bluuebunny/crossref_metadata_2025_split huggingface dataset:
Einfluß der Korngrenzen auf das Hochtemperaturkriechen reiner Metalle und Möglichkeiten quantitativer Auswertung
Authors: Heumann Theodor , Wulff Herbert 
Published: March 2014

AbstractDie Korngrenzen üben einen entscheidenden Einfluß auf das Kriechverhalten dünner Metalldrähte aus. Im Bereich hoher Temperaturen nahe dem Schmelzpunkt können bekanntlich nach der Zero‐Creep‐Methode Oberflächenspannungen und Korngrenzenenergien ermittelt werden. Eine Untersuchung der Gleichgewichtszustände zeigt, daß ein labiles und ein stabiles Gleichgewicht auftreten. Die Kriechmethode bedient sich in der Regel des labilen Gleichgewichts. Im Falle, daß der Nabarro‐Herring‐Mechanismus das Kriechen steuert, läßt sich an Drähten mit Bambus‐Struktur durch Messen der Kriechgeschwindigkeit der unkorrelierte Diffusionskoeffizient bestimmen. Einige Ergebnisse werden mitgeteilt und diskutiert.
Electrochemical Transfer across Phase Boundaries
Authors: Corish J. , Warde C. J. 
Published: March 2014

AbstractA series of experiments on Ag/α‐Ag2S interfaces in the temperature range 220–340°C are summarized. The part played by the bulk Ag/α‐Ag2S interface in the kinetics of silver sulphidation has been investigated and the rates were found to depend markedly on the type of high‐purity silver used. Measurements of the overpotentials observed at the bulk Ag/α‐Ag2S interface when the polarization phenomena occurring during sulphidation were simulated electrochemically have confirmed this dependence. Silver was found to pass readily across the Ag(vapour)/α‐Ag2S interface with an incorporation coefficient of unity. Growth and dissolution studies on a small number of silver whiskers grown in situ on an α‐silver sulphide surface indicated that silver could cross such an Ag(whisker)/α‐Ag2S interface at large current densities with very small overpotentials. The significance of this series of results is discussed with particular reference to electrochemical transfer processes across solid/solid interfaces.
Elektrochemische Untersuchungen zur Kinetik des Überganges von Silber aus festem Silber in festes Silberchalkogenid bei höheren Temperaturen
Authors: Contreras L. , Rickert H. 
Published: March 2014

AbstractMit Hilfe von Silberjodid als festem Hilfselektrolyten wurde die Auflösung von Silber in Ag2X (X = S, Se oder Te) untersucht. Hierbei wurden Untersuchungen an poly‐ und einkristallinem Material bei verschiedenen Auflagedrücken im Temperaturbereich von 200–400°C durchgeführt. Weiter wurden Messungen mit Silberwhiskern gemacht, die vor den Untersuchungen auf einer Ag2S‐Probe gewachsen waren. Die potentiostatischen und galvanostatischen Untersuchungen bei 7 kp cm−2 im Temperaturbereich 200–400°C ergaben anodische stationäre und instationäre Stromdichte‐Spannungskurven, aus denen hervorgeht, daß bei der Auflösung von poly‐ und einkristallinem Silber das chemische Potential von Silber im Silberchalkogenid stark von demjenigen im Gleichgewicht Ag/Ag2X abweicht. Die stationären Auflösungsgeschwindigkeiten bei nicht zu hohen Auflagedrücken sind proportional a2S, a2Se bzw. a2Te. Die Gleichgewichtspartialdrücke der S2‐, Se2‐ und Te2‐Moleküle sind für vergleichbare Auflösungsgeschwindigkeiten in den drei Systemen gleich. Diese Tatsache und weitere im Text beschriebene Versuche deuten auf eine Beteiligung von S2‐, Se2‐ bzw. Te2‐Molekülen, durch deren Transport über die Gasphase der Mikrospalte bei der Auflösung von Silber in die Silberverbindung hin. Nur bei hohem Auflagedruck, nämlich bei 200 kp · cm−2, erfolgt die Auflösung von Silber durch die Phasengrenze massives Silber/α‐Ag2S ohne wesentliche Hemmung. In diesem Fall liegt keine fest/fest‐Grenzfläche im eigentlichen Sinne mehr vor; Silbersulfid wird hier plastisch. Die Auflösung von Silberwhiskern im α‐Ag2S findet ebenfalls ohne große Untersättigung von Silber in Silbersulfid statt. Das deutet darauf hin, daß bei geeignetem “Mikrokontakt” nur sehr geringe Durchtrittshemmungen und damit hohe Austauschstromdichten vorliegen.
The Role of Grain and Phase Boundaries in Liquid Phase Sintering
Authors: Huppmann Winfried J. , Petzow Günter 
Published: March 2014

