bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of Impurity Precipitates on Microhardness of KBr:Ba2+ Crystals
Authors: Reddy B. Kantha , Babu V. Hari
Published: January 2007

Microhardness of KBr crystals doped with various concentration of Ba2+ have been investigated in the asgrown state and after quenching from various elevated temperatures. It is observed that hardness increases with increase in impurity concentration and at high concentration the hardness starts decreasing. Microstructural investigations have showed the formation of visible precipitates at high concentrations. The heat treatment studies showed that in crystals quenched from elevated temperatures the visible precipitates dissociate and hardness increases.
Characteristics and Applications of the Precision Sample Current Microanalysis
Authors: Bitterlich M. , Mai H.
Published: January 2007

The Sample Current Microanalysis allows the identification of binary and quasibinary constituents with a higher precision and accuracy of the analytical results and an improved spatial resolution in comparison to conventional microanalytical techniques (Electron Probe Microanalysis, Secondary Ion Microanalysis). The paper describes the additional equipment required for the utilization of this method in Electron Probe Microanalysers and Scanning Electron Microscopes and specifies the required boundary conditions for analyses of high precision. In addition to the application for typical characterization problems an evaluation of the limits of this method is given.
Effect of the Terminal Substituents on the Smectic Layer Spacings in 4‐(trans‐4′‐n‐Alkyleyelohexyl) Benzoates
Authors: Dąbrowski R. , Przedmojski J. , Baran J. W. , Pura B.
Published: January 2007

The spacings of the smectic layers are compared with the lengths of molecules of p‐substituted phenyl 4‐(trans‐4′‐n‐decylcyclohexyl) benzoates. It has been found that if the NO2, CN or CHO groups are substituted in the p‐position of the phenyl, then the smectic layers consist of dimers, whereas in the presence of the NCS, COCH3, I, Cl, Br, F substituents the smectic layers reveal a monomolecular spacing.
Effect of In and Sb Vacancies on Temperature Dependence of InSb Lattice Parameter at High Temperatures
Authors: Morozov A. N. , Abaeva T. V. , Bublik V. T.
Published: January 2007

The temperature dependence of the thermal expansion coefficient for InSb has been determined in the range 25–515 °C by precision measurements of the lattice parameter of InSb single crystals. It is shown that beginning from 460 °C the temperature dependence of the lattice parameter for InSb single crystals grown from melts of different compositions is essentially affected by vacancies in the indium and antimony sublattices. The vacancy concentration and possible deviation of InSb from the stoichiometric composition are estimated from a relative decrease in the lattice parameter.
The Crystal and Molecular Structure of the Sesquiterpenoid Silerin (Trilobolide)
Authors: Kutschabsky L. , Kretschmer R.‐G. , Ripperger H.
Published: January 2007

For the title compound a guaianolide structure is shown by X‐ray analysis. Only the relative configuration of the molecule could be established.
Effect of Impurities on the Etching of Sodium Chloride Crystals
Authors: Koziejowska A. , Sangwal K.
Published: January 2007

The results of a study of the effect of HgCl2, ZnCl2, PbCl2 and CaCl2 on the surface micro‐morphology and kinetics of etching of {100} planes of NaCl crystals in methanol and ethanol are described and discussed. It was found that addition of an impurity to the solvent leads to the formation of contrasting dislocation etch pits, and that the overall dissolution rate in a solvent decreases with an increase in additive concentration. In the case of HgCl2 impurity added to methanol terraced etch pits are observed, but their terracing behaviour diminishes with the increasing impurity concentration.
AES Depth Profiling of Nitrogen Implanted Fe(001)
Authors: Zemek Josef , Van Phac Le , Král Jaroslav
Published: January 2007

Auger electron spectroscopy (AES) combined with a well controlled ion mill is applied for the study of nitrogen implanted (N+2 ions, 120 keV) into iron single crystals in doses ranging from 8 × 1016 to 5 × 1017 N‐atoms/cm2, also with subsequent heat treatment. The nitrogen depth profiles are Gaussian‐like in shape for doses up to 1.5 × 1017 N‐atoms/cm2. Athigher doses deviations are observed. The nitride bonding state was indicated but a part of the implanted nitrogen appears to be weakly bonded.
On the Contrast Zones and Strain‐Induced Bands in the Hydrocarbon (n‐C28H58) Crystals
Authors: Prasad P. B. V.
Published: January 2007

Formation of contrast zones due to a phase change and occurrence of strain induced band patterns are discussed in the case of n‐octacosane crystals. Slip systems are considered.
On the Formation of the Garnet Phase in Oxidic High‐Temperature Solutions
Authors: Fischer K. , Sinn E.
Published: January 2007

The paper informs on the formation of the garnets Y3Fe5O12, Y3Al5O12 and Gd3Ga5O12 as primary phase in the ternary solvent mixtures PbOPbF2B2O3 and PbOMoO3B2O3. There are correlations with formerly measured oxygen ion concentrations (OIC) in the solvents:

each garnet grows in a special region of the OIC, the phase boundaries are parallel to the lines of constant OIC and

the garnet solubility increases distinctly with decreasing OIC. This emphasizes the important role of the oxygen ions for the garnet formation.

