bluuebunny/crossref_metadata_2025 huggingface dataset:
X‐Ray Characterization of Guanidine Aluminium Sulfate Hexahydrate Crystals in Relation to their Ferroelectric Properties
Authors: Robert M. C. , Lefaucheux F. , Le Bihan R. , Rafii N.
Published: January 2007

Characterization of growth defects by X‐ray topography of Guanidine aluminium sulfate hexahydrate crystals allows to set a close correlation between ferroelectric domain and growth sector patterns. The crystalline quality of prismatic sectors is much better than that of basal sectors.
On the Fit between Precipitates and Matrix in Al–Zn Alloys
Authors: Löffler H. , Ramlau R.
Published: January 2007

The quality of the fit between the precipitates occurring in Al–Zn alloys and the matrix of the Al host is considered taking into account the positions of the atoms in the lattice planes forming the possible faces of the precipitates and the neighboured lattice planes of the matrix. The quality of the fit depends on the number of (pseudo‐)coincidence sites of both planes, the density of Al atoms in the matrix plane and the misfit in the spacings of the atoms in the adjoining planes in consideration. The effect of the misfit is taken into account by means of two different models. Based upon the obtained results many of the experimentally observed features about the preferred shapes and orientations of the faces of the growing precipitates can be explained. It turned out that in both of the applied models most probably the effect of the density of the coincidence sites on the interfacial energy is underestimated.
Studies and Characterisation of Some Nd Laser Glass Rods Using Different Q‐Switching Techniques
Authors: Ghosh P. S. , Ghosh N. P. , Bhattacharya S. , Samanta L. K.
Published: January 2007

Using various Q switching techniques the performance potential of some Nd: glass rods have been analysed and compared with that of a standard rod. Second harmonics generated from such a Q‐switched system have been separated from the fundamental using suitable dispersive element.
An Optimized Shutter Position in MBE Equipments with Large Substrates
Authors: Wolf B. , Zehe A.
Published: January 2007

Large heated substrates in industrial MBE application offer the possibility to minimize the influence of shutter motion on the evaporation source temperature by shutter installation at the position of zero net flux of radiation, which is discussed in the present paper.
Low‐temperature Thermoluminescence Glow Curves in NaCl Crystals Doped with Yttrium
Authors: Reddy Ch. Gopal , Reddy K. Narasimha , Reddy M. Mutha
Published: January 2007

Thermoluminescence glow curves were recorded in undoped and yttrium‐doped NaCl crystals X‐irradiated at liquid nitrogen temperature (LNT). An attempt is made to assign the glow peaks observed to different centres such as Vk‐centres and yttrium related centres etc.
Elastic and Thermoelastic Properties of the Twinned Perovskite LaGaO3 and the Cubic Untwinned Perovskite La0.294Sr0.706Al0.647Ta0.353O3
Authors: Haussühl S. , Mateika D.
Published: January 2007

The elastic and thermoelastic constants of twinned crystals of LaGaO3 and untwinned crystals of La0.294Sr0.706Al0.647Ta0.353O3 have been measured by ultrasonic resonance methods. Both materials exhibit a quite similar elastic behaviour characteristic, as for perovskites. Employing a simple formula for ionic crystals, the elastic constants of both oxygen perovskites reveal a depression of about one third in comparison to the fluor perovskite LiBaF3.
Infrared Optical Characterization of Thermally Oxidized CuInSe2 Single Crystals
Authors: Sobotta H. , Neumann H. , Tomlinson R. D. , Riede V.
Published: January 2007

Infrared reflectivity spectra of thermally oxidized CuInSe2 single crystals are measured at room temperature in the wavenumber range from 180 to 4000 cm−1. A Kramers‐Kronig analysis of the spectra reveals seven vibrational modes with frequencies which agree with mode frequencies in In2O3. No vibrational modes due to Cu–O and Se–O bonds could be observed. The results obtained are compared with previous studies of oxidized CuInSe2 crystals.
Measurement of Temperature Fields and Convection in a Eutectic Melt(I). Influence of Ampoule and Insert Shape on Temperature Field of an AIZn Eutectic
Authors: Holeček S. , Procio M. , Pražák M. , Kubíček L.
Published: January 2007

A study has been made of the temperature field in an AlZn eutectic melt for a Bridgman‐Stockbarger arrangement of the experiment. The influence of the sizes of the ampoules and corundum inserts for the temperature measurements on the final temperature field in the specimen has been studied for different angles α contained by the gravity and the axial temperature field gradient vectors in the specimen. It has been found that an axially located corundum insert increases the convection intensity to a maximum at angles α between 45 and 60°. An influence of the insert for α = 0° is almost negligible.
Kinetics of Dissolution of Calcium Oxalate Calculi in Physiological Solutions Containing Hippuric Acid
Authors: Gutzow I. , Atanassova S. , Budevsky G.
Published: January 2007

An analysis of the thermodynamics and kinetics of crystal growth and dissolution of slightly soluble salts in physiological solutions in the presence of complexing ions is made, accounting for conditions typical in human urine. It is found that hippuric acid, a normal physiological constituent of urine, acts at increased concentrations as a dissolving agent with respect to calcium oxalate and calcium oxalate calculi. The kinetics of dissolution of crystalline calcium oxalate calculi (CaOx) in physiological solutions containing hippuric acid in different concentrations is studied, using the change in the Archimedean weight of samples, immersed in the solution.

