bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vacancy migration energy in aluminium as determined from exoelectron emission measurements
Authors: Górecki Cz. , Górecki T. 
Published: January 2007

AbstractAfter almost forty years of investigations the phenomenon of exoelectron emission (EEE) is still poorly understood. Nevertheless, the phenomenon is seriously considered as a research tool in radiation dosimetry, solid state and surface physics as well as in physical metallurgy. One of the most heatedly discussed problems is the role of the crystal lattice defects in EEE from metals (Górecki, Górecki). In the present note the possibility of determining the vacancy migration energy in cold rolled and quenched metals will be demonstrated.The measurements were performed in atmospheric air using the apparatus described by Sujak et al. The electrons were detected with the aid of an open air point counter with ethanol quenching vapour. Through the measurements the samples were illuminated with unfiltered UV radiation of a quartz lamp. The samples were prepared from industrial Al sheets of the purity of 99.75%.
Digitalapparatur für hochtemperaturwiderstandsstudium der ausscheidungskinetik in aluminiumlegierungen
Authors: Lašek J. 
Published: January 2007

AbstractGenaue Messungen des elektrischen Widerstandes ermöglichen es, Strukturänderungen in Legierungen direkt bei hohen Temperaturen isotherm oder bei Temperaturänderungen empfindlich und kontinuierlich zu verfolgen.Zur Messung und Registrierung der einzelnen experimentellen Werte wird eine Meßzentrale mit Datenausgabe auf Lochstreifen (Lašek, Hykel) verwendet. Die gleichzeitige Datenvorverarbeitung auf dem Mikrorechner ermöglicht auch die Durchführung verschiedener unerläßlicher Korrekturen. Für die berichtigten Werte Rb des elektrischen Widerstandes erhält man unter Voraussetzung eines konstanten Probenvolumens und einer homogenen Deformation den Ausdruck Rb = )2, wo R, Δl die direkt gemessenen Größen (Widerstand, Verlängerung) sind, l die ursprüngliche Probenlänge.
Phase lead determined growth of 〈100〉 — textured germanium crystallites in eutectic AgGe alloys
Authors: Vetter J. , Frühauf J. , Schneider H. G. 
Published: January 2007

AbstractAlSi type eutectics (AlSi, AgSi, AgGe, ZnGe) form 〈100〉 — textured eutectic dendrites of the semiconductor phase when a certain growth rate R and liquid temperature gradient G are held. The spacings of these eutectic dendrites λ follow the relationship: λ = (rλ ≈︁ 0.2; g ≈︁ 0.5). The exponents of this relationship can be explained by the model of phase lead determined growth. This model is based on the consideration of the analogy to dendrite growth. The AlSi type eutectics have geometrically similar morphologies for determined Gx/R‐relations (x = 1.25 in the case of AgGe) and the relation λ2R = const. is valid. In this paper the AgGe eutectic will be discussed in close detail.
Crystal agglomeration
Authors: Nývlt Jaroslav , Karel Miloslav 
Published: January 2007

AbstractThree different methods have been proposed for quantitative description of agglomeration: visual determination of the percentage of agglomeration, numerical correction of crystal size distribution leading to the degree of agglomeration and the method of decomposition of the two‐peak crystal size distribution. The effect of neglecting the agglomeration on kinetic data of crystallization calculated from crystal size distribution may be very significant.
LEED‐AES investigation on the influence of thermally segregated chromium on the oxidation of an iron‐chromium alloy
Authors: Müssig H.‐J. , Allmer F. 
Published: January 2007

AbstractWhen heating a (111)‐oriented Fe1‐xCrx single‐crystal sample (0.05 ≦ x ≦ 0.10) for 15 minutes at 550 °C an unarranged surface layer rich in chromium and nitrogen, simultaneously, with x = 0.40 will ermerge. The low‐energy Auger signals of iron and chromium were involved for characterizing the chemical bond and the high‐energy ones used for quantitative analysis. The shape and the energy position of the transitions were exactly determined by integration, background subtraction and approximate deconvolution of the Auger electron spectra measured differentiatedly. Chromium nitride layers were detected which retard probably the formation of the FeO layer compared to Leygraf et al.While the adsorption isotherm at room temperature for the surface poor in chromium and crystallographically perfect shows two erratic changes of the sticking probability, the adsorption isotherm for the surface rich in chromium is a continuous curve with a higher increase in the lower dose‐region typical for random surfaces.
The structure of the “influenced grain boundary region” of an Al‐12at.% Zn alloy in dependence on quenching conditions
Authors: Siebert P. , Kroggel R. 
Published: January 2007