Solubility models are discussed taking into consideration both previous and present results. We conclude that the garnet formation is described best by a model reaction of the type

RE rare earth elements, Y;

M Al, Fe, Ga.
A Multi Purpose Zone Melting Apparatus
Authors: Dickten G. , Eckstein J. , Heinen H. , Recker K.
Published: January 2007

The mechanic and electric design, the heaters and control elements as well as the ways of application of a new multiple purpose zone melting apparatus are described and the working method is demonstrated on the example of refining and growing purest KCl single crystals.
Reactor Problems in Modified Chemical Vapour Deposition (II). The Mean Viscosity of Quartz Glass Reactor Tubes
Authors: Kirchhof J. , Funke A.
Published: January 2007

A new method is developed for deducing viscosity data from collapse experiments with quartz glass reactor tubes. These data involve informations on temperature differences between outer and inner tube surface which are of great importance to the MCVD procedure. The present investigations supported by some deposition experiments yield the surprising result that a considerable temperature gradient exists also at rather low torch speeds. The reason for this effect is discussed.
Mechanical Behaviour of LiF Single Crystals in Compression and Tension at Temperatures from −196°C to 800°C
Authors: Scvortzova N. P. , Berezhkova G. V.
Published: January 2007

The work hardening characteristics of LiF single crystals in compression and tension has been investigated as a function of temperature. It was shown that in temperature range from 200 °C to 600 °C four stages of hardening were observed and the main part of plastic flow proceeds in stage IV. The parabolic hardening was not observed. The flow stresses and hardening rates in all stages in compression are higher than those in tension. As a temperature increase this difference decreases. The hardening rates, stresses which correspond to the beginning of the linear hardening stages and the duration of those stages decrease as a temperature increase. At temperatures above 600 °C the yield drop occured. Taking into account a good agreement between the temperature dependences of the critical resolved shear stress and τIII the assumption was made that τIII corresponds to resolved shear stress in a secondary glide system.
Electrochemical Deposition of CdTe Layers. Their Structure and Electrical Properties
Authors: Valvoda V. , Toušková J. , Kindl D.
Published: January 2007

CdTe layers have been deposited catodically on nickel substrates from an aqueous solution of CdSO4 and TeO2. The degree of erystallinity increases with increasing temperature and decreasing deposition potential. The structure of the layers is cubic with 〈111〉 or 〈110〉 texture which is determined by TeO2 concentration predominantly. Amorphous phase is found in deposits prepared at higher deposition potential or at lower temperatures of bath (60 °C). After annealing at 200 °C the amorphous deposits crystallized and pure tellurium appeared in diffraction spectra. The resistivity of the films was determined by means of I—V characteristics. Films with deposition potentials (−500 to −400) mV vs SCE are p‐type conductivity whereas at lower potentials (down to − 700 mV vs. SCE) the n‐type material is formed.
Temperature Distribution of a Floating Zone in Electron Beam Zone Melting of Molybdenum
Authors: Göbel R. , Jurisch M. , Löser W. , Martuzāne E. , Martuzāns B.
Published: January 2007

The temperature distribution in the molten zone for the electron beam zone melting of molybdenum was calculated on the basis of a heat flow model of the rod. Input parameters were the measured axial electron beam density distribution at the rod surface and the supplied power. The calculated zone shape is compared with experiments. Conclusions are drawn on the magnitude of the dimensionless hydrodynamic parameters of the floating zone in dependence on the experimental conditions.
Lattice Thermal Expansion in CuGaT2 and CuInTe2 Compounds over the Temperature Range 80 to 650 K from X‐ray Diffracion Data
Authors: Bodnar I. V. , Orlova N. S.
Published: January 2007

The lattice parameters a and c as well as the thermal expansion coefficients α⟂ and α∥ in the two principal direction for CuGaTe2 and CuInTe 2 chalcopyrite‐type compounds have been determined as a function of temperature in the range from 80 to 650 K by the X‐ray diffraction method. It is found for both the compounds the coefficient of expansion along the α axis (α⟂) is larger than that along the c axis (α∥) over the whole investigated tem‐perature range. When comparing the results for a series of the CuBIIIC compounds (BGa, In; CS, Se, Te) it is shown that the thermal expansion anisotropy increases strongly when the Ga atom replaces the In atom while it changes a little when the Te atom replaces the Se atom or the S atom.
Dielectric Relaxation on the Smectic B Phase in a Binary Mixture
Authors: Kresse H. , Stettin H. , Tennstedt E.
Published: January 2007

Dielectric relaxation measurements in the frequency range from 10 Hz to 100 kHz in the SA, SB, and SF phase of the binary system 4‐n‐pentyloxybenzylideneamino‐4′cyanobiphenyl(1)/4‐n‐octyloxyphenyl trans‐4‐n‐octylcyclohexanecarboxylate have been carried out. The systematical change of the relaxation frequency FR of I for the reorientation of the molecules around their short axes has been studied in the SB phase for different concentrations. A maximum of FR at the mole fraction 0.5 has been detected which could indicate a decrease of the three dimensional correlation in SB. The increase in FRis connected with a decrease of the activation energy of the respective relaxation process.
Interface Kinetical Limitations in Closed‐Tube Chemical Vapour Transport (I)
Authors: Paorici C. , Pessina V. , Zecchina L.
Published: January 2007

A semiempirical method is proposed, by which the role of kinetical constraints to the growth in closed tube chemical vapour transport can be evidenced.

