bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase Transition Studies of the Liquid Crystal Pentyloxybenzylidene Phenylazoaniline
Authors: Rao K. R. K. , Rao J. V. , Venkatacharyulu P. , Baliah V. 
Published: January 2007

AbstractPhase transition studies of the liquid crystal pentyloxybenzylidene phenylazoaniline are investigated with density and ultrasonic velocity measurements. The density variation with temperature confirms that the isotropic liquid‐nematic, nematic‐smectic A and smectic A‐smectic B transitions are of first order. The temperature variation of ultrasonic velocity confirms all the phase transitions. The adiabatic compressibility (βad), Rao number (Rn) and Molar compressibility (B) are estimated from density and ultrasonic velocity.
Thermoelectric Power of Sb2Te3 Films
Authors: Moorthy P. A. Krishna , Shivakumar G. K. 
Published: January 2007

AbstractThe thermoelectromotive force of vacuum deposited Sb2Te3 films on glass substrates has been measured by the integral method in the temperature range 30–250 °C. The film thickness varied between 1200–9600 Å. Thick antimony pads evaporated onto the sample at both ends served as contacts. The thermoelectric power (α) is found to be positive and increases with temperature for thinner samples and at higher temperatures a steady value is achieved. Further increase in the temperature decreases the thermoelectric power. When the film thickness is increased, α decreases. This is explained as due to the reduction in intercrystalline barrier at elevated temperatures and at higher film thicknesses.
Specific Heat and Lattice Anharmonicity in ZnSiP2 and ZnSiAs2
Authors: Neumann H. , Kühn G. , Möller W. 
Published: January 2007

AbstractThe molar specific heat at constant pressure was measured for ZnSiP2 in the temperature range from 300 to 400 K and for ZnSiAs2 from 300 to 500 K. An analysis of the experimental data showed that the contribution to the specific heat due to lattice anharmonicity can be described by a polynomial of third order in the temperature. Predictions are made regarding the expected temperature dependence of the thermal expansion coefficients and compared with existing experimental data.
Vibrational Properties of LiGaO2(I). Experimental Results
Authors: Neumann H. , Kissinger W. , Neels H. , Riede V. , Sobotta H. 
Published: January 2007

AbstractInfrared reflectivity spectra of LiGaO2are measured at room temperature in the wave‐number range from 200 to 4000 cm1for the polarization directions E ∥ a and E ∥ c. The parameters of 10 B1modes and 4 A1modes are determined by a dispersion analysis of the spectra. The results obtained are compared with previous Raman scattering measurements.
Influence of γ‐Irradiation on Some Properties of NaCl: Eu++ Crystals (I). Optical and Dielectrical Characteristics of the Dopant Ions
Authors: Suszynska M. , Opyrchal H. , Nierzewski K. D. , Macalik B. , Gubanski A. 
Published: January 2007

AbstractThe present work opens a series of papers describing a variety of properties of the same material, and deals with the effect of Eu++ ions, and y–irradiation on the optical and dielectrical characteristics of NaCl crystals. For nonirradiated crystals four types of Eu++‐related absorption spectra have been identified and correlated with I.V. dipoles and three types of precipitates stable in the well aged crystals. For the solution—treated samples the effect of irradiation was to diminish the concentration of I.V. dipoles and to change the absorption spectrum in a remarkable way. These changes are explained in terms of the formation of some dopant—related clusters different of those obtainable thermally. No spectroscopic evidences have been obtained for the radiation—induced changes of the valence state of the dopant irrespective of its dispersion degree.
Nature of the Maximum Microsegregation of Binary Alloys from Peritectic Phase Systems
Authors: Wołczyński Waldemar 
Published: January 2007