AbstractIt is known that in the AlZn alloys the nucleation and growth of the G.P. zones during isothermal ageing in the RT‐range considerably depend on the applied quenching treatment and often certain “irregularities”, e.g. an inversion of the decomposition rate with increasing homogenization temperature (Tq), are observed. Various conceptions were developed in order to explain these inversions, but none of them can consistently interpret the observed main features. For more details see Siebert and Kroggel et al. It is of interest for the present work to mention that various models were developed to explain the structure of the precipitation free zone (PFZ). They are mainly based on suggesting that the profile of the vacancies or that of the solute atoms or both in the GB‐region determine the width and the structure of the PFZ (see e.g. Synecek et al.).It was the idea of the authors to gain more information on the effect of the GB on the structure changes proceeding in its vicinity on investigating not only the width and structure of the PFZ, but the details of the structure changes occurring from the regions very close to the GB up to the midgrain in dependence on various quenching conditions (Tq and quenching rate, vq).For this reason we selected an Al‐12at.%Zn alloy produced from materials of purity 4N and aged the samples of thickness 0.12 mm, after various quenching treatments, at 100 °C for 1 h in order to attain precipitates suitable to be determined in size sufficiently accurately. The samples were annealed at Tq = 300 °C or 490 °C for 0.5 h, quenched to RT into water, fluid W250, or oil, stored at RT for 10 s, and finally aged at 100 °C for 1 h. The foils investigated in the TEM of type TESLA BS 540 operating at 120 kV were electrolytically thinned by the well‐known window method.
Mass transport during growing mercuric iodide by static sublimation method
Authors: Zaletin V. M. , Lyakh N. V. , Nozhkina I. N. 
Published: January 2007

AbstractA description of a simple model for calculations of diffusion mass transport rates for growing α‐HgI2 crystals by sublimation in iodine vapour is presented. A satisfactory agreement with experiment was obtained. Incorporation of iodine into red mercuric iodide is estimated (2 · 10−7 mole/cm3).
Development of scale formed on cooling surface towards equilibrium state
Authors: Veverka František , Söhnel Otakar , Kolařík Stanislav 
Published: January 2007

AbstractChanges in the morphology of scale deposited on the surface of a submerged cooling element during its prolonged contact with a saturated solution of oxalic acid were studied. Needle‐like crystals formed during the initial stage of oxalic acid scale depositing bring about a markedly rough surface. During a longer contact with the solution, however, the needle‐like crystals are gradually dissolved and the scale surface is becoming smooth. After a steady state has been established, i.e. when mass transfer between the solution and scale does not take place any longer, the scale recrystallises completely forming a smooth crystalline coating on the cooling wall and neither its morphology nor weight are changing any further.
On crystal growth of orthorhombic alkali acid phthalates. An application of fourier transform of crystal morphology to tracht and habitus
Authors: Schwarz H. , Fiedler R. , Follner H. 
Published: January 2007

AbstractThe orthorhombic alkali acid phthalates crystallize in three different structure types. The structure of potassium acid phthalate (P21ab) can be regarded as a basic structure. The elementary cells of ammonium (Pcab) and sodium crystals (B2ab) contain two potassium structure units which are connected to each other along [001] by a symmetry centre in the first case and by a twofold rotation axis in the second case. It will be shown that close morphological relations between the crystals also can be observed. The morphological lattices of the substances agree fairly well with the centres of gravity of the phthalate ions (HP). The reciprocal crystals have mmm (KHP, NH4HP) and mm2 symmetry (NaHP), respectively. The growth rates of the faces are proportional to the areas of the net plane meshes, divided by the number of the morphological units per growth layer. The thickness of the growth layer is determined by the morphological extinction rules. The specific surface energies are proportional to the surfaces of the reciprocal crystals parallel to the crystal faces, divided by the areas of the net plane meshes. The theoretical growth and equilibrium forms of the hydrogen phthalates are in good agreement with the experimental observations.
The crystal and molecular structure of the steroidal alkaloid 20‐epi‐kibataline
Authors: Kutschabsky L. , Pfeiffer D. , Kretschmer R.‐G. , Adam G. 
Published: January 2007

