bluuebunny/crossref_metadata_2025_split huggingface dataset:
Helium‐Cooled Straining Stage for the AEI EM7
Authors: Taylor G. , Saka H. 
Published: July 2007

AbstractThis paper describes a gas/liquid cooled, side‐entry straining stage designed for use with the normal air‐lock on the AEI EM7 HVEM. Tensile test specimens with a 1 mm gauge length can be deformed <40% strain and tilted ± 10° about one axis. Temperature is measured with a thermocouple and controlled by regulating the gas flow through the flexible transfer tube which also incorporates a radiation stop.
The Free Surface Effect on the Dislocation Mobility in Molybdenum Single Crystals
Authors: Novikov I. I. , Yermishkin V. A. , Kantor M. M. , Timofeev V. N. 
Published: July 2007

AbstractThe in‐situ high voltage electron microscopic method has been used to study the phenomenon of spontaneous screw dislocation accelerations near the wedge‐like edges of molybdenum single crystal specimens. The effects of either of the free wegde surfaces on dislocation mobility have been included in the discussion of this phenomenon. The experimental data were used to evaluate the surface image forces.
An In‐situ Investigation of the Creep Mechanisms of Aluminium at Intermediate Temperatures
Authors: Myshlyaev M. M. , Martin J. L. , Caillard D. 
Published: July 2007

AbstractIn‐situ deformation experiments are performed at 150 °C and 200 °C after a macroscopic creep test in polycrystalline aluminium. The significant microscopie events which take place during the constant strain rate stage of creep are subboundary migration and destruction, dislocation multiplication, interaction of individual dislocations with the three dimensional network inside the cells and with the subboundaries. The observations are discussed in terms of different models interpreting the measured activation energy and area.
In‐situ Straining Experiments on Glass Foils in the HVEM
Authors: Hopfe J. , Appel F. , Schmidt V. 
Published: July 2007

AbstractCrack propagation in Na2OCaOSiO2 glass foils with thicknesses between 0.4 μm and 4 μm was studied by HVEM in‐situ straining experiments. The propagation of cracks could be achieved by a stepwise loading of the glass foils in a quantitative HVEM tensile tilting stage. The contrasts observed in front of the crack tips indicate a plastic deformation of the glass foils. The influence of the imaging electrons on the mechanical properties of the foil material is discussed.
The Nature of Dislocation Damage in Electron Irradiated Al‐1% Cu and Stainless Steels
Authors: Smith B. , Fahad I. , Smallman R. E. , Loretto M. H. 
Published: July 2007

AbstractSpecimen of Al‐1% Cu aged to contain θ′ and stainless steels of various Ni and Cr contents have been irradiated in an HVEM. It has been found that the nature of the dislocation damage in the stainless steels is a complex function of composition and temperature; very irregular faulted loops, regular faulted loops and regular unfaulted loops are formed in varying proportions. In the Al‐1% Cu, aged for varying times at 190 °C to produce θ′, the ageing times influences the amount of radiation damage in a complex manner. Virtually all the visible damage in these alloys is found either at the precipitate interface or at the electron entrance surface.
Veränderung der Oberflächenstrukturen von Quarzeinkristallen infolge ihrer Wechselwirkung mit einfachen Gasen bei hohen Temperaturen (I) Behandlung mit Argon und Sauerstoff
Authors: Sokoll R. , Müller B. 
Published: July 2007

AbstractEs wurde die Struktur der drei wichtigsten Oberflächen von Quarzeinkristallen [(1011), (0111), (1010)] nach der Wechselwirkung mit Argon und Sauerstoff bei Temperaturen zwischen 773 K und 1223 K (p = 760 Torr) mittels der Beugung hochenergetischer Elektronen in streifendem Einfall (RHEED) untersucht. Dabei konnte festgestellt werden, daß sich die Oberflächenstrukturen infolge dieser Wechselwirkung irreversibel verändern. Und zwar entsteht im Fall beider Gase auf den Rhomboederflächen eine (2 × 2)‐Überstruktur, und auf der Prismenfläche eine (1 × 4)‐Überstruktur. Die Bildung dieser Überstrukturen wurde in Abhängigkeit von Temperatur sowie Reaktionsdauer untersucht, und anhand von Literaturdaten erfolgt eine Diskussion der möglichen Wechselwirkungs‐mechanismen zwischen Kristall und Gas.
Lanthanum manganite phase diagram
Authors: Karavay A. P. 
Published: July 2007