The method is based on the evaluation of the ratio (Φ) between the quantity D which is related to the semiempirically‐determined average diffusivity of the gaseous species during the growth process, and the quantity D, which is related to the maximum average diffusivity of the gaseous species as is predicted, through the choice of a suitable diffusional model, by the equilibrium thermodynamics and diffusion properties of the vapour phase.
Bond Ionicities and Structural Trends in Some LiBIIIC Compounds
Authors: Neumann H.
Published: January 2007

The individual and average bond ionicities of LiAlO2, LiGaO2, LiInS2, LiInSe2 and LiInTe2 are evaluated from spectroscopic data. It is found that in these compounds the LiCVI bond is essentially ionic in nature. It is shown that the structural properties of the compounds can be understood in terms of the average bond parameters.
The Coprecipitation of Zinc Aluminium Hydroxide Powders from Aqueous Solution with Sodium Hydroxide: Precipitate Compositions and Coprecipitation Mechanisms
Authors: Packter A. , Derry A.
Published: January 2007

Zine aluminium hydroxides were coprecipitated from different mixed metal cation solutions, at CM tot = 0.1 M and at Zn/Al2 ratios from 1 to 4, with sodium hydroxide solution. The coprecipitations were monitored by potentiometrie (pH) titration and the final coprecipitate compositions were examined by chemical analysis, infra‐red spectrophotometry and thermal analysis.

Generally, microcrystalline aluminium hydroxide was first precipitated at pH about 4; this then partially redissolved on further addition of sodium hydroxide (to form hydroxoaluminate anion) and zinc aluminium hydroxide coprecipitates were formed continuously at pHs from 5.5–6 to above 9. Their compositions were similar to the magnesium hydroxoaluminate coprecipitated from magnesium aluminium solutions.

At Zn/Al2 ratio = 1, the main phase was probably Zn(H2O)n [Al(OH)4]2; at Zn/Al2 ratio = 2, the main phase was probably Zn2(H2O)n [Al2(OH)10], whereas at Zn/Al2 ratio = 4, the main phase was probably Zn(H2O)n(OH)4[Al2(OH)10].
On the Size Distribution of Guinier‐Preston Zones Grown in an Al‐4.5 at.% Zn Alloy at Room Temperature
Authors: Hübner G. , Löffler H.
Published: January 2007

The size distribution SD of the Guinier‐Preston (GP) zones grown in an Al‐4.5 at.% Zn alloy were determined by analysis of the intensities of the small‐angle X‐ray scattering (SAXS) curves. Four different methods frequently used in the literature were applied and the obtained results were compared. In addition the SD's obtained by the SAXS methods were compared with that found by high‐resolution electron microscopic investigations. – From these comparisons conclusions were drawn.
The Coprecipitation of Magnesium Titanyl Hydroxide Powders from Aqueous Solution: Precipitate Compositions and Coprecipitation and Ageing Mechanisms
Authors: Packter A. , Derry A.
Published: January 2007

Series of magnesium titanyl hydroxides were coprecipitated at ambient temperature, from different mixed metal cation solutions at CM tot = 0.1 M and Mg/TiO ratios from 2 to 1/2), 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 main coprecipitates were «intramicellar mixtures» of microcrystalline titanyl hydroxide with excess magnesium hydroxide or of magnesium hydroxide with excess titanyl hydroxide. The coprecipitates aged in alkaline magnesium hydroxide suspension were mixtures of titanyl hydroxide, magnesium hydroxide and from fifty to ninety percent (relative to the original/magnesium content) of magnesium hydroxotitanate hydrates Mg[TiO(OH)4] · h H2O, Mg[TiO2(OH)2] · h H2O and Mg[Ti2O2(OH)6] · h H2O.
About the Fluorine Chemistry in MCVD: The Influence of Fluorine Doping on SiO2 Deposition
Authors: Kirchhof Johannes , Kleinert Peter , Unger Sonja , Funke A.
Published: January 2007

In the fabrication of quartz glass fibers for optical communication, fluorine doping gets increasing importance. In contrast to other dopants, fluorine influences the deposition of SiO2 in Modified Chemical Vapour Deposition. An equation is derived from considerations of equilibrium chemistry which yields the deposition efficiency of SiO2 as function of fluorine doping. It is compared with experimental results.
Thermal Microscopy and DSC Studies of 4‐[4‐n‐pentyloxybenzylideneamino] Azobenzene
Authors: Rao K. R. K. , Rao J. V. , Venkatacharyulu P. , Rao S. V. Chiranjeevi , Ballah V.
Published: January 2007

Phase transition studies of the liquid crystal, 4‐[4‐n‐pentyloxybenzylidene–amino]–azobenzene (PBAAB) have been investigated by thermal microscopy and Differential Scanning Calorimetry (DSC) studies. From these studies it is confirmed that the compound, PBAAB exhibits nematic, smectic A and smectic B phases. The textures exhibited by different phases are presented. The enthalpies and entropies at various phase transitions are also reported.
Thermal Expansion of SrF2 at Elevated Temperatures
Authors: Kommichau G. , Neumann H. , Schmitz W. , Schumann B.
Published: January 2007

The X‐ray method was used to determine the linear thermal expansion coefficient of SrF2 in the temperature range from 301 to 1173 K. A comparison of the thermal expansion coefficients of CaF2, SrF2 and BaF2 at T > 300 K shows that the degree of lattice an–harmonicity in the alkaline earth fluorides decreases with increasing mass of the alkaline earth atom. The results for the thermal expansion of SrF2 are used to discuss the temperature dependence of the lattice mismatch in the SrF2/InP film–substrate system.
Thermoanalytical and morphologic study of gel‐grown silver (I) chromate single crystals
Authors: Büchele W. , Lentz A.
Published: January 2007