AbstractA value of the distribution coefficient is of a significant importance for the microsegregation phenomenon. Moreover, the nature of the microsegregation is due to a given phase system, and the Sb–30 Sn alloy has been set as an example to show the maximum microsegregation which can form during solidification of this alloy. A new relation, supplementary to the Scheil equation has been proposed.
An X‐ray Diffraction Refinement of the Crystal Structure of Natural Stellerite, Ca(Al8Si28)O72 · 28 H2O
Authors: Pechar F. , Mattern G. 
Published: January 2007

AbstractAn X‐ray diffraction analysis was performed on a single crystal of natural stellerite, (Ca3.59Na0.35K0.05Mg0.06)tot.=4.05 (Al7.88Fe0.09)tot.=7.97Si28.02O72 · 38.25 H2O, orthorhombic, Fmmm, a = 13.625(2) Å, b = 18.284(1) Å, c = 17.850(2) Å. Z = 4, V = 4446.77 Å3. Refinement of 1400 independent reflections yields R = 0.0429 (Rw = 0.0479). The Si(Al)O bond distances are determined with a precision of 0.002‐5 Å. The framework of stellerite is topologically the same as stilbite 4–4–1.
Crystal and Molecular Structures of Modified Progestagens (I). 17α‐Cyanomethyl‐17β‐hydroxy‐estr‐4‐en‐3‐one, C20H27NO2
Authors: Reck G. , Hübner M. , Bohl M. , Bannier G. , Kretschmer R.‐G. 
Published: January 2007

Abstract17α‐Cyanomethyl‐17β‐hydroxy‐estr‐4‐en‐3‐one is the first member in a series of progestagens investigated systematically by X‐ray structure analyses. It crystallizes in the orthorhombic space group P 212121 with cell parameters α = 8.887(6), b = 11.814(7), and c = 16.263(2) A. The structure was solved by MULTAN‐82 and refined to R = 0.045 for 1453 observed reflections. The steroid ring A has an 1β‐sofa conformation, the rings B and C adopt chair forms, ring D is intermediate between 13β,14α‐half chair and 13β‐envelope. All rings are trans‐fused. In the present structure, OH… N hydrogen bonds link the molecules into chains parallel to α.
Residual Stress Fields in Cylindric Bridgman‐Stockbarger Crystals of Fluorite
Authors: Dressler L. 
Published: January 2007

AbstractRelationships between the residual stress fields in fluorite and the regime of temperature during the crystal growth have been examined. Beside heat conduction the internal heat transfer in the growing crystal by radiation is important, and therefore an effective anisotropy of heat transfer properties in axial and radial direction exists.
The Use of an Electrode Potential in the Investigation of a Single‐Crystal Semiconductor Matrix (II) Anisotropy of Surface Damages in Silicon Single Crystal Cutting
Authors: Gulidov D. N. , Aidelman B. L. , Yu. Charlamov V. , Chistyakov Yu. D. 
Published: January 2007

AbstractAnisotropy of the depth of surface damages in cutting of single crystal silicon along (111) plane by ID saw is investigated due to electrode potential technique. The reasons of appearance of azimuth and planar anisotropy depending on cutting rate directions are shown. In the cutting rate change in the range of 25–100 mm/min doesn't result in the change of azimuth anisotropy character. It is only abrasive action vector that is supposed to be responsible for the appearance of azimuth anisotropy.
Effect of Crucible Diameter and Sealing Pressure on Growth Features of As2Se3 Single Crystals
Authors: Kothiyal G. P. , Ghosh B. 
Published: January 2007

AbstractCrystals of arsenic triselenide were grown in tubes of diameter varying from 14 to 25 mm sealed under partial pressure of Ar in the range 60–660 Torr. The temperature range of the growth zone was independent of crucible diameter and ambient pressure under otherwise identical conditions. A particular range of ambient pressure was conducive for the growth of good quality crystals and whiskers, growth rate increasing with diameter of tube. Transition to growth stage from nucleation stage was not spontaneous in tubes of diameter ≦ 16 mm but required a temperature cycling. Results are explained qualitatively.
Decanted Interface of Salol Crystals Grown from the Melt
Authors: Pan S. K. , Inoue T. , Komatsu H. 
Published: January 2007

