bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Dislocations in KDP Crystals on Laser Damage Threshold
Authors: Endert H. , Melle W. 
Published: January 2007

AbstractThe dislocation density in KDP crystals has been determined by X‐ray diffraction topography (LANG method). A method for determining the laser damage thresholds in dependence on dislocation density is described. It is found that dislocations with a density about 103 cm−2 reduce the laser damage threshold up to a factor of two compared with perfect regions. It is shown that experimentally measured damage results can be explained theoretically.
Etching Studies on Potassium Dichromate (KBC) Crystals
Authors: Sangwal K. , Szurgot M. 
Published: January 2007

AbstractAn investigation of the revelation of dislocations in potassium dichromate (KBC) crystals by etching in water, alcohls, and in inorganic acids mixes with acetone and alcohols is carried out. It is observed that several solutions including water, alcohols and organic acids produce disslocation etch pits on various faces of KBC crystals. Observations of twining and dissolution anisotorpy of (001) faces are also presented. Etching of (001) cleavage faces of same crystals in an etchant composed from 1 part HNO3 and 3 parts acetone indicates the possible growth of another phase at low temperatures.
EBIC/TEM Studies on the Relation between Electrical Properties, Crystallographic Structure, and Interaction with Point Defects of Epitaxial Stacking Faults in Silicon
Authors: Kittler M. , Bugiel E. 
Published: January 2007

AbstractOnly after annealing, EBIC investigations on epitaxial layer defects partly gave contrasts. More information on the crystallographic structure of these defects was obtained in subsequent HVEM investigations. Experimental results confirmed the supposition that only the decoration of the crystallographic defects with additional recombination centres (impurity atoms), and not existence of the defects themselves, results in a detectable EBIC contrast. The observed getter efficiency of the various defect types is discussed. This efficiency is growing with increasing lattice distortion.
Double‐crystal Topographic Investigation of the Shape of Silicon Wafers after Oxidation
Authors: Zaumseil P. 
Published: January 2007

AbstractThe shape of silicon wafers plastically deformed by slip band production during an oxidation process is investigated with double‐crystal topography. In dependence on the Burgers vector of the slip band dislocations the tilt of parts of the wafer, especially between crossed slip bands, is observed and the wafer is curved in general. A local quantitative determination of the radius of curvature is possible.
Crystal Growth in Magnetic Fields (I) Crystallization of Me (NH4)2(SO4)2 · 6 H2O (Me = Zn, Cu, Ni, Fe) from Aqueous Solutions in Moderate Magnetic Fields
Authors: Kuschel F. , König AN , Gropp R. 
Published: January 2007

AbstractThere are several reports in the literature concerning the study of the influence of magnetic fields on nucleation and crystal growth. Because of the partially opposite findings, the question whether the application of magnetic fields especially for mass crystallization processes may be of advantage has not been cleared yet. Therefore, the displacement rates of [110] and [001] single crystal faces of four Tutton's salts Me(NH4)2(SO4)2 · 6 H2O (Me = Zn, Cu, Ni, Fe) from supersaturated aqueous solutions in a transversal direct magnetic field (B ≦ 1.4 T) has been measured and compared. Within the detection limit no reproducible effect was observed with Me = Zn, Cu, and Fe. A small growth acceleration occured in case of Ni(NH4)2(SO4)2 · 6 H2O. The results which will be completed by measurements at higher magnetic flux densities, support the viewpoint that the application of magnetic fields on crystallization of diamagnetic substances from solutions offers no real advantage.
Sintering as a result of defect structure
Authors: Schatt W. , Friedrich E. 
Published: January 2007

AbstractExperimental results are presented and conceptions are developed for the qualitative understanding of the fast densification which is frequently observed in the shrinkage stage during the sintering of disperse one‐component compacts. They are based on a dislocation multiplication in the powder particle contact regions which is temporarily connected with the contact growth. Thus, a defect structure state is developed due to which it seems possible that the powder particles as a whole move into the pore space through alternating sliding and deformation processes and get densely packed.
Helical dislocations produced by low temperature thermocycling in a Ti–Al Alloy
Authors: Lavrentev F. F. , Pokhil YU. A. , Dudko P. P. 
Published: January 2007

AbstractBy transmission electron microscopy (TEM), the structural state of a Ti–Al alloy subjected to low temperature thermocycling from 300 to 77 K has been investigated. As the result of this observation, helical dislocations were revealed with the density 109 cm−3. These were generated mainly by grain boundaries or subboundaries. Their formation is thought to be associated with thermomechanical stresses arising during thermocycling. Thermomechanical stresses at the interface of neighbouring grains, estimated with making allowance for the anisotropy of the linear expansion coefficient, appeared to be about 7 kg/mm2. It is assumed that helical dislocation formation is one of the ways in which local internal stresses are relieved.
Dielectric behaviour of the smectic I phase
Authors: Kresse H. , Buka A. 
Published: January 2007

