bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystallization of potassium sulphate from glaserite
Authors: Mazzarotta B.
Published: January 2007

The crystallization of K2SO4 from aqueous solutions of glaserite (a double salt of sodium and potassium sulphate) was investigated in an MSMPR cooling apparatus at 35 °C. The precipitation of K2SO4 at an average purity of 93 wt.% was obtained and the crystallization kinetics were derived from the experimental data. The nucleation and growth rates here obtained were, respectively, remarkably higher and slightly lower than those relevant to pure K2SO4: this behaviour may be explained by a faster nucleation and a slower growth of crystals containing also Na2SO4. The effect of small (0.05%) calcium additions to the feed was also tested, which caused an increase of supersaturation and a depression of the growth kinetics, whereas the nucleation one was not appreciably modified.
Growth of manganese tartrate trihydrate in silica gel
Authors: Ramakrishnan V.
Published: January 2007

Growth of manganese tartrate trihydrate crystals in silica gel media with manganese chloride and manganese sulphate as the reactant is attempted. The reason for the occurrence of platelets along with dendrites in the case of manganese sulphate is discussed. IR, X‐ray, atomic absorption and thermogravimetric techniques are employed to characterize the grown crystals and the results are discussed.
An X‐ray diffraction refinement of the crystal structure of natural tetragonal analcime (NaAlSi2O6. H2O)
Authors: Pechar F.
Published: January 2007

An X‐ray diffraction analysis was performed on a single crystal of natural tetragonal analcime: (Na0.99K0.01)/(Al1.05Si2.02) O6/0.99 H2O, space group I 41/acd, a = 13.726(2) Å, c = 13.684(1) Å, V = 2578.1 Å3, Z = 16, Dobs = 2.26. Refinement of 260 independent reflections yields R = 0.028 (Rw = 0.033). The mean Si(Al)O distance is 1.636 Å and tetrahedral angle is 109.35°. The framework of tetragonal analcime is topologically the same as the cubic modification.
Estimation of point defect parameters of solids on the basis of a defect formation model of melting (III). Formation entropy and concentration of schottky defects (vacancies)
Authors: Uvarov N. F. , Bollmann W. , Hairetdinov E. F.
Published: January 2007

The formation entropy of Schottky defects (vacancies) is calculated from the entropy of fusion and the concentration xL = 0.125 of vacancies within the melt at melting point Tm. The formation of vacancies is connected with a decrease of the vibrational frequency of those lattice forming particles (atoms, ions, molecules) being neighbours of the vacancies. Theoretical values of the vacancy concentrations xs agree with those xs obtained with the help of experimentally determined free formation enthalpies of the defects.
Vickers indentation hardness of Hg1−xCdxTe
Authors: Fissel A. , Schenk M. , Engel A.
Published: January 2007

The Vickers indentation hardness of Hg1−xCdxTe has been measured as a function of composition x using monocrystalline samples of Bridgman and THM crystals and polycrystalline starting material at room temperature. The microhardness varied between 220 MPa (x=0) and 440 MPa (x=1), showing a maximum of 850 MPa at x ∼ 0.75, and was different between monocrystalline and polycrystalline samples. The “hardening rate” dH/dx is strongly dependent on the composition range and is discussed in context with solid solution hardening due to elastic interactions of solute atoms with gliding dislocations and ordering effects.
On the tapering of KDP single crystals
Authors: Orbán K. , Pártay G. , Lukács A. , Vannay L. , Sárközi J.
Published: January 2007

This paper presents some new facts about KDP tapering grown from aqueous solution with supplementary SEM studies. A mathematical model is given for the tapered crystals shape.
Interatomic force constants in AIIBIVCV2 chalcopyrite compounds
Authors: Neumann H.
Published: January 2007

Force constants of the AIICV and BIVCV bonds in the AIIBIVCV2 compounds with chalcopyrite structure are estimated from experimental lattice vibration data using a simplified version of the Keating model. It is shown that the force constants depend exponentially on the bond length. The parameters of this relation are practically the same as those found for the AIVAIV, AIIIBV and AIIBVI bonds in the elemental semiconductors and binary compounds and for the BIIICVI bond in the AIBIIICVI2 semiconductors.
Electrical conductivity and thermal dehydration studies of hydrated barium oxalate and barium cadmium oxalate crystals
Authors: Dharmaprakash S. M. , Rao P. Mohan
Published: January 2007

The measurement of electrical conductivity for the investigation of the number of water molecules present in the hydrated barium oxalate, and barium cadmium oxalate lattice have been carried out in the temperature range 30 to 415 °C. The dehydration temperature and the number of water molecules jettisoned out of the structure at a particular temperature is estimated from the sharp increase in conductivity at these points. The almost abrupt increase of conductivity is attributed to the increase in the number of mobile charge carriers viz., H+ and OH− ions generated from the escaping water molecules. Samples in the form of pellets with and without silver paste applied, showed different behaviour with respect to conductivity of the material upto the completion of dehydration. The study of electrical conductivity in association with the thermal behaviour has been used to understand the mechanism of conduction.
Technological properties of CSK‐1 crystallizer for material research in space
Authors: Barta Č. , Kuhl R. , Trnka J. , Tříska A. , Regel L. L.
Published: January 2007

The crystallizer CSK‐1 is based on a tubular furnace with five heating elements. The crystallizer operates in an automatic mode, i.e., the setting up of the temperature fields, setting of the sample position in the tube and of the rate and direction of their movement are controlled by a microprocessor running according to a program stored on a magnetic tape. The crystallizer is placed on the Soviet Orbital Laboratory “MIR”.

