bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nuleation and Growth of Thin Ag Films Vacuum‐deposited onto W
Authors: Michailov E. 
Published: January 2007

AbstractAn attempt to analyse the nucleation and growth phenomenon in a typical “Stranski‐Krastanov” (SK) growth system ‐ Ag/W (PAUNOV, MICHAILOV 1979; MICHAILOV), in terms of island growth theory was made. Ag‐layers were analysed by the use of scanning electron‐and optical microscopes. A strong dependence of the nucleation kinetics on supersaturation and grain orientation was found to exist. On the basis of known rate equations, the number of atoms in the critical cluster i and the value of nucleation potential barrier E were estimated. The comparison between the experimentally obtained size‐, first nearest neighbour‐ and radial distributions and theory shows that: 1) nucleation and growth processes proceed through a surface diffusion of the atoms; 2) no coalescence between the crystallites and no crystal mobility exist.
Debye‐Waller Factors and Elastic Constants for Beryllium Oxide at Temperatures between 10 and 720 K (I). Anisotropy of Inoic Mean‐Square Displacements
Authors: Sirota N. N. , Kuzmina A. M. , Orlova N. S. 
Published: January 2007

AbstractThe Debye‐Waller factors and the mean‐square dynamics displacements of the Be and O ions in beryllium oxide are obtained from X‐ray diffraction powder data over the temperature range from 10 to 720 K for different crystallographic directions. The observed anisotropy of these mean‐square displacements is discussed.
Determination of the Rotational Viscosity and of the Elastic Constant from Measurements of Switching Times and Threshold Voltage on Planar Oriented Sc Phases
Authors: Dierking I. , Giesselmann F. , Zugenmaier P. , Pelzl G. , Schiller P. 
Published: January 2007

AbstractThe Freedericksz transition of planar oriented Sc phases was studied experimentally with an electrooptical method and the theoretically predicted reorientation along the Sc tilt cone confirmed. Measurements of the threshold voltage and the switching times lead to the determination of the rotational viscosity and the elastic constant for five selected compounds with positive dielectric anisotropy.
A First Approach to CVD Si1–xGex Layer Growth by Means of Chemical Reaction Kinetics
Authors: Kühne H. , Morgenstern Th. 
Published: January 2007

AbstractA reaction mechanism will be suggested for interpreting Si1–xGex CVD layer deposition from a silicon source and germane reaction gas mixtures in order to explain the observed silicon layer growth increase in consequence of the presence of germane. A successive substitution of the hydrogen atoms available in germane molecules by silyl groups forming a silicon containing intermediate of germane will be assumed. It will further be supposed that both the original silicon source and the germane intermediates will independently be decomposed by chemical reactions leading to Si1–xGex CVD layer deposition from dichlorosilane‐germane‐hydrogen reaction gas mixtures at temperatures in the range of 600 ≦ T(°C) ≦ 900 as recently published by KAMINS and MEYER.
A Gamma‐ray Diffraction Study of MBE‐Grown CaF2/Si(111) Heterostructures
Authors: Kurbakov A. I. , Rubinova E. E. , Sokolov A. E. , Mäder M. , Tempel A. , Tobisch J. 
Published: January 2007

AbstractMBE grown epitaxial films of CaF2 onto Si(111) substrates were investigated by gamma ray diffraction to obtain assertions about the real structure and the strain situation in the epitaxial systems. It were measured the integral reflection coefficient Ri and the angle distribution of the reflected intensity of both (111) and (333) reflections. It was found that (i) a high temperature annealing step during the wafer preparation (1200 °C) causes a drastical increase of real structure defects in the substrate material, (ii) expitaxial layers of 18 nm thickness are grown pseudomorphically, layers having a thickness of 30 nm are relaxed, (iii) the misfit dislocation network formed during the relaxation process is localized not in the deposit but in the substrate material.
Crystal and Molecular Structure of an Oligomeric 1:2 Complex of Copper (II) Azide with 4‐Methylpyridine
Authors: Goher M. A. S. , Mautner F. A. 
Published: January 2007

AbstractA 1:2 complex of copper (II) azide with 4‐methylpyridine has been synthesized and the crystal structure has been determined by X‐ray methods. The compound crystallizes in space group P21/a with a = 11,062(3), b = 19.310(6), c = 20.547(5) Å, β = 90.83(2)°, V = 4389(1) Å3, Z = 12 and R = 0.048 for 959 observed MoKα data. The structure is built up by oligomeric edge‐sharing chains of polyhedra. With the exception of a single coordinated azido group, all other azido ligands serve to bridge neighbouring copper centers [at Cu  N bond distances of 1.94(2) to 2.76(2) Å] in the μ(1,1) fashion.
A Mössbauer Study of the Interaction between Fe2O3 and TeO2
Authors: Gospodinov G. , Peev T. 
Published: January 2007

