bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical modelling of the SSD‐process
Authors: Weinert B. , Buhrig E. , Hein K.
Published: January 2007

In order to achieve a better agreement between the calculated and experimental results of crystal production by the SSD‐process, it was essential to extend the application of the modell presented earlier (Weinert et al.).

The thermal and geometrical conditions, which vary strongly during the course of the process and influence the GaP crystallisation, have never been taken into consideration. It has been attempted, in the present work, to consider these changes by dividing the total time of crystallisation into so small durations (Δt), that the evaluation model presented earlier for instant times can be successfully applied. The results of crystallisation for the total period can then be obtained through a mathematical analysis named as sequence correction of process parameters. It has been shown that an exact knowledge of the temperature distribution in the furnace will yield results which are in very good agreement with the experimental values. Moreover, the changes in the process parameters during the whole time of crystallisation have been represented graphically. — Application of this model to other systems, for example to GaAs, is also possible.
The precipitation of sparingly‐soluble metal chromates from aqueous solution in the presence of chelating organic anions: Induction periods and nucleation rates
Authors: Packter A. , Jakubowski J.
Published: January 2007

The precipitation of barium, zinc, lead, copper and silver chromates was studied in the presence of the chelating organic anions gluconate, tartrate, citrate, aspartate, glutamate and E.D.T. Aate. Generally, these chelators complex the metal cation and reduce the free metal cation and mean metal chromate concentrations in solution. The rates of nucleation with microcrystallite formation were then markedly reduced and the induction periods increased from below 1 sec to well above 100,000 sec with increasing chelator/cation concentration ratio; the experimental results were expressed by the relations;magnified image
The coefficients F at any metal chromate concentration were related in turn to the stability constants of the metal‐chelator complexes.
On the crystal structure stability of calcite‐type carbonates
Authors: Balarew Chr. , Markov L. , Petrov K.
Published: January 2007

The preparation of carbonates of the bivalent metals (Mg, Ca, Ba, Sr, Mn, Fe, Co, Ni, Cu and Zn) by two methods under ordinary conditions has been investigated. The stability of calcite type carbonates has been discussed. The shortest O—O distance (d*O—O) between two neighbouring octahedra has been proposed as a criterion for the formation of stable calcite type carbonates. The lower stereochemical boundary of the calcite carbonate stability has been found to be d*O−O ∼ 2.9 Å. The relative stability of carbonates with dO−O* < 2.9 Å (Zn, Co and Ni) has been studied with respect to their isomorphous incorporation into MnCO3.
Surface morphology of iron specimens boronized with BCl3—H—mixtures (I) influence of process parameters
Authors: Bochmann G. , Ritzel B. , Wagner W. , Marx G.
Published: January 2007

Specimens made of armco iron were boronized with 1.1 Vol.% BCl3 in H2 at 1023 K, 1123 K, and 1223 K during different periods. Afterwards, their surfaces were examined by scanning electron microscopy. As a result of variation of the process parameters the surface morphology of the boride layers formed was changed. The etch attack of the boronizing gas mixture on the substrate may be reduced by appropriate parameters.
The influence of water steam on the direct phase transformation of zeolite NaA to nepheline by thermal treatment
Authors: Lutz W. , Engelhardt G. , Fichtner‐Schmittler H. , Peuker Ch. , Löffler E. , Siegel H.
Published: January 2007

Heating of zeolite NaA leads to the consecutive formation of amorphous phase, carnegieite and nepheline in the high temperature region. These phase transformations are influenced not only by temperature but also by the presence of water (inside of the crystals). Water causes destruction of zeolite framework by hydrolytic splitting of Si‐O‐Al‐bonds in addition to thermal effects. Thus, the amorphous phase as the first product of phase transformation occurs in the presence of water steam at a lower temperature. The formation of the crystalline phases carnegieite and nepheline was observed in a temperature range, 300 K lower than usually, and without occurrence of the amorphous phase.
High‐temperature specific heat of AgInS2 and AgGaSe2
Authors: Neumann H. , Kühn G. , Möller W.
Published: January 2007

The molar specific heat at constant pressure was measured for AgInS2 and AgGaSe2 in the temperature range 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. This result is in agreement with the temperature dependence of the specific heat expected from thermal expansion data.
A fluctuation theory of normal crystal growth for the very dilute binary metallic solid solution's crystallization in the case of macroscopic systems
Authors: Chistyakov Yu. D. , Baikov Yu. A.
Published: January 2007

A theory connected with spontaneous fluctuations of the limited spectrum solid state particle concentrations in the case of binary metallic macrosystems crystallizing from the binary melts is developed. Normal kinetics was found to be realized in the case of very dilute binary metallic solid solutions within the small ‘supercoolings’ region. A comparison between the theoretical and experimental data on the crystallization kinetics of very dilute binary metallic solid state solutions within the small ‘supercoolings’ region has been made. For some types of binary metallic macrosystems the quantitative restrictions of the supercooling regions within which a fluctuation mechanism and normal kinetics are assumed to act have been established. The restrictions are conditioned by some parameters of the binary macroscopic melt and two‐phase transitional zone considered.
Polarized MoLß2.15 X‐ray emission of MoS2 and density of the Mo d‐like valence states
Authors: Dräger G. , Czolbe W. , Šimůnek A. , Lévy F.
Published: January 2007