AbstractThe decanted surfaces of a crystal grown from the melt show various kinds of solidification markings formed either during growth or decantation. Some of the special features which are peculiar to decantation were discriminated from the real solid‐liquid interface morphology by in situ observation of salol crystals under the microscope.
Formation of Pure Haematite by Hydrolysis of Iron (III) Salt Solutions under Hydrothermal Conditions
Authors: Voigt B. , Göbler A. 
Published: January 2007

AbstractComparing investigations were carried out of the hydrolysis of iron(III) sulfate, nitrate, and chloride under hydrothermal conditions with an aim to find a new way for the synthesis of pure α‐Fe2O3 (haematite). Rich yields of highly pure haematite can be precipitated from iron(III) nitrate solutions. The strong decrease of the impurity level in the hydrothermal formation of haematite permits to precipitate from impure technical solutions α‐Fe2O3 of adequate purity for many purposes.In contrast, the precipitates from iron(III) sulfate or chloride solutions obtained under comparable conditions are rather uncomplete or the phases formed contain a more or less percentage of the respective anion.
Implications of the Euclidean Normalizers of Space Groups in Reciprocal Space
Authors: Koch E. 
Published: January 2007

AbstractEach crystal structure with symmetry G exactly corresponds to i different but equivalent coordinate descriptions of the atomic arrangement and to i different but equivalent structure‐factor lists. The number i equals the index of G in its Euclidean normalizer NE(G). The isometries of one coset of G in NE(G) transform an original coordinate description and an original structure‐factor list into a certain other equivalent description and equivalent structure‐factor list. Two intermediate groups are uniquely defined: G ⫅ K(G) ⫅ L(G) ⫅ NE(G). G and K(G) are class‐equivalent whereas K(G) and NE(G) are translation‐equivalent. L(G) is the most comprehensive intermediate group from the same Laue class as G. In course of a structure determination with direct methods all information needed to “fix the origin” by appropriate restriction of some phases may be derived from the additional translations of K(G). If no anomalous scattering has been observed and if NE(G) is centrosymmetric but G is not, the positions of the inversion centers in L(G) determine the appropriate phase restriction to “fix the enantiomorph”.
Structures of the Triclinic and the Monoclinic Modification of Divascan®
Authors: Kuban R.‐J. , Szulzewsky K. , Kulpe S. , Schulz B. 
Published: January 2007

AbstractTrielinic modification: C12N4O3H16.Mr = 264.26, triclinic P1,a= 7.702(3),b= 9.420(11),c= 10.893(8) A, α = 73.37(8), β = 82.22(5), γ = 66.30(6)°,V= 638(1) A3,Z= 2,Dm= 1.360 Mg m−3,Dx= 1.362 Mg m−3, λ(MoKα) = 0,71062 A, μ = 0.1084 mm−1,F(000) = 280,T= 296 K, finalR= 0.0742, wR= 0.0758 for 1842 reflections. Monoclinic modification: C12N4O3H16·, 3/2H2O,Mr= 291.28, monoclinic P 21,/c, α = 14.075(5),b= 12.631(6),c= 16.234(5) A, β = 99.25(3)°,V= 2849(1) A3,Z= 8,Dm= 1.338 Mg m−3,Dm= 1.359 Mg m−3, λ(MoKα) = 0.71062 A, μ = 0.1134 mm−1, F(000) = 1240,T= 296 K, finalR= 0.0557,wR= 0.0691 for 1266 reflections.Comparison of the two independent Divascan® molecules of the monoclinic modification with the one of the triclinic modification demonstrates good agreement of related bond distances and angles in the molecules. Disorder of the hydroxyl groups of one Divascan® molecule of the monoclinic modification is announced by high vibration parameters of the related oxygen atom and a very short CO distance, which is not adequate to a real CO bond length.
Electron Microscope Observation of the ζ‐Mn5Ge2
Authors: Kifune K. , Komura Y. 
Published: January 2007

