bluuebunny/crossref_metadata_2025_split huggingface dataset:
X‐ray topographic study of GaSb substrates for epitaxial layer growth
Authors: Vassilev I. S. , Pramatarova L. D. , Baeva M. B. 
Published: January 2007

AbstractThe depth of the layer damaged by silicing of GaSb ingots has been determined by X‐ray topography. The changes in the defect structure of substrates after successive etching to different depths by Br2/CH3OH and 1 HF:3 NNO3:1 CH3COOH have been studied. The effect of heat treatment carried out under conditions similar to the epitaxial process of substrates with completely removed damaged layer has been investigated.
Recent advances in the theory of crystal growth in silica gel medium
Authors: Desai C. C. 
Published: January 2007

AbstractGrowth of single crystal materials by slow diffusion process in a silica‐gel medium has been used for a long time as the method of simulation of natural processes in the laboratory. Recent advances in the theory of crystal growth have been described. The suitable theory of nucleation has been developed. Attention has been paid mainly to the more general case in which the counter diffusion of two reacting materials occurs. The implications are discussed.
Positron lifetime studies of organic coatings
Authors: Süvegh K. , Szeles Cs. , White M. L. , Vértes A. , Leidheister H. 
Published: January 2007

AbstractPositron implantation and annihilation and the influence of water exposure on the annihilation properties were studied in a number of organic coatings deposited on metal substrates. Change of the lifetime spectra upon water exposure was related to the corrosion protective properties of the coatings.
Positron lifetime in mordenite
Authors: Ch. Abbé J. , Dębowska M. 
Published: January 2007

AbstractPositron lifetime spectra have been measured for mordenite pure and impregnated with various amounts of metallic gold being highly dispersed. The change of annihilation characteristics (in comparison to those corresponding to the pure mordenite), resulting both from the presence of gold particles in the zeolite matrix and the way of treatment of the zeolite during the impregnation, has been noticed.
Nickel complexes of 1,10‐phenanthroline and 2,2′‐bipyridyl with strong intermolecular interactions
Authors: Oza A. T. 
Published: January 2007

AbstractNickel complexes of 1,10‐phenanthroline and 2,2′‐bipyridyl which can have strong intermolecular interactions have been prepared in the present work. The complexes with intermolecular interactions appear pink, red or red‐violet. Two of the complexes prepared Ni(Bip)2 · Ni(CN)4 · x H2O and Ni(Phen)2 · Ni(CN)4 · y H2O indeed show strong absorption bands at 470 nm and 500 nm, respectively.
Positron annihilation in GaAs
Authors: Misheva M. , Mishev P. , Pasajov G. , Toumbev G. , Yakimova R. 
Published: January 2007

AbstractPositron lifetimes and three‐gamma annihilation in In, Cr, Te, and Sn doped GaAs have been measured. The mean τm and the bulk τb lifetimes in SI crystals are approximately 10 ps shorter than in n‐type crystals. Three‐gamma annihilation shows positronium formation in Bridgman grown samples only.
Positron lifetime study of hafnium nitride films
Authors: Brunner J. , Perry A. J. 
Published: January 2007

AbstractFilms of HfN can have expanded lattices which are restored by tempering, reflecting the presence of a high concentration of defects. The present study was made to get a qualitative understanding of the lattice relaxation on an atomic scale. The results support the proposal that the dominant mechanism is the migration of interstitial atoms into lattice vacancies.
Identification of predominant point defects in nonstoichiometric CuInse2 by X‐ray powder diffraction
Authors: Zahn G. , Paufler P. 
Published: January 2007

AbstractRefinement of structural parameter, occupancy factors and temperature factors of three indium rich samples enabled type and concentration of intrinsic point defects to be determined. Vacancies on copper and indium sites (8 and 5%, respectively) and indium atoms on copper sites (5%) were identified. Indium atoms exhibit a large thermal vibration amplitude.
On the change of low‐temperature thermal conductivity of gap after bending
Authors: Zahn G. , Merisov B. A. , Klöss G. , Ya. Khadshaj G. , Müller S. , Gavrenko O. A. , Paufler P. 
Published: January 2007

AbstractThe thermal conduction of a sulphur‐doped single crystal plastically deformed by bending at 963 K was measured between 2 and 50 K. The thermal resistivity W at temperatures > 14 K is practically independent on deformation. At lower temperatures W is found to be proportional to AT−3 before and to AT−3 + BT−2 after deformation. A is due to boundary scattering, B due to dislocations.
Polymorphic transitions of ice at a pressure up to 2500 MPa in the temperature range 90–300 K
Authors: Sirota N. N. , Bizhighitov T. B. 
Published: January 2007

