bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth and Physical Characterization of Double Cation Hydrogen Double Sulphate System Li2NaH(SO4)2 · H2O
Authors: Prabaharan S. R. Sahaya , Muthusubramanian P. 
Published: January 2007

AbstractSingle crystals of Li2NaH(SO4)2 H2O are grown from aqueous solution, containing equimolar amounts of Li2SO4 H2O and NaHSO4 from 80°C down to 30°C over a period of 15 days, resulting in large good quality crystals. The as‐grown crystals are verified by using XRD powder technique. The local structure is discussed in the light of vibrational spectroscopy. Water of crystallization is evidenced from both IR and Raman spectra. Several endothermic and an exothermic phase transition anomalies have been observed from DTA scan. Considerable weight loss is observed at 108°C from thermogravimetric study (TGA). The melting point of the material is found to be 450 °C. The density of the compound is measured to be 2.5217 g/cm3.
Effect of Gel Parameters on Nucleation and Growth of CaSO3 · 0.5 H2O Crystals in Silica Gel
Authors: Patil S. N. , Rao A. Venkateswara 
Published: January 2007

AbstractIn continuation to our previous work on the gel growth of single crystals, this paper describes the effect of concentration of feed solution, gel pH, gel density, ageing of gels, intermediate neutral gel and concentration programming on nucleation and growth of CaSO3 0.5 H2O crystals. Transparent single crystals of CaSO3 0.5 H2O have been obtained at low pH and low density gels. Gel ageing and intemediate neutral gel column reduce the nucleation centres and increase the size of crystals without affecting their quality. The nucleation density increases with the increase of concentration of feed solution. By concentration programming the size of the crystals increases.
On the Fit between the Precipitates Occurring in Al–Cu and Al–Cu–Mg Alloys and the Al‐rich Matrix
Authors: Löffler H. , Siebert P. , Kroggel R. , Heyroth W. 
Published: January 2007

AbstractThe quality of the fit between neighbouring planes of the most important metastable phases occurring in Al–Cu and Al–Cu–Mg alloys and the Al‐rich matrix is evaluated by means of geometric models. The results obtained are compared with experimental yields.
Electron Energy Loss Spectroscopy of YBa2Cu3O7–x
Authors: Richter A. , Mahmoud S. , Kleint Ch. , Ritschel M. 
Published: January 2007

AbstractElectronic excitations of Y–Ba–Cu–O polycrystalline material in superconducting form have been investigated by electron energy loss spectroscopy in reflection. The data obtained confirm recent band structure models for this material. Low electron energy losses correspond to energy levels close to the Fermi energy with an upper and lower Hubbard subband and an anionic O 2p band in the middle. Loss peaks due to interband transitions, plasmon excitations, and core electron excitations have been observed, the origin of which is interpreted by a schematic energy level diagram.
On Mechanism of Internal Stresses Formation in Electrodeposited Co‐based Alloy Films with Columnar Structure
Authors: Tochitskii T. A. , Shadrov V. G. , Boltushkin A. V. 
Published: January 2007

AbstractThe internal stresses formed in electrodeposited Co‐based alloy films with columnar structure have been investigated. It is shown that the sign and the value of the stresses are determined by the texture, amount of the adsorbed impurities (CoO and Co(OH)2) and character of their incorporation in the deposit. A preferable crystallite incorporation of the impurities promotes the formation of the tensile stresses through the substraction stacking faults formation. With the crystalline incorporation decreasing, the compression stresses mechanism, caused by the crystallization pressure prevails.
Comparison of Computed and Measured Temperature Distributions in the High‐pressure Liquid Encapsulated Czochralski (HPLEC) Configuration
Authors: Böttcher K. , Fuhrmann P. , Lux B. , Rauchfuss J. 
Published: January 2007

AbstractThe calculations of the temperature field of the InP growth system are carried out with a stationary FEM/Newton algorithm. With regard to the radiation transparency of the B2O3 layer, the limiting cases transparency and non‐transparency are investigated. With the thermocouples which are inserted into the crystal, the temporal temperature behavior at selected positions of the crystal is recorded. The shapes of the crystal/melt interface of further crystals are analysed by microscopy. Computational and experimental results agree.
A Direct Method for the Determination of Orientation Relationships Using TEM
Authors: Möck P. 
Published: January 2007