Basic technological properties of the crystallizer were studied by means of an standard probe connected with a computer and of the special ARP device, respectively. The topic of the study was especially the creation of various types of axial temperature fields and of various temperature gradients, the rate of heating and spontaneous cooling of the furnace, the temperature stability, and so on.
RHEED investigations of unusual crystalline states in amorphous SiO2 films
Authors: Peneva S. K. , Popova L. I. , Tcukeva E. A. , Atanassova E. D.
Published: January 2007

Microcrystalline regions of silicon dioxide with structures unobserved in the macro‐state are studied by Reflection High Energy Electron Diffraction (RHEED). Their formation can be understood by considering the existence of several possible relatively stable crystalline states of SiO2, with free energies higher than those of the known silicon oxides. SiO2 with structures and lattices identical to the structures and the lattices of the CaF2‐, of the rutile‐type GeO2, and of α‐PbO2 have been identified. Considerations for the state of silicon in some of these structures are also included.
Phase transition studies in 50CB and 80CB
Authors: Venkatacharyulu P. , Gupta A. V. N. , Rao J. V. , Prasad K. S. R. , Prasad N. V. L. N.
Published: January 2007

Investigations on the temperature variation of specific volume and ultrasonic velocity are carried out to study the phase transitions in the liquid crystals 4′‐n‐Pentyloxy‐4‐Cyanobiphenyl (50CB) and 4′‐n‐Octyloxy‐4‐Cyanobiphenyl (80CB). From these studies various parameters like the adiabatic compressibility (βad), molar sound velocity or Rao number (Rn), molar compressibility (B), Van der Waals constant (b) and the intermolecular free lengths (L) are estimated as a function of temperature in the isotropic as well as in the mesophases. Finally the variation of the order parameter with temperature in the nematic phase is studied and the results are discussed.
On cluster kinetics and MBE growth
Authors: Wolf B. , Gantz DP T. , Zehe A.
Published: January 2007

Based on the model of a so‐called Near Surface Transition Layer (NSTL) proposed by HERMAN and ANDERSSON we discuss the possible role of clusters during MBE growth. Moreover, intentional use of small clusters instead of single atoms as beam constituents may contribute to improvements in crystal quality even at low substrate temperature and high growth rate.
Wetting of InP by indium‐ and indium‐tin melts
Authors: Mareck DC U. , Gottschalch V. , Butter E.
Published: January 2007

Orientation dependent wetting of InP substrates by In‐ and InxSn1−x melts saturated with InP was studied using the sessile drop method. The contact angle was found to depend on the substrate orientation as follows:

It is shown that a tin admixture to the indium melt improves the wetting behaviour. Additional to the dependence on substrate orientation it was found an anisotropic wetting on all investigated faces.
Coefficient of volume expansivity and thermoacoustic parameters in certain alkoxybenzylidene butylanilines‐IA
Authors: Venkatachuryulu P. , Prasad K. S. R. , Prasad N. V. L. N. , Rao J. V.
Published: January 2007

A number of thermoacoustic parameters including the Sharma constant So are evaluated in the homologous series of alkoxybenzylidene butylanilines with m = 4 to 7, to understand whether these parameters can be used to understand the anomalous behaviour at the phase transition temperatures and pretransitional effects on either side of the transition. The Sharma constant which was shown to be a constant in a number of non‐mesomorphic systems is also found to be a constant for the mesogens belonging to this series both in their liquid crystalline as well as isotropic state. It is observed that almost all these parameters exhibit anomalous behaviour at the transition and pretransitional effects on either side of the transition. The results are discussed.
The crystallisation of alkaline‐earth metal phosphates from alkaline‐metal halide and alkali metal phosphate melts: Some preliminary solubility‐temperature phase diagram studies
Authors: Packter A. , Doherty W. O. S.
Published: January 2007

The solubility v temperature phase diagrams, for magnesium and calcium meta‐, pyroand orthophosphate solutions in the alkalineearth metal halide melts and in different alkali metal phosphate melts, have been analysed: these are the pseudo‐binary sections of the ternary P2O5MOMX2 and P2O5MONa(K)2O systems at MO/P2O5= 1, 2, and 3, respectively.

The temperature ranges and yields for crystallisations of alkalineearth, metal phosphates from these melt solutions are discussed.
The twisting of LiNbO3 single crystals grown by the Czochralski method
Authors: Erdei S. , Gabrieljan V. T.
Published: January 2007

As a result of our experimental work of mainly practical importance we established that for LiNbO3 single crystals the Mg and Fe dopants promote spirality whereas decreasing of the pulling velocity strongly reduces the propensity of the system to produce spiralshaped crystals.
Thermoluminescence and radiation‐induced volume changes in CaF2 (Mn, RE) materials
Authors: Zlateva E. , Levy S. , Gutzow I.
Published: January 2007

The thermoluminescence properties of various CaF2 materials (natural fluorite, CaF2‐glass ceramics and enamels) doped with RE oxides and Mn are investigated in details. Volumetric measurements show that γ‐irradiation leads to a change in the volume density of powder samples of these materials. Depending on the character of the sample, positive (increased volume) or negative dilatation (decreased volume) can be observed during irradiation with doses within the range 1 C/kg–9 C/kg. As time elapses, the radiation‐induced alteration of the sample volume is relaxed and after 2–3 months reaches again the initial volume density of the sample. The unexpected result of radiation‐induced volume changes are discussed in details accounting for supplementary X‐ray, electron microscopy and EPR studies.
Comparing investigation of the smectic C and A phases of the di‐n‐alkyl 4,4′‐azoxycinnamates (II) X‐ray studies
Authors: Diele S. , Schiller P. , Wiegeleben A. , Demus D.
Published: January 2007