Rhombic single crystals of silver (I) chromate were grown in silica gels. They were of tabular shape with a size of a = 0.3, b = 30 and c = 3 mm. The morphology of the crystals was interpreted by a detailed discussion of the structure. Silver (I) chromate consists of (100) layers connected along the a‐axis by silver atoms in octahedral coordination. The crystals were characterized by their powder diffraction data. Differential thermal analysis studies were made by use of single crystals. The enthalpy of the phase transformation taking place at 485.2 °C is found to be ΔHtr = 8.8 kJ/mol.
Microcracks in fatigued FCC polycrystals by interaction between persistent slip bands and grain boundaries
Authors: Dörr G. , Blochwitz C.
Published: January 2007

Persistent slip bands (PSB) are zones of high plastic strain localization in fatigued fee metals. They cannot propagate across the grain boundaries of polycrystalline specimens. Consequently, a local stress field should exist near the end of the PSB, “inducing” new PSBs in the neighbouring grain or initiating cracks within the grain boundary. This interaction between PSBs and grain boundaries will be discussed in the present paper. The observed effects may be divided into few characteristic groups, the occurrence of which depends on the geometrical relations between PSB, grain boundary and specimen axis.
Material consideration for the growth of scintillation grade NaI(Tl) crystals
Authors: Sabharwal S. C. , Ghosh B.
Published: January 2007

The starting material for any crystal growth contains a number of impurities. The level of an impurity affecting a particular property of the crystal varies from one impurity to another. We report here the effect of some select impurities usually present in NaI material on its growth and scintillation response.
On the initial stages of skeletal crystal growth
Authors: Nanev Chr. N.
Published: January 2007

The transition from isometric into skeletal form of a crystal growing under diffusion control is explained as a result of the transition from a global compensation of the super‐saturation nonhomogeneity, i.e. in the framework of the whole crystal face, to a spatially limited one. The said compensation is now possible only in the region of the macroscopically flat margin surrounding the gross morphological defect (in the form of a depression) which is the immediate result of the uneven, and unsufficient matter supply.
Precipitation studies in a foam column: Potash alum from aqueous solution using 2‐propanol
Authors: Halasz S. , Mullin J. W.
Published: January 2007

A pneumatically‐mixed foam column is described for the precipitation of potash alum from aqueous solution using 2‐propanol as the water‐miscible salting‐out agent. Controlled precipitation is achieved by first evaporating the alcohol into the foam‐producing air stream. Guidelines are given for some optimum modes of operation.
Application of neutron diffraction methods to texture studies on natural rock salt
Authors: Ertel A. , Betzl M. , Paufler P. , Voitus W.
Published: January 2007

The changes for successful texture studies using neutron diffraction on coarse‐grained natural rock salt are tested. The advantages of neutron diffraction for texture investigations of geological materials have been demonstrated and the process of specimen preparation is shortly described. For texture studies conventional angle dispersive neutron diffraction has been applied. Complete pole figures were measured using the spherical sample method and a combination of transmission and reflection geometry in diffraction experiments for rock salt slabs. Due to the small number of crystallites within the irradiated specimen volume composite pole figures had to be scanned using two or three single experiments. The initial material for our studies is natural rock salt from Zielitz mine (near Magdeburg, GDR). Pole figures were measured for the (200), (220), and (222) reflections of NaCl. The crystallographic texture of all samples investigated is weak. In general (100) fibre textures were found.
Contrast formation in plane wave topographs of quartz crystals with induced growth striations
Authors: Alter U. , Cuamba B. , Härtwig J.
Published: January 2007

A qualitative and quantitative study of the contrast formation in X‐ray plane wave topographs of quartz plates with induced growth striations is presented. Contrast distributions are calculated by means of a simple local application of the dynamical theory of the X‐ray diffraction from the perfect crystal and using a mathematical model of the lattice deformation according to the isotropic theory of elasticity. A good agreement between calculations and experimental results can be stated.
Inclusions in flux‐grown crystals of corundum
Authors: Watanabe K.
Published: January 2007

Single crystals of corundum were grown by the seeded techniques, such as stationary, seed‐rotation, and top‐seeded, from molten Na‐ or Li‐cryolite (Na3AlF6 or Li3AlF6) flux. Inclusions, which are flux inclusion, negative crystal, and cavity, included in the crystals are examined under an optical microscope, and the formation mechanism and the shape of them depending on the differences of growth technique and growth condition are briefly described.
Crystal and molecular structure of 5,6‐diphenyl‐2‐(α‐formyl‐benzyliden)‐2H‐thiopyranes
Authors: Sieler J. , Richter R. , Pulst M. , Leban I.
Published: January 2007

The crystal and molecular structure of the title compound has been determined by X‐ray diffraction techniques. It crystallizes in the monoclinic space group P21/n with cell parameters a = 6.101(3) Å, b = 14.365(6) Å, c = 21.888(7) Å, β = 90.20(4)°, Z = 4. The structure was solved by direct methods and refined by least‐squares calculations to an R value of 0.074. The molecule exists in solid state in the Z configuration. The very short intramolecular OS distance of 2.654(8) Å can be explained with polar interactions between the O and S atoms.
The crystal and molecular structure of 2,5‐dibromo‐1,4‐phenylenediyl bis(trans‐4‐ethylcyclohexanoate)
Authors: Hartung H. , Baumeister U. , Schröter R.
Published: January 2007

The title compound with the formula C2H5C6H10COO‐C6H2Br2OOCC6H10C2H5 (DPBEC) crystallizes in the monoclinic space group P21/c with a = 15.37(2), b = 5.27(1), c = 15.13(2) Å, β = 92.7(1)° and two molecules per unit cell. The structure was solved using film intensity data by heavy atom method and refined to R = 0.078.

