bluuebunny/crossref_metadata_2025_split huggingface dataset:
On Chemical Kinetics of Silicon Deposition from Silane (V) The Effect of Hydrogen Formation
Authors: Kühne H. 
Published: January 2007

AbstractIn consequence of hydrogen formation during silane pyrolysis total gas volume increases, when the reaction proceeds at constant total pressure. Any mole of silane decomposed produces two moles of hydrogen. In the present paper expressions are derived for 1st and 0.5th reaction order describing axial growth rate distribution of the isothermally proceeding reaction for the condition of constant total pressure. Those theoretically expected distributions are compared with results obtained by way of experiment on the one hand and those theoretically expected for the condition of constant gas volume on the other. It is concluded that the experimental results discussed rather agree with constant gas volume than with constant total pressure conditions. So, a compensating increase of total pressure along the tube axis might be supposed.
Thermoelastic and Piezoelastic Properties of Hexagonal RbMnCl3
Authors: Jeong S. , Haussühl S. 
Published: January 2007

AbstractTemperature and pressure derivatives of the elastic constants, indices of refraction, dielectric constants, Faraday effect and thermal expansion of RbMnCl3 near Tc = 278 K confirm the existence of a second‐order phase transition. A strongly anomalous behaviour is observed with the elastic shear stiffness c44 which possesses a positive temperature derivative and a negative pressure derivative. These properties and also the pressure derivative of the transition temperature, dTc/dp = 6.2 K kbar−1 closely resemble the anomalous behaviour of two other ferroelectric species, betaine borate and betaine hydrogen maleinate.
Thermal Expansion and Oxygen Nonstoichiometry in High‐Tc YBa2Cu3Ox Superconductor
Authors: Olekhnovich N. M. , Zhabko T. E. , Orlova N. S. , Janovich V. D. , Pashkovskii O. I. , Zykova T. L. 
Published: January 2007

AbstractThe lattice parameters as well as the axial thermal expansion coefficients for YBa2Cu3Ox superconducting oxide ceramics with different oxygen content ranging from × = 6.14 to × = 6.95 are determined as a function of temperature between 80 and 400 K using X‐ray powder diffractometry technique. The effect of oxygen concentration on the thermal expansion behaviour is regarded. The values of α are found to decrease with the oxygen content reducing and depend on the condition of heat treatment. The essential anisotropy of thermal expansion is shown to exist, with αc being larger than αa and αb. The relationship between αa and αb depends both on the sample preparation conditions and temperature.
Applied Infrared Photoluminescence in Lead Salt Crystals
Authors: Schmidt H. , Fleischer T. , Sumpf B. , Szczerbakow A. , Herrmann Ka. , Tomm J. W. 
Published: January 2007

AbstractResults on applied infrared photoluminescence investigations of lead salt chalcogenides are presented. Interpretations of spectra and wafer maps are given. The results obtained may be applied to the investigation of material properties important for laser and detector fabrication.
Some Results of the Analytical Evaluation of Isothermal Resistivity Measurements with Al – Zn – Mg Specimens
Authors: Oettel W. , Fabian H.‐G. 
Published: January 2007

AbstractIsothermal measuring curves of a series of Al‐4.5 at.% Zn‐X at.% Mg (X = 0.2, 0.5, 1.0, 1.5, 2.25, 3.0) were evaluated analytically by means of the Johnson‐Mehl‐Avrami equation. Itturned out to be possible to fit the curves completely only by assumption of two process stages. The course of the parameters obtained their dependence upon the Mg content is interpreted by means of suitable model assumptions.
Structure and Packing in Smectic E and Smectic A Phases in the Series of 4‐n‐Alkyloxy‐4′‐alkanoylbiphenyls
Authors: Diele S. , Tosch S. , Mahnke S. , Demus D. 
Published: January 2007

AbstractBy means of X‐ray investigations the structure of the SE and SA‐phases of the title compounds has been studied. The lattice parameters of the orthorhombic SE structure are given. The thickness of the smectic layers is nearly the same in the SE and SA phases and agrees well with the length of the molecules in their most stretched form. That suggests a similar conformation of the alkyl chains in both phases. A model of the packing in the SA phase is discussed which is based on a dense packing with antiparallel orientation of molecules with a non‐symmetrical shape.
Effect of Supersaturation on Disappearance of Faces of Growing Crystals
Authors: Szurgot M. 
Published: January 2007