AbstractThe high‐temperature phase of ζ‐Mn5Ge2 has been studied by electron microscopy and electron diffraction. Alloy specimens contain two types of structures with different periodicities along their c direction; one is 3.9 nm and the other 1.3 nm. Domains of these two structures make parallel intergrowth with common α‐ and c axes. Results of the previous X‐ray structure analysis are explained by the mixture of the above two structures.
Ice‐Nucleation Activity of AgI Particles on the Surface of Water and into the Volume
Authors: Genadiev N. , Michailov M. , Nenow D. 
Published: January 2007

AbstractThe ice‐nucleation activity of AgI particles is investigated. The critical supercoolings are determined for water drops with particles situated on the drop surface and suspended into the drop volume. The ice‐nucleation activity of the AgI particles decreases with the gradually penetration of the particles into the volume. A large alteration (about 10 °C) for the mean freezing temperature is established. An attempt is made to explain this phenomenon with the lowering of the nucleation work on the three‐phase particle/water/water vapour contact.
Algorithm for the Transitional Portions during the CZ Crystal Growth Using a Computer Control
Authors: Satunkin G. A. , Rossolenko S. N. , Kurlov V. N. , Red'kin B. S. , Tatarchenko V. A. , Avrutik A. M. , Tuflin Yu. A. 
Published: January 2007

AbstractA model is proposed for a non‐stationary process of diameter variation (growing out and narrowing) of the crystal, grown by the automated Czochralski technique, with the aim of obtaining the initial and final “cones” of any desired configuration. The calculations are illustrated by the experimentally grown lithium niobate crystals.
Interface Kinetical Limitations in Closed‐tube Chemical Vapour Transport (II). The CdTe:NH4Cl Growth System
Authors: Paorici C. , Pessina V. , Zecchina L. , Attolini G. 
Published: January 2007

AbstractIt has been shown that when CdTe erystal are grown by closed‐tube CVD, (HCl obtained from thermal decomposition of NH4Cl being the transport agent), large activational constraints occur which strongly limit the vapour phase mass transport.The method is essentially based on a comparison between the semiempirically determined average diffusivity of the vapour phase during the growth process and corresponding diffusivity calculated assuming that kinetical limitation is absent.The smaller (with respect to units) the ratio (ϕ) between the above defined diffusivities is, the larger the activational constraints are assumed to be.
Cadmium Incorporation in the Crystallization of Calcium Sulfate Hemihydrate from Phosphoric Acid
Authors: Tjioe T. T. , Van Woude H. Der , Verbiest J. , Durville P. F. M. , van Rosmalen G. M. 
Published: January 2007

AbstractSemi‐batch crystallization experiments of CaSO4 · 1/2H2O(HH) were performed in concentrated phosphoric acid at various H2SO4 contents in the absence and presence of additives. The influence of the operating conditions and additives on the cadmium and phosphate incorporation in the HH lattice were determined. The Cd uptake increased with raising H2SO4 content. Addition of HNO3 caused a reduced cadmium and phosphate incorporation. Addition of iodide also lowered the cadmium incorporation.The obtained results fits into a model for the incorporation of foreign ions during crystal growth. According to this model the incorporation is primarily a kinetically controlled process.
Determination of the Effective Kinetic Diameter of the Complex Molecules
Authors: Lilov S. K. 
Published: January 2007

AbstractA method for the estimation of the effective kinetic diameter of the complex molecules is suggested. The method is based on the construction of a geometrical model by using the known data for the internuclear distances and atomic radii. On the basis of the suggested method the values of the effective kinetic diameter of some molecules for which there are no respective experimental data are calculated.
The Range of Metastable Formation and the Morphology of the Crystals in the System CaCO3–MnCO3
Authors: Franke W. , Hofer A. 
Published: January 2007