AbstractBy optical and scanning electron microscopy two phenomena which influence the microstructure of liquid phase sintered materials were observed. Particle disintegration occurs when the liquid phase – probably by a dissolution reaction – attacks the grain boundaries of the solid particles. Particle coalescence is the rapid growth of one particle at the expense of a neighbouring particle by a solution‐diffusion through the liquid‐reprecipitation mechanism. Models linking both phenomena with densification are presented.
Microstructure and Physical Properties of Electro‐ and Magneto‐Ceramic Materials
Authors: Jonker G. H. 
Published: March 2014

AbstractIn this lecture a survey has been given on the importance of the ceramic structure (density, grain size, grain porosity) and the grain boundary conditions of electroceramic materials (ferromagnetics, ferroelectrics, thermistors) in relation to optimal application properties. – The contents of this lecture were mainly based on an earlier paper of Jonker and Stuyts) where also a short literature survey is given.
Magnetic Structures and Stresses in Thin Films I. Ferromagnetic Resonance Experiments
Authors: Blum J. K. , Göpel W. 
Published: March 2014

AbstractThe ferromagnetic resonance (FMR) on Ni, Fe and epitaxial Ni/Fe thin films (thickness DM = 2.4‐50 monolayers) was investigated under UHV conditions. Resonance field, lineshape, linewidth and absorbed microwave power were recorded for different film thicknesses, temperatures and deposition rates during film preparation and for different annealing procedures. The effect of H2 chemisorption on the FMR‐parameters of Ni was studied as a function of coverage θ (θmax = 0.3) after different high temperature pretreatments of the film. A phenomenological discussion of FMR results is given taking into consideration corresponding geometric film structures.
Intramolecular Electron Transfer Through a Bridging Carboxylate Group Coordinated to Two Cobalt(III)‐Ions: A Pulse Radiolytic Study
Authors: Wieghardt Karl , Cohen Haim , Meyerstein Dan 
Published: March 2014

AbstractReduction of the binuclear μ‐p‐nitrobenzoato‐di‐μ‐hydroxo‐bis[triamminecobalt(III)] cation with (CH3)2COH radicals yields a radical cation with the p‐nitrobenzoato radical being coordinated to two cobalt(III) ions at the carboxylic group. The unprotonated form of this species undergoes intramolecular electron transfer producing Co(II) (k = (3.3 ± 0.3) · 103 s−1). The role of the carboxylate group in the intramolecular electron transfer process is tentatively assessed in terms of an intramolecular outer‐sphere reaction because of lack of overlap of the donor orbitals (π) and the acceptor orbital (σ). The protonated form of the radical cation (pKa = 2.5) disproportionates via a bimolecular process without production of Co(II). The effect of two coordinated Co(III) ions as compared to only one on the properties of the nitrobenzoate radical anion are discussed.
Reaktionen von Molekülen in definierten Schwingungszuständen: VI. Energieverteilung in den Reaktionen CN(υ) + O(3P), O2*)
Authors: Schmatjko K. J. , Wolfrum J. 
Published: March 2014