AbstractThe interaction between Fe2O3 and TeO2 by vacuum sintering at various temperature was studied The compounds obtained were identified by means of Mössbauer spectroscopy. The conditions for the synthesis of Fe2 Te4O11 were found. Some influence of the experimental conditions was established.
Phase Transition Studies in Some 4‐n‐Alkyl‐N‐(4‐n‐Alkyloxy‐Benzylidene)‐Anilines
Authors: Rao P. Bhaskara , Potukuchi D. M. , Murthy J. S. R. , Rao N. V. S. , Pisipati V. G. K. M. 
Published: January 2007

AbstractThe results of phase transition investigations in two homologous series of 4‐n‐alkyl‐N‐(4‐n‐alkyloxy‐benzylidene)‐anilines, viz., 60. m and 70. m compounds using thermal microscopy, differential scanning calorimetry, density and refractive index measurements are reported. The nature of the order of various phase transitions and the pre‐transitional effects in the fluctuation dominated non‐linear regions in the vicinity of IN, IA and NA transitions are discussed in the light of the available data on other nO. m compounds.
Study on the Sensitization of Ce3+ to Nd3+ in YAIO3
Authors: Shenghui Yan , Guoqiang Yan , Yongcheng Zhong 
Published: January 2007

AbstractThis paper presents the absorption spectra, excited spectra and fluorescence spectra of Nd: YAP, Ce: YAP and Nd, Ce: YAP. It is believed that there is an energy transfer from Ce3+ to Nd3+ and it is possible to improve the laser efficiency of Nd: YAP sensitized by Ce3+.
Physical Properties of K2ZnCl4
Authors: Jeong S. Y. , Jang M. S. , Han S. K. , Haussühl S. 
Published: January 2007

AbstractLarge single crystals of orthorhombic K2ZnCl4 with optical quality have been grown by the Czochralski method. The elastic constants and their temperature and pressure derivatives have been determined from ultrasonic resonance frequencies of thick plates of different orientation and the shift of these frequencies induced by temperature and pressure changes, respectively.K2ZnCl4 shows a small elastic anisotropy. Measurement of the dielectric constant was made along the ferroelectric axis εa in the temperature from 303 K to 573 K. εa of K2ZnCI4 grown by the Czochralski‐method shows a smaller thermal hysteresis at the incommensurate‐commensurate transition point (403 K) than that of crystals grown from an aqueous solution. It explains that crystals grown by the Czochralski‐method are more purified, the pinning effect is weakened. The thermal hysteresis occurs with the same width at 10 KHz, 100KHz, 1 MHz and 10 MHz.
Growth and Spectrometric Tests on Bi4Ge3O12 Crystals
Authors: Dafinei I. , Mitroaica Gh. , Angelescu T. , Niculescu I. 
Published: January 2007

AbstractA resistance‐heated furnace with a good control of temperature gradients is used for the Czochralski growth of precipitate and colour free Bi4Ge3O12 (BGO) crystals up to 30 mm in diameter and 80 mm in length from a 45 mm diameter crucible. The quality of the grown crystals is discussed in connection with the growth conditions.Spectrometric tests made on scintillators obtained from BGO crystals are presented. A Monte Carlo program is used in order to compute the full energy peak efficiency of the detector for different energies and geometries. The computed values are compared to the experimental results.
Crystal Growth of Lead (II) Iodide from the Melt
Authors: Eckstein J. , Erler B. , Benz K. W. 
Published: January 2007

AbstractBulk Pbl2 crystals up to 20 cm3 have been grown from high purity source material in a controlled way using a modified Bridgman‐Stockbarger technique. The cleavage plane (0001) of crystals grown by a natural seed selection in a tipped‐end ampoule is nearly parallel to its axis. On a mica substrate epitaxially grown crystals cleaved perpendicularly to the axis of a specially designed double wall ampoule.
Crystallizaton Characteristics of the Alternating Tetrafluoroethylene‐Ethylene Copolymer
Authors: Dobreva A. , Nikolov A. , Kostov G. 
Published: January 2007