Die polarisierten MoLβ2,15‐Röntgenemissionsbanden von MoS2 wurden gemessen und hinsichtlich lokaler partieller Zustandsdichten (DOS) mit Hilfe der Polarisationsabhängigkeit der Winkelanteile der Übergangswahrscheinlichkeit qualitativ analysiert. Die Ergebnisse werden im Zusammenhang mit den Bindungsverhältnissen im MoS2 abgeleitet und interpretiert. Ein Vergleich der Spektren und ihrer Anisotropie mit den entsprechenden DOS von einer kürzlich berechneten selbstkonsistenten Pseudopotentialbandstruktur bestätigt die theoretischen Ergebnisse experimentell.
Sattructural changes during post‐ageing of an AlZn (15 at.%) alloy at 100 °C studied by positron annihilation, small angele X‐ray scattering and microhardness measurements
Authors: Krause R. , Dlubek G. , Wendrock G.
Published: January 2007

The positron lifetime τ, the shape parameter of the Doppler‐broadened annihilation line S, the microhardness HV and the Guinier radii rG are studied in dependence on the ageing time during isothermal ageing of an AlZn (15 at.%) alloy at 100 °C following a pre‐ageing at R.T. for 1 h after the quench. Weak effects in HV and rG are interpreted by a transformation of spherical Guinier‐Preston zones into ellipsoidal ones. At an ageing time of 104s HV decreases strongly while rG starts to increase more rapidly. This behaviour is explained by the transformation of coherent GP zones into semicoherent α′R‐particles. Incoherent part of the α′R‐particle‐matrix interface are able to localize positrons resulting in a strong increase of τ and S. The characteristic parameters τ and S of the coherent defect‐free GP zones and of the semicoherent α′R‐particles are estimated. It is concluded that positrons can be used as a very sensitive tool in detecting the transformation of coherent particles into semicoherent or incoherent ones.
Dependence of the Kβ/Kα intensity ratio on the oxidation state
Authors: Möser B.
Published: January 2007

The Kβ/Kα line intensity ratio was measured using an energy dispersive X‐ray spectrometer for samples of Ti, TiO, Ti2O3, Ti3O5, and TiO2. A steady increase of the Kβ/Kα intensity ratio was observed with increasing oxidation. For metallic titanium a value Kβ/Kα = 0.131 was obtained whereas for TiO2 this ratio is 0.1365. A similar but weaker dependence was observed for Fe and some iron oxides, too. The origin of this dependence is discussed as well as consequences for quantitative X‐ray microanalysis. Furthermore, the width of Kβ‐lines was found to be about 5 eV higher than that of Kα‐lines of equal energy.
Growth flawing and strain in hydrothermal quartz
Authors: Nanev Chr. N. , Dimitrov V.
Published: January 2007

With the aid of optical methods (including interphako microscopy) combined with chemical analysis at selected microareas (X‐ray microprobe analyser) it is shown that some macro‐defects arise during the growth of quartz single crystals due to the incorporation of foreign particles which are gathered in groups. Frequently, the strain in such crystals is inherited from the seeds. Therefore, the emphasis is laid on the optical investigation of strain in quartz.
Organometallic Vapour Phase Epitaxy of Galliumnitride Using Ga(CH3)3 · N(CH3)3‐Adduct Pyrolysis
Authors: Seifert W. , Franzheld R. , Bönisch F. , Butter E.
Published: January 2007

Epitaxial layers of GaN have been grown on {1102} sapphire in atmospheric OMCVD system using Ga(CH3)3 · N(CH3)3 adduct and NH3 as reactants. Optimum growth conditions for crystallographically perfect layers have been found at temperatures between 850 and 1000 °C. With increasing temperature the growth rate decreases whereas the concentration of free carriers increases. In photoluminescence spectra only the donor‐acceptor pair recombination could be found. It is concluded that the donor oxygen (ON) and the acceptor carbon (CN) are the dominant impurities.
Growth and Kinetic Studies of Spherulitic Gadolinium Tartrate Crystals from Silica Gel
Authors: Kotru P. N. , Gupta N. K. , Raina K. K.
Published: January 2007

Spherulitic growth of gadolinium tartrate dihydrate crystals by controlled diffusion in silica gel is reported. The influence of growth parameters e.g., reactant concentration, gel pH and gel ageing, on the size, quality and nucleation density of the spherulites has been studied. It is observed that under varying experimental conditions involving change in reactant concentrations, gel pH and gel ageing, the material crystallizes in the form of spherulites. The results of growth kinetics are discussed. Scanning electron microscopy confirms spherulites to be aggregates of single crystallites, with each micro‐sized crystal exhibiting a cuboid morphology. Surface structures exhibited by the micro‐sized crystals indicate their growth by two‐dimensional nucleation mechanism.
CVD Processes with Direct and Indirect Incorporation
Authors: Arnold H.
Published: January 2007

Indirect incorporation via adsorption, surface diffusion, and reaction at half crystal sites can be treated by the BCF theory of layer‐by‐layer growth in simple cases of CVD, even if there is strong surface coverage by adsorbed species. I that case, however, the parallel path by direct reactive incorporation of atoms into half crystal sites from the gas phase may play an important role. In any case, direct incorporation becomes the sole possibility for (normal) growth if the surface fraction yk of half crystal sites (kinks) becomes I. The continuous transition from singular faces (yk = 0) to half crystal faces (yk = l) is covered by a simplified analytical expression and can be included into an overall circuit representation of stationary CVD processes which holds for in‐situ doping, too. The model results in a good compromise between the conventional BCF treatment and Chernovs treatment of CVD surface processes.
The Coprecipitation of Basic Magnesium Nickel Carbonate Powders from Aqueous Solution: Precipitate Compositions and Precipitation Mechanisms
Authors: Packter A. , Uppaladinni S. C.
Published: January 2007