The analysis of the experimental results enables the determination of the increased solubility of CaOx in the presence of hippuric acid and to characterize quantitatively this substance as a new and very prospective dissolving agent of CaOx calculi in human urine. A discussion is also given on the possible effect of hippuric acid as a neutral regulator of CaOx‐supersaturation and crystallization in human and mammal urine.
Investigations into Phase Formation of Decomposed Ni0.5Zn0.5Fe2(C2O4)3 6 H2O Solid Solution Oxalates
Authors: Fischer S. , Langbein H. , Michalk C. , Knese K. , Heinecke U.
Published: January 2007

Homogeneous solid solution oxalates of Ni(II)‐, Fe(II)‐ and Zn(II) were prepared by coprecipitation from metal acetate solution with oxalic acid. Using Mössbauer spectroscopy, XRD, magnetic measurement and IR‐spectroscopy, the thermal decomposition of Ni0.5Zn0.5Fe2(C2O4)3 · 6 H2O and the formation process of Ni0.5Zn0.5Fe2O4 were investigated.

At temperatures between 300 and 400 °C the thermal decomposition of the Ni–Zn–Fe solid solution oxalates leads to ferrites of spinel structure, but areas with a different content of Ni and Zn are provable by Mössbauer spectroscopy. After tempering at 750 °C homogeneous ferrites arise.
Solid Inclusions in Man‐made Quartz Crystals Electron Microscopic Investigation
Authors: Kirov G. K. , Neykov H. N.
Published: January 2007

Short‐term hydrothermal experiments were carried out for a more detailed study of solid inclusions in man‐made quartz crystals. In these experiments the crystals which usually are included in quartz occur on the surface of the seed and are only partly overgrown by quartz. Optical observations and SEM and EDS investigations have shown that: 1. The formation of inclusions is a special event in the history of autoclave growth of quartz, the process being controlled by the formation of many sites of increased surface tension. 2. Epitaxial phenomena are of great importance in the formation of inclusions. 3. The solid inclusions are of quartz (30%) and of the Na‐Fe‐silicate Phase 1 (70%). Both occur as single crystals larger than 3 μm as well as clusters of crystals smaller than 2 μm. 4. The several other phases observed as inclusions are of no importance for the quality of the man‐made quartz crystals.
Phase Equilibrium in the System HgSeO4 – H2SeO4 – H2O at 100°C
Authors: Gospodinov G. , Barkov D.
Published: January 2007

The solubility of the system HgSeO4 – H2SeO4 – H2O was studied at 100 °C. The fields of crystallization of HgSeO4 H2O and HgSeO4 were established. The compounds obtamed were identified by means of chemical, X‐ray and crystal‐optical analysis. The mechanism of the thermal dissociation of the compounds obtained was studied.
To the Unified Model of Condensed State
Authors: Vlasov A. D. , Rez J. S.
Published: January 2007

The problem of unified model of condensed state can be solved by using solid‐like model of liquids. A liquid arises when in a heated crystal a universal process of microcrack formation takes place that leads to originating a great number of very small crystals: microcrystallites. In the paper the two basic notions: the effective temperature of crystal surfaces and the internal thermal stresses in crystals are discussed. These notions make possible the microcrystallite model of liquids and the unified model of condensed state. Thus, the microcracks, resulted from thermal stresses, below the melting point lead only to decreased strength of crystals but above melting point the microcracks are spread all over the crystal bulk and cause splitting of the crystal into microcrystallites that are moving freely, in short, making up a liquid. The simple relations for these processes are given. In the end of the paper the identical features of the condensed states, solid and liquid, has been considered.
Texture of Y‐ and Bi‐HTSC and Methods for its Determination
Authors: Shamray V. F. , Babareko A. A. , Efimov Yu. V. , Frolova T. M. , Myasnikova E. A.
Published: January 2007