The paper continues the investigation of the smectic C and A phases of the title compounds which has been done in Part I by DSC calorimetry. Here the layer spacings in the SC and SA phases are presented which exhibit a remarkable different temperature dependence in the SC phases within the homologous series. A tendency of a change from a second order SC/SA transition to a first order transition has been found. The layer spacings of the SA phase show a chain length dependent difference to the lengths of the molecules which may be explained by an increasing amount of gauche conformations in the higher homologues.
Morphology of TiN whiskers
Authors: Wokulski Z.
Published: January 2007

Crystallization of titanium nitride was conducted by the CVD method in a temperature range from 950 to 1450 °C using a TiCl4 + N2 + H2 gas mixture. The influence of type of substrate used on the growth on TiN whiskers was studied. It was ascertained that the growth of TiN whiskers took place at a substrate temperature T ≧ 1200 °C. On the basis of optical microscope and SEM observations and also of X‐ray examination and measurement of angles using an optical reflection goniometer, a detailed description was made of the observed TiN whiskers growth forms. It was found that [111], [110] and [001] whiskers exhibit tip shapes that are characteristic of the given orientation. From the Hartman PBC theory the nature of the faces occurring was determined. It was also shown that the most important is the {111} F face. The stoichiometric composition of the TiN whiskers obtained was estimated and it was ascertained that these whiskers have a composition from Ti0.98 to TiN0.993.
Effect of vibration frequency and sample composition on acoustic properties of YBaCuO high‐Tc superconductors
Authors: Pal‐Val P. P. , Natsik V. D. , Engert J. , Kaufmann H.‐J. , Rudolph K. , Matz W.
Published: January 2007

Temperature dependences of absorption and velocity of longitudinal ultrasound in high‐Tc ceramics YBaCuO with different Y and Ba content at frequencies 100 kHz and 7.5 MHz are studied in the temperature range 6 to 300 K. For 100 kHz three peaks at 60, 140, and 230 K are observed in the temperature dependences of decrement. Temperature dependences of sound velocity show a broad hysteresis for thermocycling. The temperature boundaries of hysteresis and peak locations are almost independent of sample composition. Sizes of hysteresis and peak heights are very different in samples of various composition. For 7.5 MHz, a peak was found at 210 K in the temperature dependences of ultrasound absorption increment. It is shown that the acoustic anomalies are due to a structural phase transition of martensitic type. Thermoactivation parameters of the main microscopic mechanism responsible for the phase transition are estimated.
Electrooptical coefficients and temperature and pressure derivatives of the elastic constants of tetragonal Li2B4O7
Authors: Bohtý L. , Haussühl S. , Liebertz J.
Published: January 2007

New values for the following properties of tetragonal Li2B4O7 are reported: dielectric, electrostrictive, electrooptic, elastic, thermoelastic and piezoelastic constants, coefficients of thermal expansion and indices of refraction. These values are considered to be of superior precision compared to earlier published data. Most elastic constants possess positive temperature derivatives. This anomalous behaviour is not reflected in the pressure derivatives. The electrooptic effects are not large enough to compete with other materials used for technical applications.
Twinned crystals of corundum grown from cryolite flux
Authors: Watanabe K.
Published: January 2007

The twinning form and its formation mechanism of corundum crystals grown from cyrolite flux by the stationary and rotational seeded methods are described briefly.
On the correlation of lattice defects to HUBER‐etch pit morphologies on (001) surface of InP
Authors: Knauer A. , Zeimer U. , Sprenger R.
Published: January 2007

Various analytical techniques (defect etching, optical microscopy, X‐ray topography (XRT), cathodoluminescence (CL) were combined to get information about the real structure of Sn‐ and S‐doped LECInP. The S‐pits, produced by the HUBER‐etch, were not only caused by microdefects, as it was described in literature. We found a correlation between S‐pits and special types of dislocations.
X‐ray studies of thermal expansion and phase transitions in (NH4)2SbF5 crystals
Authors: Waśkowska A. , Czapla Z.
Published: January 2007

X‐ray diffraction studies of phase transitions in (NH4)2SbF3 single crystals have been made by using the Bond‐type diffractometer for high‐precision measurements of the unit‐cell dimensions in a function of temperature. The principal linear thermal expansion coefficients and the linear Eulerian strain tensor have been calculated in the temperature interval 110 – 298 K. The phase transition diagram was proposed and the sequence of the phases has been compared with the results of other experimental techniques (NMR, NQR, DTA, electrophysical methods).
Microhardness of ZnSe and its change by proton implantation
Authors: Ascheron C. , Neumann H. , Kühn G. , Haase C.
Published: January 2007

The load dependence of the Vickers microhardness of the (001) plane of ZnSe crystals is studied in the load range from 5 to 160 g. From a comparison with literature data it is concluded that the microhardness of ZnSe is anisotropic according to H(001) ≈ H(111) > H (110). The indentation size effect of the (001) plane is less pronounced than that of the (110) plane. Proton implantation is found to increase the microhardness of ZnSe.
Investigations of the crystal growth of PbMoO4 by the Czochralski method
Authors: Pfeifer E. , Rudolph P.
Published: January 2007