AbstractA new method for the determination of orientation relationships has been developed. The method is based on a recently proposed direct method for orientation determination using a transmission electron microscope (TEM). The determination of the orientation relationship can be done by two different but generally applicable approaches. The first approach is especially applicable for crystals with orthogonal base vectors, the second approach is especially applicable for crystals with non‐orthogonal base vectors and the general bicrystal.
Phase Interaction in the Systems Sodium Selenate – Copper Selenate – Water and Sodium Selenate – Zinc Selenate – Water at 25 °C
Authors: Oykova T. , Mihov D. , Pavlova P. 
Published: January 2007

AbstractThe phase equilibrium in the systems Na2SeO4–CuSeO4–H2O and Na2SeO4–ZnSeO4–H2O were studied and it was established that new phases were obtained – double salts with a composition: Na2Cu(SeO4)2 · 2 H2O and Na2Zn(SeO4)2 · 2 H2O. The fields of phase equilibrium of the double salts in the triple systems were determined. The composition of the new phases was investigated by the Schreinemackers' method of physico‐chemical analysis, and the number of the water molecules of crystallization – by thermogravimetrical analysis. An X‐ray diffraction analysis of the new phases obtained was done.
Calculation for an Oriented Eutectic Interface of Constant Curvature
Authors: Wołczyński Waldemar 
Published: January 2007

AbstractCalculation of interface shape for oriented eutectic growth has been proposed for regular structure formation. The constant interface curvature has been applied in the analysis. The obtained function contains some physical factors which affects the formation of concave‐convex interface. The proposed approach has been related to the theory of completely coupled growth.
The Morphology of Some Hydrothermally Synthesized Li‐Minerals: A‐Zeolite, α‐Eucryptite, β‐Spodumene and β‐Eucryptite
Authors: Ghobarkar Habib 
Published: January 2007

AbstractThe hydrothermal treatment of glass with the composition 2 LiF, Al2O3, 3 SiO2 at 1 kbar in the range of 150 °C to 850 °C gave rise to the formation of A‐zeolite with orthorhombic unit cell with å = 10.31 Å/b̊ = 8.18 Å/c̊ = 5.0 Å (space group Pna21), α‐eucryptite, trigonal, å = 13.4 Å/bº = 13.4/Å/cº = 9.0 Å (space group R 3), β‐spodumene, pseudocubic/tetragonal, å = 7.53 Å/b̊ = 7.53 Å/c̊ = 9.15 Å (space group P43212), β‐eucryptite, monoclinic, å = 7.75 Å/b̊ = 5.2 Å/c̊ = 11.16 Å (space group P6222).The morphology and development of the mineral phases depend on the temperature of formation.
Parabolic Approximation to the Shape of Oriented Eutectic Interface
Authors: Wolczyński Waldemar 
Published: January 2007

AbstractThe calculation of interface shape for oriented eutectic growth has been presented for regular structure formation. The parblic approximation to the interface shape has been assume in the proposed model. The differences between the modes of both phases growth have been distinguished. The proposed calculation of the interface shape provides a justification for the existence of lead distance. The obtained equations contain the physical factors which affect the formation of concave‐convex interface. The periodic character of interface shape shape has been taken into account. The proposed model has been related to the theory of completely coupled growth.
Synthesis and Characterisation of Scandium (III)‐, Yttrium (III)‐, and Lanthanum (III) Violurate Complexes
Authors: Gad A. A. M. , Farag I. S. Ahmed , Awadallah R. M. 
Published: January 2007

AbstractSc3+‐, Y3+ ‐and La3+ violurate complexes were prepared. The isolated complexes are freely soluble in water, dilute mineral acids, MeOH, Me2CO, DMF, DMS, partially soluble in AcOH and insoluble in EtOH, CHCl3 and CCl4. Molecular compositions of the complexes were formulated on the basis of elemental analysis, molar conductivity and infrared spectra. The IR spectra of violuric acid and its metal complexes reveal that bonding takes place through coordination bond between the central metal ion and the oxygen atom of the oxygen atom of the oximino (CN = O) group and convalenet bond between the central metal ion and oxygen atom of the phenolic (ketonic, COH) group in the case of 1:2 and 1:3 complexes, and through coordination bond between the central metal ion and COH and NH groups in the case of 2:3 complexes. All the isomorphous complexes detected by the X‐ray powder patterns [the (2:3) Sc3+‐VA and (2:3) Y3+‐VA complexes, (1:2) Sc3+‐VA, (1:2) Y3+‐VA and (1:2) La3+‐VA complexes, and the (1:3) Y3+‐VA and (1:3) La3+‐VA complexes] have similar X‐ray, eletronic and IR spetrograms and chemical formulae. The electronic spectra in DMF and in nujol mulls characterise the octahedral stereochemistry for the investigated complexes.
Correlation and Multivariate Dependencies in the X‐ray Characterization of Cr, Al‐ZSM‐5 Type Zeolites
Authors: Marcusson P. , Kosslick H. , Maess B. , Szulzewski K. 
Published: January 2007