AbstractThe major constituent of the alkaloid fraction of the leaves of Paravallaris macrophylla Pierre has found to be the new paravallarine‐type steroidal alkaloid 20‐epi‐kibataline. The structure of this steroidal alkaloid has been determined by X‐ray analysis. The compound crystallizes in the monoclinic space group P21 with the lattice parameters a = 11.286, b = 14.250, c = 6.206 Å, β = 97.88°. The final R value was 0.067.
Precipitation processes in AlZn5Mg2CuX alloys
Authors: Nagy P. , Kovács‐Csetényi E. , Turmezey T. , Honyek G. Y. , Kovács I. 
Published: January 2007

AbstractAlZnMgCu alloys are important structural materials because of their high strengths and good stress corrosion resistance (Speidel Archambault, Chevier, Beck). The relationship between the properties and structure, as well as the formation of different phases in the ternary alloys are well known (Ungar et al.; Löffler et al.). However, the decomposition and transformation processes in the quaternary AlZnNgCu alloys are not well known at present and there are several contradictions in the literature. Only a few systematical investigations have been made on the role of Cu in the decomposition processes in the quaternary alloys (Bryant Soeno, Chigasaki).The aim of this work is to determine the effect of Cu addition on the precipitation processes in the AlZn5Mg2 alloys.
Effect of Zr and Mo in AlZn5Mg2 alloy
Authors: Turmezey T. , Kovács‐Csetényi E. , Nagy P. , Rajkovits Z. S. , Lendvai J. 
Published: January 2007

AbstractAlloy properties can considerably be improved by the addition of small amount of alloying elements, which might cause the decrease of production cost, as well.Transition metals are generally applied as addition elements in age‐hardenable aluminium alloys (Baba 1968, 1970; Groma, Kovács‐Csetenyi Lang, Vitális, Lakner). Most of the investigations are dealing with phase transition but the physical, mechanical and corrosion properties are thoroughly studied, too.It is well known that transition metals are relatively less soluble in aluminium. The reactions in the binary systems of A‐transition metal are mostly of peritectic character and due to this fact the transition elements are acting as grain refiners, however, this effect is explained on basis of their electron structure, as well (Laminov, Samsonov).Investigations were carried out on the AlZn5Mg2 with the addition of 0.2 m% Zr and 0.15 m% Mo, 0.1 m% Zr + 0.1 m% Mo and 0.2 m% Zr + 0.2 m% Mo samples, respectively. The alloys were prepared on high purity base aluminium (5N), cast in copper mould, homogenized, scrapped and finally cold rolled.
The effect of solid solution decomposition temperature on the structure, mechanical properties and stress‐corrosion resistance of AlZn5%Mg3% alloy
Authors: Szymanski J. , Karp J. , Klyszewski A. 
Published: January 2007

AbstractThe data obtained in recent years (Nicholson Klyszewski, Karp; Szymański et al. have revealed that the temperature of the first step in the precipitation treatment (e.g.) quenching, quench interruption and pre‐ageing) has a decisive effect on the stress‐corrosion resistance of commercial weldable wrought AlZnMg alloys.The paper gives an account of a study of the effect of variations in quenching interruption and pre‐ageing on structure, mechanical properties and resistance to stresscorrosion of an alloy of this group in sheet forms.
Growth mechanisms in GaAs‐VPE at low deposition temperature
Authors: Schwetlick S. , Seifert W. , Butter E. 
Published: January 2007

AbstractThe VPE growth of GaAs in the system GaAsAsCl3 with either H2 or He as the Carrier gas was studied in the range of low deposition temperatures. Down to about 670 °C the growth in the H2‐system is limited by the kinetics of chlorine desorption by molecular hydrogen. The increase in growth rate at lower temperatures results from the onset of GaCl3‐desorption (disproportionation mechanism). The addition of NH3 to the vapour phase enhances this effect. Below about 700 °C the growth rate in the GaAsAsCl3H2NH3 system becomes comparable to that in the GaAsAsCl3He‐system, where the GaCl3 desorption mechanism is the only possible growth mechanism.
Doping of epitaxial CVD silicon with arsenic or phosphorus (i). Steady state conditions
Authors: Kühne H. 
Published: January 2007

