O3] and annealed. It is found that the conduction in the semiconducting glasses is mainly due to electronic conduction. The results show that the halide ions may be introduced as modifiers for CaX2 concentration < 10 mol% (X >= F, Cl, and Br) but they are network formers at CaX2 > 10 mol%. It is proposed that at 10 mol% the network structure for all glasses seems to be the same. The dependence of resistivity on the halide ions concentration as well as the slight variation of activation energies, could be explained on the basis of electron‐lattice interaction.Mathematical expressions for fitting and describing the dependence of resistivity on CaX2 concentration are deduced and formulated by the following equations: ϱ = ϱ0 exp [± ac(1 – bc)] and ϱ ϱ= ±10 exp [± a′c(1 – b′c)] for the two regions around the critical concentration.
Ionic Conductivity Studies in Yttrium‐doped KCl Crystals
Authors: Reddy B. Jagan Mohan , Shareefuddin  , Chary M. Narasimha , Reddy Katta Narasimha 
Published: January 2007

AbstractIonic conductivity measurements have been made on Potassium Chloride crystals doped with different concentrations of Yttrium, in the temperature range 200 °C to 600 °C, to understand the nature of impurity vacancy (I–V) complexes, various types of their formation and to understand how these I–V complexes affect the conduction process. The conductivity‐temperature plots of KCl: Y showed three distinct regions. These regions are explained on the basis of Dryfus and Nowick notation, formation and dissociation of yttrium impurity precipitates.
Microhardness of Bi12SiO20, Bi12TiO20, and Bi12GeO20 Monocrystals
Authors: Pamukchieva V. D. , Trifonova E. P. , Hitova L. , Hadjiiski A. 
Published: January 2007

AbstractThe microhardness, H, of sillenite‐type monocrystals of undoped Bi12SiO20, Bi12TiO20, Bi12GeO20 and Cr‐, Fe‐, Mn‐ doped Bi12SiO20 has been investigated. The dependences of H on the surface treatment, dopants and orientation of the materials have been established. It was found that the H and dislocation density, Nd, distribution along the diameter of the sample for undoped (100)‐Bi12SiO20 are of M‐ and W‐shape, respectively.
Analysis of the Size Distribution of Product Crystals from a Continuous Crystallizer
Authors: Nývlt J. 
Published: January 2007

AbstractSize distribution of product crystals from a continuous agitated crystallizer is an important source of information of the crystallization process. The shape of the distribution curve reveals the occurrence of subsidiary processes accompanying crystallization such as attrition, agglomeration, internal or external classification, fines dissolution etc. A proper analysis of the crystal size distribution based on the MSMPR concept can serve kinetic data on nucleation and crystal growth and simultaneously give quantitative description of some of the processes mentioned above. This review paper summarizes the steps of such an analysis of the product crystal size distribution.
Crystal Structure of Angenomalin — A Furanocoumarin
Authors: Gupta Vivek K. , Rajnikant  , Goswami K. N. , Mazumdar S. K. , Gupta B. D. , Banerjee S. K. 
Published: January 2007

AbstractThe crystal structure of angenomalin (8,9‐dihydro‐8‐(1‐methylethenyl)‐2 H‐furo[2,3‐h]‐1‐benzopyran‐2‐one) was determined by X‐ray structure analysis. It crystallizes in the orthorhombic space group P212121 with cell parameters a = 5.210(1), b = 10.407(1), c = 20.478(2) Å. The structure was solved by direct methods and refined to R = 0.037. The coumarin moiety is planar and the crystal structure is stabilized by van der Waals interactions.
Defect Structure in Te‐doped GaAs Single Crystals after Plastic Deformation (II). Dislocation Slip and Cell Formation
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 II quantitative details of the appearance of slip and cell formation are given. Leading segments of gliding half loops are mainly of 60° type. Cell walls were formed by multiple slip of perfect dislocations.
The Improvement of Superconductivity in PbxBi2‐xSr2CaCu2Oy
Authors: Wang Y. S. , Bennema P. , Schreurs L. W. M. , Beers C. J. , Wunk J. , Van Der Linden P. 
Published: January 2007