AbstractThe dielectric behaviour of 4‐n‐butyl‐4′‐n‐dodecyloxyazobenzene was investigated in the smectic A, C and I phases from 102 to 3 ṁ 106 Hz. In all phases a dielectric relaxation process could be found which is connected with the reorientation of the molecules around their short molecular axes. At the phase transition SC/SI a step of one decade was observed in the relaxation frequencies.
Growth of sizable single crystals of Y–Co Compounds
Authors: Warchol S. , Modrzejewski A. 
Published: January 2007

AbstractThe Bridgman method was used for the growth of sizable single crystals of Y2Co17, Y2(Co, Fe)17, Y2(Co, Al)17, Y2(Co, Fe, Cu)17, Y2(Co, Fe)23, and YCo5. Yttrium metal was melted in Co or Co–Fe ‘container’ placed in Al2O3crucible coated with BN layer. The crystals were grown at a rate of a few millimetres per hour by lowering the crucible in the heating zone of induction furnace.
Structures of Azomethine Imines of the Pyrazolidone‐(3)‐type, (III) The Structure of 1‐[Anthryl‐(9)‐methylene]‐pyrazolidone‐(3)‐betaine
Authors: Kulpe S. , Seidel I. , Geissler G. 
Published: January 2007

AbstractC18H14N2O, Pbca,a= 19.541(4) Å,b= 14.800(2) Å,c= 9.572(3) Å,Z= 8,U= 2768.3 Å3,Dx= 1.32 g cm−3, μ(MoKα) = 0.93 cm−−1, crystal size 0.5 × 0.2 × 0.1 mm, colourless. FinalR= 0.077 for 1177 independent reflections excluded those with |F0| < 8 σ(F0).The intensities were measured with an automatic diffractometer. The azomethine imine unit of the molecule has a geometry in approximate agreement with a polymethinic electron structure. The conjugation of the azomethine imine unit with the anthryl unit is only small. The anthryl ring and the five membered pyrazolidone ring include a dihedral angle of 65.4°. The main intermolecular forces are C–H … N hydrogen bridges.
Investigations of Dissolving Mechanically Processed Quartz Grains
Authors: Steinike U. , Hennig H.‐P. , Richter‐Mendau J. , Kretzschmar U. 
Published: January 2007

AbstractThe dissolution of polycrystalline quartz strained by compression and shear or by impact crushing in 1‐N NaOH lead to different results. The defects of the impact crushed quartz grains, measured as crystallinity by X‐ray methods, are not preferentially concentrated in regions near the surface. It is assumed that in this case the corners and edges of the quartz grains are preferred centers of defects.
Defects in implanted and Czochralski silicon
Authors: Salisbury I. G. 
Published: January 2007

AbstractRod‐like defects, a6〈114〉 and a/3〈111〉 faults, and a/2〈110〉 loops may all be generated by self‐interstitial aggregation during the annealing of implanted or Czochralski silicon, and several models, intended to account for one or more of these, are compared. It is concluded that the rod‐like defects are {113} faults, and that the three faulted defects form independently (i.e. they are not related in an „evolutionary”︁ sequence). The dipolelike a/2〈110〉 loops probably result from the unfaulting of {113} faults, while other perfect loops are generated by the shear of a/6〈114〉 defects. At a given temperature, the latter appear considerably more likely to unfault than the a3〈111〉 faults. The structure of the {113} fault remains uncertain.
On the morphology of the unidirectionally solidified AgSi eutectic alloy
Authors: Chrost Krystal , Frühauf Joachim , Schmidt Günther 
Published: January 2007

AbstractIt is known that the structure of anormal eutectics occurring in the systems metal‐Si, metal‐Ge strongly depends on the conditions of growth ‐ that is, on the solidification rate R and the temperature gradient G. Structures occurring in the unidirectionally solidified AgSi eutectic alloy with morphology corresponding to region B according to classification adopted by HELLAWELL for the system AlSi were investigated. For the description of the morphology, three parametres were adopted: λ ‐ distance between the centres of Si crystals, d ‐ length of arms of cross‐like crystals, b ‐ thickness of Si plates.It has been found that at similar morphologies of Si crystals, expressed by constant values of the relation λd, the known relation λ2R = const. is fulfilled, too.
The defect structure of ammonium sulphate single crystals
Authors: Van Enckevort W. J. P. , Boeshaar H. J. , Linden W. H. Van Der , Van Der Hoek B. 
Published: January 2007