The fully stretched DPBEC molecules exhibit exact Ci symmetry. Their packing in the crystal is characterized by a non‐parallel (cross) arrangement of the molecular long axes.
Texture investigations of MnAl magnets by neutron time‐of‐flight diffraction
Authors: Fuentes L. , Feldmann K. , Walther K. , Drechsler L. P. , Doerfel I. , Vlassova E. N. , Matorin V. I. , Betzl M.
Published: January 2007

In the present work the connection between magnetic properties and texture of two samples of the tetragonal MnAl phase is investigated. The specimens have been prepared by different cold deformation methods to get various texture types. For texture analysis neutron time‐of‐flight technique has been applied. Some aspects of the mathematical treatment of experimental data has been discussed. The main texture components in the inverse pole figures are inclined with respect to the direction of easy magnetization. Therefore, improved magnetic properties of the material can be expected using more optimal preparation techniques.
Microhardness studies of ammonium hydrogen tartrate single crystals
Authors: Desai C. C.
Published: January 2007

Single crystals of ammonium hydrogen tartrate AHT NH4HC4H4O6 have been grown employing the controlled reaction between NH4Cl and (CHOHCOOH)2 by slow diffusion process in silica gels. The variation in the microhardness of AHT crystals has been determined using Vicker's microhardness indentor. The effects of annealing and quenching on the mechanical properties of these crystals have been studied. It is observed that: (i) irrespective of the relative orientation of the indentor and the crystal, the median vents initiated at the sharp indentation edges, (ii) the microhardness of the crystals depends on the applied load, (iii) the microhardness of the crystal is independent on the duration of loading, and (iv) maximum plasticity is observed in quenched crystals. The implications of this behaviour are discussed.
Morphology of sic epitaxial layers grown by temperature gradient zone melting (I). Dependence of the crystallization boundary smoothness on the epitaxial layers growth conditions
Authors: Peev N. S. , Tairov Yu. M. , Smirnova N. A. , Kalnin A. A.
Published: January 2007

The dependence of the smoothness of the crystallization boundary on the temperature gradient zone melting conditions is investigated. The observed depth of the crystallization boundary is compared with the depth, calculated by the method proposed by D. E. TEMKIN.
A new equation for the temperature dependence of density of saturated aqueous solutions of electrolytes
Authors: Sangwal K.
Published: January 2007

A new empirical three‐parameter equation d = d0 exp[β′(T – T0)2] (where β′, d0, and T0 are constants for a salt) has been proposed to describe the dependence of density d (g/ml3) of saturated aqueous solutions of electrolytes on temperature T (K) in the whole range of temperature in which solubility increases or decreases with an increase in temperature.
Crystal structure determination of 2‐acetylamino‐4‐benzoyl‐5,5‐dimethyl‐4,5‐dihydro‐1,3,4‐thiadiazolin, C13H15N3O2S
Authors: Kuban R.‐J. , Schulz B.
Published: January 2007

Thiosemicarbazone is receiving increasing interest because of the biological activity of some of its derivatives. Mr = 277.35, space group P212121, Z = 4, a = 9.290(3), b = = 11.512(2), c = 13.286(2) Å, V = 1421 (1) Å3, Dm = 1.29(1) Mg m−3, Dx = 1.296 Mg m−3, λ(MoKα) = 0.71062 Å, μ = 0.230 mm−1, F(000) = 584, T = 296 K, final R = 0.028 for 1255 reflections. All hydrogen atoms were located. The structure determed by X‐ray analysis confirms the chemical results. The structure analysis of the title compound is described and its molecular and crystal structure discussed.
Melting temperatures of NaClO3‐NaBrO3 mixed crystals
Authors: Subhadra K. G. , Hussain K. A.
Published: January 2007

The melting points of mixed crystals of sodium chlorate and sodium bromate have been determined. The variation of melting point with composition is non‐linear with negative deviations from linearity. This negative deviation from linearity is attributed to a possible increase in the vacancy concentration in mixed crystals as compared to the pure end crystals.
Grain size distribution in the Kolmogorov model for nucleation and growth: Heterogeneous versus homogeneous nucleation
Authors: Lorenz B.
Published: January 2007

A theory of grain size distribution in nucleation and growth reactions described by the KOLMOGOROV model is developed. The distribution of agglomerates of growing and impinging nuclei is explicitely calculated for the two cases of heterogeneous and homogeneous nucleation. The results are compared and discussed with respect to the investigation of the nucleation mechanism in crystallization processes.
Surface preparation of AB semiconductors (Cd3As2, Zn3As2, Cd3P2, Zn3P2) under ultra‐high vacuum conditions
Authors: Hupfer A. , Schulze S. , Hirsch D. , Żdanowicz L.
Published: January 2007

The UHV surface preparation of AB materials (crystals and thin films) has been monitored with XPS and AES. Clean and stoichiometric surfaces of AB crystals were prepared by means of low energy ion bombardment and subsequent low temperature annealing. Stoichiometric Cd3As2 and Zn3P2 thin films with very low amounts of C and O were deposited by the evaporation of bulk material in the UHV. The quality of prepared AB crystal and thin film surfaces was sufficient to carry out density of states investigations (UPS, RELS) with success.
Some aspects of the technology of lead salt diode lasers used in gas monitoring systems
Authors: Tomm J. W. , Sumpf B. , Herrmann Karin , Szczerbakow A.
Published: January 2007

A rather simple method of lead salt diode laser fabrication is described. The optimization of the diffusion process forming the pn‐junction is especially discussed with regards to the various carrier concentrations of the as‐grown crystals. Liquid nitrogen cooled lead salt diode lasers of the described type meet all demands of a laser based air pollution monitoring device.
Point defects in GaP single crystals investigated by mechanical damping
Authors: Klimm D. , Paufler P.
Published: January 2007

