bluuebunny/crossref_metadata_2025_split huggingface dataset:
Collective Translational Motions in Binary Mixtures of Hexafluorobenzene with Benzene and Cyclohexane as Studied by Self and Mutal Diffusion Measurements
Authors: Weingärtner Hermann , Braun Bernd M. 
Published: July 2012

AbstractMutual and self‐diffusion coefficients have been measured for binary mixtures of hexafluorobenzene with benzene and cyclohexane at 25°C. The results have been used to calculate velocity correlation coefficients which characterize collective translational motions among the various interaction partners. For comparison, velocity correlation coefficients have also been calculated from literature data on benzene‐cyclohexane mixtures. The resulting coefficients are compared with predictions for ideal reference systems. While the C6H6C6H12 system exhibits fairly ideal behaviour, correlated motions between like molecules in C6F6C6H12 mixtures in excess to those expected for an ideal system indicate self association of the components. Correlated motions between unlike molecules in C6F6C6H6 mixtures indicate preferred mutual association of C6F6C6H6. The results are in agreement with the conclusions drawn from the behaviour of the thermodynamic excess functions.
Polarized Absorption Spectra of Tetracyanoplatinate(II) Single Crystals
Authors: Tuszynski W. , Gliemann G. 
Published: July 2012

AbstractPolarized single crystal absorption spectra of Mx[Pt(CN)4]·nH2O with M = Na, Sr, Ca, Ba, Mg at T = 10 K and 300 K are reported. From structural details of the spectra the energetic order of the low lying excited electronic states can be established.
Transfer of Multicomplexed Ions Across the Interface Between two Immiscible Electrolyte Solutions I; Fe(II, III), Ni(II) and Zn(II) Ions Complexed by Bidentate Nitrogen Bases
Authors: Homolka Daniel , Wendt Hartmut 
Published: July 2012

AbstractTransfer from water to nitrobenzene of Iron(II) and (III), Ni(II) and Zn(II) complexed in the aqueous phase by one, two and three molecules of o‐phenanthroline and o,o'‐bipyridine was investigated using cyclic voltammetry. The kinetically inert complexes of Fe(II), Fe(III) and Ni(II) are keeping their ligand‐metal bonds intact and are transferred reversibly from water into nitrobenzene. The uncomplexed metal ions are not transferred within the voltage range limited by transfer of the ions of the aqueous and nonaqueous supporting electrolyte. Ease of phase‐transfer is greatly enhanced by complexation with the organic ligand and successive addition of the first, second and third bidentate nitrogen base changes the Gibb's transfer enthalpy of the Ni(II) by approximately equal amounts (ΔΔG° ≈ − 37 kJ/Mol;). The molecular structure of the complex ligand bears only a minor but clearly discernible influence on the Gibb's transfer enthalpies as demonstrated for Ni(II)‐phenanthroline and bipyridine complexes. Comparative investigation of phase transfer of Fe(II)‐and Fe(III)‐trisphenanthroline complexes reveals that due to higher charge of the Fe(III)‐complexes they are more strongly solvated in aqueous solution and hence less easily extracted into nitrobenzene than Fe(II)‐ complexes. Voltammograms for transfer of complexed zinc ions which form kinetically (fast) labile complexes in water as well as in nitrobenzene are to a great deal determined by fast homogeneous kinetics. ‐ In particular mono‐ and bicomplexed zinc ions (ZnL2+ and ZnL2+2) undergo rapid disproportionation with preferential formation of triscomplexed zinc (ZnL2+3) in the nonaqueous phase. Diffusion coefficients of differently complexed species in water are determined and show a shift to lower values with increasing degree of complexation.
Defect Structure and Transport Properties of Manganese Oxides: (II) The Nonstoichiometry of Hausmannite (Mn3δO4)
Authors: Keller M. , Dieckmann R. 
Published: July 2012

AbstractThe deviation from stoichiometry δ in hausmannite (Mn3δO4) has been thermogravimetrically studied as a function of oxygen activity between 1000 and 1130°C for the low temperature phase (α‐Mn3δO4) and between 1200 and 1350°C for the high temperature phase (ß‐Mn3δO4). A cation deficit is observed at high oxygen activities and a cation excess at low oxygen activities. In the temperature range investigated, it is concluded that the dominant defect species in both phases are cation vacancies at high oxygen activities and manganese interstitials at low oxygen activities. In addition, based on the present nonstoichiometry data, the phase diagram of the maganese‐oxygen
Thermodynamik fester Fe ‐Ni Legierungen: Massenspektrometrische Bestimmung der thermodynamischen Mischungseffekte und Berechnung des Schmelzdiagramms
Authors: Tomiska J. , Neckel A. 
Published: July 2012