AbstractBased on neutron diffraction studies the magnetic moments have been calculated and the magnetic phase relation has been determined in the lanthanum manganite samples (LaMnO3) with different degree of crystallographic lattice distortions. It is established that with the decrease of the distortions the ferromagnetic phase content increases at the expense of the antiferromagnetic phase. The lanthanum manganite phase diagram has been plotted from the obtained data.
Infrared light scattering and absorption microscopy investigations at dislocations in GaAs crystals
Authors: Löschke K. , Tempel A. 
Published: July 2007

AbstractIn recent years a number of experiments have been published dealing with the light scattering at small particles. All of these experiments have been made in the visible spectral range. In this paper we report an experimental arrangement for infrared light scattering by dark‐field illumination. Preliminary results of the observations of dislocations in GaAs crystals are given. The scattering images are correlated with results obtained by means of absorption microscopy with infrared light. Helix‐like fine structures of dislocations are found mainly arranged in the 〈110〉 directions.
Structural and electrical properties of CuIn0.7Ga0.3Se2 epitaxial layers on GaAs substrates
Authors: Schumann B. , Neumann H. , Tempel A. , Kühn G. , Nowak E. 
Published: July 2007

AbstractEpitaxial layers of CuIn0.7Ga0.3Se2 could be prepared by flash evaporation onto (111)A‐oriented GaAs substrates in the substrate temperature range Tsub = 745 … 870 K. At Tsub = 745 … 820 K the films had the chalcopyrite structure, at Tsub = 820 … 845 K an additional pseudohexagonal phase was found. Indications to the presence of a sphalerite phase were found at high substrate temperatures. Films grown at Tsub ≦ 750 K were always n‐type conducting and showed a largely pronounced impurity band conduction effect. At Tsub ≧ 860 K the films were always p‐type conducting and two acceptor states with ionization energies of some 10−3 eV and of 125 … 140 meV were found.
Studies on configuration of dislocations and dissolution of cleavage steps of magnesium orthosilicate crystals
Authors: Desai C. C. , John V. 
Published: July 2007

Abstract(010) cleavages of magnesium orthosilicate crystals have been etched in concentrated hydrochloric acid vapour at room temperature, in the melts of potassium and sodium hydroxides at 400°C, and also in the aqueous solutions of KOH, NaOH, and their mixtures at boiling points. The configuration of isolated dislocations have been described. Bent, branched, stepped and the inclined nature of dislocation lines have been investigated. The effect of dissolution ledges on the size and morphology of etch pits has been discussed. The implications are discussed.
Veränderung der Oberflächenstrukturen von Quarzeinkristallen infolge ihrer Wechselwirkung mit einfachen Gasen bei hohen Temperaturen (II). Behandlung mit Wasserdampf und Chlor
Authors: Sokoll R. , Müller B. 
Published: July 2007

AbstractUnter den gleichen experimentellen Bedingungen wie im Fall von Argon und Sauerstoff wurde die Struktur der drei wichtigsten Oberflächen von Quarzeinkristallen nach der Wechselwirkung mit den gegenüber SiO2 reaktiven Gasen Wasserdampf und Chlor mittels RHEED untersucht. Dabei entsteht infolge der Wechselwirkung auf den Rhomboederflächen wiederum eine (2 × 2)‐Überstruktur, während sich auf der Prismenfläche sowohl eine (1 × 3)‐ als auch eine zweite Überstruktur mit gedrehter Elementarmasche bilden. Auch hier erfolgt anhand experimenteller Befunde die Diskussion eines möglichen Wechselwirkungsmechanismus, und es werden Aussagen über die Größe der sich strukturell umwandelnden Kristallbereiche getroffen.
Hydrothermal etching of flux grown phenakite (Be2SiO4) single crystals
Authors: Shindo I. , Kawada I. , Kojima H. 
Published: July 2007

AbstractThe etching studies were made on flux grown phenakite (Be2SiO4) single crystals to elucidate the twinning phenomenon and the growth mechanism. The sharp and distinct etch pits and the twin boundaries were successfully obtained after the hydrothermal etching. From the etching and the X‐ray precession experiments, it was conjectured that the phenakite had an inversion twin along the c axis. The twinning should be originated during the earlier stage of growth where the dendritic and acicular crystals were grown and thereafter the twinned crystals grew to the prismatic crystals during the latter stage with decreasing the temperature.
Shape of thermal etch pits and crystal structure in tellurium crystals
Authors: Bhatt V. P. , Trivedi Mira D. 
Published: July 2007