AbstractIn the present work the phase P—T diagram of ice is constructed in the temperature range 90–250 K and is ascertained at temperatures 250–300 K and pressures up to 2500 MPa. A new modification of ice — ice XII — was found. Compressibility and Grüneisen coefficients for a number of ice modifications were determined.
Infrared optical characterization of (Cu2GeSe3)1−x (CuGe2P3)x mixed crystals
Authors: Riede V. , Sharif N. , Neumann H. , Omar M. S. , Sobotta H. 
Published: January 2007

AbstractInfrared reflectivity spectra of (Cu2GeSe3)1−x(CuGe2P3)x mixed crystals with x = 0.1 and 0.2 are measured in the wave‐number range from 180 to 4000 cm−1. An analysis of the spectra reveals contributions from five vibrational modes and from free carriers to the reflectivity. The results are compared with previous measurements for Cu2GeSe3 and CuGe2P3.
Interference pattern of X‐ray waves inside the crystal and its image in vacuum in double‐field approximation (I)
Authors: Aslanian V. G. , Bezirganian H. P. , Bezirganian P. H. 
Published: January 2007

AbstractThe distribution of intensity of the interference field during simultaneous superposition of all the four Bloch waves in a two‐mode case has been investigated. It is shown that the distribution of intensity of the total field in the upper layers of the crystal is of a periodic character in two mutually‐perpendicular directions. In the lower layers, where the first field is absorbed, a sinusoidal distribution occurs only in the direction of the reciprocal lattice vector.
Energy bands of the BCC metals rubidium and cesium
Authors: Radwan A. M. 
Published: January 2007

AbstractEnergy bands of BCC rubidium and cesium are calculated for the first time using the full non‐local but energy‐independent Shaw's optimized model potential. The energy dependence of the potential is then included as first order perturbation. The effects of changing the model potential and of reversing the sign of the depletion charge d are reported. The Fermi energy EF is calculated in all cases. Our results are compared with those obtained by other authors. The band gap at N is very small for both metals, except when all model potential parameters are increased considerably (50% to 100%).
Solidification behaviour of organic eutectics and 1:1 addition compound: p‐Phenylenediamine‐resorcinol system
Authors: Rai U. S. , Mandal K. D. 
Published: January 2007

AbstractThe phase diagram of p‐phenylenediamine‐resorcinol system, determined by thaw‐melt method, shows the formation of a 1:1 molecular compound and two eutectics. The linear velocity of crystallization, determined by measuring the rate of movement of growth front in a capillary, indicates that crystallization data obey Hillig‐Turnbull equation:

Where u and n are constants and ΔT is undercooling. X‐ray diffraction data of the molecular compound, eutectics and pure components infer that these eutectics are not simply the mechanical mixture of the two components and there is preferential ordering of atomic planes during their formation. The infrared studies carried out on this system reveal the intermolecular hydrogen bonding between two components forming the molecular compound. Using experimental values of heats of fusion, entropy of fusion and excess thermodynamic functions were also calculated.
Photoconductivity of rare‐earth‐doped (CdSe, ZnS)
Authors: Bhushan S. , Giriya L. C. 
Published: January 2007

AbstractPhotoconductivity rise and decay curves of (CdSe, ZnS) doped with La and Dy separately are investigated as a function of ambient temperature and pressure, electrode material and cell thickness. Using a number of metal electrodes Fe is found to give maximum IPC/IDC ratio for (CdSe, ZnS): La and Cu for (CdSe, ZnS): Dy. Due to change in temperature, maximum IDC and IPC are found to 70 °C. A possible mechanism is proposed for thermal and photo‐excitations in terms of these results. At lower ambient pressure the photocurrent is found to be low. Cell thickness effect also shows changes in IPC.
Chemical reactions during alkaline treatment of dealuminated Y zeolites — impossibility of aluminium reinsertion into the framework
Authors: Lutz W. , Lohse U. , Fahlke B. 
Published: January 2007

AbstractDuring the alkaline treatment of dealuminated Y zeolites the non‐framework aluminium species and parts of the dealuminated SiO2‐rich framework are dissolved in the alkaline medium. After reaching certain concentrations of silicate and aluminate anions in the solution an aluminium‐rich gel (Si/Al = 1.7) precipitates. The aluminosilicate gel is well‐ordered in short ranges and gives rise to discrete peaks in the 29Si MAS NMR spectrum.No evidence for aluminium reinsertion into the zeolite Y framework was obtained.
Diamagnetism and some peculiarities of interatomic interactions in Cu2Sb
Authors: Vitkina Ts. Z. , Zhigadlo N. D. , Ryzhkovskii V. M. 
Published: January 2007

