bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure determination of polytypes (I)
Authors: Sedlacek P. , Kuban R.‐J. , Backhaus K.‐O. 
Published: January 2007

AbstractCrystal structure determination of polytypes with diffraction methods can be divided into two steps. The first step is the structure determination of the building unit of the polytypic substance (in most cases layers). The second step is the determination of the stacking sequence of the corresponding building units. The stacking can be ordered as well as disordered. Various methods for solving these problems are described. The aim of this paper is to treate these methods from a uniform point of view.
Surface structure of obliquely deposited layers and liquid crystal alignment
Authors: Hauck G. 
Published: January 2007

AbstractThe dependence of the orientational action of obliquely deposited SiOx layers on the deposition angle and the residual gas pressure has been investigated. The variation of the pressure gave rise to a modification of the general dependence of the pretilt angle of liquid crystals on the deposition angle. A model has been developed which explains the action of all deposition parameters on the orientational behaviour of liquid crystals. In a first step, some tendencies of the layer formation are stated. Thereby, in a second step, it is possible to explain the change in the orientation at variations of deposition parameters using the knowledge of these tendencies and experimentally stated informations on the relative change of layer parameters.
The influence of crucible moving on growth rate and perfection of SSD‐GaP crystals
Authors: Weinert B. , Kirsten P. , Siegel W. 
Published: January 2007

AbstractThe influence of the crucible moving (lowering, rotation) during the SSD growth of GaP on the growth rate and the crystal quality is investigated. The crucible lowering leads to an improvement especially of the crystal quality characterized by the size of the single crystalline regions and by the homogeneity of the impurity incorporation. On the other hand, the crucible rotation yields no noticeable improvements (in the case of constant frequency) or a strong increase of the growth rate connected with a deterioration of the crystal quality (accelerated rotation).
The nematic reentrant phase in binary mixtures composed of a 4‐(trans‐4‐alkylcyclohexyl)‐1‐(2‐cyanoethenyl)‐benzene and 60CB
Authors: Dąbrowski R. , Jadźyn J. , Przedmojski J. , Baran J. 
Published: January 2007

AbstractIt is shown that the smectic A phase in the 4‐(trans‐4‐n‐alkylcyclohexyl)‐1‐(2‐cyanoethenyl)‐benzene EPCH homologous series has a partially dimolecular structure of Ad type. The EPCH compounds show a virtual SAd → Nre transition revealed in mixtures of 60CB with members of the homologous series with five or more carbon atoms in the alkyl chain. The temperature dependences of electric conductivity and electric permittivity of the 8EPCH‐60CB mixture have been tested in the three successive phases, Nre, SAd and N.
The current understanding of epitaxial CVD silicon layer doping in the light of modelling and theory development (IV). The problem of more‐than‐one kind of dopant species
Authors: Kühne H. 
Published: January 2007

AbstractIn Part IV of the present treatise epitaxial silicon layer doping governed by the ratelimiting action of more than one kind of dopant species in the gas is investigated on the theoretical basis which has been derived in the previously published parts. It is shown that both the general reaction scheme of forward and backward reaction steps and the general differential equation statement of counterbalancing the fluxes of those reaction steps and the dopant incorporation flux are suitable for solving the problem under consideration. Only two of the four incorporation‐limiting reaction mechanisms, being discussed in the more recent literature, fulfill the requirements needed to agree with experimental findings on the one hand and with the limiting case situation of equilibrium incorporation on the other. Arsenic has been selected as the demonstrating dopant element.
Characterization of epitaxial group II fluoride films on (100)‐oriented GaAs substrates by ion backscattering and channeling
Authors: Flagmeyer R. , Schumann B. 
Published: January 2007

AbstractLattice matched (Ca, Sr)F2 and related fluoride films grown on (100)GaAs substrates were investigated by Rutherford backscattering/Channeling. This technique allows the characterization of the 30–250 nm thick heteroepitaxial layers with respect to chemical composition, film thickness, interface roughness and crystalline perfection. The first flash evaporated GaAs/fluoride/GaAs structure are briefly reported.
Are in‐growth surface reactions during MBE controlled by a “Quasi‐Gas transition layer”?
Authors: Wolf B. , Zehe A. 
Published: January 2007