AbstractGrowth conditions affect the velocities of disappearance and lifetime of faces of growing crystals. Supersaturation is a factor which causes either an increase or a decrease in velocities of disappearance of faces and their lifetime depending on the mechanism and kinetics of growth of disappearing and adjacent faces. The possible relationships between velocities of disappearance of faces, their lifetime and supersaturation have been derived and discussed.
The Growth of Some Aromatic Hydrocarbons Single Crystals from the Melt
Authors: Marciniak B. 
Published: January 2007

AbstractThe present work summarizes results concerning growth of anthracene, pyrene, p‐terphenyl, carbazole, and phenanthrene single crystals by Bridgman method. The temperature conditions and rate of crystal growth as well as seeding conditions have been determined and discussed in the aspect of purity grade of considered materials.
The Lithium Niobate Piezooptical Features
Authors: Mytsyk B. G. , Pryris Y. A. V. , Andrushchak A. S. 
Published: January 2007

AbstractPiezooptical effect (POE) in LiNbO3 crystals is analytically described considering crystallophysical axes of positive directions choice. All the piezooptical coefficients have been determined and correlation of the absolute piezooptical coefficients (POCs) and coefficients, describing stress‐induced birefringence, has been carried out. The POE indicating surface sections, which adequately reflect the anisotropy effect, have been constructed.
On the Formation of Titanite
Authors: Steinike U. , Uecker D.‐Chr. , Köhler Th. , Plötner W. , Schierhorn E. , Jancke K. , Hennig H‐P. 
Published: January 2007

AbstractThe formation of titanite (CaTiSiO5) out of the starting materials quartz and titanate (CaTiO3) is investigated in dependence on the mechanical activation. The formation temperature may be lowered by the use of mechanically disturbed quartz. There are optimal conditions for the reaction concerning the mechanically generated disorders. Cristobalite is an intermediate. The formation of titanite is ascribed as one‐sided bulk diffusion of Ca‐ and Ti‐ions (or corresponding oxygen complexes) into a quartz lattice being in the state of transformation and as a surface reaction of Si‐ions (or corresponding oxygen complexes) on the titanate surface.
Synthesis and Structural Characterisation of 2‐Aminoacetophenonesalicylaldazine Complexes of Some Bivalent Transition Metal Ions
Authors: Singh B. , Singh U. R. 
Published: January 2007

AbstractMetal(II) complexes M(aas)2 [M = Mn. Co, Ni, Cu and Zn, Haas = 2‐aminoacetophenonesalicylaldazine] have been prepared and characterized. Magnetic and spectral data such as electronic, ESR, and IR are used to establish the stereochemistry and mode of bonding of azine in the complexes. X‐ray diffraction study suggests orthorhombic unit lattice for Co(aas)2, Ni(aas)2, Cu(aas)2 and Zn(aas)2 complexes.
A Study on the First Order Phase Transitions in Hydrocarbon Crystals
Authors: Prasad P. B. V. 
Published: January 2007

AbstractA polarization hot stage microscopy study was made on the phase transitions in n‐octacosane and n‐hexatriacontane hydrocarbon crystals. Advancement rates of transition fronts of high temperature phase in low temperature phase were measured. Transition in the interior layers was detected. In order to explain the observations, we propose a model, which involves intrachain defects in the extended chain configuration. This model is an advanced stage of the model proposed by STROBL, basing on the SAXS results.
The Spontaneous Strain in an Aluminate Sodalite System Determined by Synchrotron and Sealed Tube X‐radiation
Authors: Melzer R. , Hu X. , Pennartz P. U. , Löchner U. , Depmeier W. 
Published: January 2007

AbstractLattice parameters in the mixed aluminate sodalite system (Ca1‐xSrx)8 [Al12O24] (CrO4)2 have been determined on the Aachen/Frankfurt (Darmstadt)/Tübingen powder diffractometer at DESY/Hasylab, Hamburg, FRG, with synchrotron radiation (SR) of a wavelength of γ = 1.383 Å. From these data the values of the spontaneous strain for tetragonal and orthorhombic samples were calculated. The synchrotron data were compared with those obtained by using a conventional Guinier camera with sealed tube CuKα1 X‐rays. In the mixed system a concentration range Δx of abcut 4 mol%, i.e. in the composition range x from 0.23 to 0.27, exists, in which the conventional technique still indicates cubic symmetry, whereas synchrotron data clearly exhibit tetragonal peak splitting. In order to determine the phase diagrams of mixed aluminate sodalites – or of comparable systems – and to interpret the physical properties of the phases correctly, sealed tube X‐rays are of limited value. Availability of SR beamtime is a crucial factor in the experiments.
Thickness Dependence of Electrical and Structural Properties of FTO Films
Authors: Amanullah F. M. , Pratap K. J. , Babu V. Hari 
Published: January 2007