AbstractIn this paper we present the results of recent studies on the improvement of superconductivity in PbxBi2‐xSr2CaCu2Oy single crystals by preventing impurities incorporation, employing ZrO2 crucible for crystal growth and post annealing the as‐grown crystals in vacuum or argon. It is realized that the superconductivity of as‐grown crystals is improved.
Growth Kinetics of High‐Tc and Low‐Tc Phases in Bi2‐xPbxCa2Sr2Cu3Oy Superconducting Compounds
Authors: Rao D. Mangapathi , Somaiah T. , Haribabu V. , Venudhar Y. C. 
Published: January 2007

AbstractSuperconducting samples of the composition Bi2‐xPbxCa2Sr2Cu3Oy (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) are prepared by co‐decomposition of metal nitrates. DTA, TGA, density, and porosity studies have been performed on these samples. Characterisation techniques like XRD, SEM, EDXA, d.c. resistance, and a.c. magnetic susceptibility have been employed to study the growth of High‐Tc (HTP) and Low‐Tc (LTP) phases upon lead substitution for bismuth. Results have revealed the growth of HTP with increase in Pb conc. up to x = 0.3. Further increase in Pb appears to results in the deterioration of HTP resulting in the formation of LTP and Ca2PbO4 impurity phase. Transport critical current density (Jc) measurements performed on the samples indicate that Pb doping followed by densification remarkably improves the current carrying capacity of the materials.
Preferred Crystallization of Epitaxially Grown Silicon on Boron‐doped Silicon Substrates
Authors: Stergioudis Georgios 
Published: January 2007

AbstractThe recrystallization of silicon layers on a silicon substrate using X‐ray analysis and X‐ray topography was examined. A preferred crystallization was observed. The crystallites resulting from this process seem to grow along the dislocations consuming part of the elastic energy of the dislocations.
Effect of Melt Convection on the Growth of Nd: YAG Crystal by the Czochralski Method
Authors: Hou Y. , Bai F. , Wang S. 
Published: January 2007

AbstractThe effect of melt convection on the formation of constitutional supercooling defects was studied simply by changing the shape and size of the Ir crucible. The experimental results show that there is a favourable ratio of crucible diameter d to depth h, i.e. d/h is about 1, and a moderate range of the crystal rotating rate must be avoided to grow a quality Nd: YAG crystal.
Surface Coarsening on High‐Tc Superconducting Single Crystals
Authors: Wang Y. S. , Van Der Eerden J. P. , Bennema P. , Schreurs L. W. M. , Wnuk J. , Van Der Linden P. 
Published: January 2007

AbstractSurface coarsening on high Tc superconducting single crystals is proposed to be due to the effect of impurity adsorption on the collective motion of growth steps. Differential interference contrast microscopy (DICM), scanning tunneling microscopy (STM), and polarized optical microscopy (POM) were used for the surface phenomena observations.
Lattice Vibrations and Interatomic Forces in AIIB2IIIC4VI Defect‐Chalcopyrite Compounds (II). Analysis of Nonpolar Optical Modes
Authors: Neumann H. 
Published: January 2007

AbstractA simplified version of the Keating model originally derived for defect‐chalcopyrite compounds is extended to include all AIIB2IIIC4VI compounds with ordered arrays of vacancies. It is shown that the trends and frequencies of the nonpolar optical modes of these compounds can be described within this model. Simple scaling laws for the interatomic force constants are proposed and compared with corresponding relations for other binary and ternary compounds with tetrahedral coordination.
Impedance Measurements on Sintered Discs of Sodium Metavanadate
Authors: Saradhi B. V. Bahuguna , Prasad G. , Bhimasankaram T. 
Published: January 2007