Investigation of the texture of Y‐ and Bi‐HTSC materials by X‐ray techniques involves certain difficulties owing to the peculiarities of their crystal structure which causes the arrangement of reflexes in dense groups and practically precludes the formation of a pole figure from an isolated reflex. The texture of Y‐ and Bi‐HTSC materials has been investigated by constructing direct pole figures in an automatic texture diffractometer DAPT YM 1 in CuKα emission from groups of reflexes which are unresolvable under the test conditions. The choice of groups of reflexes was dictated by the type of texture formed. With a basal texture of packing of powders, the following groups have turned out to be the most suitable for the YBa2Cu3O7–x phase (123): (013) + (110) + (103), 2θ = 32.3 – 32.8º and (014) + (005) + (104), 2θ = 38.5 – 38.8º. They include the reflexes which are structural and superstructural relative to a bcc subcell with a rather slight orthorhombic distortion, with its tripling along the “c” axis forming a cell of (123) compound. For the Bi2Sr2CaCu2O8 phase, there have been used the groups of reflexes (008) + (111) + (1.4/54), (0.0.10) + (1.6/5.4) + (0.9/5.1), (0.0.12) + (1.6/5.8) + (204) + (119). (115) + (1.6/5.4) + (0.1/5.9), and (117) + (0.9/5.1) + (1.6/5.6) + (1.4/5.8), 2θ with respectively 23.2 – 24.0º, 29.1 – 29.7º, 35.1 – 35.2º, 36.5 – 28.4º, and 29.7 – 31.4º. They also include reflexes from the lattice constructed by multiplication of a perovskite cell with α = 5.40 Å, b = 5.41 Å and c = 30.6 Å along the “b” axis. Y‐HTSC‐based materials also contain a component of shear texture which is close to such a texture in bcc metals. The texture of Y‐ and Bi‐HTSC materials is relatively stable in hightemperature annealing. The nature of the effect of annealing at moderate temperature is different.
Infrared Absorption Spectra of CdIn2Te4
Authors: Riede V. , Neumann H. , Krämer V. , Kittel M. , Sobotta H.
Published: January 2007

Transmittance and reflectance spectra of CdIn2Te4 are measured in the wavenumber range from 200 to 4000 cm–1. In the range from 200 to 400 cm–1 the spectra are governed by two‐phonon combination mode absorptions. In the wavenumber range above 400 cm–1 absorption coefficients below 1 cm–1 and a constant reflectivity of about 0.21 are found.
A Direct Method for Orientation Determination Using TEM (I). Description of the Method
Authors: Möck P.
Published: January 2007

A new method for orientation determination has been developed. The orientation of crystals of a high symmetry (especially cubic crystals) can be determined immediately while working on the transmission electron microscope (TEM). For the application of the method the TEM must be equipped with a specimen‐tilt goniometer. By tilting the specimen the angles of the stereographic projection are obtained from no more than two easily identified Kikuchi poles on the screen. The stereographic projection can be constructed from these angles. The indices of the crystal orientation direction (and any other lattice direction) can be calculated from the angles between this direction and the base vectors. These angles can be measured using a Wulff net in the stereographic projection of the transmitted crystal.
Synthesis of BaCuO2 by Different Ways
Authors: Krüger Ch. , Reichelt W. , Lubahn U. , Scheler H. , Oppermann H.
Published: January 2007

In order to optimize the synthesis of BaCuO2, different modes were developed and estimated. Wet chemical powders produced by coprecipitation of oxalates or hydroxycarbonates were characterized and their reactivity is compared with the conventional ceramic process of firing a mixture of BaCO3 and CuO by DTA, XRD and IR‐investigations.

This becomes possible, because the decomposition of these chemical precursors to BaCO3 and CuO is finished up to 600 °C. Hence, the same reaction for the formation of BaCuO2 is monitored.
A Direct Method for Orientation Determination Using TEM (II). Experimental Example
Authors: Möck P.
Published: January 2007

A recently described direct method for orientation determination using a transmission electron microscope (TEM) is demonstrated on an experimental example.
Growth of Single Crystals of Calcium Sulfite in Silica Gels
Authors: Patil S. N. , Rao A. Venkateswara
Published: January 2007

The paper reports on the growth of single crystals of calcium sulfite, CaSO3 0.5 H2O, by reaction of aqueous solutions of CaCl2 and Na2SO3 in silica gels. Na2SO3 incorporated gels give spherulites whereas CaCl2 incorporated gels give transparent single crystals. The morphology of the crystals depends on the region of the gel and the type of reactant incorporated into the gel‐forming solution. Initially formed precipitate and dendrites are converted into good quality single crystals by dissolution and recrystallization processes.
Kinetics of Non‐isothermal Overall Crystallization in Polymer Melts
Authors: Dobreva A. , Gutzow I.
Published: January 2007

A simple formalism describing the non‐isothermal crystallization kinetics in cooling runs at small undercoolings is suggested. A general mathematical method for analyzing processes of non‐isothermal phase formation, accounting for the proper temperature course of the nucleation rate and of the linear growth velocity is developed. It allows analytical description of cooling or heating DSC or DTA experiments in the whole range of possible crystallization temperatures.