AbstractThe defect structure of larger ammonium sulphate crystals, grown from aqueous solutions, has been studied by means of X‐ray diffraction topography after Lang's method. Several types of dislocations were identified. Moreover it was found that no relationship exists between growth rate and dislocation density, which implies that crystal growth proceeds via two‐dimensional nucleation. No difference was found in the defect structure of crystals grown from pure water solutions and from aqueous solutions with 10 – 20% glycerine as additive: In both cases neither growth bands nor sector boundaries were found. On the other hand, crystals grown in aqueous solutions contaminated with Mn2+ and Fe3+ revealed growth bands and for Fe3+ a mosaic‐like structure.
Impact damage in MgO single crystals
Authors: Remón A. , Piqueras J. , Llopis J. , Ballesteros C. 
Published: January 2007

AbstractOptical absorption has been used to study the impact damage in MgO and MgO:Li single crystals. The results are similar to that obtained in compressed crystals, except in MgO:Li with stable Li° defects, in which the impacts do not produce an increase of the 5.7 eV absorption band.
Structures of azomethine imines of the pyrazolid‐3‐one‐type (V). The structure of 1‐[pyrenyl‐(1)‐methylene]‐5,5‐dimethyl‐pyrazolid‐3‐one‐betaine.
Authors: Kulpe S. , Seidel I. , Geissler G. 
Published: January 2007

AbstractC22H18N2O, P21, a = 7.473(2), b = 13.563(3), c = 18.264(3) Å, β = 115.49(4)°, Z = 4, U = 1670.9(6) Å3, Dx = 1.295 Mg m−3, μ(MoKα) = 0.855 cm−1, crystal size: 0.3 × 0.2 × 0.2 mm, colour: yellow. Final R = 0.086 for 1973 independent reflections excluding those with |F0 < 3σ(F0). The intensities were measured with an automatic diffractometer. There are two symmetrically independent molecules in the unit cell. The azomethine imine parts of the molecules are similar to those of four other relevant structures determined by X‐ray analysis. A polymethinic part of a molecule is linked with an aromatic part via the bond C(4)–C(5). The mean pyrenyl plains and the mean plains of the five membered rings include dihedral angles of 29.6° for molecule A and 23.7° for molecule B.
Precision lattice parameter determination of coloured quartz monocrystals
Authors: Grosswig S. , Härtwig J. , Alter U. , Christoph A. 
Published: January 2007

AbstractSeveral possibilities for the determination of relative lattice parameter changes and for the absolute measurement of lattice parameters are discussed. Special attention has been given to a measuring device for the high‐precision lattice parameter determination according to the BOND method. This device allows to determine the lattice parameters with a relative accuracy of 2 × 10−7. As an example the methods discussed are applied to the investigation of a smoky coloured quartz crystal plate and the results obtained by them were compared.
On batch homogeneity in horizontal CVD reactors (I). Model of heating the process gas
Authors: Richter F. 
Published: January 2007

AbstractA model of heating of the process gas during its flow along the heater is given as a supposition for a modelling of the batch homogeneity with layer deposition and gas phase etching processes in horizontal CVD‐reactors. An analytical expression is derived for the resulting longitudinal temperature profile T(x) in dependence of gas properties, suszeptor temperature, geometric parameters of the reactor, and gas flow rate.
Dielectric relaxation and Freedericksz effect
Authors: Kresse H. 
Published: January 2007

AbstractWe have found that the dielectric anisotropy Δ′ of 4‐n‐butyloxy‐4′‐n‐pentyl‐azobenzene is positive at all frequencies. There is in the MHz region a dielectric dispersion for ϵ′” only which gives a decrease of Δ′. By means of Freedericksz effect was investigated a new variant for the dependence of electrical orientation on the frequency.
Double heterostructure lasers prepared by LPE on medium‐quality GaAs substrates under controlled as vapour conditions
Authors: Novotný J. , Šrobár F. , Zelinka J. 
Published: January 2007