The thermal conditions at the liquid/solid interface are characterized by temperature measurements in the melt and on the growing crystal with 〈001〉‐seed orientation. The thermal boundary layer was determined, from which the relation of effective thermal conductivity of the liquid and solid phase was found to be λl,eff/λs,eff = 0.25. The liquid/solid interface is extremly convex towards the melt and has a conical shape. When the crystal diameter reaches a certain value the cone was truncated with the formation of a facet in the centre. This typical interface shape is mainly the result of a difference between the effective thermal conductivity of melt and crystal.
On the thermodynamic stability of disperse systems
Authors: Bliznakov G. M. , Delineshev Sv. P.
Published: January 2007

Investigation has been carried out on the effect of the surface activity of capillary or surface active substances (impurities), called surfactants (i.e. the effect of the lowering (Δσ) of the specific surface energy after impurity adsorption at the solid/gas, solid/liquid, liquid/gas or liquid/liquid interface), on the thermodynamic equilibrium in a polydisperse system. Attention has been paid to the fact that the presence of a surfactant with an activity within the range 0 < Δσ < σ0 (where σ0 is the specific surface energy of an adsorption‐free interface) reduces the thermodynamic driving force for the appearance of the Gibbs‐Thomson effect and for the recondensation (recrystallization) processes in the heterogeneous polydisperse system.

It is shown that with an impurity activity Δσ = σ0, the supersaturation becomes zero and the condensed phase formations should be, irrespective of their size and shape, in equilibrium with one another because their vapour pressure becomes equal to that of an infinitely large phase. In this case the Gibbs‐Thomson effect completely disappears, the system become thermodynamically stable and, regardless of its polydispersity, it can exist infinitely long. The behaviour of such a heterogeneous system, which is far from its critical point (the system temperature is T ≪ Tcritical), is similar to the behaviour of a system in the region of its critical point: the surface tension becomes nearly equal to zero, and the fluctuations sharply increase.

The case when the surfactant activity is so high (Δσ > σ0) that σa = σ0 − Δσ < 0 (σa, specific surface energy of the interface in the presence of a surfactant), is of special interest. It represents a paradox in the phase formation theory: as a result of the adsorption of an impurity with such a high activity, the condensed phase surface would be destabilized and the phase would be spontaneously dispersed.
A contribution of diffusion‐induced structural changes on the anisotropy of the diffusion of P in Si
Authors: Larikov L. N. , Bogdanov E. I. , Maximenko E. A.
Published: January 2007

It was investigated the contribution of diffusion‐induced structural changes on the anisotropy of P diffusion into the monocrystalline Si. Generation and distribution of dislocations by solute diffusion of phosphorus in silicon (100) and (111) provides for further different depth penetration of diffusion precipitation up to anisotropic diffusion in cubic crystals.
Infrared lattice vibrations of In2O3
Authors: Sobotta H. , Neumann H. , Kühn G. , Riede V.
Published: January 2007

Infrared reflectivity spectra of In2O3 samples pressed from powdered material are measured at room temperature in the wavenumber range from 180 to 4000 cm−1. A Kramers‐Kronig analysis of the spectra reveals eleven vibrational modes. The results obtained are compared with group theoretical predictions and with existing experimental data.
Dynamic etching of natural rhombohedral calcite cleavage planes
Authors: Mehta B. J. , Sidpara G. R.
Published: January 2007

Dynamic etching of natural rhombohedral calcite cleavage plane in low concentration of monocarboxylic acid (such as formic, acetic and propionic acids) is studied and interesting results are obtained. Eccentricity of rhombic etch pits increase indefinitely as stirring rate increase in low concentration of monocarboxylic acids, whereas peak value of eccentricity is obtained with stirring rate when there is a change in etch pit morphology. Change in etch pit morphology and change in eccentricity with stirring rate is explained with the help of lateral reaction rates along various directions. Eccentricity variation with stirring rate is compared with concentration variation with concentration of different monocarboxylic acids.
New X‐ray rietveld refinement of kaolinite from Keokuk, Iowa
Authors: Smrčok Ľ. , Gyepesová D. , Chmielová M.
Published: January 2007

The positions of 13 non‐hydrogen atoms in the structure of kaolinite from Keokuk, Iowa, were refined in the space group C1 using the constrained X‐ray Rietveld refinement. The precision and accuracy of the atomic positions are better than those previously reported. The most frequent e.s.d.'s of the positional parameters range from 0.003 to 0.005; the SiO bond distances are from the interval 1.56(4)–1.68(3) Å, and the AlO from 1.80 (5) to 2.07 (5) Å. The ditrigonalization angle α characteristic for tetrahedral sheet was found to be 9°, this value is in good agreement with the 11° reported from single crystal data. The correction for preferred orientation was in the form of exp (G cos (2α)), the final factors of agreement were Rwp = 23.1%, RF = 9.2% and S = 1.4.
Mathematical modelling of crystal growth processes in gel
Authors: Cipanov A. V. , Goshka L. L. , Kolosov S. I. , Ruzov V. P.
Published: January 2007