The results of the theoretical analysis at small undercoolings are compared with the measurements performed with a number of polymer melts and a satisfactory agreement between theory and experiment is observed.
Gross Dissolution of Natural Rhombohedral‐shaped Calcite in Glacial Acetic Acid
Authors: Sidpara G. R. , Mehta B. J.
Published: January 2007

Gross dissolution of natural rhombohedral‐shaped calcite crystals in different concentrations of glacial acetic (0.3 to 3.4 M) diluted by distilled water is studied. Activation energy of reaction between calcite crystal and acetic acid is calculated and found constant. The preexponential factor is not constant with different concentrations. Weight loss per unit surface area versus concentration of acetic acid is plotted at various temperatures (30 to 55 °C). It is found that the maximum weight loss per unit surface area occurs with 2.5 M of glacial acetic acid for the above temperature range. The value of the pre‐exponential factor is also maximum at 2.5 M of acetic acid. The maximum weight loss per unit surface area is explained with the help of ionic conductivity and viscosity of the etchant.
Crystal and Molecular Structure of mer‐Co(4‐CH3C5H4N)3(N3)3
Authors: Mautner F. A.
Published: January 2007

The crystal structure of mer‐Co(4‐CH3C5H4N)3(N3)3has been determined by single crystal X‐ray methods at 300 K. The compound crystallizes in the monoclinic space group C 2/c, a = 19.087(6), b = 16.769(4), c = 15.845(4) Å, β = 119.04(2)°, V = 4434(2) Å3, Mr = 464.42. Z = 8, Dx = 1.391 Mgm−3, F(000) = 1920, λ (MoKα) = 0.71069 Å, μ = 0.802 mm−1. The cobalt(III) ions are octahedrally coordinated to three azide groups and to three 4‐methyl‐pyridine molecules to form isolated coordination polyhedra.
The Crystal and Molecular Structure of a Gibberellin A3 Pyrazoline Ester
Authors: Kutschabsky L. , Voigt B. , Adam G.
Published: January 2007

The three‐dimensional structure of the gibberellin A3 pyrazoline ester 1 has been established by X‐ray analysis. The compound crystallizes from acetone/hexane in the orthorhombic space group P 212121 with four molecules in the unit cell of dimensions a = 8.853, b = 9.642, c = 23.307 Å. The final R‐value is 0.038 for 1957 reflections.
Entropical Structure Measures in One‐dimensional (1‐D) Crystallography – A Paradigm
Authors: Leuschner D.
Published: January 2007

A model of a generalized one‐dimensional crystallography is evolved by means of specific examples. Its taxonomy is given on the basis of the entropical actual global structure measure.
Al–SnSe2 Schottky Barrier
Authors: Patel S. S.
Published: January 2007

Shottky barrier diodes are fabricated on SnSe2 crystal grown by direct vapour transport method. The barrier is produced by thermal evaporation of aluminium on as grown single crystal of SnSe2. The barrier height of Schottky diodes are estimated using current‐voltage characteristics, and activation energy measurement. The barrier height is estimated about 0.49 eV. The implications are discussed.
Rapid Thermal Diffusion of Zinc in GaAs
Authors: Nowak E. , Kühn G. , Morgenstern T. , Schumann B.
Published: January 2007

Rapid thermal diffusion of zinc into semi‐insulating GaAs from spin‐on silica films was investigated for various temperatures and heating rates with halogen lamps as the heat source. Dependent on the heating rate two types of SIMS profiles were observed. The degree of electrical activation of zinc was different as measured by the Hall effect. In some cases at high zinc concentrations, a ZnGa2O4 film on the GaAs surface was formed.
Lattice Vibrations and Interatomic Forces in AIIB2IIIC4VI Defect‐Chalcopyrite Compounds (I) Keating Model Considerations
Authors: Neumann H.
Published: January 2007

The lattice vibrations of the AIIBIII2CVI4 semiconductors with defect‐chalcopyrite structure are treated in a simplified version of the Keating model considering only interaction with nearest neighbours and assuming that all anions occupy their ideal lattice sites. It is found that in this model the frequencies of the nonpolar and polar modes with highest energy are determined by the properties of the BIII–CVI sublattice alone. The frequencies of all the other optical modes depend not only on the AII–CVI and BIII–CVI interactions but are also influenced by the presence of the ordered array of vacancies. The results obtained are compared with previous model considerations.
Annealing Effects on Photoconductivity Spectra of CuInSe2 Single Crystals
Authors: Slifkin M. A. , Al‐Rahmani A. , Imanieh M. , Tomlinson R. D. , Neumann H.
Published: January 2007

Photoconductivity spectra of as‐grown n‐type and p‐type CuInSe2 single crystals and of crystals annealed under maximum and minimum selenium pressure are measured in the photon energy range hv = 0.75 – 3.0 eV and as a function of temperature in the range T = 80 – 320 K. A model with trapping of minority carriers is used to explain the temperature dependence of the photoconductivity. The trap energies present in the samples depend on their preparation conditions.
On Chemical Kinetics of Silicon Deposition from Silane (VI). The Effect of Wafer Diameter
Authors: Kühne H. , Harnisch H. , Puk P.
Published: January 2007