AbstractDie Energieverteilung in den Produkten der Reaktionen (1) CN(v) + O(3P) und (2) CN(v) + O2wurde an Hand der Besetzung der Schwingungszustände des Produkts CO(v′) untersucht. CN‐Radikale wurden dabei durch Blitzphotolyse aus Dicyan erzeugt und absolute CO(v′)‐Konzentrationen durch zeitaufgelöste Resonanz‐Absorptionsspektroskopie im Infraroten mit Hilfe eines kontinuierlichen CO‐Lasers bestimmt. – Für den Elementarschritt (1) zeigt die gemessene Verteilung CO(v′= 0,1, …, 13), daß die Reaktion gleichzeitig über die Wegemit der Geschwindigkeitskonstantenk1= (1,0 ± 0,4) · 1013cm3/mol · s bei 298 K abläuft. Eine primäre Schwingungsanregung des Reaktanden CN(v= 0, 1, …, 6) wird auf dem Reaktionsweg (1a) mit einem Anteilf′v= 0,5 auf die Schwingungsanregung des Produkts CO(v′) übertragen. – In der Reaktionbeobachtet man im Reaktionsweg (2a) eine CO(v′)‐Bildung in den Zuständenv′= 0,1, …, 4.
Proton NMR Relaxation Studies on Solutions of Mn(ClO4)2 in Dimethylsulfoxide
Authors: Goldammer E. V. , Kreysch W. 
Published: March 2014

AbstractProton spin‐lattice and spin‐spin relaxation times of DMSO solutions with Mn(ClO4)2 between 298 K ⩽ T ⩽ 413 K have been measured over a relatively wide frequency range (10 kHz ⩽ v ⩽ 90 MHz). Three regions exist where the relaxation times of solvent DMSO are frequency dependent. It is possible to extract from these experimental data structural and dynamical parameters such as the number of complexed DMSO molecules, their mean lifetime in the first solvation sphere around the metal ions, and/or the rotational diffusion constant of the [Mn(DMSO)6]2+ complex. These data are necessary for a better understanding of the EPR relaxation mechanism of manganese ions in the same environment, where considerable line broadening at higher temperatures (T ⩾ 373 K) has been observed.
Electron Transfer Reactions at Oxide Electrodes Involving Tunnelling through a Space Charge Barrier
Authors: Schmickler Wolfgang 
Published: March 2014

AbstractElectron exchange between the conduction band of an oxide electrode and a redox electrolyte in the presence of a space charge barrier is investigated. Two electron transfer mechanisms through the barrier are studied in detail: direct elastic tunnelling and resonance tunnelling via localized states in the band gap. Current/overpotential characteristics are calculated for both mechanisms in dependence on various system parameters such as the Debye length and the band bending. Though the characteristics have a number of features in common, some criteria can be established to distinguish between the two types of tunnelling. The theoretical results are compared with data from several experimental studies; there is evidence that both tunnelling mechanisms occur in real systems.
Substitution Reactions of Beryllium (II) Ion in Mixed Solvents. II. Solvent Exchange between the Inner Solvation Shell and the Bulk in Dimethyl Sulphoxide and Dimethyl Sulphoxide/Water Mixtures
Authors: Füldner H. H. , Devia D. H. , Strehlow H. 
Published: March 2014

AbstractProton magnetic resonance spectra of Be(NO3)2 solutions in mixtures of water and dimethylsulphoxide (DMSO) have been measured at different solvent compositions and temperatures at 270 MHz. The relative amounts of the solvated species Be(OH2)i(DMSO)4−i have been determined. The total solvation number was 4. The kinetics of solvent exchange has been studied in DMSO. The proton exchange in pure aqueous solutions may be explained in terms of a protolysis reaction. The solvent molecule preferentially solvating the beryllium ion is DMSO in water rich solutions and water in DMSO rich solutions.
Mixtures with Complex Formation. Melting Curves and Model Calculations
Authors: Kohler Friedrich 
Published: March 2014

AbstractA dystecticum is considered which is caused by complex formation, where evidence of the complex in the liquid state is found by non‐thermodynamic methods. The relation between melting curve, heat of complex formation and heat of melting is derived for this case, assuming that the activities of the components are known. The theory is applied to the systems acetic acid + trifluoroacetic acid and triethylamine + trifluoroacetic acid. Model calculations are reported for carboxylic acid systems; the evaluation of the melting curves is in overall agreement with the association constants used in the model calculations.
The Optical Absorption Spectrum of Fluid Sulfur up to Supercritical Conditions
Authors: Weser G. , Hensel F. , Warren W. W. 
Published: March 2014