AbstractDuring the systematic study of thermal etching of tellurium crystals, various shaped thermal etch pits were observed on the {1010} cleavage faces of this crystal. An attempt has been made to explain the shape of non‐dislocation and dislocation etch pits. A simple model based on crystal structure and bonding of atoms has been suggested to explain the shape of etch pits.
Positron annihilation in oriented single crystals of calcite: Two photon angular correlation
Authors: Ramasamy P. , Gnanam F. D. , Krishnan S. , Laddha G. S. 
Published: July 2007

AbstractPrecision measurements of the angular correlation of two photon annihilation in oriented single crystals of calcite are reported. 10 millicurie Na22 was used as the positron source and the resolution of the angular correlation set‐up was 0.7 milliradian. Measurements were made parallel and perpendicular to optic axis and also for the (100) plane. Using the Goldanskii and Prokopev model for polaron states for positrons in ionic crystals the FWHM is used to calculate the effective masses of positrons and anion effective charges for different crystallographic directions. The observed variations of effective charge must be taken as the direct experimental evidence for charge distortions.
Effect of neutron irradiation on stratigraphy in calcium fluoride single crystals
Authors: Desai C. C. 
Published: July 2007

AbstractNatural single crystals of calcium fluoride have been cleaved along {111} planes and a number of matched pairs have been obtained. One piece from etch pairs have been irradiated with thermal and pile neutrons, the flux varying from 1.3 × 104 to 3.0 × 1013 neutrons cm−2. After irradiation, the irradiated and their non‐irradiated counterparts have been matched. They were then etched simultaneously in 0.2 N hydrochlorid acid for the same period. The stratigraphical etch patterns produced have been studied optically. There is no exact correspondence of the stratigraphical etch patterns have been observed on the irradiated and non‐irradiated matched pairs. The disappearing in the stratigraphical pattern of the irradiated crystals increases with increase in the dose of irradiation. The implications are dicussed.
On the end products of mica thermic decomposition
Authors: Vasilyev E. K. , Lapides I. L. 
Published: July 2007

AbstractMicas of muscovite‐biotite‐lepidolite series were investigated thermographically. The end products of heating these micas were studied by the X‐ray powder diffraction method. γ‐Al2O3, Quartz, spinels, hematite, leucite, β‐eucryptite, amorphous phase (glass) and α‐kalsilite (probably) are present in the annealed products depending on composition and structural peculiarity of initial micas.
Structure defects investigation of GaAs and AlxGa1−xAs epitaxial layers
Authors: Vasilevskaya V. N. , Konakova R. V. , Melnikov G. D. , Semenova G. N. , Tkhorik Yu A. 
Published: July 2007

AbstractThe paper is concerned with the results of investigation of structure defects in gallium arsenide and Al0.3Ga0.7As epitaxial layers. It was found that structure defects in layers under investigation are responsible for the excess component of the Schottky diode's reverse current.
Hyperfine structure of EPR spectra of Cr5+ ions in irradiated sodium dichromate crystals
Authors: Alybakov A. A. , Gubanova V. A. , Tojchiev N. 
Published: July 2007

AbstractEPR spectra are studied of X‐irradiated sodium dichromate crystals grown from an aqueous solution by evaporation at 31°C. Doublet lines of EPR‐absorption are attributed to the Cr5+ ions in the CrO43− and CrO3− radicals resulting from radiation decomposition of Cr2O72− and being in the lattice in two unequivalent positions. Hyperfine structure caused by interaction of an unpaired electron with Cr53 nucleus were observed both at liquid nitrogen and room temperatures. For the line, caused by CrO43− radical, gy and Ay directions coincide and angles both between Ax, gx and Az, gz make up ∼ 25°. The spectrum is described by usual spin Hamiltonian for S = 1/2 with following parameters (T = 77 K): for CrO: gz = 1.984, gy = 1.970, gx = 1.961, |Az| = 8.2 · 10−4 cm−1, |Ay| = 13.7 × 10−4 cm−1, |Ax| = 36.1 · 10−4 cm−1; for CrO3−: gz = 1.915, gy = 1.975, gx = 1.985, |Az| = 32.2 · 10−4 cm−1.
Temperature dependence of doping element incorporation with the chemical vapour deposition of epitaxial silicon (V). Incorporation of arsenic
Authors: Kühne H. , Sperling R. 
Published: July 2007