Magnesium nickel carbonate hydrate catalyst precursors were coprecipitated from mixed metal cation solutions (Cmtot = 1 M) with different sodium hydrogen carbonate‐sodium carbonate solutions. The course of precipitation was monitored by potentiometric (pH) titration and the final coprecipitate compositions were determined by chemical analysis, infra‐red spectrophotometry and thermal analysis. Generally, the coprecipitates are solid solutions of basic nickel carbonate hydrate with magnesium carbonate, of composition mMgCO3. n[NiCO3. bNi(OH)2]. hH2O. m = 0.77 to 1.00, n = und 2.00, h = 2 to 4; the MgCO3 contents and the Ni(OH)2/NiCO3 ratios (b) increase with increasing pH of the carbonate solutions. The ionic equilibria involved in different coprecipitations are discussed.
On Peculiarities of Chemical Bond in the ZnP System from the Magnetic Susceptibility Data
Authors: Vitkina Ts. Z.
Published: January 2007

The measurements of magnetic susceptibility of the Zn‐P system compounds have been performed and their Langevin diamagnetic component has been calculated. The influence of the degree of covalency of bonding on the value of diamagnetic constituent of the compounds has been investigated. It is shown that the semiconductor compounds of the Zn‐P system have preferably covalent character of chemical bond.
Surface Roughening and Second Neighbour Interaction. A Monte Carlo Simulation
Authors: Tkayanov A.
Published: January 2007

The structure of (100) surface of simple cubic crystal is studied by means of Monte Carlo method, the first and the second neighbour interactions being considered. For different energies of second neighbour interaction the roughening temperatureTRis obtained. The ratiokTR/L(Lis the latent heat) remains constant and equal to 0.19. In order to calculate the roughening temperatureTRof a (100) crystal face with attractive interatomic forces it is not necessary to know separately the bond energies of first, second, etc. neighbour interactions. For this purpose it is sufficient to know only the latent heat.
Polytypism in CdI2: A Consequence of Restrictions in Close‐packed Arrangements
Authors: Wahab M. A. , Kant Rajni
Published: January 2007

Based on theoretical and experimental observations, it has been established that the polytypes 2H and 4H act as basic structural units as regard to the formation of CdI2 polytypes. As a result of this, some general rules have been formulated which help understand (i) the nature of restrictions in the close‐packed arrangements and to deduce the genuine CdI2 polytypes, and (ii) the classification of CdI2 polytypes into various possible groups. This further helps to conclude that (i) the CdI2 polytypes are simply a consequence of restrictions in the close‐packed arrangements, (ii) the concept of stacking fault is superfluous as far as the formation of ordered polytypes are concerned, and (iii) the identification of CdI2 polytypes on the basis of intensity data has limited implications unless some practical use of polytypes are found.
Short‐Range Order in FeCrNi Alloys
Authors: Braude I. S. , Pecherskaya V. I. , Bolshutkin D. N. , Chernik M. M.
Published: January 2007

The short‐range atomie order in Fe82−xCr18Ni−x (x = 15, 20, and 25 wt%) alloy single crystals has been studied by the x‐ray diffuse scattering technique. Diffuse ring around the central node was found for all alloys. Analysis of the intensity distribution allowed to determine the short‐range order partial parameters. Correlations in atom arrangements in the regions of about 10–12 Ångstrom in diameter were found to be characteristic for the alloys studied. It is assumed, that regions of the structural short‐range order become magnetic clusters at the sufficiently low temperatures.
AgGaSe2 on {100} and {110} GaAs—Special Features of Epitaxial Growth
Authors: Tempel A. , Schumann B.
Published: January 2007

AgGaSe2 thin epitaxial layers onto {100} and {110} oriented GaAs substrates were prepared by flash evaporation technique and investigated by the RHEED method (reflection high energy electron diffraction). Special epitaxial relationships were found and the results will be discussed.
Electrical Conductivity and Crystal Structure of Pure and SrCO3‐doped K2CO3
Authors: Guth U. , Babwisch F. , Wulff H. , Möbius H.‐H.
Published: January 2007

Electrical conductivity of pure and SrCO3 doped potassium carbonate has been investigated in the temperature range between 350 and 800 °C. Sintered carbonate mixtures were analysed by X‐ray powder diffraction techniques at room temperatures. The conductivity of SrCO3 doped K2CO3 increases nearly linear up to 10 mol.% and decreases in the range between 20 and 50 mol.% continously. X‐ray diffraction patterns do not show changes up to 10 mol.% SrCO3 in the host lattice. The compound K2Sr(CO3)2 was found for samples containing 15–50 mol.% SrCO3. The lattice constants of hexagonal crystals which are isotypic with K2Ca(CO3)2 are a0 = (534 ± 1) pm and c0 = (1352 ± 2) pm.
Studies on Surface Structures and Etch Patterns on Habit Faces of Gel‐grown Crystals of Iodates of Barium, Strontium, and Calcium
Authors: Joshi M. S. , Trivedi S. G.
Published: January 2007

Microtopographical studies on habit faces of gel grown crystals (of different habits) of iodates of Ba, Sr, and Ca are illustrated and described. Etch patterns on these faces are illustrated and correlated to the observed growth patterns on the respective faces. Growth mechanism of the crystals is explained in light of the observed surface structures and etch pits suitably produced.
Plasma Etching of Niobium‐SiOxLayers
Authors: Schelle D. , Tiller H. J.
Published: January 2007

CF4‐plasma etching of niobium and SiOxlayers has been investigated in a r.f. diode reactor. Etch rates increase linearly with increasing power density and also increase with pressure. The etch rate ratio can be changed using different etch gases or operating in different plasma modes (PE or IEPE). Changing from the ion enhanced plasma etching mode (IEPE) to plasma etching mode (PE) the etch rate ratio is changing by an factor of ten.