AbstractResults are reported for magnetic susceptibility measurements of high purity Cu2Sb which characterize it as a diamagnetic. The observed anomalies of magnetic susceptibility, electrical resistivity and linear expansion coefficient in the neighbourhood of 370 K verify the existence of a phase transition of nonmagnetic origin in this temperature range. The analysis of the peculiarities of interatomic interaction in Cu2Sb indicates the covalent character of the bonding. The value of the strength of the CuCu and CuSb bond is evaluated. It is shown that the CuCu bond in the Cu2Sb compound is the most strong one.
Microcomputer programming of dosage rate during batch precipitation
Authors: Jones A. G. , Teodossiev N. M. 
Published: January 2007

AbstractApplication of a microcomputer control system to programme the dosage rate during a batch precipitation is described. The technique is tested with the drowning‐out precipitation of potassium sulphate from aqueous solution using acetone. Programmed dosage controls the transient supersaturation and crystal growth rate thereby improving the product crystal size distribution. A consequent improvement in filtrability characteristics is also indicated.
On the structure of thin plasma‐treated thermal SiO2 films
Authors: Popova L. I. , Atanassova E. D. , Peneva S. K. , Tcukeva E. A. 
Published: January 2007

AbstractOxygen‐plasma‐treated thin thermal SiO2 films (15–100 nm) have been studied by Reflection High Energy Electron Diffraction (RHEED). The presence of unconventional type microcrystalline regions (not only tetrahedrally coordinated) in the amorphous matrix of the oxides is established. Thinner oxides (15–50 nm) are more sensitive to the plasma action. In general, oxygen plasma leads to an additional deformation and decomposition of the initial crystalline forms and causes a degradation of the electrical parameters of the samples.
Magnetic and electric properties of the ternary alloys AB
Authors: Vitkina Ts. Z. , Smolyarenko E. M. , Trukhan V. M. 
Published: January 2007

AbstractThe results of experimental studies of the electrophysical and magnetic properties of solid solutions based on the AB compounds with anion (Zn3(PxAs1−x)2 and cation (ZnxCd1−x)3 P2 substitution are reported. The Zn3(AsxP1−x)2 solid solutions are characterized by p‐type conductivity (∼ 1015  1017 cm−3), low Hall mobility and conductivity of ∼ 10−2 — 10−3 ohm−1 cm−1. In the (ZnxCd1−x)3P2 solid solutions the samples rich in zinc are p‐type, those rich in cadmium — n‐type, the carrier concentration is ∼ 1016 — 1018 cm−3. From the measurements of the magnetic properties of the above mentioned alloys it is shown that in the investigated solid solutions a transition from the structure with direct optical transition to those with indirect optical transition occurs.
Temperature variation of the phonon frequencies in V3Si along the [110] direction by the X‐ray inelastic scattering
Authors: Sirota N. N. , Poluchankina L. P. , Orlova N. S. 
Published: January 2007

AbstractThe investigation of the intensity of X‐ray diffuse scattering by the lattice vibrations along the second‐order symmetry axis in V3Si single crystals is performed at different temperatures from 300 to 8 K and the phonon dispersion curves in this direction are determined. It is found that the phonon frequencies of all modes decrease with lowering temperature.
On the morphological instability of the growing crystals (III). Micro‐interferometric investigations of the morphological stability of KDP crystals growing from aqueous solutions
Authors: Staynova M. , Nanev Chr. 
Published: January 2007

AbstractThe paper is aimed at the elucidation of the limits to which the faceted forms of KDP crystals preserve their stability and beyond which a skeletal growth from stagnant solutions takes place. In order to avoid the natural convections the experiments were performed in two‐dimensional cells. On the basis of quantitative criteria, it has been shown that the kinetic regime of growth has been replaced by a diffusion one when the concentration on the crystal surface drops with respect to the bulk value with 0.1% to 0.2%. The critical size above which the KDP crystal no longer retains its polyhedral growth mode in a diffusion regime since a gross morphological defect in the form of a depression appears on its (010) face has been compared with the theoretical expressions derived by Cahn and Chernov.
Anisotropic plasma etching of P‐doped poly‐Si with CCl4/He
Authors: Handke R. , Krzikalla R. , Lippert Gud. 
Published: January 2007