This paper suggests a mathematical model of processes occurring during nucleation and crystal growth in gels. Calculations showed that there is a locality in a gel that provides the best conditions for nucleation and growing of crystals. Possible reasons restricting crystal growth are discussed. The qualitative agreement of calculations and experimental data allows to assume that the model suggested adequately describes processes occurring during crystal growth. Experimental data interpretation in terms of the model allowed to obtain the diffusion constants of reagents in a gel and the crystal growth rate.
Electron microscopic investigations on optical oxide single crystal
Authors: Malicskó L.
Published: January 2007

Scanning and transmission electron microscopic methods including energy dispersive X‐ray spectrometry and reflection high energy electron diffraction as well, were used for the inspection of the growth, the shape‐processing and the laser irradiation induced defects in pure and doped optical oxyde single crystals. Some general results will be presented and discussed in the light of theoretical predictions.
Reversible and irreversible field‐induced deformations in planar and weakly‐tilted smectic C phases
Authors: Pelzl G. , Schiller P. , Demus D.
Published: January 2007

It was found that the dielectric reorientation of planar or weakly‐tilted Sc phases can take place by domain wall motion accompanied by hysteresis effect. For special boundary conditions the field‐induced deformations can become irreversible. At high electric fields an irreversible transition of a planar texture into a schlieren texture is observed. The experimental results are interpreted threoretically.
The investigations on the synthesis of zeolite ZSM‐5 (II)
Authors: Wilkosz J. , Stobiecka E. , Dudek B.
Published: January 2007

Physical parameters, i.e. the effect of temperature and time of crystallization on the content of zeolite ZSM‐5 in the obtained preparations were investigated. Two standard reacting mixtures were tested. The mixture of ethanol and ammonia was used as a templating agent. The phase composition of the preparations was determined on the ground of the X‐ray diffraction method.
Melting and crystallization of silicon layers on insulator with millisecond lamp heating
Authors: Aleksandrov L. N. , Zinovyev V. A.
Published: January 2007

Melting and crystallization of silicon layers in a SOI structure (SiSiO2Si) at millisecond lamp heating have been studied by model calculations using the solution of conduction equation. Pulse heating conditions that do not lead to silicon substrate melting under SiO2 have been determined. For pulses of 1 and 4.4 ms duration the silicon melt lifetime on the SiO2 surface has been estimated. The lengths of the crystal oriented growth from windows in the SiO2 layer that open the single‐crystalline silicon substrate have been measured (25 and 64 μm).
Some results of microscopic and X‐ray investigations of calcium carbide
Authors: Hahne B. , Gordziel W. , Meerbote E.
Published: January 2007

The structure of calcium carbide is investigated using thin sections and ground sections. Depending on chemical and other factors, calcium carbide occurs in three types of structure, which are interpreted as conversion products resulting from a high‐temperature structure.

The pavement‐like structure containing CaC2‐I is present in industrial carbide with a low content of nitrogen. With increasing fraction of lignite high‐temperature coke used for carbon supply as a substitute for coal coke in the production of carbide, the particle size decreases, and the micro hardness increases.

The interlocked structure with CaC2‐II and higher contents of nitrogen, which has been detected in carbide produced in the laboratory, is extremely dense. No grain sizes can be given. This kind of carbide produced in the laboratory has a lower micro hardness than industrial carbide.

The mixed crystal structure is typical of carbide with a high content of sulphur. CaC2—CaS‐I is present as a phase.

In all three types, the respective carbide phases have a marked lamellar structure. No typical shapes of crystals can be detected. In consequence of poor crystal formation, the information obtained with a microscope about the phases contained in the material investigated is complemented by X‐ray diffraction methods.
Photoemission core level and satellite study of TixRu1−xoxide layers
Authors: Wagner N. , Horx M. , Jacobs M.
Published: January 2007

Combined photoemission core level and satellite structure investigations of pyrolytic titanium‐rich TixRu1−x‐oxide layers (0.90 ≦ x ≦ 0.97) and RuO2 layers on titanium are used to gain structural and compositional information about these electro‐catalytically active surfaces. By means of this method deviations from stoichiometry, the formation of carbon interstitials and the growth of anatase by ruthenium loss could be pointed out.
Kinetic investigations within the transition region from polyhedral to skeletal growth mode (III). Growth kinetics of the basal face of zinc single crystals and its edge under diffusion conditions
Authors: Iwanov D.
Published: January 2007

The growth kinetics of the basal face and its edge of zinc single crystals grown from zinc vapours in the presence of argon at pressures 5 – 250 Torr has been investigated simultaneously. The alterations of the crystal size R and the length of the basal edge a with time t have been measured at constant temperature and supersaturation. It is shown that the R2(t) and a2(t) dependences change their initial shape into linear at one and the same moment. It is established that the transition from a kinetic to a diffusion regime can be determined both by the kinetic critical size Rk and by the kinetic critical size ak. It is found also that in the kinetic regime the lateral growth rate of the basal edge is higher than the normal growth rate of the {0001} face. During the growth in a diffusion regime the R2(t) and a2(t) curves of a given single crystal become parallel, due to the isotropic character of the transport processes of the material. The rate determining role of the diffusion in the parent phase on the growth of the basal face and its edge is demonstrated.
On the chemical vapour transport of nickel titanate with selenium tetrachloride
Authors: Bieger W. , Piekarczyk W. , Krabbes G. , Stöver G. , van Hai Ngyen
Published: January 2007