On the basis of etch rate dependences on process parameters and thermodynamic data it has been suggested the generation of flourine radicals as the rate limiting step. A general etching model has been proposed, which explains qualitavelty and quantitatively (on account of data from literature) the measured results.
The Structure of 4‐n‐Hexyle‐6‐(4‐cyanophenyl)‐1,5‐diazobicyclo [3.1.0]‐hexanone‐(2), C17H21N3O
Authors: Kulpe S. , Seidel I. , Menz I. , Geissler G. , Tomaschewski G.
Published: January 2007

Mr = 283.2; monoclinic, P 21/c, a = 9.631(7), b = 21.268(16), c = 8.488(8) Å, β = 107.13(9)°, Z = 4, V = 1661.8(9) Å3, Dx = 1.42 Mg m−3, final R = 0.134 for 605 independent reflections excluding those with |Fo| < 3σ|Fo|). Intensities were measured with an automatic diffractometer. The compound is a product of a photoreaction. The five membered ring and the three membered ring of the bicyclic diaziridine group and the six membered ring of the 4‐cyanophenyl group are nearly perpendicular one to another. The 4‐cyanophenyl group is in exo‐position to the five membered ring of the bicyclic diaziridine group. The C(4) atom and the aliphatic hexyle group are in respect to the five ring in trans‐position.
Crystallization and Separation of Pentaerythritol from Lubricating Oil Dispersant Additives
Authors: Najim N. A. R. , Barker P. E.
Published: January 2007

The experiments and techniques used in the study of the crystallization characteristics of pentaerythritol (PE) from a certain lubricating oil dispersant additive are presented. These experiments were performed with a view to improving the filtrability of the dispersant product and also to reduce the potential for sediment formation in the dispersant product during storage. Successfully tested methods for the elimination of this sediment formation at storage are also presented.
Physical Properties of Liquid Crystalline 5‐n‐Hexyl‐2‐(4‐n‐alkyloxyphenyl)‐pyrimidines
Authors: Hauser A. , Selbmann Ch. , Rettig R. , Demus D.
Published: January 2007

In 8 compounds of the substance class 5‐n‐hexyl‐2‐(4‐n‐alkyloxyphenyl)‐pyrimidines the clearing temperatures, transition enthalpies, densities and refractive indices were measured. Packing fractions, pressure dependence of the clearing temperatures, polarizabilities, order parameters and the anisotropy of the local field were calculated.
Effect of Fast Electron Irradiation and Annealing on the Luminescence in GaAs(Zn) crystals. Irradiation‐induced 1.26 and 1.39 eV Emission Bands
Authors: Glinchuk K. D. , Guroshev V. I. , Prokhorovich A. V. , Zayats N. S.
Published: January 2007

The effect of 2.2 MeV electron irradiation and subsequent annealings on the photoluminescence in zinc‐doped p‐type GaAs crystals is studied and analyzed. Rather strong emission bands peaked at hvm (77 K) near 1.26 eV (induced by electron irradiation) and 1.39 eV (induced by annealing of irradiated crystals) are observed. Evidence is presented that the 1.26 and 1.39 eV emission bands occur due to radiative electronic transitions in AsiZnGa and VAsZnGa pairs induced by irradiation and annealing of irradiated crystals, accordingly. The observed variations in the intensities of the 1.26 and 1.39 eV emission bands upon irradiation and subsequent annealings of GaAs(Zn) crystals are explained in terms of irradiation and annealing‐induced variations in the amount of 1.26 and 1.39 eV radiative centres resulting from: a) the effective interaction of mobile radiation‐induced defects in the arsenic sublattice with zinc atoms leading to the formation of AsiZnGa and VAsZnGa pairs; b) the thermal dissociation of AsiZnGa and VAsZnGa pairs on individual components.
Crystal Growth from Silica Gels and Single Crystal Structure of Bariumchromate
Authors: Lentz A. , Büchele W. , Schöllhorn H.
Published: January 2007

Rhombic single crystals of bariumchromate were grown in silica gels up to 1.5 mm in size. The influence of the initial pH‐value of the gel and the kind and concentration of reactants are studied. The crystal structure has been determined. The compound crystallizes in space group Pnma, with cell dimensions a = 9.113(4) Å, b = 5.528(3) Å, c = 7.336(4) Å and Z = 4. The structure was refined to R = 0.062 on the basis of 364 reflections. Every barium atome, centered in a distorted archimedian antiprism, is coordinated to 8 oxygen atoms each belonging to a chromate tetrahedron. Interatomic distances and bond angles were calculated.
The Morphology of Analcime
Authors: Ghobarkar H. , Franke W.
Published: January 2007

Synthetic analcime crystals were grown on hydrothermal conditions using different starting materials. The morphology of the crystals was compared with respect to natural analcime and the observations of HÖLLER as well as the Donnay‐Harker rule and geo‐metrical considerations.
Studies on Induced Smectic Phases (VI). The Role of the Ratio of the Molecular Lengths in Binary Mixtures of Smectogens
Authors: Szabon J. , Weissflog W. , Pelzl G. , Diele S. , Demus D.
Published: January 2007

In a number of binary systems composed of liquid crystalline terminal‐polar and terminal‐nonpolar compounds the SA phase induction was studied in dependence of the molecular length ratio r of the mixing components. It was found that there is a connection between the maximum temperature of the SAN or SA‐Is transition curve and the molecular length ratio r. Up to a certain ratio the smectic induction increases and after that it reaches a saturation.