AbstractRecently a new growth model for Molecular Beam Epitaxy (MBE) was presented in literature (HERMAN, ANDERSSON), that assumes a gas‐like transition layer between the ordered crystal and the vacuum. Known experimental results fit the picture of a disordered layer on top of a growing crystal which reacts much quicker with residual gas constituents than the static surface does. Following this idea, consequences of the “Near Surface Quasi‐Gas” model (NSQG model) with respect to increased chemical reactivity during MBE growth are discussed in the present paper.
Phase structure of boride layers on iron substrates with electroplated cobalt layers
Authors: Bochmann G. , Klaus E. , Fritsche G. , Wagner W. 
Published: January 2007

AbstractSpecimens made of Armco iron were electroplated with cobalt and then boronized with 2.2 vol% BCl3 in H2 at 1223 K. The boride layers obtained show the sequence of crystallographic phases which is (Co, Fe)B, FeB, Fe2B, substrate material.
Irradiation plus annealing‐induced 1.20 eV emission band in p‐type GaAs
Authors: Glinchuk K. D. , Guroshev V. I. , Prokhorovich A. V. 
Published: January 2007

AbstractThe effect of 2.2 MeV electron irradiation and subsequent annealings on the luminescence of tellurium‐compensated p‐type GaAs crystals is studied and analyzed. A comparatively strong emission band peaked at hvm near 1.20 eV (induced by radiative electron recombination in TeAsVGa pairs) appears in irradiated annealed (at T ≧ 250 °C) compensated p‐type GaAs. The data obtained testify about the following: a) electron irradiation of GaAs creates stable (at T ≦ 200 °C) defects not only in the arsenic sublattice of GaAs, but in its gallium sublattice too; b) radiation plus annealing (r.p.a.)‐induced TeAsVGa pairs are characterized by a rather high (compared to that for grown‐in TeAs VGa pairs) probability of electron radiative transitions in them. The electrical characterization of the r.p. a.‐induced 1.20 eV radiative centres (TeAsVGa pairs) is given.
Nb redeposition on Si during plasma etching of Nb/SiO2/Si layers investigated by RBS
Authors: Schelle D. , Tiller H.‐J. 
Published: January 2007

AbstractThe redeposition of electrode material (Ni, Cr, Al) and material of a Nb layer on silicon surface during plasma etching of Nb, SiO2 and Si by a CF4 plasma has been investigated by Rutherford Back Scattering spectrometry. It is shown that a steady state

exists, what causes a Nb contamination of etched Si surfaces. Obviously this steady state concentration (Nb)ads is influenced by additional redeposition of non‐etchable electrode material as Ni, Cr and Al.
On the correlation between anisotropy of gyrotropic and magnetic properties of samarium and terbium orthoferrites
Authors: Sirota N. N. , Lomako I. D. 
Published: January 2007

AbstractRare earth orthoferrites are interesting for investigation and promising materials for practical application. This paper deals with the existence of the correlation between the polar diagrams of polarization plane rotation obtained by us (SIROTA, LOMAKO 1976, 1978, 1979) and those of magnetic torques plotted from the data of BELOV et al. 1967, 1968a, 1968b). In this case the relationship is established between the optical anisotropy and crystallographic magnetic anisotropy of the orthoferrites crystals under investigation.
Mössbauer spectra and electronic properties of titanomagnetite
Authors: Melzer K. , Šimša Z. , Łukasiak M. , Suwalski J. 
Published: January 2007

AbstractSeveral Mössbauer studies of Ti‐Fe spinels have been reported in the literature for x ≦ 0.8 (BANERJEE et al.; VANLEERBERGHE et al.) or for x ≦ 0.05 (UMEMURA et al.). BHADURI measured the Mössbauer spectra of the whole system (0 ≦ x ≦ 1) and suggested that TixFe3−xO4 samples with x < 0.5 show the properties of delocalized electrons; whereas those with x > 0.6 may be regarded as n‐type semiconductors with localized electrons.We present measurements of electrical properties and Mössbauer spectra of synthetic TixFe3−xO4 single crystals with x = 0; 0.24; 0.5; 0.72. It is seen that the electronic behaviour strongly depends on the content of titanium. At a composition of approximately x = 0.65 a transition from n‐ to p‐type of electrical conductivity occurs. 57Fe Mössbauer data of the samples for different temperatures obtained of the spectrum computer analysis using a least squares fit program are given. The Mössbauer spectra below and above the Néel temperature demonstrate the distinct decrease in mobility of electrons in dependence on the Ti content. It is evident from the Mössbauer spectrum of the sample Ti0.72Fe2.28O4 recorded above the Néel temperature that Titanium is incorporated into the spinel structure of this system only in a four valent state.
Investigation of the single crystal growing process of neodymium‐doped YAG garnets using radiotracers
Authors: Waliś L. , Jaskólska H. , Janusz Cz. 
Published: January 2007