AbstractThe fact that defect formation in (Ga, Al)As LPE layers can be suppressed by the presence of arsenic vapour is employed to improve properties of double heterostructure (DH) lasers. The controlled vapour pressure (CVP) method is implemented using a modified LPE horizontal carbon boat. Growth kinetics study under near‐equilibrium conditions shows that the presence of arsenic vapour diminishes the growth rate of aluminium‐containing layers; no such influence has been observed with the GaAs layers. The CVP method, compared with the customary LPE, has a beneficial effect on the DH surface and cross sections perfection, as well as on the lasing characteristics (differential quantum efficiency, threshold current). Observed values of the parameter T0, characterizing temperature dependence of the laser threshold current, fall into the vicinty of 200 K. The results have been obtained on medium‐quality GaAs substrates.
Simple theoretical estimate of surface energy, bulk modulus, and atomization energy of AIBIIIC compounds
Authors: Neumann H. 
Published: January 2007

AbstractThe specific surface energy of the (112) face of the chalcopyrite structure AIBIIIC2VI compounds is calculated accounting for contributions from long‐ranged, metallic forces and short‐ranged, directional covalent forces. From the surface energies the bulk modulus and the atomization energy of all AIBIIIC2VI compounds are evaluated. A comparison with experimental data shows that the trends in these quantities are correctly described whilst their absolute values are overestimated by not more than about 10%.
Characterization of treated pbte surfaces by means of RHEED and RBS
Authors: Salewski W. , Schenk M. 
Published: January 2007

AbstractDifferently treated PbTe surfaces have been investigated by means of reflection high energy electron diffraction (RHEED) and Rutherford backscattering (RBS). It has been shown that chemical lap polishing followed by heat treatment is the best method to fulfil the requirements of the following epitaxy process concerning the absence of contaminations, the high structural surface perfection, and the flatness of the substrates.The influence of heat treatment on surface perfection, and chemical composition in the surface region has been investigated to determine the optimal conditions for the tempering step before epitaxy.
Isothermal contact of III–V saturated solutions with different III‐V substrates: Two mode of behavior
Authors: Bolkhovityanov Yu. B. 
Published: January 2007

AbstractA correlation is established between the relaxation mode of non‐equilibrium solid‐liquid interfaces and the sign and magnitude of the lattice mismatch between a substrate and the solid which is in equilibrium with the liquid phase contacting the substrate. For a positive mismatch of a resulting film and the substrate the relaxation proceeds via substrate dissolution or spatially separated dissolution and growth; for a negative mismatch the melt droplets penetrate into the substrate. To illustrate this correlation we use examples from the literature as well as our own experimental results on isothermal contact of binary and ternary III‐V melts (saturated with respect to native solids) with different III‐V substrates.
Fluctuation mechanism of normal crystal growth during solidification of binary metallic melts
Authors: Chistyakov Yu. D. , Baikov Yu. A. , Schneider H. G. , Ruth V. 
Published: January 2007

AbstractA recently published theory on the solidification of a one‐component melt has been extended to the more complex case of binary systems. The theory is based on the model of a two‐phase transitional zone existing between the crystalline phase and the melt. The concentration of solid state atoms within each mono‐atomic layer of the transitional zone are assumed to fluctuate due to thermal fluctuations. A crystal growth law has been derived expressing the crystallization velocity in terms of probability functions describing these concentrations fluctuations. When certain restricting conditions concerning the atomic interaction energies within the transitional zone and the distribution of the atoms among the solid and liquid phases at supercooling are fulfilled the crystal growth law attains a simple form predicting for small supercoolings a growth rate proportional to supercooling (linear growth law), roughly proportional to physical parameter θAA, and with a weak dependence on another parameter Δ.
Growth and morphology of p‐terphenyl single crystals
Authors: Borecka B. , Lipiński A. 
Published: January 2007

AbstractThe results of a preliminary investigation of the growth and morphology of p‐terphenyl crystals grown by sublimation and by solvent evaporation methods are reported. It was observed that lozenge–shaped (001) crystal plates are obtained from xylene and benzene solution while dendritic crystals by sublimation. Crystallographic orientation of the plates and microscopic observations of as‐grown crystal surfaces are also described.
The morphotropy phase transition in PZT‐Pb(WCd)O3‐ ceramics
Authors: Kwapuliński J. , Kupriyanov M. 
Published: January 2007

AbstractThe changes of the crystal lattice parameters of the solid solution formed on the basis of PbTiO3 and PbZrO3 with the constant addition of 10 mol percent PbW0.5Cd0.5O3 has been investigated. In samples containing 37.5 to 45.5 mol percent of PbTiO3 the coexistence of two phases was observed. In this concentration region the change of lattice constant and homogeneous parameter of deformation appeared.
Formation and properties of carbon black at high‐temperature pyrolysis of hydrocarbons and the role of ions
Authors: Schierhorn E. , Spangenberg H.‐J. , Lachmann J. , Steinike U. 
Published: January 2007