The studies were completed by X‐ray and calorimetric measurements in selected binary systems.
Influence of γ‐Irradiation on Some Properties of NaCl:Eu++ Crystals (III). Strengthening Effects
Authors: Suszyńska M. , Czapelski M.
Published: January 2007

Mechanical strength of europium‐doped NaCl crystals was studied as function of dopant concentration and dopant dispersion state as well. It has been found that the yield stress of the solution‐treated samples is determined by the Snoek‐type reorientation of dipoles in the stress field of moving dislocations. For as received samples the precipitation strengthening mechanisms are postulated.

Irrespective of the dispersion state of europium, the strength of all NaCl:Eu++ crystals can be remarkably changed by the room temperature irradiation. Although the yield stress increments can be explained in frames of the precipitation‐strengthening mechanisms, the radiation‐induced processes depend on the primary disprsion e state of the dopant. As far as the solution‐treated samples the clustering of I.V. dipoles is of main importance, it is necessary to assume that dispersion of precipitates is required to achieve the strength of irradiated as received samples.
Crystal and Molecular Structure of the Smectogen 1‐[4‐n‐heptylbenzoyl]‐2‐[cyanoacetyl]‐hydrazine
Authors: Pfeiffer Doris , Kretschmer Rolf‐Günter , Hoffmann Siegfried
Published: January 2007

The compound 1‐[4‐n‐heptylbenzoyl]‐2‐[cyanoacetyl]‐hydrazine crystallizes in the triclinic space group Pl̄ with two molecules in the unit cell and the lattice parameters a = 4.702, b = 8.640, c = 20.906 Å, a = 97.50, β = 92.79, γ = 100.19°. The structure was solved by direct methods and refined by full‐matrix least squares calculations to the final residual value R = 0.039.
The Problem of a Near Surface Quasi‐Gas Transition Layer in MBE
Authors: Herman M. A.
Published: January 2007

A survey of experimental data related to the problem of a near surface quasi‐gas (NSQG) transition layer in molecular beam epitaxy (MBE) has been presented and the arguments suggesting the existence of such a transition layer have been discussed. Subsequently, the application of the NSQG layer concept to morphological stability analyzis of MBE and to the phase‐locked MBE has been discussed. The experimental data presented suggest that in growing extremely flat layer structures, e.g., superlattice structures, a growth mode for MBE should be chosen in which the NSQG layer is maximally thin, however, when growing planar epilayers over patterned substrates such MBE growth mode should be chosen in which the creation of a thick (on an atomic scale) NSQG layer would be possible.
Kinetics of Etching of Dislocations in Ferroelectric Ammonium Hydrogen Tartrate Single Crystals
Authors: Desai C. C. , Hanchinal A. N.
Published: January 2007

Ferroelectric crystals of Ammonium Hydrogen Tartrate (AHT) have been synthesised using the controlled reaction between NH4Cl and (CHOHCOOH)2 by diffusion process in silica gel medium. (010) cleavages of AHT crystals have been etched in 1.0 M and 1.5 M solutions of SrCl2 solution. The lateral and normal velocities of the growth of pits were measured at different temperatures. The time dependence of the growth of the pit dimensions is found to be linear, whereas the temperature dependence of the growth of pits is found to be exponential, viz. \documentclass{article}\pagestyle{empty}\begin{document}$ \[V = A\,\exp \left({\frac{E}{{kT}}} \right)\] $\end{document}. The dissolution parameters, e.g. the activation energies and the pre‐exponential factors for dissolution along the surface and along the dislocation lines have been computed. It is observed that the activation energy (E1) of dissolution along [001] direction is found to be greater than the activation energy (Eb) along [100] direction and the implications are discussed.
Peculiarities in the X‐ray Spectral Microanalysis of the SnTeI System
Authors: Assenov R. , Moshnikov V. , Patarov B. , Yaskov D.
Published: January 2007

This is an examination of the methodological specificities of the roentgenospectral microanalysis of the SnTeI system, involving the application of a graphoanalytical method used in the analysis of ternary systems according to data calculated for the binary ones. The calculations were made on an ES 1060 computer in FORTRAN‐4. The calculations are for different selection angles of the microanalyzer, and for a broad interval of values of the accelerating voltage. In this manner the method offered is applicable to any type of microanalyzer, and not only to the Cameca MS‐46 used by us.
Liquid Phase Epitaxy of SiC in the System TbSiSiC by Temperature Gradient Zone Melting (II). Liquid Phase Epitaxy of SiC from TbSi Solvent
Authors: Peev N. S. , Tairov Yu. M. , Smirnova N. A. , Kalnin A. A.
Published: January 2007

The liquid phase epitaxy of SiC by the gradient temperature zone melting in the SiTb solvent is studied. A new variant of this growth method is presented. The comparison of the new variant with the previous one shows that the new variant allows for epitaxial layers with significant better electrophysical properties. It is easier and can be carried out at lower temperature.
Structure of the OD‐disordered 2‐Hydroxy‐4‐methoxy‐2H‐1,4‐benzoxazin‐3‐one, C9H9NO4
Authors: Kutschabsky L. , Kretschmer R.‐G. , Schrauber H. , Dathe W. , Schneider G.
Published: January 2007