AbstractFor an earlier described zeolite synthesis (Kosslick et al.) X‐ray diffraction measurements were done. The relations between the intensities of X‐ray peaks and background to other characterizing parameters were analyzed using statistical methods. it was found that the X‐ray data are a “fingerprint” of the synthesized zeolites, because the crystallinity and structure influences many other properties of the samples. Therefore, the used X‐ray data allow a comprehensive characterization of the synthesis products.
Elastic and Thermoelastic Properties of Triclinic K2Cr2O7
Authors: Haussühl S. 
Published: January 2007

AbstractLarge single crystals of optical quality of triclinic K2Cr2O7 have been grown from aqueous solutions. Their morphological and growth properties are not compatible with point symmetry 1. Complete sets of the elastic constants and their temperature derivatives were determined from ultrasonic resonances of plane‐parallel plates. The elastic behaviour and also the thermal expansion are highly anisotropic. Owing to very strong photoelastic effects these crystals are suited for certain acousto‐optic deflection devices.
Crystal Growth in Gels at Elevated Pressures: The Upper Limit of Temperature for Metastable Formation of Aragonite
Authors: Franke Walter A. , Mehran Nosrat‐Aga 
Published: January 2007

AbstractBoth rapid precipitation and diffusion controlled gel growth were applied to crystallize calcium carbonate at temperatures in the range of 100 °C to 270 °C. The amount of aragonite was determined by means of X‐ray diffraction data. The morphology of the aragonite crystals are described. Metastable formation of aragonite was observed only at temperatures below 270 °C.
Crystal Growth in Gel: Nuclei and Precipitation Distribution in Gel
Authors: Brevnova O. A. , Goshka L. L. , Ruzov V. P. 
Published: January 2007

AbstractThe investigation of the gel structure and properties influence upon the crystallization processes have been carried out and are reported in this paper. The gel acidity and nucleation centers distribution are chosen as the parameters describing this process. The analytical approximations for the nucleation and precipitation density along the gel column are proposed. It has been shown that in the view of the parameters chosen it is impossible separately to determine the gel structure and proton concentration effects on crystallization processes.
Growth and Properties of BeO · 3 Al2O3 (BHA) Single Crystals
Authors: Peicong Pan , Xiaoshan Ma , Zhiwei Hu 
Published: January 2007

AbstractLarge single crystal of BeO · 3 Al2O3 (beryllium hexa‐aluminate or BHA) doped with chromium up to 20 mm in maximum diameter and 60 mm long were grown by Czochralski method. Thechnological conditions of crystal growth have been introduced and key factor leading to a successful growth is a adequate composition of starting charge mixture other than stoichiometry. The crystal structure, absorption spectra and fluorescence spectra of BHA: Cr3+ have been measured. Vibronic side band of the fluorescence spectra is from 700 nm to 900 nm.
Synthesis of Fine‐grained NaA‐type Zeolites from Superalkaline Solutions
Authors: Hadan Marianne , Fischer Falk 
Published: January 2007

AbstractThe synthesis of NaA‐type zeolite from superalkaline reaction mixtures by influence on the formation‐ and transformation rate of the polymorphous phases according to the Ostwald step rule is discussed. The appearence time of NaA as a single crystallization product is described in dependence on the reaction conditions. The kinetics of the zeolite crystallization and the property alterations of the reaction products in dependence on the time are investigated in the pilot scale.
Modelling of Thermal Conditions in GaAs Crystal Growth by the Gradient Freezing Technique (I) Fundamentals
Authors: Hein K. , Buhrig E. , Göhler H. 
Published: January 2007

AbstractIn the gradient freezing process crystal growth is fully controlled by influencing the thermal conditions. The method described in this publication combines measurements with Si phantoms with their modelling by calculation and the extrapolation of the material properties to GaAs. Results show that the gradients in time and space and the crystallization rate are interrelated and influenced by technological and design factors. For process control in the gradient freezing process, accurate knowledge of the differences between the time‐temperature programs given by the automatic control system and the actual thermal regime in the crystal is required.
Comparative Consideration of Photoreflectance and Electroreflectance Spectra of Semiconductors (I) Theoretical Relations
Authors: Neumann H. 
Published: January 2007