AbstractBoth slow precipitation, hydrogen carbonate transport at room temperature as well as hydrothermal decomposition of oxalates were used to grow mixed crystals in the system CaCO3–MnCO3. The limits of the immiscibility gap below 400 °C and the range of metastable formation at low temperatures were investigated Changes of the morphology of the crystals dependent on the temperature of formation and their composition are described.
Formation of a Special Intermediate during Phase Transformation of Zeolite NaA to Nepheline
Authors: Lutz Wolfgang , Fichtner‐Schmittler Helga , Richter‐Mendau Jürgen , Becker Gudrun , Bülow Martin 
Published: January 2007

AbstractIn the process of phase transformation of zeolite NaA to nepheline under hydrothermal conditions a special intermediate occurs. This is due to the high reaction rate of nepheline formation in the presence of water molecules. Consequently, the usually observed amorphous material with high condensed silica does not occur as separate phase. – The intermediate which is formed due to the destruction of the long‐range order of zeolite is significantly short‐range ordered. The phase transformation process starts at the outer surface of zeolite crystals, thus generating a diffusion barrier for sorption uptake processes.
Lattice Vibrations and Interatomic Forces in LiInS2
Authors: Sobotta H. , Neumann H. , Riede V. , Kühn G. 
Published: January 2007

AbstractInfrared reflectivity spectra of LiInS2 are measured at room temperature in the wave‐number range from 180 to 4000 cm−1. The parameters of four optical modes are determined by a dispersion analysis of the spectra. From the interatomic force constants determined from the sphalerite‐like modes in the lattice vibration spectrum it follows that the Li–S bond is considerably weaker than the InS bond.
Microcomputer Programming of Temperature in a Batch Cooling Crystallizer
Authors: Jones A. G. , Akers S. R. G. , Budz J. 
Published: January 2007

AbstractA new highly flexible batch crystallizer control system and suite of software using a BBC model B microcomputer to programme the cooling rate and log data is described. The programs were tested satisfactorily with the cooling crystallization of potassium sulphate solutions. Both linear and controlled cooling increased the mean crystal size with lower coefficient of variation compared to natural cooling crystallization with a consequent improvement in filtrability characteristics.
The Coprecipitation of Magnesium Iron (III) Hydroxide Powders from Aqueous Solution: Precipitate Compositions and Coprecipitation and Ageing Mechanisms
Authors: Packter A. , Derry A. 
Published: January 2007

AbstractSeries of magnesium iron(111) hydroxides were coprecipitated at ambient temperature from different mixed metal cation solutions, at CM tot = 0.1 M and Mg/Fe2 ratios from 4 to 1/4, with sodium hydroxide solution. The relevant single precipitations and the coprecipitations were monitored by potentiometric (pH) titration and the final coprecipitate compositions were examined by chemical analysis, infra‐red spectrophotometry and thermal analysis.The coprecipitates onto aged α‐FeOOH were simple mixtures of α‐FeOOH and Mg(OH)2. The main coprecipitates were either «molecular inclusion mixtures» of microcrystalline α‐FeOOH with excess Mg(OH)2 or similar mixtures of Mg(OH)2 with excess α‐FeOOH and some ten‐twenty percent (relative to the Mg content) of magnesium hydroxo‐ferrate(III) hydrate Mg[Fe(OH)4]2 · h H2O. The coprecipitates aged in alkaline magnesium hydroxide suspension at 20 °C and 40 °C were mixtures of Mg(OH)2, α‐FeOOH and forty to ninety percent (relative to the Mg content) of Mg[Fe(OH)4]2 · h H2O.The related α‐FeOOHNaOH and α‐FeOOHMg(OH)2 equilibria and the different coprecipitation mechanisms are discussed.
Interatomic Interaction in Zn3(PxAs1–x)2 Solid Solutions
Authors: Vitkina Ts. Z. , Orlik L. K. , Smolyarenko E. M. , Ttrukhan V. M. 
Published: January 2007