AbstractOptical absorption spectra in the range 0.5–4.9 eV (250 to 2000 nm) are reported for fluid sulfur up to 1100°C and at pressures up to supercritical pressures. An absorption band at 360 nm at 145°C is attributed to a few percent cyclo‐S6 (c‐S6) in the predominantly cyclo‐S8 (c‐S8) liquid. No anomaly in the rate of red shift of the absorption edge is observed at the polymerization temperature (160°C). Above this temperature an absorption band due to diradical chains is observed at low energy (∼1.4 eV). Investigation of the density dependence of the spectra of the dense fluid results from overlapping bands due to c‐S8, S3, and S4.
Pure Nuclear Quadrupole Resonance of Ionic Halides. III. 127I‐NQR Study of Higher Order Phase Transitions in Anilinium Iodide, C6H5NH⊕3I⊖, and 4‐Chloroanilinium Iodide, 4‐ClC6H4NH3⊕I⊖
Authors: Pies Wolfgang , Schahbazi Morteza , Weiss Alarich 
Published: March 2014

AbstractThe 127I‐ and 35Cl‐NQR spectra of anilinium iodide, C6H5NH⊕3I⊖, and 4‐chloroanilinium iodide, 4‐ClC6H4NH⊕3I⊖, have been investigated in the temperature range 77 ≦ T/K ≦ 307. Both compounds undergo a higher order phase transition as seen by the discontinuities in the slope of v = f(T) at the respective transition temperatures T11,1. C6H5NH⊕3I⊖: T11,1 = (241 ± 1) K;4‐ClC6H4NH⊕3I⊖: T11,1 = (100.6 ± 0.5)K. For C6H5NH⊕3I⊖, (∂v/∂T)p is discontinuous only for v(5/2 ⇌ 3/2) and not for v(3/2 ⇌ 1/2). This indicates that the transformation is accompanied by the same shear mechanism of the unit cell as in C6H5NH⊕3Br⊖. The I⊖ and Br⊖ quadrupole coupling constants of C6H5NH⊕3I⊖, 4‐ClC6H4NH⊕3I⊖, and C6H5NH⊕3Br⊖ in the critical region are related to an order parameter s ∞ [(Tc – T)/Tc]n · s vanishes with a critical exponent n = 1/2 on approaching Tc = T11,1 when a correction is considered for the part of v = f(T), which is not due to the phase transition. Otherwise, n = 1/3 is found.
Hydrogen Absorption and Hydride Formation in Ti3Sn
Authors: Rudman P. S. , Reilly J. J. , Wiswall R. H. 
Published: March 2014

AbstractHydrogen absorption isotherms in the α2(DO19)‐phase of Ti3Sn have been determined in the pressure range 0–1000 Torr and in the temperature range 500–850°C. The data yield ΔH̄H = −50.6 kJ and ΔS̄XSH = −52.7 J/K, close to the α‐Ti, and α2‐Ti3Al values. The dominant role of tin, like that of aluminum, appears to be to limit the available interstitial sites to octahedral sites with only titanium atoms as first neighbors, and of which there are 0.25 per metal atom. At temperatures above 500°C the α2‐phase transformed into an α3(Ti3SnH)‐phase. The structure has been determined from x‐ray diffraction data and thermodynamic arguments to be E21 which is simply a FCC variation of the α2(HCP) structure with identical interstitial site occupancy.
The Electrical Properties of Gold‐Based Liquid Alkali Metal Alloys
Authors: Nicoloso N. , Schmutzler R. W. , Hensel F. 
Published: March 2014

AbstractWe present conductivity σ and partly thermopower S measurements for the liquid alkali metal‐gold alloys at the equiatomic composition. The conductivity ranges from very high values for metallic LiAu to relatively small values for ionic CsAu. The conductivity data indicate that in the liquid the transition from ionic to metallic character takes place between RbAu and KAu.
The He(I) Photoelectron Spectrum of Cyclobutene‐1,2‐dione and o‐Benzoquinone
Authors: Schang Peter , Gleiter Rolf , Rieker Anton 
Published: March 2014

AbstractThe He(I)photoelectron spectra of cyclobutene‐1,2‐dione (1), o‐benzoquinone (4) and alkyl substitution products of 1 and 4 have been recorded. The first bands of the spectra have been assigned on the basis of molecular orbital calculations and qualitative band shape criteria.
Neutronenstreuung – Eine Methode zur Untersuchung der Struktur und Dynamik von Mineralien
Authors: Fuess H. 
Published: March 2014