AbstractA modified theoretical model of dopant incorporation is discussed, while comparing it with the Reif‐Dutton model. In contrast to the Reif‐Dutton model, which has been based on the adsorption step of dopant substances, the modified model is related to the real dopant incorporation step and its backreaction as the rate controlling factors. By that a thermodynamical decomposition equilibrium of the dopant source material may be established without being influenced by the dopant incorporation. Each component of the decomposition equilibrium acts as a source for making dopant atoms available for incorporation. Equivalent to the Reif‐Dutton model the modified model describes the growth rate influence of the layer on the incorporation of dopants and additionally enables the temperature dependence, total pressure dependence and the specific features of dopant incorporation at high concentrations to be explained.
Study of inclusions and growth bands in potassium bichromate crystals grown from aqueous solutions
Authors: Szurgot M. , Sangwal K. , Karniewicz J. 
Published: January 2007

AbstractThe nature of inclusions and growth bands in potassium bichromate crystals obtained from aqueous solutions and their formation in relation to growth temperature and supersaturation are investigated. It is observed that impurities present in solution, fluctuations in growth temperature and high growth rates are responsible for their formation.
On the ordering of Cr1‐xAlx alloys (x < 0.33) leading to microprecipitations of X‐ and β‐phases
Authors: Dłużewski Piotr 
Published: January 2007

AbstractThe analysis of electron diffraction patterns of Cr1‐xAlx alloys with 0.16 ≦ x ≦ 0.24 has been performed. The diffraction vectors describing the position of X‐phase spots were corrected to the new 0.769 < 0.004 〈111〉value. The ordering model of Cr1‐xAlx alloys with x < 0.33 is discussed in connection with physical properties. The new identification of the X‐phase as Cr4Al displacive modulation structure is proposed.
On the madelung constant of the nonstoichiometric tin dioxide crystal containing conducting electrons
Authors: Horodecki A. J. , Skowron A. , Precht W. 
Published: January 2007

AbstractThe nonstoichiometry of the conducting tin dioxide is assumed to be due to the doubly ionized oxygen vacancies. The use of a potential of the type e−r/λ/r for the nearest tin ions surrounding the vacancy results in a dependence of the Madelung constant on the defect concentration that exhibits a soft maximum. Various summation topologies are discussed.
On the elements of the dislocation structure of deformed corundum
Authors: Kirichfnko V. V. , Voinova N. N. 
Published: January 2007

AbstractIt is found by the method of transmission electron microscopy that the main elements of dislocation structure of deformed corundum are spatial triple dislocation nodes, recombination zones and dislocation network fragments. The structure of dislocation nodes is analyzed. It is shown that the nodes in corundum are the “rigid” constructions.
The effect of silica substitution on electrical conduction in nickel ferrite
Authors: Satyanarayana R. , Ramana Murthy S. 
Published: January 2007

AbstractThe electrical conductivity and Seebeck coefficient for nickel ferrite and nickel ferrite with 5% silica has been studied as a function of temperature. The lattice constant and the existence of a single phase are established from X‐ray studies. Both the ferrites exhibit a transition near the Curie temperature with a change in slope of the conductivity (log σT) versus temperature (103/T) curves. It is found that the activation energy in the paramagnetic region is higher than that in the ferrimagnetic region for both the ferrites.
Nucleation at changing density of monomers
Authors: Kashchiev Dimo 
Published: January 2007

AbstractThe kinetics of nucleation at constant supersaturation are analyzed when the process occurs at changing density of those monomers (atoms or molecules) that start the nucleation chain of consecutive bimolecular reactions. The Zeldovich kinetic equation is solved for arbitrary time variation of the monomer density and exact general expressions are obtained for the time dependence of the nonstationary nucleation rate J and the density N of nuclei formed in the system up to time t. Exponential decrease and increase of the monomer density are considered as examples, and the corresponding J(t) and N(t) dependences are analytically found.
The electrolytical coloration of synthetic quartz crystals with induced growth striations
Authors: Bernhardt Hj. , Woitzik B. 
Published: January 2007

AbstractElectrolytical coloration of quartz crystals with induced smoky quartz striations has been investigated, and compared with the arrangement of smoky quartz stripes after X‐irradiation. Investigations have been made on z‐, s‐, −x‐ and +x‐regions of the crystal after application of an electrolytical current in z‐direction.
Doping of epitaxial CVD silicon with arsenic or phosphorus (II). Non‐steady state conditions
Authors: Kühne H. 
Published: January 2007