The dependence of mechanical damping of LEC (liquid encapsulated Czochralski) crystals of GaP: S was measured in the temperature range 300… 600 K and at frequencies near 70 and 140 kHz, respectively. In samples of different stoichiometry two peaks could be observed: Peak A at 350 K and peak B at 450 K. Peak A is attributed to the relaxation of point defects near the surface, peak B is probably due to Ga vacancies.
Phase transition studies in the liquid crystal p‐cyanophenyl trans‐4‐pentylcyclohexane carboxylate
Authors: Gupta A. V. N. , Rao J. V. , Prasad N. V. L. N. , Venkatacharyulu P.
Published: January 2007

Investigations on specific volume and ultrasonic velocity measurements (at four different fixed frequencies) as a function of temperature are carried out in the liquid crystal p‐cyanophenyl trans‐4‐pentylcyclohexane carboxylate. From these studies various physical parameters like adiabatic compressibility, molar sound velocity, molar compressibility, van der Waals constant and intermolecular free lengths are evaluated. The variation of the order parameter with temperature at the four different fixed frequencies is also studied and the results are discussed.
Dielectric properties of ferroelectric lead hydrogen phosphate single crystals
Authors: Desai C. C. , Ramana M. S. V.
Published: January 2007

The ferroelectric lead hydrogen phosphate (LHP) single crystals have been grown by employing the gel technique. The controlled reaction between lead nitrate and orthophosphoric acid solutions by diffusion process in gel medium has been used. The dielectric constant (ϵ′) and the dielectric loss (ϵ″) have been measured for the first time as a function of frequency in the range 102 to 104 Hz. They have also been determined as a function of temperatures in the range 300 to 680 K. The polarisation effect contributing to the dielectric constant has been studied. It has been observed that the mechanism of the dielectric behaviour is different in the lower and higher temperatur and frequency ranges. The activation energy of the oscillators has been calculated and found to be 1.12 eV. Attempt has been made to draw some qualitative conclusions, taking in view, the existing theories of various kinds of polarization and implications have been discussed.
Microhardness investigations on gel‐grown barium cadmium oxalate mixed crystals
Authors: Prakash S. M. Dharma , Rao P. Mohan
Published: January 2007

Microhardness characteristics of barium‐cadmium oxalate crystals were undertaken using the indentation technique and the results there of are reported. The observed results were compared with the microhardness values of barium oxalate dihydrate and cadmium oxalate trihydrate crystals. The indentation induced cracks etched in 1N HCl reveal the surface of the dislocation pattern arround indentation mark. The mixed crystals show higher values of microhardness than the components barium oxalate dihydrate and cadmium oxalate trihydrate crystals.
Theoretical aspects of the crystal growth in gel
Authors: Desai C. C.
Published: January 2007

Crystal growth by diffusion process in a gel medium has been utilized for a long time as method of simulation processes in the laboratory. The suitable theory of crystal growth in gels has been developed. Attention has been made mainly to the more general case in which the counter‐diffusion of two reacting substances occurs. The implications are discussed.
Diffusion of iodine in lead telluride
Authors: Assenov R. , Moshnikov V. A. , Yaskov D. A. , Andreev A. P. , Bestaev M. A.
Published: January 2007

By using the non‐stationary thermal‐probe method, investigations were carrieed out on the distribution of the coefficient of thermal electromotive force along the depth of monocrystals of lead telluride, subjected to isothermal saturating annealing in vapours of alloying compositions. The alloying composition consisted of powdered lead telluride, synthesized by the iodide method, and contained elevated concentration of the metallic component and iodine. The PbTe monocrystals were obtained from the vapour phase and had a natural cut. The results of the investigations testify to considerable changes in the concentration of the electrically active proper defects within the entire volume of the crystals, this being obviously connected with diffusion of vacancies from the crystal volume.
Model describing the resistance against structural changes and the hardness of crystalline solids
Authors: Heegn Hanspeter
Published: January 2007

On the basis of knowledge concerning the thermodynamic state and the structure of unelastically deformed solids the present paper derives a model for the description of the resistance of solids against mechanically induced structural changes. The concentration of dislocations, the external specific surface, the particle size of primary crystallites and the amorphization are important for characterizing the solids in the state of stress. The results of model calculations are compared with data available from literature on MOHS hardness and microhardness of crystalline solids. The results show a sufficient correlation independent of the nature of solids.
Microhardness studies of K1−xRbxCl crystals
Authors: Balaramaiah A. , Pratap K. J. , Babu V. Hari
Published: January 2007

The microhardness measurements have been made on pure crystals of KCl, RbCl and mixed crystals of K1−xRbxCl. Microhardness varies non‐linearly with composition being maximum near at the eqimolar composition. Microhardness values calculated from lattice parameter data are in good agreement with experimental data. The difference in the size of the ion constituting the mixed system is responsible for the internal strains giving rise to imperfections and inturn responsible for the non‐linear variation of microhardness with composition.
Phase transition studies in certain thermotropic liquid crystals thermal microscopy and DSC
Authors: Venkatacharyulu P. , Gupta A. V. N. , Rao V. Subba , Rao J. V.
Published: January 2007