The chemical vapour transport (CVT) of NiTiO3 with SeCl4 is reported. In addition to small NiTiO3 crystals a more or less quantity of solid NiCl2 is deposited in the deposition zone. At higher temperature gradients the solid which is deposited besides NiCl2 is NiO. The transport behaviour is satisfactory explained using two thermodynamical models: the model of connected equilibrium states and the four‐stage model.
Lattice parameter variation in inp related to the dopant element and doping level
Authors: Knauer A. , Kräusslich J. , Kittner R. , Staske R. , Bärwolff A.
Published: January 2007

The variation of the lattice constant was determined across (001) InP wafers from 〈111〉 grown LEC INP: S and InP: Sn + Ga + As monocrystals. The variation correlates to the free carrier distribution. The enrichment of dopants results in lattice spacing in the crystal core (especially for InP: Sn + Ga + As), which occupy a larger region as dopant enrichment do.
In‐situ doping of LPCVD poly silicon (II). Temperature influence
Authors: Kühne H. , Puk P. , Gericke M. , Bertoldi W.
Published: January 2007

Poly silicon deposition by pyrolysis of silane under low pressure conditions has been investigated with respect to the influence of temperature when simultaneously in‐situ doping of the deposited layer takes place.

The growth rate of poly silicon is retarded in the presence of phosphine provided that a certain lower PH3/SiH4‐ratio has been exceeded. It has been shown how that lower ratio depends on temperature.

Increasing PH3/SiH4‐ratio not only slows down layer growth rate but also the apparent activation energy of the layer forming reaction. An empirical equation describing the temperature dependence of that activation energy has been derived. Phosphine adsorption has been discussed as a cause of both layer growth rate and activation energy reduction. Additionally, incorporation of phosphorus during layer growth has been investigated with respect to the total amount and the electrically active concentration, the latter measured after a postdeposition anneal at 1000 °C.
Defects in quartz crystals initiated during their hydrothermal growth
Authors: Nanev N. , Wilkens M.
Published: January 2007

A complex investigation (performed by means of X‐ray topography, γ‐ray diffractometry, optical methods) of the defects in as‐grown and tempered quartz single crystals has been described. The results should contribute to the improvement of the quality of hydrothermally synthetized quartz.
Influence of annealing conditions on structural properties of YBaCu oxide superconductors
Authors: Rauschenbach B. , Neelmeijer C. , Schuster G. , Knothe P. , Erfurth W.
Published: January 2007

The chemical composition, the topography, and the defect structure of high‐temperature superconducting YBaCu oxide samples have been studied in dependence on the annealing conditions by scanning electron microscopy, energy dispersive X‐ray analysis, Rutherford backscattering, nuclear reaction analysis, and transmission electron microscopy. The topography is characterized by smooth and rough grains. The chemical composition of samples varies in dependence on the annealing time and temperature. The microstructure of the superconducting material is dominated by a lamellar twin structure.
Filled SAphases in binary liquid crystalline systems of terminal‐nonpolar compounds (III). The role of the molecule length of the rod‐like component
Authors: Pelzl G. , Humke A. , Diele S. , Ziebarth S. , Weissflog W. , Demus D.
Published: January 2007

The phase diagrams of 8 binary systems of liquid crystals are presented whereby one component is a “biswallow tailed” compound and the second component is a member of the homologous series of 4,4′‐bis‐n‐alkyloxy‐azoxybenzenes. In all phase diagrams studied induced smectic A phases occur. X‐ray investigations give evidence that in the binary systems of short‐chain homologues the layer spacing d of the smectic A phase is clearly greater than the average molecular length L̄, whereas in the systems of long‐chain homologoues d is found to be somewhat smaller than L̄. The results are interpreted on the basis of a simple packing model.
Optical absorption spectra of magnesium‐implanted GaP
Authors: Hörig W. , Bouamama Kh. , Neumann H. , Nobes M. J.
Published: January 2007

Optical absorption spectra of magnesium‐implanted GaP single crystals are measured in the photon energy range below the fundamental edge. It is found that implantation results in the formation of exponential absorption tails with tailing energies up to about 0.8 eV and absorption coefficients up to about 105 cm−1 at 2.0 eV. The results are compared with optical measurements on GaP single crystals implanted with other ions and with optical absorption data of amorphous GaP.
Effect of temperature on dielectric properties of SnO2/Sb2O3 mixed thin films
Authors: Kumar J. Siva , Rao K. V. Styatanarayana , Rao U. V. Subba
Published: January 2007

Thin films of various thicknesses in the MIM structure have been prepared from the powder of SnO2/Sb2O3 mixed sample by the thermal evaporation technique in a vacuum of 10−5 Torr. Dielectric properties of SnO2/Sb2O3 mixed thin films have been studied with temperature starting from LNT to RT and above RT and frequency ranging from 100 Hz to 16 kHz. The activation energy for the migration of charge carriers in SnO2/Sb2O3 mixed thin films has been calculated and it is found to be 0.23 eV. The results thus obtained on dielectric properties of SnO2/Sb2O3 mixed thin films are presented and discussed.
The current understanding of epitaxial silicon layer doping in the light of modelling and theory development (X). Once more autodoping mechanism
Authors: Kühne H.
Published: January 2007

Special disadvantages associated with interpreting and describing the course of autodoping profiles by means of applying the “consequent” as well as the “improved” conception of dopant incorporation will be discussed. In order to find a solution of the problem special lateral autodoping experiments were carried out. Substrate wafer surfaces were exposed to a defined arsine flow under epitaxy‐near conditions but without the supply of silane. After the arsine flow had been stopped a thin epitaxial layer was intrinsically deposited on the exposed surfaces and after that, the dopant dose incorporated measured. In this way a time‐dependent increase of dopant dose in the layer with adsorption‐like behaviour and a growth rate dependent increase with gas‐phase‐doping‐like behaviour has been confirmed.