AbstractTheoretical relations for photoreflectance and electroreflectance spectra of semiconductors are derived without any restrictions regarding the modulation field. For very low modulation fields it is found that the responses of both types of spectra are directly proportional to each other with the electroreflectance signal just twice as large as the photoreflectance signal. At moderate and high modulation fields the spectra are no longer proportional to each other.
The Thermal Response Function of Traditional Knudsen‐Cells in MBE
Authors: Wolf B. 
Published: January 2007

AbstractPrecise thermal control of Knudsen‐type evaporation cells in MBE requires basic knowledge on the thermal behaviour of the cell on any alteration of the heating power. This paper deals with the cell's response in temperature, when the cell is subject to a jumplike change in heating power. Particular care is devoted to deviations from pure exponential behaviour, if the temperature transition function between two equilibrium states is concerned. It is shown, that the jump response function for a finite increase in heating power is equivalent to that of an infinite small one, whereby an effective temperature — amounting to 70% of the temperature jump height — has to be introduced.
On the Inhomogeneity of Refractive Index of CaF2 Crystals for High Performance Optics
Authors: Dressler L. , Rauch R. , Reimann R. 
Published: January 2007

AbstractCaF2‐crystals belong to the standard materials, used in optical precision instruments. As well as the traditional optics for microscopy new developments in the field of DUV‐lithography (projecting lenses made out of CaF2 and quartz) need a homogeneity of the refractive index in the order of 10−6, but over much larger volumes (diameter of the projecting lenses for lithography >100mm). Some interesting physical connections between the real structure of the crystals and the homogeneity of refractive index are discussed.
Comparative Consideration of Photoreflectance and Electroreflectance Spectra of Semiconductors (II). Numerical Calculations for n‐type GaAs
Authors: Bouamama Kh. , Neumann H. 
Published: January 2007

AbstractPhotoreflectance and electroreflectance spectra of n‐type GaAs are calculated as a function of the doping level, the field modulation and the broadening energy. As a general result it is found that, except in the limiting case of very low modulation fields, the electroreflectance and photoreflectance signals are not proportional to each other. The influence of the various parameters on the spectra is discussed.
“Amorphous” Precursors of α‐Al2O3: An Electron Optical Study
Authors: Brand P. , Dietzmann P. 
Published: January 2007

AbstractBasic aluminium chloride gels are thermally decomposed into X‐ray amorphous products. Corundum begins to crystallize in them about 400 °C on certain conditions. Electron optical examinations on powders of corundum‐forming gels and of their decomposition products show in an essential part aggregates of sheetlike components as powder particles. These have sharp electron diffraction patterns. The interpretation of diagrams proves the existence of two different structures with similar lattices, which are evidently related to those of diaspore and corundum. A defect structure is to be assumed for the corundum crystals formed.
The Thermal Conductivity of Monocrystalline Gallium Garnets Doped with Rare‐Earth Elements and Chromium in the Range 6–300 K
Authors: Sirota N. N. , Popv P. A. , Ivanov I. A. 
Published: January 2007

AbstractThe effect of the additions of rare‐earth elements Nd, Sm, Eu and Tb on the thermal conductivity of gadolinium‐gallium garnets and besides the influence of the joint doping with Nd and Cr on the thermal conductivity of gadolinium‐gallium and more compound gadolinium‐scandium‐gallium, gadolinium‐magnesium‐zirconium‐gallium and yttrium‐scandium‐gallium garnets have been investigated.
Crystal Growth and Structure of 4‐Aminobenzophenone (ABP)
Authors: Genbo Su , Zhengdong Li , Fen Pan , Youping He 
Published: January 2007

Abstract4‐aminobenzophenone C6H5COC6H4NH2 (ABP) is a good organic Nonlinear Optical (NLO) material. The bulk crystal has been grown by cooling method from organic solution, and the crystal structure determined by X‐ray diffraction.
Modelling of Thermal Conditions in GaAs Single Crystal Growth by the Gradient Freezing Technique (II) Technology
Authors: Hein K. , Buhrig E. , Richter Th. 
Published: January 2007