AbstractAn anisotropic and very selective etch process for high P‐doped polycrystalline Si has been developed using statistical methods for experimental design and analysis. Mixtures of CCl4 and He served as etching gas system. It is shown that only a low number of trials is needed to get good information about the process. One example is presented for the generation of a regression polynom and a computer graphic.
Beilby layers on crystal surfaces
Authors: Vlasov A. D. , Rez J. S. , Fil'chenkov M. L. 
Published: January 2007

AbstractA concise review of Beilby's amorphous surface layers, discovered in early years of the twentieth century, is presented. While being treated mechanically the crystals form these layers characterized by an enhanced hardness and specific optical, electrical, and magnetic properties. The temperature stresses arising from a periodic contact of the abrasive with the crystal surface are supposed to be a reason for Beilby layer formation. A mathematical description of propagation of the temperature waves is given. The temperature wave amplitude is shown to be e times attenuated at the distance from the crystal surface being about the grain size.
Discontinuous dielectric reorientation in the SI phase of 4‐n‐Nonyl‐4′‐n‐nonyloxy‐azobenzene
Authors: Pelzl G. , Schiller P. , Demus D. 
Published: January 2007

AbstractPlanar oriented samples with positive dielectric anisotropy were used to study the dielectric reorientation in SI phases. It was found that the dielectric reorientation is characterized by the rotation of the molecule director around the layer normal. The field‐induced deformations do not arise simultaneously in the whole sample but they start in certain regions and grow continuously by domain wall motion. Depending on the boundary conditions three types of field‐induced deformations can be observed at different thresholds. An attempt has been made to interprete this behaviour on the basis of a simple model.
A synchrotron X‐ray diffraction study on structural changes of polycrystalline calcium hydroxyapatite during acid dissolution — methodic aspects
Authors: Pritzkow W. , Rentsch H. , Grosshans W. A. , Wroblewski T. 
Published: January 2007

AbstractA procedure has been developed for following structural changes of pure synthetic calcium hydroxyapatite during its demineralization in a hydroxyethylcellulose solution. The procedure consists of demineralization and simultaneous powder diffraction patterns recorded with synchrotron X‐ray radiation. Experimental details will be described.
Crystal structures of two quenched CuInSe phases
Authors: Hönle W. , Kühn G. , Boehnke U.‐C. 
Published: January 2007

AbstractThe crystal structures of the δ‐phase with a composition of Cu0.46In1.18Se2.00 and of a Cu‐poor β‐phase with a composition of Cu0.39In1.20Se2.00, both quenched from 750 °C, have been determined with single crystals. The δ‐phase crystallizes with a = 576.2(4) pm in the ZnS‐type structure (space group F43m), the β‐phase with a = 575.5(3) pm, c = 1152.0(4) pm and Z = 4 in a new structure type for tetrahedral structures with the space group P42c. In both compounds the cations are statistically distributed together with vacancies. The number of vacancies is estimated from the crystal structure analyses and results to be (Cu0.54(2)In1.15(2)□0.30(2)) Se2 for the δ‐phase and (Cu0.36In1.09□0.55) (Se1.80□0.20) for the Cu‐poor β‐phase.
Experience with the diffusion‐grown surface layer on calomel single crystals (Hg2Cl2) exhibiting a higher refractive index
Authors: Barta Č. , Barta Č. , Gilar O. , Pavlíček Z. , Brožek V. , Hájek B. 
Published: January 2007

AbstractThe article deals with experience obtained in production of surface layers on calomel single crystals (Hg2Cl2), exhibiting higher refractive indexes, using the gaseous diffusion over the crystalline Hg2Br2. The values of the diffusion coefficient at three various temperatures (312, 352.5, 367.5 °C) were determined together with its approximate temperature dependence. This dependence was specified by finding characteristical values of the frequency factor (D0 = 7.1024 cm2 s−1) as well as the activation energy of the diffusion process (Q = 421.5 kJ · mol−1). Rise of equilibrium concentration of Br has been observed on the sample surface which corresponds to the production of a compound of composition 3 Hg2Cl2 · 2 Hg2Br2. Four different diffusion layers were produced showing a refractive index enhanced by 1.6 to 6.3% at the maximum in the depths of 14 to 342 μm. The investigated process renders possible to produce a light guiding surface layer on the calomel single crystals.
Photoconductivity decay and calculation of lifetime in ZnTe
Authors: Nagabhooshanam M. 
Published: January 2007