AbstractTheoretical expressions are developed suggesting how the non‐steady state dopant incorporation is influenced by the parameters of the layer deposition process. Expressions for the transient doping profile are dealt with taking into account two different mechanisms of the overall rate controlling step. The one is based on the assumption made by Reif and Dutton that the adsorption step, which is followed by a solution equilibrium, is the rate controlling step, the other is based on the idea that the dopant incorporation reaction and its backreaction, following after the adsorption of dopant particles, are controlling the overall incorporation.
Growth micromorphology of stearic acid crystals
Authors: Swamy R. S. N. , Prasad P. B. V. , Bhagavan Raju I. V. K. 
Published: January 2007

AbstractGrowth and micromorphology of stearic acid crystals grown by solvent evaporation method has been studied. The effect of the solvent and the rate of evaporation of the solvent on the growth micromorphology has been investigated. The formation of spherulitic growth features, rhombic platelets of B‐ and C forms having growth spirals associated with solution channels and twinned crystals involving B‐B, C‐C, and B‐C forms is observed. The complexity of the twins involving the B‐ and C forms is discussed.
Chemical dissolution of calcite cleavages in aqueous solutions of sodium hydroxide
Authors: Shah A. J. , Pandya J. R. 
Published: January 2007

AbstractOptical study of isotropic and anisotropic etch rates by controlled chemical dissolution of calcite cleavage surfaces employing aqueous solution of sodium hydroxide at various etching temperatures is presented. The etch rates are found to be independent of etching time. The isotropic etch rates are found to be smaller than anisotropic etch rates, whereas Arrhenius plots yield activation energy for anisotropic dissolution greater than that for isotropic etching. It is also shown from a comparative study of chemical effect of various etchants on calctie cleavages that for a given plane shape of dislocation etch pits the activation energy is constant and independent of etching temperature and etchant concentration and that it is a characteristic of the etchant and not of the crystal.
Magnetic phase transitions in the Mn1‐xCrxSe (x ≦ 0.4) system
Authors: Galyas A. I. , Makovetskii G. I. 
Published: January 2007

AbstractNeutron diffraction and magnetic investigations have been made on the Mn1‐xCrxSe (0 ≦ x ≦ 0.4) system solid solutions. Evidence is found of the appearance of magnetization in the samples with composition 0.05 ≦ x ≦ 0.4, exceeding in value that of antiferromagnet. The temperatures of magnetic transition, obtained from the magnetic measurements, do not fit the temperatures of disappearance of antiferromagnetic ordering obtained from the neutron diffraction studies. The antiferromagnetic structure with compositions 0.03 ≦ x ≦ 0.3 is analogous to the α‐MnSe structure. The results are discussed under assumption of simultaneous coexistence of phases with different type of magnetic ordering.
Growth of borax crystals by spiral mechanism
Authors: Takoo R. K. 
Published: January 2007

AbstractBorax crystals grown at low supersaturation values are described. A brief report about microtopographical studies of these crystals is presented. Growth spirals observed on almost all the habit faces except those in contact with the bottom of the nucleation cell are described and discussed. It is established that all these crystals have platelet form in the initial stages of crystallization and as growth proceeds they develop and grow by spiral mechanism. The conditions under which the screw dislocations play the role in the development and growth of the crystals have been worked out.
SEM studies on hydrothermally grown VSZ‐3 and VSZ‐4 crystals
Authors: Joshi M. S. , Rao P. Mohan 
Published: January 2007

AbstractMorphology and surface features of two varieties of hydrothermally grown zeolite microcrystals viz: VSZ‐3 and VSZ‐4 are studied by employing SEM. VSZ‐3 crystals have prismatic and prismatic pyramidal habits, whereas VSZ‐4 crystals are only prismatic with hexagonal cross‐section. In light of the scanning electron microscopic studies the plausible mode of nucleation and growth of these zeolite crystals are proposed.
TEM and X‐ray investigations of defect structure of PbSnTe crystal
Authors: Morawiec J. , Auleytner J. , Furmanik Z. , Jȩdrzejczak A. 
Published: January 2007

AbstractThe Pb0.8Sn0.2Te single crystal grown by the Bridgman technique was examined by X‐ray and TEM methods. The X‐ray reflection topography revealed that the PbSnTe crystal consisted of monocrystallinic blocks with linear dimensions of 1–5 mm separated by low angle boundaries of tilt‐twist character. “As grown” defects observed by TEM method have been identified as single perfect dislocations and dislocation pairs. A mean density of dislocations inside the crystal blocks was no more than 103 cm−2. Except “as grown” defects rows of mobile dislocations were observed. All of dislocations lines were characterized by the same type of Burgers vector, i.e. b = 1/2a〈110〉.