From the results desorption rate constant as well as its temperature dependence has been evaluated and a mechanism of autodoping concluded. The latter is characterized by both adsorption and desorption of dopants. Adsorption is expected to take place mainly outside of substrate wafer surface before layer growth begins. Desorption from those adsorption regions proceeds after layer growth has started leading to a time‐dependent, decaying partial pressure of dopants in the gas. That partial pressure of dopants regulates autodoping.
IR‐ and 27Al‐NMR‐spectroscopic studies on thermal decomposition products of basic aluminium chlorides
Authors: Brand P. , Müller D. , Gessner W.
Published: January 2007

The formation of corundum by thermal decomposition of basic aluminium chlorides was studies by means of spectroscopic methods (IR, 27Al‐NMR). It was tried to get information about the short‐range order, because favourable structural conditions in the amorphous precursors for the formation of corundum were supposed. For this purpose IR‐spectroscopy turns out to be the less informative method. 27Al‐NMR‐spectra show resonances of tetrahedrally, octahedrally and fivefold coordinated Al in the decomposition products. The corundum proceeds from sixfold and fivefold coordinated Al.
On steady‐state modelling of the high‐pressure liquid encapsulated czochralski (HPLEC) crystal growth of InP (Conduction Model)
Authors: Böttcher K. , Krüger A. , Schleusener B.
Published: January 2007

The steady‐state temperature distribution of the growth system is calculated at various stages of the growth process. The results indicate a serious influence of the thermal transparency of the B2O3. The heater power which has to be adjusted in order to achieve a constant diameter growth is calculated as an inverse problem.
A new method of enlarging the cross‐section of KDP using ADP crystals as seed
Authors: Feng Pan , Jinkui Liang , Genbo Su , Qinglan Zhao , Youping He , Yisen Huang
Published: January 2007

A new method of enlarging the cross‐section of KDP crystals using an easily enlarged ADP crystal as seed for a KDP crystal, has been investigated. The growth characteristics of the ADP seeds (Z‐plate, cap, and parallelly spliced seeds) at KDP supersaturation have been observed. Chemical etching was used to characterize the grown crystals, and chemical analysis to determine the composition of both the region of the seed and the grown crystal. The mechanism of this kind of growth is discussed. In conclusion this growing method should be qualified for enlarging the cross‐section of KDP crystals.
Infrared photoluminescence ‐ a tool for HgCdTe crystal research
Authors: Tomm J. W. , Schmidt H. , Werner L. , Herrmann K. H.
Published: January 2007

Material and structural parameters of narrow‐gap p‐type HgCdTe are investigated by infrared photoluminescence. The method is used for analyzing the energy gap, the carrier lifetime, and heterointerfaces and to monitor defects like inclusions. The spatial distribution of the quantities mentioned has been investigated by applying the mapping technique known for III – V semiconductors. The methods is a powerful tool for both crystal growth and device manufacturing.
Three X‐ray diffraction methods for testing of large disk‐shaped or lentiform CaF2‐crystals for high‐performance optics
Authors: Dressler L. , Kafka F. , Krässlich J. , Wehrhan O.
Published: January 2007

Three methods (Lang‐topgraphy, one‐crystal‐rocking curves with scan‐step‐registration, two‐crystal‐diffractometry (TCD) with a large registered area) were tested. The reached parameters as well as advantages and disadvantages are discussed. The purpose of the examination is the application of CaF2‐crystals with high diameters (⪆ 100 mm) in high‐performance optics for the UV‐lithography. Especially in this context the influence of defects of the crystal structure on the index of refraction has been examined.
Origin of defect centers in multilayered GaInAs and their influence on photoluminescence spectra
Authors: Popov A. S. , Ivanova E. A.
Published: January 2007

The one‐, two and three‐layered GaInAs structures grown on GaAs substrates by LPE have been investigated. The luminescence analysis with HeNe laser‐beem excitation and crystal diffractions were used for characterization of the structures. It was established that the thickness of the first layer has an optimum, below which the influence of structural defects is considerable.
Comparative Photoemission Study of the CuInC Chalcopyrite Compounds
Authors: Sommer H. , Weiss A. , Neumann H. , Tomlinson R. D.
Published: January 2007

Photoemission spectra of all CuInC2VI chalcopyrite compounds are measured at Hel line excitation and of CuInS2 also at excitation with ZrMζ radiation. It is found that the In5s – chalcogen p bonding states shift to lower binding energies with increasing anion mass. The energetic position of the S3s band of CuInS2 is also determined. The experimental results obtained are compared with previous measurements and with theoretical band structure calculations.
Auger depth profiling of BaTiO3 ceramics
Authors: Berndt K. , Rammelt B. , Heichler S. C. W.
Published: January 2007

We investigated the sputter depth profiling of BaTiO3 by means of Auger Electron Spectroscopy. A quantitative analysis was done for ceramic and single crystal material. Sputtering yield for 2 and 3 keV Ar+ ions was determined. For under UHV conditions fractured specimens no preferential sputtering was found. Mechanically polished or contaminated ceramic specimens show preferential sputtering of Ba or Ti. Using sputtering – heating cycles we succeeded in preparing non‐contaminated but ion beam mixed surfaces which are stable upto 150 °C.
General classification of crystalline materials used in modern technology
Authors: Brekhovskikh S. M. , Rez J. S.
Published: January 2007