Changing substrate diameter, when depositing poly silicon by decomposition of silane in a hot‐wall tube reactor under LPCVD‐conditions, alters total substrate surface area as well as the distance between wafer periphery and tube wall. From a theoretical point of view both quantities are expected to take an influence on the steepness of axial layer growth decay. Relovant experimental results confirm the theoretical considerations, if an additional effect of flow resistance will be taken into account.
Lattice Constant of AlAs
Authors: Leszczynski M. , Micovic M. , Mendonca C. A. C. , Ciepielewska A. , Ciepielewski P.
Published: January 2007

The value of AlAs lattice constant was established in two ways. First, by extrapolating the results for AlxGa1−xAs LPE (aAlAs = 5.6608 Å) and MBE grown epitaxial layers (aAlAs = 5.6620 ± 0.0001 Å). Second, for AlAs MBE‐grown epitaxial layer (aAlAs = 5.6620 ± 0.0001 Å). The measurements were performed with a high accuracy X‐ray diffractometer and compared with results of photoluminescence measurements.
The Influence of the X‐ray Wavelength on the Behaviour of Polar Kossel Reflections
Authors: Geist V. , Nolze G.
Published: January 2007

The Kossel effect permits a determination of polar directions in non‐centrosymmetrical structures. To identify polar reflections unambiguously, differences — as large as possible — in their fine structures are necessary. These differences considerably depend on both the diffraction geometry and the characteristic X‐ray wavelength applied. The reasons of such behaviour are deliberated upon hereinafter and a good harmony achieved of theoretical predictions and experimental findings.
Electron Spin Resonance of Mn2+ in Hemimorphite
Authors: Vassilikou‐Dova A. B. , Eftaxias K.
Published: January 2007

The Electron Spin Resonance of Mn2+ in natural crystals of hemimorphite was studied at RT, X‐band. No fine structure other than the central M = | + 1/2 〉 ⇆ | −1/2 > transition with allowed (Δm = 0) and forbidden (Δm = ±1) hyperfine transitions were observed.

The spectrum was fitted with the spin Hamiltonian parameters g = 2.001, A = −84.6 × 10−4 cm−1. The crystal field parameter D was estimated equal to (8 ± 2) × 10−3 cm−1. The most striking result is the size of the hyperfine splitting constant favoring occupancy of sixfold coordinated sites.
Experimental Determination of f″ for Ga and In From Bijvoet Ratio
Authors: Saravanan R. , Mohanlal S. K. , Chandrasekaran K. S.
Published: January 2007

The imaginary components of the anomalous dispersion correction terms for the heavy atoms gallium and indium, evcaluated from a systematic and precise experimetal measurement of the Bijvoet ratios for the spherically ground single crystals of GaP and InP, are reported. The procedure used is based on the work of Engel and Sturm who refined the crystal structures involving light atoms using anomalous scattering and employed the measured structure factors to evaluate the f″ values of the heavy atoms. In the present work, instead of refining the crystal structure, the structure factors are obtained using a refinement program. The experimentally evaluated f″ values are in very close agreement with the reported theoretical values.
Structure Characterization of EDTA Transition Metal Complexes (II) Study on Ba[Co(HEDTA)H2O]2 · 4H2O
Authors: Yugeng Zhang , Jianmin Li , Jifa Fan
Published: January 2007

The d‐d transition spectrum of Ba[Co(HEDTA)H2O]2 · 4H2O crystal was measured at room temperature and experimental results are explained quantitativley by using the ligand field theory and the radial wave function of non‐free Co(II) ion. The crystal structures and the electronic structures of M/Co‐EDTA (M=Ba, Sr, Ca, Mg) complexes are also discussed.
Stress, Strain, and Symmetry of Pseudomorphically Grown Epitaxial Layers
Authors: Tempel A. , Mäder M.
Published: January 2007

The complete stress and strain tensors and the point symmetry of pseudomorphically grown epitaxial layers are calculated from the epitaxial relationship and the elastic constants of the deposit material. The angle misalignment of crystallographic directions in the deposit due to the strain is also calculated and results are given for the epitaxial systems CaF2/Si(100) and CaF2/Si(111).
Growth and Morphology of Hollow Bi2Te3 Whiskers by Physical Vapour Deposition Method
Authors: Kunjomana A. G. , Mathai Elizabeth
Published: January 2007

Hollow crystals of bismuth telluride have been grown by the physical vapour deposition (PVD) method. Whisker crystals as long as 10 mm have been grown and were identified by X‐ray analysis. The possible mechanism for the growth of hollow whiskers has also been suggested.
The Distribution Coefficient of Isomorphous Admixtures for KCIKBrH2O, K2SO4(NH4)2SO4H2O and KNO3NH4 NO3H2O Systems at 298 K
Authors: Dejewska B.
Published: January 2007