Investigations on the phase transition studies in the thermotropic liquid crystals, (1) pcyanophenyl trans‐4‐propylcyclohexane carboxylate, (2) p‐cyanophenyl trans‐4‐pentyl‐cyclohexane carboxylate, (3) 4′‐n‐pentyloxy‐4‐cyanobiphenyl and (4) 4′‐n‐octyloxy‐4‐cyanobiphenyl are carried out by the thermal microscopy and the differential scanning calorimetric (DSC) studies. These studies reveal that the first three mesogens exhibit a single mesophase while the fourth one exhibits a smectic A phase in addition to the nematic phase. The textures exhibited by these mesogens in their mesophases and their transition temperatures, enthalpies and entropies are presented.
Evaporite minerals succession
Authors: Balarew Christo
Published: January 2007

An explanation is given for the crystallization succession during sea‐water evaporation, namely for the differences between the equilibrium solubility diagram of the marine‐type system and the “solar diagram”: The magnesium ions are known to exist in sea‐type solutions predominantly as hexaaqua complexes. Highest crystallization rates and lowest supersaturations required for nucleation should be exhibited by the magnesium salts, crystal structures of which incorporate unchanged hexaaqua magnesium complexes. For the salts with crystal structures in which the water molecules from the magnesium hexaaqua ions are partially or completely replaced by other ligands, the nucleations require high supersaturations and for this reason they do not appear in the “solar diagram”.

This model is used to explain also some genetic pecularities of evaporite deposits: primary evaporite minerals are those which occur according to the “solar diagram” of crystallization. The evaporite minerals featuring in the equilibrium diagram and absent in the “solar diagram” occur in nature most frequently as secondary minerals.
Effect of structural transformations on the texture of NiFe base alloys
Authors: Betzl M. , Vlasova E. N. , Djakonova N. B. , Matorin V. I.
Published: January 2007

1. Processes of texture formation were studied in three NiFe system alloys containing Mo and Ti (alloy No. 1), Cr, Ti and Al (alloy No. 2) and Co, Ti and Al (alloy No. 3). The deformation texture is identical in all alloys which agrees with the proximity of stacking fault energies as estimated from X‐ray data.

2. Annealing leads to a pronounced diffusion and alteration of the texture in alloy No. 1, but does not alter the texture type and intensity in alloy No. 2, whereas in alloy No. 3 the typical strain texture components are intensified.

3. Structure processes governing texture formation were identified as recrystallization in alloy No. 1, and oriented γ–γ′ transformation in alloys No. 2 and 3 where the intergranular boundaries were blocked by heterogenous precipitation of phases not possessing fcc structure.
Antistructure disorder and its relation to dislocations in III–V semiconductors
Authors: Figielski T.
Published: January 2007

Intimate relationship between antistructure defects and dislocations occurs in GaAs which manifests itself as: (i) appearing of spatial correlation between grown‐in dislocations and the EL2 defects (component of the latter are AsGa antisites), (ii) similar suppression of the concentration of EL2 and dislocation density due to the doping with donor impurities, (iii) generation of AsGa antisites during the plastic deformation of a crystal. Al these effects can be understood in terms of the dislocation‐mediated generation of AsGa antisites via absorption of Asi interstitials at dislocation jogs. Large anion (cation) precipitates appearing at dislocations are pointed out to be important for both antisite and dislocation generation under certain conditions.
Electrical transport properties of CdTe:Sb films
Authors: Pratap K. J. , Nagabhushanam M. , Balaramaiah A. , Babu V. Hari
Published: January 2007

Hall coefficient and dc conductivity measurements are made on p‐type CdTe:Sb films grown by vacuum evaporation technique on glass substrate. The grain boundary potential barrier, which is found mainly to limit the mobility of carriers is calculated as a function of film thickness. The n‐type conduction is found to dominate over p‐type conduction above about 330 K. The ratio of electron to hole mobility is also calculated.
Thermal expansion in CuAlTe2 compound
Authors: Orlova N. S. , Bodnar I. V.
Published: January 2007

The lattice parameters a and c as well as the axial thermal expansion coefficients α ⟂ and α ∥ in the CuAlTe2 chalcopyrite‐type compound are determined as a function of temperature in the range from 80 to 650 K by a X‐ray diffractometry technique. The data obtained are used to evaluate the axial ratio c/a, the tetragonal distortion δ = 2 — c/a, the interatomic distances for CuTe and AlTe bonds and their temperature coefficients. It is found that the thermal expansion behaviour of CuAlTe2 is similar to that of other CuBIIICVI2 compounds in having a relatively small expansivity along the c‐axis and a large one in the perpendicular direction. When comparing the results for a series of the CuBIIICVI2 compounds (BAl, Ga, In; CS, Se, Te) it is shown that the correlations between the thermal expansion coefficients α ⟂, α ∥, αm, dδ/dT and the tetragonal distortion δ, as well as the molar mass of the compound take place.
High‐temperature heat capacity, thermodynamic properties and debye temperature of CuGe2P3
Authors: Neumann H. , Nowak E. , Omar M. S.
Published: January 2007

The heat capacity at constant pressure of CuGe2P3 is measured in the temperature range from 180 to 550 K. Standard enthalpies and entropies relative to 298.15 K are calculated from the heat capacity data. The Debye temperature in the high‐temperature limit is estimated to be about 710 K.
Annealing study of He‐irradiated Ni samples
Authors: Lemahieu I. , Segers D. , Deschepper L. , Dorikens‐Vanpraet L. , Dorikens M. , Stals L. , Mommaert C. , Severne G.
Published: January 2007