AbstractRadioisotopic methods of investigation of Nd behaviour during pulling of single crystals of YAG‐type garnets were applied. For the investigation of homogeneity of Nd distribution an autoradiographic method was used, and for the determination of Nd contents in single crystals and Nd effective partition ratios — techniques of radiotracers and gamma spectrometry. The conclusions from this work can find technological application.
X‐ray study of the reaction products in obtaining lead telluride by a low‐temperature iodide method
Authors: Assenov R. , Moshnikov V. , Saunin I. , Yaskov D. 
Published: January 2007

AbstractResults from X‐ray studies of the products of the reaction in obtaining lead telluride by the iodide method are presented. It is demonstrated that PbI2 condenses at the flow of the inert gas on the cool parts of the reactor at the isothermal annealing of the synthesized material. This is in agreement with the assumption about the self‐alloying of PbTe as a result of the higher solubility of Pb under conditions of dissolving PbI2 in lead telluride.
Crystal growth of Mg‐ and Ti‐substituted hexagonal ferrites from PbO‐B2O3 based melts
Authors: Nevřiva Miloš 
Published: January 2007

AbstractCrystals of Mg and Ti‐substituted hexaferrites have been prepared as perspective materials for the photoelectrochemical conversion of solar energy by means of anodes. The melts on the basis of PbOB2O3 were used to grow both bulk crystals and thin films. In the chosen system the primary crystallization field of hexaferrites was found. The crystals were grown by conventional unseeded crystal growth using (ACRT) accelerated crucible rotation technique to ensure their good quality and homogeneity. The size of the crystals varied from 10 to 23 mm in diameter. Maximum total content of Mg2+ and Ti4+ amounted to 2 atoms per formula unit of hexaferrite.
Low‐temperature precipitation in NaCl: Eu++ monocrystals
Authors: Suszyńska M. , Gubański A. , Opyrchal H. 
Published: January 2007

AbstractIt has been shown that the macroscopic features of the as grown NaCl crystals containing up to about 140 m ppm of Eu++ ions agree well with the main characteristics of the Na2EuCl4 phase present in these crystals.Thermal decomposition of the NaCl:Eu++ solid solution leads to the formation of the mentioned Na2EuCl4 phase at temperatures not very much higher than 273 K. The kinetics of this process is governed by the pipe diffusion which leads to the growth of the small impurity aggregates already present in quenched samples.
Method for complex X‐ray diffraction analysis of TiN coatings
Authors: Valvoda V. , Černý R. , Kužel R. , Dobiášová L. 
Published: January 2007

AbstractA complex of X‐ray diffraction methods for study of polycrystalline thin layers is presented. It is based on the approximation of measured profiles by suitable analytical functions. An application to TiN coatings prepared by PVD method on high‐speed steel is presented. The necessity to investigate several diffraction parameters (position, integral intensity, breadth, asymmetry) of more reflections is emphasized.
Multifrequency ultrasonic investigations in the liquid crystal 5 OCB
Authors: Gupta A. V. N. , Rao J. V. , Venkatacharyulu P. 
Published: January 2007

AbstractThe specific volume and ultrasonic velocity measurements (at four different fixed frequencies) are carried out in the liquid crystal 4′‐n‐pentyloxy‐4‐cyanobiphenyl (5 OCB). From these studies various physical parameters like adiabatic compressibility, molar sound velocity, molar compressibility, van der Waals' constant and intermolecular free lengths are estimated. The variation of the order parameter at the four frequencies is also studied. The results are analysed.
Crystal‐ and molecular structure of 19‐nor‐digitoxigenin
Authors: Scharfenberg‐Pfeiffer D. , Höhne E. , Wunderwald M. 
Published: January 2007

Abstract19‐nor‐Digitoxigenin crystallizes in the orthorhombic space group P 212121 with four formula units C22H32O4 per unit cell. The lattice parameters are a = 7.082, b = 12.476, c = 21.486 Å. The crystal structure was determined by direct methods and refined by a least‐squares procedure to the discrepancy factor R = 0.042. — The orientation of the lactone ring relative to the steroid skeleton was found to be the opposite of that known for digitoxigenin.
Specific heats of FCC solid solutions of the Bi2O3–Er2O3 system
Authors: Berezovskaya Yu. , Budurov S. , Spasov T. 
Published: January 2007