AbstractBased on the knowledge previously obtained with regard to the incorporation of phosphorus as an equilibrium‐determined process, theoretical values of the enthalpies of the different possible incorporation equilibria are calculated for the incorporation of arsenic into the growing silicon epitaxial layer. The sublimation enthalpies of elemental arsenic, the formation enthalpy of arsine and the enthalpy of solubility enter into the equation. The results compared to the present experimental data of other authors are discussed.
Nitrogen segregation on the (100) surface of an austenitic chromium‐nickel steel studied by LEED and AES
Authors: Fehrmann U. , Müssig H.‐J. , Storbeck F. , Thielsch R. , Uhlmann K. 
Published: July 2007

AbstractAt temperatures above 700 K, the annealing of austenitic stainless steel under ultra‐high vacuum conditions results in the segregation of nitrogen, accompanied by the increase of chromium concentration at the surface. Both the elements enrich at the surface, so that a constant ratio of the detected amounts is reached. Thus we conclude the formation of a chromium‐nitrogen compound. — Due to the segregation of nitrogen, we observed the formation of a p (2 × 2) superstructure in the LEED pattern. From a kinematic interpretation of the (00) beam intensity measured we suppose the nitrogen to be arranged in fourfold sites and to have an atomic radius of 0.054 nm.
Auger spectrometric studies on fracture surfaces of tool steel
Authors: Romhányi K. , Csih Zs. Szász , Gergely G. , Menyhárd M. 
Published: July 2007

AbstractThe fracture surfaces of tool steel K‐13 (Hungarian Standard) were studied by Auger electron spectroscopy. Notched specimens of 3 × 3 mm2 were fractured in UHV (6 × 10−8 Pa) with a fracturer (Riber FR 100) and studied with a CMA analyser (Riber OPC 103). With our modification the fracturer was operated within the −150°C −+230°C temperature range. The fracture surfaces were tested with a scanning electron microscope (JEOL JSM 35). The evaluation of Auger spectra was based on the PHI (PALMBERG et al.). Handbook, however the backscattering correction of Jablonski was applied in some cases. The choice of adequate fracturing temperature proved to be very important. Low temperature fracture of this steel alloy is producing very rigid transgranular fracture. The effects of sample heat treatment and of fracturing temperature as well were studied in details. The Auger spectra of fracture surfaces are strongly affected by the heat treatment of the samples. The grain boundary fracture surface of a sample austenitized at 1100°C quenched and tempered at 600°C exhibited a strong enrichment of P, correlating with the enrichment of Cr, V and Mo. The transgranular fracture surface of the same sample but without tempering corresponded to the bulk composition. In some cases and spots on the fracture surfaces, giant S or P peaks were associated with secondary phases (inclusions) on the SEM pictures.
A unified treatment of thickness homogeneity problems in CVD (II). Cold‐wall reactors
Authors: Arnold H. 
Published: July 2007

AbstractChemical vapor deposition in susceptor‐heated horizontal reactors is included into a simple treatment of reactant depletion and its compensation, given previously. Extending the model of EVERSTEYN et al. (including thermodiffusion), the whole range from diffusion control to reaction control is covered. At diffusion control, the condition for constant deposition rate along large reactor lengths cannot be satisfied by the usual tilting of a plane susceptor out of the direction of the main gas stream. From this point of view, the model statements (at least in the approximation that neglects entrance effects) are less favorable than for vertical epitaxy reactors.
On the influence on tracht and habit of urea crystals (II)
Authors: Gaedeke R. , Wolf F. , Bernhardt G. 
Published: July 2007

AbstractIt is shown that during crystallization urea forms mixed crystals, adsorption mixed crystals, and epitaxial growth from aqueous solutions with inorganic salts, the lattice parameters of which are lying within the tolerance of efficiency parameters of urea. The extent of the formation of mixed crystals is determined by the composition of the solution. The slats added to the solution affect changes of tracht and habit of urea and thus are important for improving storage and transport properties. Similar results can be found for modified melts of urea.
Investigations on the structural perfection of bridgman‐grown PbTe single crystals
Authors: Mühlberg M. 
Published: July 2007

AbstractIt is reported on the possibility of improving the structural perfection by the Bridgman method, shown with the example of the influence on the low‐angle grain boundary substructures in PbTe arranged in growth direction. In the employed crystal growth apparatus temperature gradients from 15 to 100°C/cm and solidification rates from 0.33 to 4.2 mm/hr could be achieved. The low‐angle grain boundary substructure was characterized by X‐ray‐topographic and etch investigations on (100)‐orientated ingots. The thermal conditions during the growth affect the structural perfection decisively. An axial spot dependence of etch pit density and substructure abundance was observed. By reducing the cooling rate during growth — expressed by the product of temperature gradient G and solidification rate V — it is possible to obtain more perfect PbTe‐crystals. It seems that the diameter l of the substructure cells which was lying between 0.5 and 2 mm, is related to the cooling rate G · V by the functional coherency l ≈ 1/√G · V. The choice of different initial melt combinations up to 1 at.% Te‐surplus exerted no influence on the abundance of the low‐angle grain boundaries. The in literature suggested connection of low‐angle grain boundary substructure with phenomena resulting from a constitutional supercooling could not be established.
Influence of seeding of the solutions on the crystallization of fibrillar sodium trimolybdate
Authors: Hodorowicz S. , Surga W. 
Published: July 2007