AbstractFluorine (0.8 M) doped tin oxide films of various thicknesses were prepared on heated glass substrates (520 °C) by spray pyrolysis technique. The chemical and thermal stabilities of FTO films were found to be very good. The characterization has been done by XRD and found to agree with the reported results. As thickness of the film increases, intensities of peaks increased. From the X‐ray diffraction data, grain size of the crystallites have been calculated. The electrical and structural properties were studied for different thicknesses. Hall measurements showed that thicker films have relatively high Hall mobilities compared to those of thinner films. The high carrier concentration showed that the films are degenerate. The relationship between carrier concentration and Hall mobility revealed that the ionized impurity scattering centres were the dominant cause of scattering.
Doping of GaAs with Donor Impurities Te and Sn during Liquid Phase Epitaxy from Mixed Gallium  Bismuth Melts
Authors: Yakusheva N. A. , Pogadaev V. G. 
Published: January 2007

AbstractThe electrical properties of GaAs epilayers doped with donor impurities Te and Sn during LPE from mixed Ga  Bi melts in temperature intervals from 850 to 820 °C and from 700 to 630 °C were investigated. The analysis of incorporation of Te and Sn into crystallizing GaAs considering preliminary association of impurity and compound component atoms in the liquid agree satisfactory with experimental data providing the presence of additional concentration of nonequilibrium arsenic vacancies on the (111)B surface of growing layer, which is not conditioned by activity of compound components in the liquid. It is shown that the main factor, determining the incorporation of donor impurities Te and Sn into GaAs during epitaxy from mixed Ga  Bi solvents, is the change of Ga and As concentrations ratio in the liquid.
A Semiclosed Technique of Zinc Diffusion in InP
Authors: Krieghoff T. , Nowak E. , Kühn G. , Schumann B. , Höpner A. 
Published: January 2007

AbstractA novel semiclosed diffusion technique for InP has been developed. As diffusion source an InP wafer evaporated with a thin layer of metallic zinc was used. The source is separated at a distance of 150 μm from the sample. The dependence of the zinc concentration and the free‐hole concentration on the thickness of the zinc layer and the time was investigated. The technique makes it possible to obtain free‐hole concentration of (8 ± 2) · 1018 cm−3.
Growth Kinetics of Adenine Sulphate Crystals
Authors: Zachovà Jana , Nitsch K. , Matuchovà Marie , Durchan M. 
Published: January 2007

AbstractThe kinetics of growth and dissolution of adenine sulphate in 1.5 mol · 1−1 H2SO4 at different super‐ and undersaturations has been studied. The solubility of adenine sulphate in H2SO4 was determined over the temperature range 20–50 °C. The growth rate of the (100) face is by about 25% higher than that of (111) and the crystal habit is changed by a high supersaturation almost to a bipyramide. The surface diffusion was determined as a prevailing processes and the BaS model gives the best fit with experimental data.
A Study of the Nucleation Kinetics, Linear Growth and the Overall Crystallization Kinetics of Meltspun Pd80Si20 Amorphous alloy
Authors: Spassov Tony 
Published: January 2007

AbstractNucleation kinetics, linear growth rate and overall isothermal crystallization kinetics of PdSi amorphous alloy are studied by means of DSC and optical microscopy. It is found that both the histograms of the crystallite sizes and the DSC isotherms (resp. the time dependences of the degree of transformation α(t)) are best described by the model comprosing the simultaneous occurrence of two reactions of crystallization: heterogeneous as well as homogeneous non‐stationary nucleation with subsequent three‐dimensional growth in both cases.From the fit of the experimentally measured and the calculated according the model thus proposed distribution curves Ni(Φ) the stationary rates of heterogeneous and homogeneous nucleation, the number of quenched‐in nucleation sites and the transient time lags of heterogeneous and homogeneous nucleation have been estimated. Using the values of these parameters kintic curves degree of transformation vs. time have been generated, which are closed to the exerimental x(t) curves obtained by means of DSC at isothermal conditions.
Synthesis and Size Optimization of Crystals Grown by the Mixed Gel‐Solution Technique
Authors: Santos A. 
Published: January 2007

AbstractTwo experimental devices have been used with the aim to optimize the synthesis of single crystals by means of the mixed gel‐solution technique. These consist of a gel source‐reservoir saturated at T0 and a vessel of aqueous solution saturated at Tf. T0 > Tf. In such devices, the evlution of the supersaturation in the vessel of aqeous solutions allows that the grwoth process to be controlled by such a source‐reservoir and the crystal itself. Average growth rates of 3 and 4 mm/day have been found for KDP crystals.
Influence of Second and Further Neighbours on the Presence of Faces in Crystal Habit
Authors: Prywer Jolanta 
Published: January 2007