AbstractFor the first time specific heats of the fcc solid solutions (Bi2O3)1−x(Er2O3)x in the temperature range 350–1000 K were measured by means of Differental Scanning Calorimetry. Samples were also investigated with thermal expansion. A possibility of tetragonal distortion with subsequent transformation in δ* phase is supposed for (Bi2O3)0.80 (Er2O3)0.20. Thermodynamic data on (Bi2O3)1−x(Er2O3)x compared with ideal solutions are discussed.
Sputter depth profiling of GaAlAs double heterostructures using auger electron spectroscopy
Authors: Chassé T. , Heichler W. , Langhammer J. , Zwanzig W. 
Published: January 2007

AbstractSputter depth profiles of GaAlAs double heterostructures had been taken by the help of Auger electron spectroscopy (AES). The sputtering ion beam consisted of either N+ — or Ar+ ions. In the case of using N+ ions an essentially better depth resolution was found comparing with Ar+ ions, especially in a sputter depth of some μm. Investigations of the sputter—crater using Scanning Electron Microscopy (SEM) and Electron Probe Micro Analysis (EPMA) showed, that the improved depth resolution during N ion sputtering is a result of the essential lowered sputter induced surface roughness. This should be caused by the stronger amorphisation of the target surface using N ions which is a consequence of the chemical reactions taking place at the surface with the sputtering ions.
Positron annihilation studies of binary Ni‐based alloys
Authors: Michno Z. , Gorecki T. 
Published: January 2007

AbstractPositron annihilation studies of Ni–1 at. % X (X = Pb, In and Zn) alloys have been performed. The experimentally observed changes in the parameters connecting the shape of angular correlation curve with the kind and concentration of crystal lattice defects are correlated with the values of the vacancy‐solute binding energy calculated from the vacancy model of melting.
Semistatistically defected wurtzite crystal containing pairs of metal‐non‐metal vacancy
Authors: Horodecki A. J. 
Published: January 2007

AbstractBasing upon the wurtzite structure the unit cell of a semistatistically defected crystal is defined as containing four unit cells of an ideal crystal and one pair of metal and non‐metal vacancy. It is shown that all of possible coordinates of these vacancies lead only to three different squares of structure amplitude. The results are used for discussion of peculiarities of X‐ray pattern of CdS thin films.
Influence of free convection on the formation of growth defects in potassium bichromate crystals grown from aqueous solutions
Authors: Szurgot M. , Sangwal K. 
Published: January 2007

AbstractThe influence of free convection on the formation of inclusions, growth bands and dislocations in potassium bichromate crystals grown by self‐nucleation and on freely hanging seeds from aqueous solutions in a wide range of temperature is studied. It is found that in free convection all the three types of defects appear mainly in the top sectors but in stirred solutions the slow‐growing faces are more defective.
Studies of positron annihilation at metal vacancies with two‐component positron‐electron density functional theory
Authors: Boroński E. 
Published: January 2007

AbstractRecently, the fully self‐consistent two‐component density‐functional theory for electronpositron systems has been developed. The scheme is applied here in further calculations of positron annihilation in metal vacancies. In particular, angular correlation of positronelectron annihilation photons for Al vacancy is calculated and compared with conventional result. As important in some cases, the influence of self‐interaction corrections on the results is discussed. Besides, the positron binding energies to vacancies containing H and He are calculated. They are considerably different then ones obtained in one‐component approach.
Vacancy formation enthalpy in AgZn alloys
Authors: Chabik St. 
Published: January 2007

AbstractEffective vacancy formation enthalpy (Hv) for AgZn alloy was determined by means of positron annihilation method. It was found that Hv decreases linearly with increasing Zn content for the α‐phase. For the ξ and β′‐phase the Hv does not change and is equal to 0.53–0.55 eV.
Crystal and molecular structure of (2–3‐η‐2‐Butyne‐1,4‐diol)‐bis‐(triphenylphosphan)‐nickel(O) Ni{[(C6H5)3P]2 (C4H6O2)}
Authors: Görls H. , Schulz B. , Rosenthal U. , Schulz W. 
Published: January 2007