For the systems KCIKBrH2O, K2SO44‐(NH4)2H2O and KNO3NH4NO3H2 O equilibrium investigations have been performed and the distribution coefficients of isomorphous admixtures have been determined. For each solid solution the changes of the distribution coefficient D, the dependencies between the values of the real and ideal distribution coefficients and the directions of energetic changes in these systems during the co‐crystallization of isomorphous and isodimorphous admixtures have been discussed.
On the Presence of Faces in the Habit of Growing Crystals
Authors: Szurgot M.
Published: January 2007

Presence and size of a face in the habit are conditioned by the value of relative growth velocity RA/Rcrit A with respect to the critical growth velocity. It has been established that during the growth of crystals only certain values of relative growth velocities RA/Rcrit A occur. Faces of KBC crystals realize values of RA/Rcrit A between 0 and 2. Unity is the demarcation level below which appearance and above which disappearance of faces takes place. Edges and corners of crystals are places where new faces appear during changes in growth conditions.
The Hydrothermal Synthesis of Petalite Mineral Phases and their Morphological Changing by Increasing of Temperature
Authors: Ghobarkar Habib
Published: January 2007

In this investigation the Petalite minerals were synthesized hydrothermally at different temperatures from a glass with the composition Li2CO3:Al2O3: SiO2 and the relation 1: 1: 8. On that occasion the following mineral phases arised:

at low temperatures (410°C) α‐petalite (unit cell å = 11.737 Å/b̊ = 5.17 Å/c̊ = 7.63 Å, space group P2/a);

At 490 °C α‐petalite was splitted to quartz and an orthorhombic β1‐petalite (unit cell å = 18.24 Å/c̊ = 10.54 Å/c̊ = 10.57 Å, space group PmCn). β1‐petalite could be observated until 1000 °C.

at 560 °C tetragonal β2‐petalite (unit cell å = 7.50 Å/c̊ = 9.07 Å, space group P 43212) in parallel with β1‐petalite;

Behind 750 °C β2‐petalite was not observed.

Behind 900 °C a pseudohexagonal mineral phase developed from β1‐petalite. May be it is possible to indicate this phase as hexagonal (unit cell å = 5.217 Å/c̊ = 5.464 Å, space group P 6222 or P 6422). The author suggests to denote this phase as β3‐petalite.
The Effect of Water on Precipitation from Organic System
Authors: Liszi Dr. I. , Bodor B.
Published: January 2007

An organic compound [(5‐propylthio)‐lH‐(benzimidazol)‐2‐yl‐(carbamic acid‐methyl ester)] was dissolved by conc. HCl in water‐acetone mixtures. The solution was precipitated by NH3‐solution which was diluted with pure water, acetone‐water mixtures and pure acetone, respectively. Acetonewater ratio (weight‐fraction) was the same in the solution‐, and precipitating material when the diluting material was acetone‐water mixture. The NIELSEN homogeneous nucleation theory was applied to determine the interfacial tension, σ, the value of which decreased with increasing the water content in the system. This result agrees well with literature data on the wetting behaviour of organic solid compounds in organic solvent‐water systems.
The Back‐Side Morphology of LPE‐Grown AlGaAs/GaAs/AlGaAs Heterostructures after the Complete Removal of the GaAs Substrate by Selective Etching
Authors: Bolkhovityanov Dr. Yu. B. , Hairi E. H. , Yudaev V. I.
Published: January 2007

As‐grown surfaces of AlGaAs/GaAs/AlGaAs heterostructures were stuck down the glass disks and after that the GaAs substrates were removed completely by selective chemical etching. As a result the back‐surface of the heterostructures became open to light. The influence of different factors on the back‐surface planarity and on the density of such specific defects as holes in the GaAs layer have been investigated. It is shown that the density of holes can be decreased to a value less than 1 hole/cm2 if a glove‐box maintained under a pure N2 atmosphere and connected with LPE installation is used.
Effect of Sintering Temperature on Thermoelectric Power of Mixed LithiumZinc Ferrites
Authors: Ravinder D.
Published: January 2007

Thermoelectric power of polycrystalline lithium‐zinc ferrites having the compositional formula Li0.5−x/2ZnxFe2.0−x/2O4 (where × = 0.2, 0.4, 0.6, 0.8, and 1.0), sintered at 1200, 1250 and, 1300°C has been investigated over the temperature range 300 to 450 K by the probe method. The Seebeck coefficient (Q) is found to decrease with increasing sintering temperature, whereas the carrier concentration (n) and the charge carrier mobility (μ) are found to increase with increasing sintering temperature. Among all the mixed lithium‐zinc ferrites, the one having a zinc content of 0.6 mole has a minimum value of Seebeck coefficient and maximum value of charge carrier concentration.
Material Characterization of Chemically Deposited Photoconducting CdS Films
Authors: Bhushan S. , Sharma S. K.
Published: January 2007