Scientific bases of the general classification of crystalline materials such as single crystals, polycrystalline materials and glass ceramic have been expounded. In the systematic procedures the materials are signified by the applicability formulas. Materials belonging to the certain taxons as well as their ability to carry out some official functions under the given conditions of the relationship with the factors of the environment are also determined by the applicability formulas.
Diode n‐p CuInSe2 Structures Fabricated by Oxygen Implantation
Authors: Medvedkin G. A. , Yu. Rud V. , Yakushev M. V.
Published: January 2007

The influence of oxygen implantation on the electrical features of n‐type CuInSe2 single crystals has been studied. n‐p type conversion in the implanted region has been observed. Photoelectric characteristics of the fabricated structures have been examined. It has been shown that ion implantation allows to fabricate CuInSe2 photoconverters with the absolute current sensitivity up to Si = 33 mA/W at 300 K.
X‐ray powder diffraction and Raman spectroscopy studies of phase transitions in zinc(II) hexaaquonitrate below 300 K
Authors: Borzęcka‐Prokop B. , Kapturkiewicz E. , Weselucha‐Birczynska A. , Hodorowicz S. A.
Published: January 2007

Structural phase transitions in zinc(II) hexaaquonitrate have been studied below 300 K by Raman spectroscopy and X‐ray powder diffraction. Changes of A1 nitrate and OH bands together with diffractograms as functions of temperature are presented. The compound undergoes several transitions and four previously unreported modifications were found and characterized.
Empirical relationship between hall mobility and hole concentration in heavily doped p‐type GaAs
Authors: Neumann H.
Published: January 2007

Using Matthiessens' rule and assuming a constant mobility contribution due to lattice scattering an empirical relation is derived for the Hall mobility at room temperature in p‐type GaAs as a function of the hole concentration in the range from 1018 to 1020 cm−3. The resulting empirical concentration dependence of the mobility due to ionized impurity scattering is compared with the Brooks‐Herring formula. The degree of compensation of p‐type GaAs liquid phase epitaxial layers doped with germanium is estimated from the measured Hall mobility and compared with corresponding data obtained from an analysis of the temperature dependence of the hole concentration.
Preparation and optical absorption properties of one‐dimensional organic electron conductors
Authors: Robles‐Martínez J. G. , Salmerón‐Valverde A. , Soriano C. , Alonso E. , Zehe A.
Published: January 2007

A series of metal containing organic compounds of the M[HNAFIN]2 · 2TCNQ‐type, being M either Ni, Pd, Pt, Cu or Zn, have been prepared and studied in respect to infrared absorption spectra. Characteristic IR absorption spectra for each of the compounds are manifest, depending on the nature of the metal introduced. In particular is the C  N stretch mode absorption spectrum for Ni‐containing compounds rather sharp and single peaked, while Pt and Zn containing compounds present more complex features.
Growth and microhardness studies of melt‐grown lead (II) chloride single crystals
Authors: Sagayaraj P. , Sivanesan S. , Baskar K. , Gobinathan R.
Published: January 2007

In the present work, lead (II) chloride material is purified by directional solidification and single crystals of PbCl2 are grown by vertical Bridgman technique employing double zone furnace. The growth conditions and the problems overcome are discussed. The grown crystals of pure and K+‐doped crystals are cleaved and subjected to microindentation tests. The validity of Kick's relation is checked, the value of K1 the standard hardness number and n the work‐hardening coefficient are discussed. The microhardness behaviour of pure and K+‐doped lead(II) chloride have been compared.
Preparation and fundamental physical properties of Sn2SbS2I3 and Pb2SbS2I3 compounds
Authors: Starosta V. I. , Kroutil J. , Beneš L.
Published: January 2007

The oriented ingots of isostructural compounds Sn2SbS2I3 and Pb2SbS2I3 were prepared using a modified Bridgman method. The lattice parameters of the prepared orthorhombic compounds have been determined by a X‐ray powder diffraction analysis. From the spectral response of the photoconductivity the following values for the forbidden zone of the prepared sulfides‐iodides were found: Eg(Sn2SbS2I3) 1.5 eV, Eg(Pb2SbS2I3) = 2.0 eV.
Influence of the Curvature Dependence of Interfacial Energy on Homogeneous Nucleation Kinetics
Authors: Kožíšek Z.
Published: January 2007

Influence of the curvature dependence of surface tension on nucleation rate and cluster distribution function is studied. When the curvature dependence of the interfacial energy of a cluster, σ, is taken into account the number of monomers decreases, in contrast to the case when σ = const. Decrease of monomers caused the decrease of nucleation rate.
Effect of Buoyancy‐driven Convection on Surface Morphology and Macromorphology of Potassium Bichromate Crystals
Authors: Szurgot M.
Published: January 2007

Surface topography and macromorphology of potassium bichromate crystals grown from unstirred aqueous solution depend on diffusion and convection. Micromorphology of as‐grown surfaces is a source of quantitative data on the local values of the degree of supersaturation σ at various parts of crystals. Micromorphology and values of growth velocities of faces, differently located in space with respect to the gravitational force show that upper parts of the crystals grow at about 5–25% lower values of σ than the lower ones. The cause of convection changes of size and number of faces is the characteristic distribution of supersaturation around the crystal induced by movement of the solution.