AbstractImpedance measurements of sintered discs of sodium metavanadate (NaVO3) are investigated in the frequency range 10 KHz to 1 MHz and in the temperature region from room temperature (≈ 30 °C) to 450 °C. A.C. conductivity is calculated from the data. D.C. Conductivity in measured in the temperature range 150 to 450 °C. Debye type of relaxation effects are observed in the loss measurements. The activation energy of the dipoles involved in the relaxation is estimated to be 0.76 eV. The activation energy for A.C. conduction in the temperature range 380 to 450 °C is about 0.78 eV. The relaxation phenomenon observed is explained in terms of space charge polarisation due to defects.
Crystal Growth and Elastic Properties of Hopeite, Zn3(PO4) · 4 H2O
Authors: Haussühl S. , Friedrich M. 
Published: January 2007

AbstractSingle crystals of orthorhombic Zn3(PO4)3 · 4 H2O of optical quality with dimensions up to 12 × 10 × 8 mm were grown from aqueous solutions of ZnSO4 and NaH2PO4 by controlled diffusion of NH3 into the solution. The elastic constants cij and the thermoelastic constants Tij = dcij/dT, T temperature, were determined from ultrasonic resonance frequencies of thick plates in the range between 5 and 40 MHz and between 250 and 320 K. In respect to the longitudinal elastic stiffness hopeite behaves quasi isotropically, however, the elastic shear stiffness shows a large anisotropy of about a factor 2.5. Above 260 K the shear stiffness c66 possesses a quite anomalous temperature dependence (T66 > 0). Further, the linear thermal expansion reveals a strong anisotropy (α11 = −3.3, α22 = 3.4, α33 = 33 · 10−6/K).
A Solvent for Liquid‐Phase Layer Growth on BaF2 Substrates
Authors: Trifonova E. P. , Kushev D. B. , Duharska K. 
Published: January 2007

AbstractLead diiodide has been proposed as a solvent for liquid‐phase growth of PbTe layers on BaF2 substrates. The contact with pre‐eutectic (PbI2‐PbTe) solutions has resulted in deposition of PbI2 islands of spherical cupola shape. The relatively small contact angle (16–25) indicates heterogeneous nucleation. At certain experimental conditions dense layers of PbI2 have also been prepared. This crystallization is an indirect evidence for good wettability of the BaF2 substrate.
Study of the Concentration Distribution of SiC Vapour in the Crystal Growth Zone
Authors: Lilov S. K. , Yanchev I. Y. 
Published: January 2007

AbstractIn the present work the gas dynamics in the growth zone of SiC crystals is investigated. It is shown that the propagation of SiC vapour from the growth cavity walls towards the lids is effected by diffusion. On this basis the calculation of the concentration distribution of SiC vapour (n), the equilibrium vapour concentration (ns), and the supersaturation \documentclass{article}\pagestyle{empty}\begin{document}$ \left({\alpha {\rm = }\frac{{n - n_{\rm s} }}{{n_{\rm s} }} \cdot {\rm 100\%}} \right) $\end{document} in the crystal growth zone at different radial and axial temperature gradients is carried out by solving the Laplace equation in cylindrical coordinates for a stationary case corresponding to the conditions of crystal growth. The received results are compared with the available experimental data which gives a possibility for explaining some of the observed peculiarities during SiC crystal growth from the vapour phase by the sublimation method.
Mechanical Properties of Copper Films
Authors: Chourasia N. C. , Kalkundri S. B. , Gadgeel V. L. 
Published: January 2007

AbstractMechanical properties of vacuum‐deposited copper films have been studied on various well cleaned and polished substrates. The density reaches the bulk value for a film thickness of 4 μm and above. The strain developed during the growth of film was found to be tensile and is dependent on nature of the substrate. The adhesion of film was observed to be thickness — and time of ageing dependent. The results are discussed.
Compressibility in the Orthorhombic Phase of AgInS2 from the X‐ray diffraction data under high pressure
Authors: Orlova N. S. , Turtsevich G. A. , Bodnar I. V. 
Published: January 2007

AbstractThe compressibilities for different crystallographic directions in the orthorhombic modification of the ternary AgInS2 compound were studied as a function of pressure up to 4.5 GPa by the X‐ray poweder diffraction method under high pressure. The anisotropy of compressibility was found to exist and between the principal components of compressibility tensor the relation χc > χa > χb was observed. For the orthorhombic modification the bulk modulus is smaller than that for tetragonal one.
X‐ray Topographic Defects' Contrast on Synthetic Quartz
Authors: Chirilă R. , Csiki Z. 
Published: January 2007