The X‐ray diagrams of the title compound show pronounced maxima on diffuse streaks parallelc* and unusual extinctions. The intensity distribution is compatible with the assumption of a disordered (OD) structure consisting of one kind of layers. The structure contains ordered domains with the crystal data: monoelinic, space group P 21/a, lattice parametersa= 15.910(5),b= 8.365(4),c= 15.747(5) Å, β = 120.34(6)°,V= 1809 Å3,Z= 8,Mr= 195.1,Dx= 1.432 Mg m−3, μ(MoKα) = 0.36 mm−1, finalR= 0.129 for 859 observed reflections. The asymmetric unit is constituted of two crystallographically independent molecules related by a pseudo glide plane. The crystal used for X‐ray analysis proved to be twinned.
Investigation of the Crystalline State of Identical Sample Domains by Means of Divergent X‐ray Beam Technique in the Direction of Transmission and Reflection in the Scanning Electron Microscope (SEM)
Authors: Däbritz Siegfried , Horn Herwig R. , Kleinstück Karlheinz , Waltinger Hanns , Hoffmann Volker
Published: January 2007

A supplementary device to a scanning electron microscope allows the simultaneous taking of wide‐angle interferences in the directions of transmission and back reflection of identical specimen areas. A developed computer program simulates the complete reflex system so that the identity with the pattern is obtained. This results, on the one hand, in qualitative and quantitative statements concerning the real structure of the specimen and, on the other hand, shadings of reflexes caused by the target holder tube can be distinguished from interruptions of reflexes caused by the grain size effects. The efficiency of the supplementary device for the characterizing of mono‐ and polycrystalline specimens is demonstrated by several examples.
X‐Ray Study of the Reaction Products in Tin Telluride Synthesized by a Low‐Temperature Iodide Method
Authors: Assenov R. , Moshnikov V. A. , Saunin I. V. , Yaskov D. A.
Published: January 2007

An examination is made of the separate stages of obtaining SnTe by the low‐temperature iodide method, involving X‐ray studies of the reaction products after each stage. It is demonstrated that the tin iodide, released at the isothermal annealing of the initial charge in the reactor, is in the form of SnT4, and not SnT2 as had been considered before.
Study of the Electronic Absorption Spectrum of Crystals of Transition Metal Iodate
Authors: Jianmin Li , Yongfeng Zhang , Jifa Fang
Published: January 2007

The electronic absorption spectra of spherocrystals of Ni(IO3)2 · 2 H2O, Mn(IO3)2 and 3 Cu(IO3)2 · 2 H2O were measured. Some new absorption peaks were obtained. Measured energy splitting by low‐symmetric crystal field and spin‐forbidden transitions are clearer than the results of diffuse reflection spectrum. And the experimental results were interpreted theoretically by means of nonfree radial wave functions and ligand field theory. The experimental results and the calculated values coincide.
Efficient conditions for the growth of MoO3 single crystals under oxygen atomsphere
Authors: Mohnhaupt M.
Published: January 2007

Single crystals of MoO3 have been grown under an oxygen atmosphere using a horizontal tubular furnace. The temperature and pressure necessary to grow satisfactory crystals in oxygen along [100] and [010] directions are determined.
Suppression of epitaxial silicon layer doping with boron in the presence of hydrogen chloride
Authors: Morgenstern Th. , Kühne H. , Kokovin G. A. , Testova N. A. , Titov A. A.
Published: January 2007

The present paper informs about thermodynamic calculations of the BClH system, carried out irrespective of data, already published by other authors. It further deals with recent experimental results on silicon doping with boron in the presence of hydrogen chloride, the layer growth rate being varied. Finally the possibility of quantitatively interpreting the suppressing influence of hydrogen chloride on the doping of silicon with boron is discussed.
Phenomenon of the maximum inhomogeneity in solidification of alloys from the peritectic‐eutectic phase systems
Authors: Wołczyński W.
Published: January 2007

An application of the Scheil equation with the purpose to: 1 describe the maximum dendritic microsegregation phenomenon, i.e. amount of the solid solution in function of the initial composition of alloys from the AgSb phase system, 2 determine the nature of the maximum microsegregation in the Ag–30 Sb and Ag–10 Sb alloys is presented.

A new relation, supplementary to the Scheil equation is proposed.
Characterization of water‐containing alunite (loewigite)
Authors: Aslanian S. , Minkova N.
Published: January 2007

Chemical analyses, IR‐spectra, differential‐thermal analyses and X‐ray diffraction studies of water‐containing alunite were carried out. These results were compared with those obtained for alunite. Group‐theoretical analyses of the vibrational spectra of alunite were performed. It is shown that water‐containing alunite has a structure similar to that of alunite, but inclusion of water molecules causes a lowering in symmetry and explains differences in the mineralogical characterizations of both alunites.
Reduction of crystal surface roughness to augment anti‐Caking Properties
Authors: Sarig S. , Fuchs J. , Kahara F.
Published: January 2007

Ammonium bromide crystals were grown in quiescent and stirred batch systems and in a continuous laboratory crystallizer at steady state. Urea was added in concentration of 5–20 ppm. The crystals were filtered out, dried, sieved and inspected by Scanning Electron Microscope. The effect of urea was evaluated by comparison between crystals grown by one of the techniques without an admixture and those grown within the presence of urea.