AbstractThe fundamentals of the gradient freezing process were dealt with in the first part of this publication. The second part describes aspects of the thermal technology of the process. Temperature measurements in model crystals and temperature field calculations show how the thermal conditions are influenced by the quality of furnace design, the size and position of the charge, installations in the furnace, and the effect of the melting enthalpy. A characteristic example of the gradient freezing technique is derived from the results.
On the Kinetics of Interface Processes on Silver Halide Crystals
Authors: Winzer A. 
Published: January 2007

AbstractIn the present paper the activation energies of the transport of Ag+ ions in AgCl and AgBr crystals are calculated with the help of a quantum theoretical equation involving the frequency of the optical phonons of the crystal lattice, the mean coordination number for the diffusing ion, and the vibrational quantum number. Comparison of the calculated activation energies with values available from the literature, which were obtained by measurements of electrical conductivity, dielectric loss, diffusion and mass transfer processes, shows good agreement.
Ultrasonic Investigations in the Liquid Crystal p‐Cyanophenyl‐trans‐4‐Propylocyclohexane Carboxylate
Authors: Venkatacharyulu P. , Gupta A. V. Nagaraja , Rao K. R. K. , Rao J. V. 
Published: January 2007

AbstractThe variation of ultrasonic velocity with temperature in the liquid crystal p‐cyanophenyl‐trans‐4‐propylcyclohexane carboxylate at four different fixed frequencies is studied. From the observed temperature variation of the ultrasonic velocities, relaxation parameters like adiabatic relaxation time, velocity at infinite frequency in the isotropic as well as in the nematic liquid crystalline phases are determined. The results are discussed.
Sythesis and Characterization of Li3B5O8(OH)2 Crystals
Authors: Byrappa K. , Shekar K. V. K. , Gali S. 
Published: January 2007

AbstractLi3B5O8(OH)2 crystals were obtained in the system Li2OB2O3H2O under hydrothermal conditions at fairly lower PT conditions. The crystals obtained were characterized through various techniques: XRD, wet chemical analysis and the measurement of ionic conductivity.
Evolution of Optical Transmittance in Precipitants Solutions. A Computer Simulation
Authors: Martín J. , García‐Ruiz J. M. , Alcántara R. 
Published: January 2007

AbstractWe present a computer simulation model of the evolution of the transmitted light intensity traversing a reservoir that contains a supersaturated solution. From the analysis of the noise associated with the main signal, it seems to be possible to differentiate whether mass precipitation occurs by homogeneous nucleation or by pure crystal growth.
Investigation of Residual Oxide Layers on GaAs Surfaces
Authors: Marinova Ts. , Krastev V. , Yakimova R. 
Published: January 2007

AbstractGaAs(100) and (111) oriented samples, treated by means of different chemical procedures, are studied by X‐ray photoelectron spectroscopy (XPS). The thickness and composition of the residual oxide layers are estimated using the intensity ration of Ga 3d and As 3d core levels from the substrate and the oxide overlayers, respectively. Residual oxides containing As2 O3 and Ga2 O3 on GaAs surface are observed. The thickness of the oxide layers is found to range from 3Å to 15 Å. Optimal conditions for pre‐epitaxial surface preparation of GaAs substrates are suggested.
Holographic Studies of Diffusivities of KDP and DKDP in the Solutions
Authors: Xiling Yu , Xuefeng Yue 
Published: January 2007

AbstractThe solution diffusivities of KDP and DKDP are measured accurately and conveniently by holography with a reference‐fringe system being introduced into the hologram. The influences of solutions with different concentrations, concentration gradients, deuterium concentrations and at different temperatures on the diffusivities have been studied in detail for KDP‐H2O and DKDP‐D2O systems. The problems of how to measure diffusivity accurately are discussed on the basis of diffusion mechanism and experimental technique. The activation energies for the diffusion of KDP and DKDP around the saturated solution in the temperature range of 20–50 °C are about 16 · 103J/mole and 25 · 103J/mole, respectively.
Investigations on the Quasi‐binary Subsystem VNb9O25Nb2O5
Authors: Schadow H. , Oppermann H. , Grossmann O. 
Published: January 2007

AbstractBy X‐ray phase analysis in connection with chemical transport reactions it was proved that two boundary phases coexist in the pseudo‐binary subsystem VNb9O25Nb2O5. The maximum solubility of V2O5 in solid Nb2O5 which was spectrometrically determined in corresponding chemically transported samples of the system is 0.37% (n/n).