AbstractInfluence of growth volocities of further neighbours on the presence of faces in crystal habit has been analysed. It was established that the consecutive neighbour affects the face size only after the disappearance of the previous neighbour. The formula for the critical growth velocity governing disappearance of a face which includes the closest and further neighbours has been derived and discussed.
Investigation of the Solution Status of TGS and ATGSP Crystals
Authors: Wang O. W. , Fang C. S. 
Published: January 2007

AbstractThis paper reports on the solubility curves of TGS and ATGSP crystals with different pH's. The relationship of (010) growth rate in solutions with different pH varied with the supersaturation, has been studied. The influence of pH on the metastable region of solution have been measured. The experimential results are discussed with respect to the structure and viscosity of solution and the solubility of the crystals. Finally the optimum conditions for the rapid growth of TGS and ATGSP crystals is given.
Thomas‐Fermi Dielectric Screening in Some Binary Semiconductors
Authors: Shajan X. Sahaya , Mahadevan C. 
Published: January 2007

AbstractThomas‐Fermi (TF) dielectric functions. ϵ(k) and ϵ(r) have been estimated for some binary semiconductors. TF functions obtained are found to be in excellent agreement with those calculated by the empirical pseudopotential method.
Light Intensity Variation Studies of MoS2/Electrolyte Interface
Authors: Patel S. G. 
Published: January 2007

AbstractPhotoelectrochemical characterization of natural and synthetic molybdenum disulphide prepared by direct vapour transport technique have been carried out. The quality of the MoS2/electrolyte junction for photovoltatic applications was assessed examining the effect of varying light intensity on current voltage behaviour. For measurements at low intensity a broad light source was used. The ideality factor (n) was determined for these junctions by modelling the MoS2/electrolyte junction in terms of a Schottky barrier. The effect of intensity in the efficiency of the PEC solar cells has also been studied in detail. All the observations have been described and the implications have been discussed.
Growth and Characterization of Direct‐connecting AlGaAs/GaAs TJS Light Emitting Device on SI GaAs Substrate by LPE
Authors: Chang L. B. , Lan H. 
Published: January 2007

AbstractHigh output power (above 3 mW/facet) AlGaAs/GaAs Transverse‐Junction Stripe light emitting diodes have been grown on Semi‐Insulating (100) GaAs substrates by Liquid Phase Epitaxy. these light emitting diodes utilize a “Direct‐connecting” transverse‐junction stripe structure, which can confine the transverse‐current and reduce the series resistance. By thinning the thickness of the “effective active‐layer” of this structure, a room‐temperature pulsed lasing operation is also achieved with a threshold current as low as 35 mA and a peak wavelength around 904 nm. This “Direct‐connecting” transverse‐Junction Stripe light emitting device with a Metal‐Semiconductor Field Effect Transistor on an electrical isolated semi‐insulating substrate in the future.
Initial Growth Stages of Man‐made Quartz Crystals and Growth Mechanism of their (0001) Face
Authors: Kirov G. K. 
Published: January 2007

AbstractIn a series of short term runs it has been shown that in the course of the non‐stationary part of the hydrothermal process the quartz seed plate is subject to: 1. fast and deep dissolution; 2. very slow dissolution‐and‐growth; 3. a shallow complementary etching; 4. mass formation of crystallization centres; 5. tangential and normal growth of these centres accompanied by their aggregation into larger growth units. Every one of theses processes produces a specific structure on the actively growing (0001)‐face. The last process which continues also when the temperatures are stationary, creates the well known “cobble structure”. As the growth continues the prolonged aggregation increases perceptibly the growth rate and makes the cobble structure coarser and coarser.
Radial Distribution Analysis of the Structural Disordering in Mechanically Treated Silicon Powder
Authors: Šepelák V. , Tkáčová K. , Števulová N. 
Published: January 2007

AbstractThe changes in structure brought about by energy‐intensive planetary grinding of silicon were investigated. The interpretation of the RDF obtained by X‐ray diffraction analysis lead to the conclusion that the mechanically treated silicon is in a partially crystalline state. The spatial arrangement of the Si atoms is disturbed in a radial distance around 0.47 nm. The diametral size of the preserved regions d < 0.94 nm exceeds almost twice the size of the unit cell of Si and is of the same range as the size of crystallites in the mechanically treated silicon powder.
The Nature of As‐related Defects in Semi‐Insulating GaAs Bulk Crystals
Authors: Mo P. G. , Wu J. , Fan X. Q. , Zhu J. , Zhou Y. D. , Tan H. Z. 
Published: January 2007