In quiescent batch solution pure ammonium bromide crystals grow in fern‐like large dendritic forms. Urea suppresses the characteristic branching. Stirring changes the habit into aggregates of small globular crystals. The addition of urea to a stirred batch system causes growth of separate ovoid crystals.

In a continuous crystallizer, at steady state conditions seemingly loose agglomerates of ammonium bromide are formed. No change visible at low magnification is brought forward by the addition of urea. However, at high magnifications the crystal surface of the pure ammonium bromide is brush‐like and rough, retaining the dendritic tendencies in the range of microscopic sizes. The addition of urea smoothes the surface.

The roughness of the pure ammonium bromide surfaces may explain its strong caking tendencies. Reduction of the roughness will probably decrease the caking in the polycrystaline mass. This assumption has to be checked in industrial production.
Growth of tartrate crystals of type R2 (C4H4O6)3 · xH2O (R = Nd, Dy) in silica gel
Authors: Kotru P. N. , Raina K. K. , Gupta N. K.
Published: January 2007

Spherulitic crystals of neodymium and dysprosium tartrates have been grown by controlled diffusion in silica gel. The operative mechanisms of crystallization are discussed and the morphological development of the spherulites is described. The adsorption property of gel is observed to play an important role in the growth of the spherulitic crystals.
Growth and microscopic studies of yttrium aluminium garnet single crystals
Authors: Kumar J. , Thirumavalavan M. , Gnanam F. D. , Ramasamy P.
Published: January 2007

A study has been made to understand the growth history and growth mechanism of flux grown yttrium aluminium garnet (YAG) single crystals. Etching has been done to reveal the growth patterns of flux grown crystals. Optical and scanning electron micrographs are presented. Optical micrographs were taken under polarised light and oblique incident light. The nature and origin of growth hillock is elucidated.
Oxidation of solid aluminium silicon alloys in air
Authors: Yaneva S. , Stojanova L. , Markov T.
Published: January 2007

The kinetics of oxidation of solid Al–Si alloys in air was studied at temperature interval between 490 °C and 532 °C. The initial time intervals in which oxidation is governed by a parabolic quadratic low were found form the weight time‐gain curves. At temperature higher than 512 °C the exponent of the parabolic ratio differs from 2.

It was shown the influence of the alloying element Si on the oxidation and the effective activation energies of oxidation of AlSi alloys were calculated. They are considerably higher than the effective activation energies for pure aluminium.
Characterisation of MoSexTe2−x (0 ⩽ x ⩽ 2) electrodes in terms of energetic location of valence and conduction bands
Authors: Agarwal M. K. , Patel P. D. , Joshi R. M.
Published: January 2007

The layer type MoSexTe2−x (0 ≦ x ≦ 2) has been grown by chemical vapour transport technique. The photoelectrochemical solar cells have been fabricated using the grown crystals as photoelectrodes and platinum grid as counter electrode in aqueous iodine/iodide solution. The optical band gap determination has been done from the study of the spectral response of the cells. The location of valence and conduction band edges and flat kind potentials have been evaluated using Mott‐Schottky plots.
Crystal structure determination of bis‐dimethyl heptamethine cyanine chloride, C11N2H19Cl · 4 H2O
Authors: Kulpe S. , Kuban R.‐J. , Schulz B. , Dähne S.
Published: January 2007

Mr = 286.59, monoclinic superposition structure C 121,Z= 4,a= 15.248(3),b= = 6.942 (3),c= 9.074(1) Å, β = 120.1(1)°,V= 827(1) Å3,Dm= 1.13(1) Mg m−3,Dx= = 1.15 Mg m−3, λ(MoKα) = 0.71069 Å, μ = 0.243 mm−1,F(000) = 312,T= 296 K, finalR= 0.061 for 802 reflections. All hydrogen atoms were located. The structure consists of chloride anions, bis‐dimethyl heptamethine cyanine cations and water molecules. The structure of bis‐dimethyl heptamethine cyanine chloride is disordered, e.g. there exist partial coincidence operations, leading to more than one stacking mode of the bis‐dimethyl heptamethin cyanine chains. The crystal structure consists of rows of molecule along thea‐axis. The CC bonds show the bond length compensation, typical of polymethines, towards a partial double bond (mean value 1.38 Å) between formally sp2‐hybridized C atoms. The CN bond lengths to the methyl carbon atoms (mean value 1.49 Å) correspond to normal CN single bonds. The valence angles at the C atoms of the heptamethine chain clearly alternate and deviate systematically from 120°. This is also observed in other structures of a similar type.

The structure determined by X‐ray analysis confirms the chemical results.
The crystal and molecular structure of hydrazine‐N, N′‐dicarbonic‐acid‐di‐(4‐chlorophenyl)‐ester Dihydrate, C14H10Cl2N2O4 · 2 H2O
Authors: Reck G. , Just M. , Koch R.
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 C2/c with cell parameters a = 30.719(8), b = 5.016(3), c = 10.946(8) Å, and β = 106.08(3)°. The structure was solved by direct methods and refined to R = 0.038. The drug molecule consists of two chemically identical parts, symmetry related by a two‐fold axis coinciding with that of the space group. Hydrogen bonds connect water and drug molecules forming infinite layers parallel to the y, z‐plane.
The precipitation of alkaline‐earth metal‐nickel, aluminium (chromium (III) and iron (III)), silicyl(titanyl and zirconyl) hydroxide, carbonate and oxalate precipitate precursors for alkaline‐earth metal oxyanion salt ceramics and allied materials – a review of small scale laboratory studies and industrial patents
Authors: Packter A.
Published: January 2007