AbstractThe alternating tetrafluoroethylene‐ethylene (TFE‐E) copolymer has been studied with respect to its crystallization by using differential scanning calorimetry and optical microscopy. The value of the specific surface energy σ at the melt/crystal interface is calculated to be about 2 · 10−3 J/m2. The nucleating activity Φ of TiO2 particles introduced into TFE‐E copolymer is estimated to be approximately 0.9. The temperature dependence of the nucleation rate and of the linear growth velocity are constructed in the whole region from the melting temperature Tm to the vitrification temperature Tg. The minimum cooling rate for the formation of a crystal‐free TFE‐E copolymer glass is calculated and its value amounts to 104 K · min−1.
A Thorough Reconsideration of in‐situ Doping Theory of Epitaxial Silicon Layers
Authors: Kühne H. 
Published: January 2007

AbstractThe adsorption‐desorption limited doping mechanism as suggested by REIF and DUTTON to explain in‐situ doping of epitaxial CVD silicon layer will thoroughly be discussed in comparison to the more general transport‐reaction limited mechanism as originally suggested by SHEPERD, Distinctive and common features will be highilighted and discussed with respect to composite layer growth.
On the Critical Growth Velocities for the Presence of Faces on Growing Crystals
Authors: Szurgot Marian 
Published: January 2007

AbstractFaces of three‐dimensional crystals have been divided into edge and corner ones to describe the phenomenon of their disappearance and appearance during the crystal growth. The expression for the critical growth velocity governing the presence of corner faces has been derived and verified and the validity of the previous relationship (SZURGOT, PRYWER) for the edge faces confirmed. Three nearest neighbours control the presence of corner faces and two neighbours decide on the edge faces.
X‐ray Characterization of Defect Structure in LEC Annealed GaAs Crystals
Authors: Czekalski T. , Zielińska‐Rohozińska E. 
Published: January 2007

AbstractWafers of commercially available semi‐insulating (SI) Czochralski‐grown GaAs crystals have been annealed at temperatures near the melting point (> 1100 °C) both for relatively short and long time and then rapidly quenched into cold water. Heat‐treated crystals have been investigated by X‐ray transmission diffraction topography. Cellular structure pattern of the as‐grown sample is replaced by images of precipitates spread out over whole sample. This suggests that the excess arsenic condenses as As precipitates with nucleation sites not correlated with cell walls.
The Polytypoidic Structure of the High‐Tc Superconducting System Bi2Sr2Can–1CunO2n+4 and its Superconductivity
Authors: Hengnan Zhou , Yuanjin Lu 
Published: January 2007

AbstractThe polytypoidic structures in the Bi‐system of superconductors characterized by X‐ray, electron diffraction and TEM technique are described. A strong incommensurate modulated diffraction was observed by these methods in the 2223‐phase. In addition, we revealed the Laue streaks for the one‐dimensional disorder, the banded structure perpendicular to the c‐axis. We suppose that the intergrowth is an indication of the displacement in the Bi‐O layers. It is evident that the polytypoidic concept allows us to describe the structure and physical properties of these superconducting phases in a unified manner. So it is shown that the polytypoidism is a general feature of the Bi‐system materials.
Electron Paramagnetic Resonance of VO2+ in M2Zn(SeO4)2 · 6H2O(M=K, Rb) Single Crystals
Authors: Saroj  , Yadav S. K. , Jain V. K. 
Published: January 2007

AbstractThe EPR spectrum of VO2+ has been studied in single crystals of K2Zn(SeO4)2 · 6H2O and Rb2Zn(SeO4)2 ∼ 6H2O at ∼9.45 GHz. VO2+ substitutes for Zn2+ have preferential orientations in the lattice. The V = O of the intense vanadyl center is nearly along the longest ZnH2O direction. Spin‐Hamiltonian parameters have been evaluated from single crystal as well as from powder spectra.
Polarizabilities of Binary Mesophase Mixtures Containing 4,4′‐Di‐Ethoxy‐Azoxybenzene
Authors: Reddy R. N. V. Ranga , Murthy V. R. 
Published: January 2007

AbstractThe applicability of the modified Lippincott‐δ‐function model (ML δ P) method is tested for binary mesophase mixtures. Using this method, the polarizabilities, polarizability anisotropies and order parameters of binary mesophase mixtures containing 4,4′‐di‐ethoxy‐azoxybenzene are evaluated and compared with the reported values. A close agreement is observed between the estimated values and reported values.
Crystal Structure and Growth Morphology of Nickel Superthin Films
Authors: Mikhailov I. F. , Borisova S. S. , Fomina L. P. , Babenko I. N. , Melnik N. N. , Pudonin F. A. 
Published: January 2007