AbstractPeculiarities of the interatomic interaction in the Zn3(PxAs1–x)2 (0 ≦ x ≦ 1) solid solutions are discussed in terms of the magnetic susceptibility data. It is shown that the dependence χmol(x) has a break at x ≈︁ 0.15 which is, apparently, associated with the transition from the structures with indirect optical transitions to those with direct optical ones in the above mentioned system. In the framework of the MOLKAO model the magnetic susceptibility is divided into the Langevin diamagnetic and the Van Vleck paramagnetic components.
Simplified Treatment of Transient Doping Behaviour in CVD(I)
Authors: Arnold H. 
Published: January 2007

AbstractPhysiochemical reasons are discussed for the delayed response of doping concentrations within epitaxial semiconductors (Si and III‐V compounds) to changes of the input partial pressure of dopant species for CVD processes. A simplified circuit representation for doping is used that takes care of five serial process steps, the first three of which are the topic of this work (Part I).Among the corresponding storage phenomena in which the gas phase is involved, those with adsorptional influences are to be expected as most important for transient behaviour. Storage of dopant species at the semiconductor surface is included into the circuit representation, as it has been done by Reif et al. for silicon doping. Moreover, adsorption at the reactor wall is represented approximately, assuming equilibrium with the gas phase.
Theoretical Study of Intragranular Heterogeneity of Deformation and Crystal Rotation
Authors: Wierzbanowski K. , Berveiller M. 
Published: January 2007

AbstractThe paper deals with the problem of the intragranular heterogeneous deformation. The grains of a deformed polycrystal are divided in general into subgrains (or deformation zones). In each subgrain a different set of slip systems and consequently a different crystal rotation may occur. We have examined theoretically both the homogeneous and the heterogeneous deformation in tension of a grain using the model of the plastic inclusion(s) in an elastic matrix. The crystal structure and orientation as well as the interactions between slip systems have been taken into account. For both situations (homogeneous and heterogeneous) we have compared resulting deformation energies, active slip systems and crystal rotations. We conclude that for some configurations of heterogeneity it is possible to minimize the total deformation energy.
The Order‐Disorder Structure of Carbamazepine Dihydrate: 5 H‐Dibenz [b, f] azepine‐5‐carboxamide Dihydrate, C15H12N2O · 2 H2O
Authors: Reck Günter , Dietz Günther 
Published: January 2007

AbstractThe crystal structure of the title compound has been determined by X‐ray diffraction techniques. The structure was solved by MULTAN‐82 using the space group Aba2. The atomic parameters were refined by full‐matrix least‐squares calculations in Abam to the conventionalR‐value of 0.105, but it is impossible to interpret the results with normal space group symmetry as the title compound is an order‐disorder (OD) structure consisting of two kind of layers. The OD‐groupoid family isAb21A1[1/4·0].
Coincidence‐Site Lattices in the Rhombohedral System
Authors: Doni E. G. , Fanides Ch. , Bleris G. L. 
Published: January 2007

AbstractCoincidence orientations in the rhombohedral system are examined by means of the CSL model. The rotation matrix R producing a CSL, the generating function ∑ and the equivalent descriptions of the same CSL in direct and reciprocal space are analytically computed. As an application, Tables of CSLs for the approximation of typical rhombohedral materials are presented.
4,2 K‐Photoluminescence Study of the Annealing Process in Neutron‐irradiated Silicon
Authors: Sickert J. , Herzog R. , Flade T. 
Published: January 2007

AbstractDescribed are experimental results of impurity characterisation and defect kinetic studies aimed at investigating annealing processes in neutron‐irradiated silicon. In addition to Hall effect and resistivity measurements, low‐temperature luminescence spectroscopy has been made use of for the physical characterisation, making it possible to determine shallow impurities and observe their kinetic during annealing, especially with respect to phosphorus activation, along with the changes in the electrical properties.