AbstractThe crystal and molecular structure of (2–3‐η‐2‐Butyne‐1,4‐diol)‐bis‐(triphenylphosphan)‐nickel(O) has been determined by X‐ray structure analysis. It crystallizes in the tetragonal space group 14 with the cell parameters a = b = 22.277(3), and c = 15.118 (4) Å. The structure was solved by the heavy atom method and refined to R = 0.0716. The coordination geometry about the nickel atom is trigonal‐planar. Each molecule is hydrogen bonded to two neighbours. The result is an eight‐membered oxygen ring.
Crystal and molecular structure of N‐(Diethylaminothiocarbonyl)‐N′‐phenyl‐benzamidine
Authors: Braun U. , Sieler J. , Richter R. , Leban I. , Golič L. 
Published: January 2007

AbstractThe crystal structure of the title compound has been determined by X‐ray diffractometer data collected on a CAD‐4 diffractometer. C18H21N3S crystallizes monoclinic, space group P 21/n with a = 8.939(1) Å, b = 18.992(3) Å, c = 10.416(2) Å, β = 97.29(2) Å and Z = 4. Least‐squares refinement gave a value of R = 0.107 for 2647 observed reflections. The molecule has a configuration which can be described best by Z, E′ and exists in the tautomeric enamine form. The molecules form infinite chains connected by intermolecular N—H … S interactions, with H … S distances of 2.46 Å.
Study of the chemical reactions' influence on semiconductor films structure formation by the Monte‐Carlo method
Authors: Aleksandrov L. N. , Kogan A. N. , Bochkova R. V. , Tikhonova N. P. 
Published: January 2007

AbstractThe investigation by the Monte‐Carlo method of the growth of the silicon epitaxial film at a chloride CVD system has allowed to find out the composition of adsorption layer, the micromechanism of the reactions of Si atoms building‐in into the growing crystalline layer and the growth conditions influence on the growth rate and film surface roughness. The change of adsorptive layer composition in the system SiCl4—HCl—H2 (fraction of adaatoms, silicon atoms built‐in a crystal and molecules SiCl2) depending on temperature has been determined. The change of silicon film growth rate depending on temperature and concentration change of SiH2Cl2 has been established and the contribution of growth mechanism (with participation of adatom, silicon atoms and molecules SiCl2) into the total rate of film growth has been shown.
A study of the effect of depletion charge on the stable crystals structures of heavy alkalis
Authors: Radwan A. M. 
Published: January 2007

AbstractIn the framework of second‐order perturbation theory and model potential formalism we investigate the effect of variation of depletion charge on the prediction of stable crystal structures of K, Rb, and Cs. In the formal calculation the HCP structure is found to have the lowest energy for all three metals, even though the phonon contributions were added in case of K. Nevertheless, we were able to predict correctly the observed BCC structure by changing the sign of the depletion hole charge.
Habit, dislocation densities, and microhardness of NaClO3‐NaBrO3 mixed crystals
Authors: Hussain K. A. , Subhadra K. G. , Kishan Rao K. 
Published: January 2007

AbstractResults of a systematic study of growth habit, dislocation densitics, and microhardness of the NaClO3—NaBrO3 mixed crystals are presented. A drastic change in habit of NaBrO3 for small additions of NaClO3 was observed. The composition dependence of dislocation density for this system is found to be highly non‐linear. A non‐linear composition dependence of microhardness, with positive deviations from linearity was also observed. This increase in hardness is correlated with the enhanced dislocation density in the mixed crystal.
Dielectric studies on pure and doped sr (NO3)2
Authors: Srinivas M. , Sirdeshmukh Lalitha 
Published: January 2007

AbstractSingle crystals of pure and Na+‐doped strontium nitrate were grown by slow evaporation of aqueous solution. Systematic measurement of dielectric constant (ϵ) and loss (tan δ) have been carried out in the frequency range of 100 Hz to 100 kHz at temperatures ranging from room temperature to 420 °C. A.C. conductivity (σ) is obtained from the data on ϵ and tan δ, ϵ, and σ were found to show anomalies around 300 °C. The results are discussed in the context of order‐disorder phase transition.
Thermo emf studies on CdTe:Sb Thin Films
Authors: Pratap K. J. , Nagabhushanam M. , Amanullah F. M. , Hari Babu V. 
Published: January 2007

AbstractThermal transport properties have been studied on as‐grown and annealed CdTe:Sb thin films of different thicknesses and concentrations of Sb. These films were prepared by sequential vacuum deposition of CdTe and Sb on clean and hot glass substrates held at 210 °C temperature at a constant rate of deposition. From these studies all the films were found to be p‐type. It is also observed that the thermoelectric power increases with Sb concentgration, thickness of the film and with annealing process.Fermi‐energy variation with temperature have been calculated on the basis of thermo emf data. All these results have been explained on the basis of defects introduced by Sb doping.