AbstractIn the present study the linear defects in several synthetic quartz have been surveyed by X‐ray topography using Lang method. The grown‐in dislocations produced by layers displacement around holes, precipitates or inclusions are discussed. Each growth zone is described with their own defects pattern and some correlations with the external morphology of the crystal are stated. There are also pointed out the asymmetry of the defects for every growth zone and the specific role in the growth mechanism of the s‐growth zone. In the final part of the work there are outlined the general and the specific conclusions.
Microtopographical Characterization of Vapour‐grown SnS2Single Crystals
Authors: Arora S. K. , Patel D. H. , Agarwal M. K. 
Published: January 2007

AbstractThin flakes of tin disulphide single crystals grown using direct vapour transport have been subjected to characterization to unfold their growth mechanism. Two types of spirals. viz. those having opposite orientation present on the same face and those present on the opposite finished faces are significantly discussed.
Ultraviolet Reflectivity of TlSbS2
Authors: Merkel M. , Kleint Ch. , Neumann H. , Horak J. 
Published: January 2007

AbstractReflectivity spectra of TlSbS2 single crystals are measured in the photon energy range from 1 to 12 eV. The spectra exhibit 19 structures which are compared with previous measurements and discussed in terms of theoretical band structure calculations. The optical functions are calculated for the photon energy range covered in the experiment.
FT‐IR and Raman Spectra of Ammonium Hydrogen Tartrate and Potassium Hydrogen Tartrate Crystals
Authors: Kolandaivel P. , Selvasekarapandian S. 
Published: January 2007

AbstractFT‐IR and Raman spectra of ammonium hydrogen tartrate [NH4HC4H4O6] and potassium hydrogen tartrate [KHC4H4O6] have been measured. Vibrational assignments have been made for both the internal and external vibrations. Because of the free rotation of the NH4+ ion, it forms only weak hydrogen bonds with the oxygen atom.
Phase Resolution Method of PA Spectra in Copper(II)‐EDTA Complexes
Authors: Yugeng Zhang , Guiwen Zhao 
Published: January 2007

AbstractThe complexes crystals of Cu(H2EDTA) · H2O and CaCu(EDTA) · 4 H2O were synthesized and their photoacoustic spectra were determined in the region of 300–800 nm at room temperature. A method used to directly monitor both position and strength of the absorption bands of respective electronic states were proposed. With the amplifier and phase spectra all absorption peaks of different electronic states could be distinguished. The PA spectra were also explained by the 3d orbit radial scaling theory. All the d‐d transition absorption peaks calculated are in good agreement with the experimental values. In addition, the non‐radiative relaxation process and the relaxation time of excitation electron were discussed with the PA spectra.
The Phase Relations in the Quasi‐Binary System LiBaF3AlF3. A Search for New Fluoride Laser Hosts
Authors: Al‐Mansour M. , Wallrafen F. 
Published: January 2007

AbstractIn a search for new fluoride laser host materials (esp. with an Al site for Cr3+ doping) the phase relations in the join LiBaF3AlF3 of the ternary concentration diagram LiFBaF2AlF3 were investigated by difference thermal analysis method from 15 samples with different compositions. A new congruently melting compound LiBaAlF6 (Tm = 785 °C) was found. The α‐β‐phase transformation at 671 °C prevents the growth of β‐LiBaAlF6 single crystals from the own melt and the application to laser technology.
Double‐Heterostructure Indium‐Tin Oxide/InGaAsP/AlGaAs Lasers
Authors: Takahashi N. S. , Hunyu Y. , Shibano E. , Mochizuki N. , Kurita S. 
Published: January 2007

AbstractThe fabrication and characterization of double‐heterostructure (DH) laser that utilizes an indium‐tin oxide (Ito) transparent cladding and top contact layer. The first room‐temperature lasing operation has been obtained form ITO/InGaAsP/AlGaAs DH laser diode at threshold current density of 12.1 kA/cm2. The interfacial recombination velocity of ITO/InGaAsP Interface was estimated to be 4.9 × 104 cm/s from a simple model to account for high threshold current, and optical measurements of spontaneous emission and lasing spectra from top stripe window and facet were done.
Thermo‐acoustical Parameters of Some Semiconductors
Authors: Reddy R. R. , Kumar M. Ravi , Rao T. V. R. , Sharma B. K. 
Published: January 2007