Results of SEM, XRD and absorption measurements were obtained to characterize the chemically deposited undoped and rare earth doped CdS films. SEM studies present the crystalline nature of undoped CdS. In Presence of NaF layered growth takes place which finally results in cabbage type growth. In presence of rare earths cabbage and crystalline growth are observed. XRD studies of undoped CdS show combination of cubic as well as hexagonal phases. Presence of impurities results in change in itensity of peaks along with appearance of some new peaks. The absorption coefficient studies show a band gap of 2.41 eV for undoped CdS.
Lattice Variation and Stability of NaClKCI Mixed Crystals Grown from Aqueous Solutions
Authors: Shajan X. Sahaya , Sivaraman K. , Mahadevan C. , Sekharam D. Chandra
Published: January 2007

An attempt to improve the stability of NaClKCl mixed system was made by adding KBr to it. Crystals were grown by the slow evaporation method and characterized by X‐ray diffraction measurements. A large improvement in stability was observed with crystals grown from (NaCl)x (KCl)0.9−x(KBr)0.1 than from NaxK1−xCl solutions.
Carry‐over ‐ A Fundamental Problem in the MOVPE Growth of Heterostructures
Authors: Keller B. P. , Brühl H. G. , Seifert W.
Published: January 2007

We have investigated the MOVPE growth of GaAs, GaP, and InP using TMGa‐TMN (trimethylgallium‐trimethylamine), TMIn‐TMN (trimethylindium‐trimethylamine) and the hydrides arsine and phosphine in reactor cells covered with products of preceding deposition processes. By measurements of the misfit Δa/a we find that besides arsenic also gallium and at higher growth temperatures even indium can be transferred from the predepositions into the epilayer. The mobilization of gallium is possible due to alkyl exchange reactions with indium‐methyl‐species. Indium is most probably mobilized due to its high vapour pressure at high growth temperatures. The extent of carry‐over is limited within a range of a few percent impurity concentration.
Formation Volume of Schottky Defects (Vacancies) in Inorganic and Organic Compounds and the Defect Formation Mechanism of Melting
Authors: Bollmann W.
Published: January 2007

The formation volumeVsof Schottky defects is given byVs= (hs/L) ΔVfwithhs= 8L(formation enthalpyhsof Schottky defects and heatLof fusion given in same units; ΔVf= change of volume due to melting). If there are phase transitions within the solid,Land ΔVfmust be replaced by (L+ ΔHt) and by (ΔVf+ ΔVt), respectively (Dr.Htand ΔVtrefer to the heat(s) of transition(s) and to the volume change(s) due to transition(s), resp.). The pressure dependence of the melting point isdTm/dp= (TmVs)/hs. Independent on the sign ofVsany increase of the Schottky defect (vacancy) concentration above the maximum concentration possible within the solid decreases the melting point thus resulting in the observed surface melting. The melting point is fixed by the characteristics of Schottky defect formation (hs,ss,Vs) and by the bulk modulus of the solid (ss= formation entropy of Schottky defects).
Effects of Group III Cation Substitution in the Raman Spectra of Some Defective Chalcopyrites
Authors: Attolini G. , Bini S. , Lottici P. P. , Razzetti C.
Published: January 2007

We report on the Raman spectra of CdIn2Se4 and ZnIn2Se4 obtained in a transparency region. These spectra have a disordered‐like appearance at high frequencies. A comparison is made with the Raman and IR spectra of the similar compounds CdGa2Se4 and ZnGa2Se4. The overall vibrational behaviour is mainly determined by the anion and a correspondence may be observed between the frequencies of some high energy polar modes. A strong non‐polar breathing mode is observed at nearly the same frequency in all these compounds. The observed similarities between the spectra are discussed within the frame of the existing simplified models.
Study on the Phase equilibrium in the Systems Sodium Selenate — Cadmium Selenate — Water and Sodium Selenate — Manganese Selenate — Water at 25 °C
Authors: Oykova T. , Mihov D.
Published: January 2007

The phase equilibrium in the systems Na2SeO4CdSeO4H2O and Na2SeO4MnSeO4H2O were studied and it was established that new phases were obtained — double salts with a composition: Na2Cd(SeO4)2 · 2 H2O and Na2Mn(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 and the number of the water molecules of crystallization were investigated, respectively by the Schreinemackers' method of physico‐chemical analysis and thermogravimetrical analysis. An X‐ray diffraction analysis of the new phases obtained was done.
Catalyzed Nucleation of Poly (Vinyl Chloride)
Authors: Dobreva A. , Gantcheva T. , Gutzow I.
Published: January 2007

Microscopically visible crystallization in a typical non‐crystallizing organic polymer ‐ poly(vinyl chloride) (PVC) is achieved by dissoloving it in an appropriate solvent (cyclohexanone) and inducing the nucleation by introducing various insolube crystallization cores ‐ microcrystals of noble metals (Au, Pd, Pt, Rh, Ir, Ru, Os). It is established that the higher the melting temperature of the metal the higher its activity as a crystallization core in the heterogeneous nucleation of PVC.