AbstractNeutron scattering is complementary to X‐ray techniques for structural studies. Inelastic scattering offers additional possibilities to investigate lattice dynamics and diffusion of molecules. Applications on the cation distribution in garnets and the Si/Al relation in feldspars are reported. Examples on hydrogen bonds are cited for bayerite (β‐Al(OH)3), the chlorite mineral penninite and for the zeolite scolecite. The diffusion of water molecules in natural zeolites is studied by inelastic incoherent neutron scattering. An example is given for natrolite. Preliminary charge and magnetization densities for fayalite (Fe2SiO4) are reported. The experimental phonon dispersion curves for anhydrite (CaSO4) are compared with results from theoretical model calculations.
Binding and Oxidation State of Uranium in Recent Phytogenic Sediments, Peats, and Lignites of Selected Areas, Influenced by Physico‐Chemical Parameters
Authors: von Borstel Dieter , Halbach Peter 
Published: March 2014

AbstractThe high bog plateau “Drei Horste” at Lake Oderteich in the Upper Harz Mountains (Western Germany) shows uranium(VI) being dissolved from a granitic bedrock and transported by oxidizing waters containing humic and fulvic acids. Uranium(VI) is deposited in phytogenic sediments and in peat layers. In the sediments the concentration of uranium correlates with the content of functional acid groups. The binding between the organic substance and uranium is based on ion exchange, as shown by experiments with fractions of different isolated humic substances. – Uranium in lignites from “Date Creek”, Arizona, USA shows a significant correlation to organic carbon. The proceeding coalification from peat to lignite causes a change in the binding of uranium: uranium in organic binding is to be observed in low grade ores (<0.1% U) only. High grade ores (>0.1% U) have uranium in inorganic binding mainly. The oxidation state in organic low grade ores is controlled by their contents of organic reductants and of humic acids. Prerequisites for the formation of high grade ores in “Date Creek” were a low E vs. SHE‐level (formation of coffinite) and an availability of organic (humic acids) and inorganic (zeolites) exchange sites for the remaining portion of uranium(VI).
Krustenbildung auf Oberflächen kristallisierender Salzsolen und ihre Beeinflussung durch Tenside
Authors: Herz D. , Hamann D. , Petrick H.‐J. , Elbeshausen K. , Cammenga H. K. 
Published: March 2014

AbstractSkeletal crystal growth on the surface of saturated natural brines plays an important role in the petrological formation of salt minerals in Sebkhas, Schotts, salt lakes, Playas etc. Very recently it has been realized that skeletal crystal growth and salt crust formation also occur on the sump surface in salt caverns used for underground gas storage. As shown in this contribution, skeletal growth and crust formation on natural brines can be suppressed by certain surface active agents, some of which also reduce the evaporation rate of brines considerably. Perfluorinated fatty alcohols of the type CnF2n + 1C2H4OH, specially prepared for these purposes, are very effective with both respects. On the other hand, skeletal growth and crust formation may be enhanced considerably by the addition of suitable additives, so that salt crusts of high stability and low porosity can be produced at will, which themselves are very powerful evaporation suppressants and may be used as such in salt caverns in the future.
Noble Gas Immobilization in Zeolites
Authors: Penzhorn R.‐D. , Schuster P. , Leitzig H. , Noppel H. E. 
Published: March 2014

AbstractIt was discovered that the noble gases Ar, Kr and Xe can be trapped firmly in type A zeolites as well as in mordenites and chabazites when the molecular sieves are hydrothermally vitrified at temperatures between 340 and 650°C in the presence of pressurized gas. The occurrence of trapping in an amorphous nonzeolitic species was demonstrated by X‐ray diffraction, neutron scattering and electron scattering. The change in structure of loaded zeolites is also manifested by a substantial loss in sorption capacity for water as well as an almost complete disappearance of the specific surface area. – The gas release rates at temperatures below 550°C were found to be extremely low. The activation energies for the diffusion of Kr through amorphous Ca and Mg exchanged 5 A zeolite were determined to be 209 ± 15 and 187 ± 16 kJ/mol respectively. The estimated diffusion coefficients are exceedingly small. The trapped gas is neither liberated by hot water nor by liq. Rb at 150°C.
Solubility of Gases in Liquids. 15. High‐Precision Determination of Henry Coefficients for Carbon Monoxide in Liquid Water at 278 to 323 K
Authors: Rettich T. R. , Battino Rubin , Wilhelm Emmerich 
Published: March 2014