AbstractThe thermo‐acoustical parameters of some compound semiconductors are evaluated in terms of the coefficient of thermal expansion, on the assumption that the Moelwyn‐Hughes parameter is the dominant factor. The Moelwyn‐Hughes parameter has been utilised to establish some simple relations between the lattice Grüneisen parameter, Beyer's, non‐linearity parameter, Rao's acoustical parameter, Sharma's thermo‐acoustical parameter, the fractional available volume, the repulsive exponent of intermolecular potential, the Anderson‐Grüneisen parameter and the molecular constant. A relationship between the isothermal, isochoric, and isobaric Grüneisen parameters has also been studied. An estimated parameter Y is found to have values close to 0.11 form which one may infer that the normal modes of vibrations contributing to heat capacities are very small. Sharma's parameter has been found to be approximately constant in the case of semiconductors studied.
Simulation and Experiment in X‐ray Topography and Diffractometry
Authors: Köhler Rolf 
Published: January 2007

AbstractX‐ray double crystal topography and high resolution diffractometry reveal very small deformations of the crystal lattice. However, this information can be directly obtained from the topographs or diffractometer curves only if certain conditions are fulfilled. Generally a deformation model has to be used, that is compared to the measurements by simulation calculations based on the dynamical diffraction theory. Trial and error allow to adapt the parameters of the model. An example illustrates that with a few parameters an automatic fit is possible.
Crystal Structure of 1‐Phenyl‐3‐Methyl‐5‐Pyrazolone Perchlorate (ES‐1)
Authors: El‐Shora A. I. , Abdeen A. M. , Gaballa G. A. 
Published: January 2007

AbstractThe crystal of ES‐1 belongs to the orthorhombic system, space group Pbca. Unit cell parameters were determined by least squares method and found to be: a = 16.256(8), b = 15.359(8), and c = 9.918(5) Å. The structure was solved by direct methods using the program SHELX86. The refinement was carried out using isotropic thermal parameters then followed by several cycles of anisotropic least squares to a final value of R0 = 0.073 for 1226 observed reflections. The hydrogen atoms were located from a difference Fourier map. Torsion angles calculation showed that rings A and B are planar as expected. All the calculations were carried out on a PC‐Computer at physics department, Tanta University.
Electrical Conductivity of Tetrathiafulvalene‐9‐Dicyanomethylene‐2,4,5,7‐tetranitrofluorene(TTF‐DT4‐NF)
Authors: Salmerón‐Valverde A. , Robles‐Martínez J. G. , Juárez‐Posadas J. , Galindo‐Guzmán A. , Zehe A. 
Published: January 2007

AbstractWe deal with optical properties of TTF‐DT4NF together with electrical conductivity measurements made with rod‐like samples carrying a silver paint contact at both ends. Schottky barrier formation was observed in each case, although strongly modified by tunneling carries across the only thin barriers formed due to a high impurity content of the samples. In the higher voltage range non‐ohmic bulk conductivity behaviour is manifest.
Low‐temperature LPE Overgrowth of InGaAs/InP Mesa Heterostructure
Authors: Follner Procházková , Novotný J. 
Published: January 2007

AbstractPreparation of planar buried mesa ridge (PBMR) epitaxial wafers suitable for integrated optoelectronic circuits is presented. For this purpose the LPE growth of InP and InGaAsP (λg = 1.3 μm) below 600 °C on nonplanar ridge pattern was realized. Etching of the InGaAsP/InP ridge structure with ridge of 2–2.5 μm was found to be reproducible when HBr:H2O2:H2O etchant was used. The best PBMR epitaxial wafers were obtained via regrowth in multiple‐bin sliding boat by two thin layers of InP using a combination of one‐ and two‐phase growth processes between 600 and 594 °C.