The reverse process‐oriented crystallization of a foreign substance ‐ NaCl crystals on PVC films is also demonstrated. This result gives an indication of precrystalline structures in seemingly amorphous PVC films.
Study on the Course of Crystallization of Gallosilicate with MFI Structure
Authors: Tuan V. A. , Fricke R. , Jänchen J. , Kosslick H.
Published: January 2007

The kinetics of nucleation and crystallization of zeolite Ga‐ZSM‐5 crystallized in the system 15 Na2O * xGa2O3 * 100 SiO2 * 13 TPABr * 4400 H2O is investigated. The course of crystallization is followed by different methods: XRD, MIR, TG‐DTA, n‐hexane adsorption. NH3‐TPD and pH‐measurement.

The low apparent activation energies of nucleation En = 42.5 KJ/mole and crystallization Ec = 20.4 KJ/mole show that the incorporation of gallium into the framework of the zeolite is not as difficult as expected from the disruptive nature of this process. Other synthesis parameters, e.g. temperature, alkalinity and gel composition have a major influence on the crystallization process. Here the nucleation is pronounced influenced whereas the crystal growth is only marginally influenced.

The physico‐chemical characterization proves the formation of „reactive”︁ and catalytic active gallosilicate species already in the gel, which are assumed to take part directly in the crystal growth process.
Infrared Lattice Vibrations of TI3AsS4
Authors: Neumann H. , Sobotta H. , Riede V. , Kamba S. , Syrbu N. N. , Golovei M. I.
Published: January 2007

Infrared reflectivity spectra of TI3AsS4 single crystals are measured at room temperature in the wavenumber range from 30 to 4000 cm−1 for the polarization directions E‖ c and E ‖ a. An analysis of the spectra with the Kramers‐Kronig method reveals 10 infrared active modes for each of the polarization directions. On the basis of theoretical estimates the modes due to TI‐S and As–S bond vibrations are identified.
Influence of Enhanced Gravitation on the Growth of Ammonium Oxalate Monohydrate Crystals from Aqueous Solutions
Authors: Mielniczek E. , Jakubczyk M. , Sangwal K.
Published: January 2007

The growth behaviour of ammonium oxalate monohydrate crystals on seeds from aqueous solutions under terrestrial and enhanced gravity conditions has been investigated. It was found that all types of faces on the crystals revealed growth layers on them. The faces of the crystals obtained under both terrestrial and enhanced gravity conditions on seeds hung on nylon threads show cracks, trapped inclusions and macrospirals, while the faces of the crystals grown on seeds in fixed holders under enhanced gravity conditions are devoid of cracks, inclusions and macrospirals.
Deformation Induced Micro‐Twins in CdTe?
Authors: Wwinkler M. , Schenk M. , Hähnert I.
Published: January 2007

Room‐ and high‐temperature micro‐indentation experiments have been performed to answer the question if, concerning a material with very low stacking‐fault energy like CdTe, deformation induced twinning occurs in these substances during or shortly after growth.

Micro‐twins appear in consequence of room‐temperature deformation only, whereas microindentation at 565°C does not produce any twins, but leads to widely expanded dislocation glide‐figures, due to dislocation climbing and/or cross‐gliding.
Pattern Formation in Interacting Suspensions
Authors: George K. C. , Abdulkhadar M.
Published: January 2007

The observation of periodic bands and macroscopic deposits, when suspensions of silver and arsenious trisulphide are allowed to interact in a gel medium may be due to a chemical instability of autocatalytic reaction mechanism of colloid growth and nucleation.
A Study of Diffusion by High‐temperature Electron Probe Microanalysis
Authors: Gorfu P. , Blasek G. , Däbritz S.
Published: January 2007

The diffusion between a thin layer and an underlying substrate, with the formation of an intermetallic phase, was studied by electron probe microanalysis (EPMA) measurements with a simultaneous heating of the sample (High‐temperature EPMA ≡ HT‐EPMA). A thin‐film EPMA model calculating the thicknesses and compositions of two thin layers on a substrate (WALDO) was used. A new method with some necessary assumptions has been developed for determining the phase growth coefficients of intermetallic phases from HT‐EPMA measurements by iteratively comparing the measured and calculated X‐ray intensities. Results from the binary system of CuSn are in good agreement with others achieved by different methods reported in the literature. Differences in the case of the binary system of CuIn are discussed.
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

The 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

Copolymers 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

Lattice 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

Experimental 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

Some 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

Ionic 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

The 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

Size 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.
The Landau Theory of the Ordering Transitions of the Early Ditransition‐Metal Carbides
Authors: Franzen H. F.
Published: January 2007

Landau's theory of symmetry and phase transitions is applied to the ordering transitions reported for the dimetal carbides of V, Nb, Mo, Ta, and W.
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

The 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

At 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

In 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.