AbstractNi superthin films of t = 0.3–3.5 nm thickness prepared by radio‐frequency sputtering have been studied by mordern X‐ray methods, such as reflectometry, fluorescence analysis and grazing‐beam structure analysis. The results have shown that the films were polycrystalline and their densities correspond to bulk values for nickel already at the early stage of growth. None oxides were found in Ni films. The model of earliest stage film growing have been suggested: film begins to grow by the island mechanism, but the crystallization front remains perfectly plane during the growth.
Preparation of High‐quality InGaAsP/InP Heterostructures for Edge‐emitting 1.3 μm LED's
Authors: Novotný J. , Vyhnalík L. , Zelinka J. 
Published: January 2007

AbstractEffects of varying the composite heterostructure geometry have been investigated in the context of InGaAsP/InP (λ λ= 1.3 μm) non‐coherent radiation sources. The study has been guided by a preliminary theoretical analysis and complemented by evaluation of the statistics in sample ensembles. Optimum construction diodes emit 600–700 μW/facet of optical power. The added quaternary layer of intermediate bandgap (Λg λ= 1.1 μm) has been found to have benefical effect on the quantum efficiency and reproducibility of the manufacturing process.
On the Chemical Reaction Mode of Polysilicon Deposition from Silane
Authors: Kühne H. 
Published: January 2007

AbstractSilane decomposition and silicon layer growth will be described by way of theory taking into account heterogeneous as well as homogeneous reaction mode and 1st as well as 0.5th order of the chemical reaction. Comparing axial layer growth rate distribution and total substrate surface area effect on the latter with respect to theoretical and experimental results (for the process conditions investigated), it will be shown that the deposition of undoped poly silicon is characterized by a heterogeneous reaction mode, whereas chemical reaction is of first reaction order in the temperature range above 973 K and of 0.5th reaction order below 973 K. The deposition kinetics of strongly in‐situ phosphorus doped poly silicon is shown to be in agreement with a homogeneous reaction mode of 0.56th reaction order.
The Description of the Isothermal Decomposition Processes in AlSc Alloys by means of Electric Resistivity Measurements and TEM Investigations
Authors: Wolter R. , Siebert P. , Fabian H.‐G. 
Published: January 2007

AbstractThe decomposition behaviour of two AlSc alloys (cSc = 0.18; 0.36 at.%) after direct quench to room temperature and subsequent ageing at temperatures in the range 200 °C ≦ Ta ≦ 550 °C was investigated by means of isothermal resistivity measurements and TEM. In the temperature range 325 °C ≦ Ta ≦ 400 °C both alloys show independent of the Sc content an “inversion” of the decomposition kinetics, obviously caused by the transition of the coherent into the incoherent Al3Sc phase.
Near‐edge Optical Properties of CuInSe2 Studied by Photoacoustic Spectroscopy
Authors: Zegadi A. , Neumann H. , Slifkin M. A. , Tomlinson R. D. 
Published: January 2007

AbstractOptical absorption spectra of n‐type CuInSe2 single crystals were evaluated by means of photoacoustic spectroscopy in the photon energy range from 0.94 to 1.02 eV. At photon energies below 0.99 eV the spectra exhibit exponential tails that are ascribed to the presence of shallow impurity states. At higher photon energies the absorption coefficients follow the relation for direct allowed optical transitions between parabolic bands. The parameters of this relation are determined and compared with previous measurements.
Quench Hardness Anisotropy of Rhombohedral Crystals. Sodium Nitrate
Authors: Joshi D. R. , Pandya J. R. 
Published: January 2007

AbstractThe effects of quenching temperature and orientation of Knoop indenter on microhardness of cleavage planes of synthetic sodium nitrate crystals are studied for the range of applied loads (20–160 g) in the high load region. Phenomenological approach was followed to obtain an empirical relation connecting Knoop hardness number, orientation, and quenching temperature. Anisotropic indices are also determined. The implications are discussed.
Hardness Anisotropy of Rhombohedral Crystals of Calcite. Variation of Hardness with Orientation
Authors: Joshi D. R. 
Published: January 2007

AbstractThe variation of hardness of rhombohedral single crystals of calcite with orientation of longer diagonal of Knoop indenter with respect to direction [100] on a cleavage plane (100) is studied. The Knoop hardness number H which has a constant value in the range of high loads (40–80 g) varies with orientation A and quenching temperature. By following phenomenological approach, an empirical relation √HA = mA + C is developed from these studies. The effects of crystal anisotropy and thermal treatment of specimens after indentation are also discussed.
Refractive Indices, calculated orientational order Parameters, and Polarizability Anisotropies of Liquid Crystalline 3‐(4‐Alkyl‐phenyloxy)‐propane‐1,2‐diols
Authors: Hauser A. , Hamann A. , Tschierske C. , Pelzl G. 
Published: January 2007