AbstractIsothermal photoconductive decay in p‐ZnTe was used to determine the energy levels associated with the native defect acceptors as 0.024, 0.017, and 0.011 eV. The capture cross‐section and carrier lifetime were computed at different temperatures (77–200 K) by conjuncting these results with some theoretical equations. The results were explained on the basis of Zn vacancies and vacancy complexes.
Paramagnetic centers in X‐irradiated KH2PO4 crystals doped with chromium
Authors: Alybakov A. A. , Abdrazakov A. A. , Arbotoev O. M. , Kudabaev K. 
Published: January 2007

AbstractEPR spectra of X‐irradiated KDP: CrO single crystals are studied both at room and liquid nitrogen temperatures. It is found that X‐irradiation of doped KH2PO4 (KDP) crystals at 77 K creates uncharged H2PO4 radicals parallel with HPO−4 ion‐radicals. It is shown that a part of the impurity chromium ions enters the crystal lattice in the trivalent state. As a result, paramagnetic centers with Cr5+ ions of a different origin are formed by X‐irradiation in KDP: CrO: Cr5+ of an electronic nature (appearing in the reaction CrO + e− → CrO) and Cr5+ of a hole nature (resulting from a successive capture of two holes by Cr3+ ions). Thermal stabilities of these paramagnetic centers are found to be different. Principal g‐values are determined for all investigated centers.
Influence of the quenched‐in state on the decomposition kinetics of Al‐21 at.% ZnX at.% Mn Alloys
Authors: Wendrock G. , Major B. , Löffler H. , Ciach R. , Król J. 
Published: January 2007

AbstractThe structure changes proceeding in a series of Al‐21 at.% Zn‐X at.% Mn alloys (X = 0, 0.13, 0.32, 0.6, and 2.0) were investigated during ageing at 80 °C by X‐ray (diffraction line analysis as well as small‐angle scattering) and TEM examinations. The main results are the following. (i) Mn additions of 0.6 at.% rise the boundary of the one phase region (TPB) for about 50 K. (ii) Mn additions accelerate the lamellar mode of decomposition, the mean size of the GP zones, however, is profoundly diminished. (iii) If quenching the specimens from Tq = Trhn + 15 K < TPB (Trhn is the upper limit temperature of the onset of rapid homogeneous nucleation of Guinier‐Preston (GP) zones) instead from Tq = 470 °C > TPB, the lamellar mode of decomposition is significantly accelerated, but the mean size of the GP zones growing between the lamellas is diminished.
Crystal structure of marmesin, C14H14O4, 2‐(β‐hydroxyisopropyl)‐2,3‐dihydro‐6,7‐furano‐coumarin
Authors: El‐Kordy M. , Farag I. S. Ahmed , Will G. 
Published: January 2007

AbstractThe unit cell parameters of this compound were determined by least‐squares calculations from the adjusted angular setting of 25 general reflections. The crystals are monoclinic with the following crystallographic data: a = 5.718(1), b = 13.794(4), c = 7.861(1) Å, β = 100.53(2)°, Z = 2 and Dx = 1.34 g · cm−3. The space group according to the systematic absences is P21.The structure of this compound was solved by direct methods and refined by full matrix least‐squares with anisotropic temperature factors to R = 0.04. The refined atomic positions indicate a considerable strain within the molecule. The structure is built up from molecules connected by H‐atoms forming infinite chains along b‐axis.
Optical absorption spectra of epitaxial layer ‐ gradient layer ‐ substrate systems
Authors: Neumann H. 
Published: January 2007

AbstractTheoretical relations are derived for the photon energy dependence of the absorption coefficient of epitaxial layer — gradient layer — substrate systems assuming a spatially linear variation of the gap energy in the gradient layer. It is shown that optical absorption measurements on such systems can be used to determine the gap energy of the epitaxial layer. Numerical calculations for the system GaAs0.3P0.7—GaAs1—xPx—GaP are presented.
Organometallic vapour phase epitaxy of galliumarsenide using Ga(CH3)3 · N(CH3)3‐adduct as precursor
Authors: Seifert W. , Ploska K. , Schwetlick S. , Butter E. 
Published: January 2007

AbstractEpitaxial layers of GaAs have been grown by MOVPE using trimethylgallium‐trimethylamin‐adduct (TMGa‐TMN) as the Ga‐precursor. In comparison to the growth system using pure TMGa no significant influence on growth conditions and materials parameters could be found. The deposited GaAs is of fairly high quality with room temperature mobilities of 6700 cm2/Vs at free electron concentrations of about 1 × 1015 cm−3. No hints to nitrogen incorporation could be found.