AbstractThe solubility of carbon monoxide in pure liquid water was measured in the pressure range 60 to 110 kPa and the temperature range 278 to 323 K with a high‐precision apparatus of the Benson‐Krause type. These data are used to derive Henry coefficients H2, 1(T, Ps, 1), the temperature dependence of which is accounted for by both a Clarke‐Glew type fitting equation and a power series in T−1. The imprecision of our measurements is characterized by an average deviation of H2, 1(T, Ps, 1) from these smoothing equations of about ±0.04%. From the temperature variation of H2, 1(T, Ps, 1) the partial molar quantities pertaining to the solution process (such as standard changes in enthalpy and heat capacity) are obtained. In addition, Ostwald coefficients are given in tabular form at rounded temperatures. Experimental results are compared with values calculated via scaled particle theory.
Solubility of Hydrogen in β‐Ti1 ‐ yRey
Authors: Bressel Burkhard , Weiss Alarich 
Published: March 2014

AbstractCubic body centered β‐phase alloys Ti1 ‐ yRey were studied by X‐ray diffraction, mass density measurements, and by measurements of their hydrogen solubility. In the pressure range 0.005 ≦ p(H2)/bar ≦ 1 the solubility of hydrogen decreases strongly with increasing mole fraction of Re. Typical equilibrium values for (Ti1 ‐ yRey)Hx are at T = 650°C: y = 0.18, x = 0.48; y = 0.27, x = 0.23; y = 0.33, x = 0.006. The lattice constants of the alloys increase slightly with increasing hydrogen content. Also the relative partial molar enthalpy at infinite dilution, \documentclass{article}\pagestyle{empty}\begin{document}$ \Delta \bar H_H^0 $\end{document}, increases with increasing Re‐content.
Flüssigkeitsähnliche Struktur in Suspensionen von Sulfonlatexkugeln
Authors: Härtl W. , Versmold H. , Wittig U. 
Published: March 2014

AbstractBy emulsion polymerization of styrene and vinylbenzene sulfonic acid monodisperse latex particles with sulfate and sulfonate surface groups were prepared. After careful cleaning, solid‐ and liquid‐like ordered suspensions of different particle concentration were obtained. Static and dynamic light scattering as well as electron micrographs were used to determine the particle size. Further, pH and conductivity experiments were carried out for the determination of the latex particle charge. For liquid‐like ordered suspensions of different concentrations the structure factor S(Q) and the radial distribution function g(r) are presented. These two quantities are discussed in terms of the rescaled mean spherical approximation (RMSA) of Hansen and Hayter.
Sterische Stabilisierung und Flockung von wäßrigen TiO2‐ und SiO2‐Suspensionen durch Polymerenadsorptionsschichten
Authors: Christakos G. , Hofmann U. , Weick B. , Joppien G. 
Published: March 2014

AbstractThe effect of adsorbed polymers on the stability of aqueous TiO2 and SiO2 suspensions was studied by a centrifugation technique in combination with spectrophotometric particle concentration determinations. TiO2 suspensions showed a marked resistance against sedimentation following the adsorption of polyvinyl alcohol) at higher concentrations and room temperature. The sedimentation velocity was lowest at pH = 5.9. An increase or decrease of the pH or of the adsorption temperature brought about destabilization. Aqueous SiO2 suspensions could be stabilized by adsorbed poly(oxyethylene) at pH 6.8 and 7.3 but were destabilized after adsorption of this polymer at lower pH values via the formation of a viscoelastic gel structure. The observed effects are interpreted as steric stabilization in the TiO2 and SiO2 adsorption systems and as bridging flocculation in the SiO2 system at low pH. They are correlated with adsorption isotherms of the polymers established by a turbidimetric concentration determination method.