Positron annihilation lifetime measurements were performed in helium‐irradiated Ni foils for annealing temperatures between 300 K and 1400 K. The samples were also examined by T.E.M. It is shown that immediately after the irradiations two kinds of vacancy clusters are present, some of them containing He‐ions and the others being empty. The empty vacancy clusters anneal out before 800 K, while the vacancy clusters containing He grow in size as a function of annealing temperature.
Influence of impurities on texture and structure formation through recrystallization of aluminium killed cold rolled steel
Authors: Iordanova I. , Bojinov V. , Iliev L.
Published: January 2007

The microhardness, electric resistance, volume of the unit cell, texture, form and size of ferrite grains and cementite particles depending upon recrystallization of cold rolled steel 08 killed with Al are investigated. Some conclusions about the morphology of solution of carbides and nitrides and about the influence of impurities on the recrystallization texture are drawn. Some recommendations about technology of annealing of preliminary aged cold rolled steel 08 killed with Al are given.
Positron lifetime studies in pure and chromium intercalated 2HNbSe2
Authors: Dhanalakshmi S. R. , Nagarajan T. , Ramasamy S. , Viswanath R. N. , Manivannan A. , Rao G. V. Subba
Published: January 2007

The layered 2 HNbSe2 belongs to a class of very interesting low dimensional conductors which exhibits CDW instability at 32 K. In our earlier paper we have established the two dimensionality of the Fermi surface, in these layered compounds by positron angular correlation technique. The reduction in Fermi level along the basal plane due to CDW transition has been already demonstrated by the Japanese group. But the sensitivity of positron lifetime and Doppler broadening techniques for CDW transition is controversial. The Japanese group report drastic changes in Doppler broadening parameters whereas the American group do not find such a change. Positron lifetime measurements have been performed on pure and Cr intercalated 2 HNbSe2 with Cr concentration 0.25, 0.33, and 0.5 with a view to assess the origin of the second lifetime component. The results show that there are two lifetime component τ1 ∼ 205 ps and τ2 ∼ 440 ps having intensity I2 ∼ 29%. On Chromium intercalation the intensity I2 decreases systematically. The trapping rate of positrons shows a systematic decrease with increase of Cr content indicating that the second lifetime arises due to positron annihilation in van der Waal's gap. The defect free annihilation rate λf was found to increase on intercalation indicating a charge transfer from the guest intercalates to the host MCh2 conduction bands.
OD approach to the polytypism in CdP2
Authors: Fichtner K.
Published: January 2007

The structures of CdP2 are described as stacking sequences of layers of CdP4 tetrahedra. On the basis of the OD theory of Dornberger‐Schiff, the stacking possibilities are derived and convenient stacking notations proposed. The idealized layer structure is given, the percentage of α‐CdP2 for any stacking sequence defined. The symbol of the OD groupoid family is P11(n)2m · (4) x, y with parameters x = y = 1/2 and (4+), (4−) as the two alternative transformations from layer to layer. The net constants are a = b ≈ 5.29 Å; the “thickness” of a layer is c0 ≈ 4.95 Å.
Microhardness scaling and bulk modulus‐microhardness relationship in AIIBIVC chalcopyrite compounds
Authors: Neumann H.
Published: January 2007

An analysis of experimental microhardness data shows that the microhardness of the AIIBIVCcompounds can be described by a simple scaling law which depends only on the unit cell volume and the melting temperature. On the basis of this result a simple bulk modulus — microhardness relationship is proposed and used to estimate the bulk moduli of the compounds. The results are compared with existing literature data.
Study of the growth mechanism in the ADP‐type anion‐doped crystals
Authors: Alemaykin F. M. , Kogan A. N. , Yudina T. B.
Published: January 2007

A simultaneous simulation of the growth process in the A(K)DP‐type anion‐doped crystal and growing of this crystal from aqueous solution under controlled conditions has made it possible to analyse the mechanism of impurity influence on the growth rate of various crystal faces. The anisotropy of the face growth rate and the capture coefficient of various impurities by the faces have been determined by the difference in dissolution heats and in sizes of replacing ions. The increase in energy change, when the ion in a solution enters a crystal, causes an increase in the growth rate and the capture of impurities by the face with the largest change. Breaking of one of the joined faces and increased growth of another one resulted in forming of the new faces, i.e. in changing crystal morphology.
Physico‐chemical properties of pure and x‐ray irradiated single crystals of KAP
Authors: Varma K. B. R. , Raju A. R. , Rao K. J.
Published: January 2007

Single crystals of potassium hydrogen phthalate (KAP) have been grown by slow evaporation method from aqueous solutions. Thermal analyses indicate that KAP crystals decompose into phthalic anhydride and KOH around 520 K. Electrical properties of single crystals of KAP have been studied along with the effect of X‐ray irradiation of the crystals. The electrical transport appears to be associated with tunneling of protons. The irradiated crystal exhibits lower dielectric constant and higher ac conductivity.
Anisotropy effect of high‐momentum of ADAP in diamond‐like semiconductors
Authors: Arutyunov N. , Baltenkov A. , Segal I.
Published: January 2007

A high‐momentum component of angular distributions of annihilation photons (HMC ADAP) has been studied experimentally and theoretically in single crystals of germanium, silicon and gallium arsenide and in a single crystal and polycrystal silicon. The model oe the process of positron annihilation with electrons of ion cores has been suggested and the calculations of HMC ADAP curves have been performed for crystallographic directions [111], [110] and [100] of a dimond‐like lattice. It has been established that ADAP anisotropy characteristics in a single crystal of germanium are slightly dependent on the temperature in the range of ΔT = 300÷930 K. It has been concluded that HMC ADAP anisotropy is caused by annihilation of thermalizod positrons with electrons of outer shells of ion cores in crystal lattices of dimond‐like semiconductors.