AbstractAn effect of the seeding of solutions on the crystallization of fibrillar sodium trimolybdate is described. The crystallization was studied in three solutions of initial molybdenum concentration CMo = 0.250 M and degree of acidity Z = 1.20, 1.25, and 1.33. The abridgment of the total time of the process respects only to the period of nucleation. At the moment of the acidification of the solutions different forms of isopolymolybdates come into existence.
An unusual type of unmixing in NaCl‐KCl mixed crystals at room temperature
Authors: Andreev G. A. , Buritskova L. G. 
Published: July 2007

AbstractWater‐catalysed decomposition of solid solutions of NaCl–KCl has been investigated at room temperature. The “wet” decomposition proceeds at abnormally high rate as compared to the usual “dry” decomposition. The formation and movement of the decomposition boundary is characteristic of the “wet” process. The influence of divalent impurities and partial decomposition of the usual type has been studied on the rate of the decomposition boundary movement. The mechanism of the unmixing is suggested which involves two interrelated process: the phase separation and formation of a system of interlocking microcracks acting as channels for the water transport from the surface into the bulk of the crystals. The open porosity resulting from the unmixing is confirmed experimentally.
Formation of submicron growth defects during vapour deposition of GaAs films
Authors: Lavrentieva L. G. , Ivonin I. V. , Krasilnikova L. M. , Vilisova M. D. 
Published: July 2007

AbstractIn electron microscopy investigation of the growth surfaces of GaAs films deposited in CVD systems specific growth defects were detected. The form of the defects resembled that of “the pinning sites” observed earlier on silicon films deposited in ultra‐high vacuum (ABBINK et al.; PCHELYAKOV et al.). However, it turned out that the particles which caused the step accumulation and depression formation can move with the growing surface. These defects consisting of liquid particles and depression around them were called “step retardation sites” (SRS). The basic features of defect formation and their influence on the concentrating of impurities and forming of impurity inhomogeneities are discussed.
On the Influence of Short R.T. preageing on the formation of the η′‐phase in an Al‐Zn(4.5 at.%)‐Mg(2.5 at.%) alloy
Authors: Radomsky M. , Löffler H. 
Published: July 2007

AbstractThe influence of short R.T. preageing (1 min) after quenching from 480 °C into RT‐water on the formation of the η′‐phase in an Al‐Zn(4.5)‐Mg(2.5) alloys has been investigated by means of TEM, XSAS, resistivity, and hardness measurements in the ageing temperature range between Ta = 120 °C comparing samples directly quenched (DQ) to Ta and those quenched into RT‐water, kept there for 1 min, and subsequently stored in an oil‐bath of Ta (IQ). At Ta ≦ 170 °C both heat treatments result in finely distributed precipitates of the η′‐phase accompanied by a fairly high hardness value. But at Ta ≧ 180 °C the DQ leads only to few coarse heterogeneously formed η′‐ and η‐precipitates, whilst the IQ yields qualitatively the same precipitation structure as already described at Ta ≦ 170 °C even till 280 °C. These results are interpreted assuming that.A1) the limitation temperature of homogeneous formation of η′ is located at about Th = 175°c andA2) during the pre‐ageing at RT “nucleation sites” are formed as already suggested by RYUM, which are able to act as sites for heterogeneous formation of η′ even at Ta > Th.Hints are obtained that the formation of these “nucleation sites” is not so strongly governed by the quenched‐in excess vacancies as discussed in the literature.
On the possibility of strain determination by section topography in the parallel Geometry
Authors: Maciaszek M. 
Published: July 2007

AbstractA new approach to the problem of strain determination in a crystal by means of X‐ray radiation is presented. In the proposed experiment the border of the windows etched in silicon oxide layer which covers the surface of the silicon crystal, is image using a section topography and geometry in which the edge of the windows is placed parallel to the vertical X‐ray beam axis. That geometry allows to obtain the images giving the possibility of more Precise and easier determination of strains, because the interference fringes (Pendellösung) are considerably narrow. Their position can be defined with better precision.