AbstractThe thermal decomposition of hydrocarbons during high‐temperature pyrolysis is described, and the resulting formation of carbon black is explained by a radical mechanism. Structural properties of acetylene and plasma blacks determined by electron microscopy and X‐ray diffraction are given. Measurements with an electrical probe revealed a direct relation between the ion density in the plasma and the number of primary carbon black particles.
An estimation of the angular correlation curves being characteristic of positron annihilation in dislocations, vacancies, and vacancy clusters in Ni
Authors: Dlubek G. , Meyendorf N. , Brümmer O. 
Published: January 2007

AbstractAngular correlation curves are measured in Ni‐0.1 at.% Sb; 90% cold‐rolled during isochronal annealing. The behaviour of the parameters S, W, and R is interpreted by the formation of three‐dimensional vacancy clusters nucleated at Sb atoms. Using results of positron lifetime measurement previously performed we estimate the angular correlation curves being characteristic of positron annihilation in bulk, dislocations, vacancies and vacancy cluster of different size (n = 5, 10, 20, and 50 vacancies per cluster).
Reactivity of CCl4 plasma against SiO2 surfaces
Authors: Tiller H.‐J. , Göbel R. , Breitbarth F.‐W. 
Published: January 2007

AbstractSiO2 is etched considerably by a CCl4 plasma at surface power densities of about 0.3 W cm−2. This etching process is investigated by the SiCl4 formation with aid of mass spectroscopy where final products of the etching process and the extracted ions were studied in dependence on time in a closed plasma volume. The primary step of the etching process is the activation of SiO2 by the plasma involving breaking of siloxan bridges.The overall mechanism of the SiO2 etching by the CCl4 plasma is proposed in form of magnified image The rate limiting constants are k0 and k3. The SiCl4 formation is decreased or inhibited by an admixture of Cl2, H2, O2 or CO to the CCl4 plasma.CCl4‐Plasmen führen zu einem Ätzangriff an SiO2‐Oberflächen. Dieser Ätzprozeß ist bei Leistungsdichten an der zu ätzenden Oberfläche von > 0,3 W cm−2 deutlich über eine SiCl4‐Bildung nachweisbar. Der Primärschritt ist eine Aktivierung der SiO2‐Oberfläche durch das Plasma, die zu Bindungsbrüchen der Siloxanbrücken führt.
Mesoscopic and microscopic aspects of the PSB formation mechanism in fatigued FCC monocrystals
Authors: Blochwitz C. , Burmeister H.‐J. , Kremling U. 
Published: January 2007

AbstractPersistent zones of plastic strain localization (PSBs) can be observed in fatigued fee monocrystals above the “nucleation cycle number” Nn and the “nucleation stress” amplitude τn, respectively. They follow after temporary strain localizations existing at N < Nn and being discernible by oscillations of the relative shape of the hysteresis loops (VH) or by strain bursts. Using a simple rheological model the frequency of internal stresses of mesoscopic wave length (“mesoscopic stresses”) was determined for Ni monocrystals fatigued at four different plastic strain amplitudes up to Nn. A “mesoscopic threshold stress” τ* has been found to be exceeded within the whole volume of the dislocation‐dense regions (DRs) at N ≧ Nn. By comparison of τ* with the stress for the operation of Frank‐Read sources of the segment lengths l0 at the border of the DRs, it might be assumed that above Nn and τn respectively a mechanism of dislocation sources acts, compensating the high annihilation rate of movable dislocations in the zones of strain localization. In so doing the formation of persistent zones of strain localization becomes possible, in which the “ladder‐like” dislocation structure of the final PSBs develops successively.
Surface morphology and growth mechanisms of argyrodite‐type Cu6PS5 hal crystals
Authors: Fiechter S. , Eckstein J. , Van Enckevort W. J. P. , Binsma J. J. M. 
Published: January 2007

AbstractSingle crystals of Cu6PS5Hal (Hal = Cl, Br, I) have been grown by dissociative sublimation and by chemical vapour transport with P, S, Hal, CuHal and combinations thereof as transporting agents in the temperature range 800 to 1000 K. Microscopic observation of the tetrahedral faces revealed several growth features. Macrosteps, closed loop steps and surface protuberances are always accompanied with the presence of liquid CuHal/Cu2S droplets on the growing crystal surface. The phenomena are characteristic for a two‐dimensional Vapour‐Liquid‐Solid growth mechanism. In the absence of CuHal/Cu2S liquid phase, direct growth from the gas phase (VS growth) takes place leading to hillocks and growth spirals with low step heights (∼ 5–10 Å).