The alkaline‐earth metal – nickel, aluminium, chromium III, iron III, silicyl, titanyl and zirconyl hydroxide, carbonate and oxalate coprecipitates are the precursors for the preparation of the corresponding alkaline‐earth metal oxyanion salt refractories, magnetics, dielectric and optical ceramics, cements and allied materials. The small‐scale laboratory studies on the coprecipitations of these precursor materials, their compositions and the coprecipitation mechanisms are reviewed and the relevant industrial patents are described (140 references).
Formation of inclusions in CaF2 single crystals
Authors: Dressler L. , Reimann R.
Published: January 2007

It is reported on formation of inclusions during the Stockbarger growth of CaF2. It the centre of this paper, hollows (gaseous or vacuum inclusions) are considered. Two different kinds of formation processes being possible under special growth conditions are discussed (segregation of gaseous impurity, entrapment of impurity‐rich liquid at cell boundaries of growth cells).
The current understanding of epitaxial CVD silicon doping in the light of modelling and theory development (I) empirical foundations and process controlling equations
Authors: Kühne H.
Published: January 2007

The paper sequently published in five parts deals with the logical interdependence between the technological process of silicon layer doping and the situation of its being empirically governed on the one hand, and its being theoretically explained on the other. The present first part of the paper concerns a brief description of epitaxial CVD silicon layer deposition and layer doping, the main controlling parameters of the latter, and how doping is governed by these parameters. The empirical basis knowledge linking the measuring control values of the process to specific layer properties in the form of control graphs, are transformed to more general empirical control equations of layer doping. Finally, representing the doping process analogous to cybernetic systems, an empirically based and nearly complete model equation is presented.
Twin laws explained by partitions of space
Authors: Follner H.
Published: January 2007

Twin laws of monoclinic potassium feldspars, potassium sulphate, cerussite and hexabromobenzene can be explained by partitions of space. The face indices of the crystals denote points of a lattice in the reciprocal space. A Fourier transform leads to the morphological lattice. The reciprocal crystal is the Dirichlet domain of the morphological lattice and the structural content consisting of groups of atoms or molecules is the morphological unit. The bond strength between neighbouring morphological units is proportional to the area of the common face of the reciprocal crystals. The reciprocal crystal represents the energetical structure of a crystal. Twins can be explained by continuation of the energetical structures across the twin boundaries. The symmetry operations result from pseudosymmetries of the reciprocal crystals. It is possible to predict planes favoured for the formation of twins or parallel grown individuals.
Heat capacity and lattice anharmonicity in CdBIVC chalcopyrite compounds
Authors: Möller W. , Kühn G. , Neumann H.
Published: January 2007

The heat capacity at constant pressure of CdSiP2, CdGeP2, CdSnP2 and CdGeAs2 is measured in the temperature range from 300 to 500 K. The anharmonic contribution to the heat capacity is evaluated and it is shown that the degree of lattice anharmonicity decreases with increasing atomic weight of the constituent atoms of the compounds. Comparing the temperature variation of the heat capacity and of the thermal expansion coefficient some conclusions are made regarding the interatomic potential in the AIIBIVC compounds.
Thermal expansion anisotropy and individual bond expansion coefficients in ternary chalcopyrite compounds
Authors: Neumann H.
Published: January 2007

The individual bond expansion coefficients of the AIIBIVC and AIBIIIC2VI chalcopyrite compounds are calculated from the principal linear thermal expansion coefficients of the lattice parameters using the regular BC tetrahedron model and a model with a temperature independent free parameter of the lattice. It is shown that the bond expansion coefficients derived from the latter model are in better agreement with the trends found for the interatomic forces in the chalcopyrite compounds and observed for the thermal expansion coefficients in the binary AC, AIIC and BC compounds.
Dielectric studies of lead nitrate phosphate single crystals
Authors: Desai C. C. , Ramana M. S. V.
Published: January 2007

Ferroelectric Lead Nitrogen Phosphate (LNP) single crystals have been synthesized using the controlled reaction between lead nitrate and orthophosphoric acid solutions by slow diffusion process in silicagel medium. The colourless transparent LNP crystals upto 6 × 4 × 3 mm3 in size have been grown at room temperature. The dielectric measurements have been carried out in the temperature range between 300 to 690 K. The effect of applied frequency on the dielectric constants and dielectric losses has been investigated. It has been observed that the mechanism of the dielectric behaviour is different in the lower and higher frequency and temperature ranges. The activation energy of the oscillators has been calculated and found to be 1.125 eV. Attempt has been made to draw some qualitative conclusions, taking in view, the existing theories of various kinds of polarizations and implications.
Natural convection during directional solidification of an AlZn eutectic
Authors: Tuček V. , Holeček S. , Kubíček L.
Published: January 2007

A study was made of the buoyancy convection of melt provoked by temperature gradient of an orientation identical to that of the gravity vector. The convection was assessed on the basis of temperature fluctuations in the melt. The critical Rayleigh numbers for periodic and turbulent flow were determined. Both periodic and turbulent flow gives rise to transverse “bands” in the structure of the eutection obtained by directional solidification. The intensity of unstable flow affects the number of eutectic crystallites in the sample.
Structure determination of polytypes (II)
Authors: Sedlacek P. , Kuban R.‐J. , Backhaus K.‐O.
Published: January 2007

In this part different methods for structure determination of polytypes with diffraction methods are described. These methods are applied to periodic polytypes consisting of one or more sorts of layers and to disordered polytypes consisting of one sort of layers. Furthermore an example for the determination of the structural principle is given.