AbstractFor a novel variant of smectic structures the SA+ phase of the homologous 3‐(4‐alkyl‐phenyloxy)‐propane‐1,2‐diols the refractive indices ne and no were measured in dependence on the temperatue. The polarizability anisotropy, the orientational order parameter, and the packing fraction were calculated using a mean field fitting method. The components of the internal field tensor were included in the fitting procedure. The increasing mobility of the alkyl chain for higher homologues reduces the orientational order in the smectic layers and also the birefringence which is very small. The molecular polarizabilities are increasing nearly linearly with the elongation of the alkyl chain. The small alternation of the polarizabilities corresponds to the alternating change of the length‐to‐breadth ratio. The calculated packing fractions are enhanced for higher homologues.
Binary Systems of Swallow‐Tailed and Laterally Branched Liquid Crystals and their Dielectric Behaviour
Authors: Heinemann S. , Kresse H. , Weissflog W. 
Published: January 2007

AbstractSwallow‐tailed liquid crystals were mixted with four laterally branched substances in order to investigate the influence of molecular geometry on the correlations of molecules in the short range order. Besides the isobaric phase diagrams the results of dielectric measurements on oriented probes in the frequency range from 10 Hz to 100 kHz are discussed. Microscopic as well as dielectric investigations show that laterally branched molecules destroy the antiparallel arrangement of swallow‐tailed substances and in this way destabilize the smetic A phase. It is possible to put in order laterally branched substances according to its “destroying” influence.
Effect of the Presence of Crystals on Nucleation Parameters
Authors: Nývlt J. 
Published: January 2007

AbstractMetastable zone width measurements in aqueous solutions of 18 well soluble substances have been used for the characterization of the nucleation process in absence and in presence of crystals. As could be expected, it has been confirmed that the specific surface energy of the critical nucleus is only slightly decreased by the presence of crystals. The effect is almost negligible for the critical nucleus size. Both of these quantities can be correlated with the solubility of the substance.
Characteristic Growth Features and Etching of InBi Single Crystals
Authors: Pandya G. R. , Vyas S. M. 
Published: January 2007

AbstractThe characteristic growth features observed on the top free surface of InBi single crystals grown by the zone‐melting method are reported. These features are analysed by stereographic technique and a possible mechanism responsible for the appearance of the characteristic growth features is discussed. A new etchant capable of revealing dislocations inclined to the cleavage plane is also reported.
Further Investigation of the Growth of Spliced KDP Seeds and its Mechanism
Authors: Feng Pan , Jin‐Kui Liang , Gen‐Bo Su , You‐Ping He , Yi‐Sen Huang , Bing‐Rong Huang , Qing‐Lan Zhao 
Published: January 2007

AbstractThis work deals with the further study of the growth and mechanism by splicing some seeds, e.g. three seeds arranged in two kinds, four seeds, and n × n (n = 3,4) seeds, and furthermore a dish of pressed powder, which can be considered as a lot of spliced seeds. In addition, it was studied the effect of the different flow shapes of the stirred solution and the effect of the faults of growing faces of splicing seeds.
Halogen Form in Calcium Borate Glasses Containing Iron
Authors: Gohar I. A. , Megahed A. A. , Assem E. E. 
Published: January 2007

AbstractSome halogen‐doped calcium borate glasses containing iron have been prepared according to the precentage molar composition [(30‐X)CaO · xCaX2 · 10 Fe2O3 · 60 B2O3)] and annealed. Scanning electron micrographs of heat‐treated glasses show that the microstructure consists essentially of two phases. By introducing the halogen ion one of the primary phases (Ca‐rich borate) decreases in its volume and a new phase appears and exists as crystalline form. A secondary phase can also be produced which segregates in Ca‐rich borate as droplets. Magnetic susceptibility, molar volume, and infrared measurements revealed that at concentrations of CaX2 < 10 mol% the halide ions may be introduced as modifiers and as network formers at CaX2 concentrations > 10 mol%.
Diffraction Elastic Constants for Textured Materials — Different Methods of Calculation
Authors: Baczmański A. , Wierzbanowski K. , Haije W. G. , Helmholdt R. B. , Ekambaranathan G. , Pathiraj B. 
Published: January 2007

AbstractA systematic review of different types of traditional averages for diffraction elastic constants in textured materials is given. In addition a new type of average, which recently was suggested, is presented. These averages are of vital importance for a correct interpretation of internal (e.g. residual) stress measurements.The theoretically predicted diffraction elastic constants are compared with the experimental ones for rolled steel samples; there exists good agreement between theory and experiment.