AbstractThe behaviour of As‐related defects in SI (semi‐insulating) GaAs are studied from the viewpoint of the origination of As‐related precipitates, generation and evolution of EL2 during postgrowth and the possible defect interactions involved EL2 variation under As overpressure annealing. The precipitates were identified as elemental As and As‐rich GaAs polycrystalline grains and their features depend on the growth process. A defect interaction model has been proposed on the generation/annihilation of EL2 assigned as AsGa VAs VGa complex respect to non‐stoichiometry such as Asi VGa and VAs.
LPE Growth of GaInAsP/InP Heterostructures for 1.3 μm Planar Buried Mesa Lasers
Authors: Novotný J. , Procházková O. 
Published: January 2007

AbstractLPE heterostructure growth processes devised to prepare GaInAsP/InP planar buried mesa ridge (PBMR) lasers are described. A combination of supercooling and two‐step cooling regimes of LPE was used to grow InGaAsP/InP heterostructures with the active layer flanked by two waveguiding layers. The optical waveguide geometry was optimised to yield minimum threshold current density. Low‐temperature (600°C) LPE process was employed to regrow the etched mesa structure. The prepared PBMR laser devices with optical resonator lengths of 250 μm exhibited room temperature threshold current values near 20 mA and T0 values in the range 60–70K. Optical power‐versus‐current characteristics were linear up to 25 mW.
Crystal Structure of 1‐(2‐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

AbstractThe crystals of 1‐(2‐pyridymethyl)‐2,4,6‐triphenylpyridinium perchlorate are monoclinic, space group P 21/b. The unit cell parameters are a = 18.941(5), b = 19.502(6), c = 15.135(5),y = 115.99°(2), Z = 8, d0 = 1.31(3), dx = 1.319 g/cm3. The structure has been determined by direct methods and refined by block diagonal least squares to R0 = 0.08 for 2520 reflections. The phenyl rings in both molecules (I) and (II) are planar. These rings are twisted with respect to the central pyridyl rings.
Thermodynamic Evaluation of the Nickel‐rich Part of the NiZn‐System
Authors: Vassilev George P. 
Published: January 2007

AbstractOptimization of thermodynamic and phase diagram data about the solid and liquid NiZn solutions is performed. The temperature and concentration dependence of the Gibbs free excess energy is described by means of second degree polynomials. The calculated liquidus and solidus curves have been compared to the experimental ones.
High‐pressure Synthesis and Properties of Manganates with Ilmenite Structure
Authors: Troyanchuk I. O. , Derkachenko V. N. , Shapovalova E. F. 
Published: January 2007

AbstractA2+Mn4+03(A  Ni, Co, Mg, Cu) manganates with ilmenite structure have been obtained by solid phase synthesis at high pressure and temperature. The synthesis conditions for single phase samples have been determined, and investigations of the magnetic, electric, magnetooptic, and resonance properties were carried out.
LPE Growth of Ga1 – xInxSb Multi‐grading Layers
Authors: Xiuying Gong , Okitsu Kazuhiko , Ozawa Tetsuo , Hawakawa Yasuhiro , Yamaguchi Tomou , Kumagawa Masashi 
Published: January 2007

AbstractElectronegativity difference approach (ENDA) has been successfully employed to obtain good prediction of the In atomic fraction, energy bandgap and lattice constant of the Ga1 – xInxSb/Ga1 – yInySb/GaSb system. Nearly lattice‐matched GalnSb epilayers with In atomic fraction of 0.42 have been obtained by the liquid phase epitaxy. The cut‐off wavelength was 2.2 μm at room temperature.
Gettering Properties of Praseodymium in InGaP LPE Growth
Authors: Lai M. Z. , Chang L. B. 
Published: January 2007

AbstractPraseodymium (Pr) is added to the InGaP growth melt during Liquid Phase Epitaxy (LEP) for the first time. The epilayers are grown by using a supercoling method, on (100) Cr‐doped Semi‐Insulating (SI) GaAs substrates at a growth temperature of 790°C. An examination of the electrical properties reveals that, depending on the amount of Pr in the growth melt, n‐tpye InGaP epilayers with room temperature electron concentrations in the range of 3.4 × 1016 cm−3 to 5.3 × 1015 cm−3 and electron mobilities from 730 to 1310 cm2/Vs can be prepared. The photoluminescence spectral results show that by increasing the amount of Pr in the growth melt, smaller Full Width at Half Maximum (FWHM) values and better band edge (BE) recombination intensities result.