AbstractThermodynamic investigations on solid Fe‐Ni alloys (f.c.c.‐phase) have been performed by means of a mass spectrometer in combination with a high temperature Knudsen cell unit. The “Algebraic Intensity‐Ratio”‐method (A.I.R.) has been applied for determing the thermodynamic excess functions. The molar excess Gibbs energies GE, the molar heats of mixing HE, and the molar excess entropies SE are negative over the whole range of composition. At 1623 K the minimum value of GE is ‐2350 J/mol (57.6 at % Ni), the minimum value of HE is ‐3950 J/mol (63.6 at % Ni), and the minimum value of SE is ‐1.04 J/mol K (70.2 at % Ni). The thermodynamic activities aj show slight negative deviations from Raoult's law. Using the results of this work, the thermodynamic results from mass spectrometric studies on liquid Fe ‐Ni alloys, and literature data for the enthalpies and heat capacities of Fe and Ni the phase diagram has been redetermined, using a generally applicable procedure for the calculation of the equilibrium compositions of coexisting phases. The applied procedure is based upon the generalized Newton method for the numerical solution of equations.
Zweidimensionale Modellnetzwerke
Authors: Rehage H. , Veyssié M. 
Published: July 2012

AbstractWe have studied the tensio‐active properties of acrylate diesters at the oil‐water interface. Measurements of the interfacial tension indicate that the molecules are subsequently adsorbed at the interface. The amphiphatic compounds in the monolayer can be polymerized and cross‐linked by UV irradiation. The gelation process of the two‐dimensional system has been studied by measuring the shear mechanical properties. We observed a clear transition from a viscous solution to a cross‐linked gel state. The two‐dimensional films behave like rubber elastic systems. The elasticity depends strongly on the concentration of the cross‐linking agent. The polymerisation of mixed films of monoacrylates and diacrylates can be used to built up two‐dimensional structures with defined rheological properties.
Ordnugszustände in binären Systemen aus Poly(vinylidenfluorid) und Poly(vinylfluorid)
Authors: Vonneguth K. , Trafara G. , Hummel D. O. 
Published: July 2012

AbstractBinary systems of poly(vinylidene fluoride) (PVDF) and poly(vinyl fluoride) (PVF) have been studied by differential scanning calorimetry and X‐ray diffraction. The polymers were prepared by 60Co‐γ‐inducted bulk polymerization at 273 K. The increase of the glass transition temperature of PVDF in binary systems with low concentrations of PVF can be explained by a partial miscibility of the components in the non‐crystalline state. In the same way the higher thermal stability of PVF in the binary systems up to temperatures of 30 K above the melting point of PVF can be explained. PVDF and PVF crystallize separately. There is no indication of the formation of mixed crystals of the two polymers. On the other hand, the crystallization of PVDF is influenced by the presence of PVF.
Liquid‐Liquid Phase Separation in Multicomponent Polymer Systems. XXIV. Thermodynamics of Polymer Blends
Authors: Koningsveld R. , Kleintjens L. A. , Leblans‐Vinck A. M. 
Published: July 2012

AbstractWithin its own scope the classic Flory‐Huggins‐Staverman theory for macromolecular systems can easily be extended so as to deal with lower consolute miscibility behaviour as such, as well as in combination with upper consolute miscibility in the same system. A further improvement is achieved if the different numbers of nearest‐neighbour contacts the various repeat units and molecules can make are accounted for. Strong bimodality of lower consolute cloudpoint curves seems to call for the introduction of free‐volume terms. Some consequences of such bulk mixture terms are discussed briefly.
Eine Apparatur zur Bestimmung von Tieftemperatur‐Flüssigkeits‐Dampf‐Gleichgewichten und Messungen im System N2‐NO
Authors: Scheunemann U. , Wagner H. Gg. 
Published: July 2012

AbstractA new apparatus for the measurement of low temperature vapour‐liquid equilibrium data is described. The vapour recirculation method is used for the mixture to reach equilibrium in a cell equipped with glass windows. Samples of both phases can be withdrawn and analysed with high precision by optical absorption in the UV‐region. Measurements were made for the system nitrogen‐nitric oxide along three isotherms between 113 and 120 K. The area test showed thermodynamic consistency of the data. The deviations of the mixtures from ideality are large, caused by dimerization of the NO in the liquid. The maximum excess Gibbs energy is about 500 J/mol.
An Orbital Fragmentation of Static Dipole Polarizabilities of Atoms of the First Three Rows. Ground State and Valence State Properties
Authors: Schmidt Peter C. , Böhm Michael C. , Weiss Alarich 
Published: July 2012

AbstractWithin an ensemble averaged variant of the local density approximation (LDA) a computational framework is developed that allows for a straightforward orbital resolution of atomic static dipole polarizabilities α˜D. The accuracy of the method as well as its computational expenditure are roughly comparable with numerical coupled Hartree‐Fock (CHF) variants. The calculated values for the ground state configurations of the atomic species of the first three rows (LiF, NaCl, KBr) are in good agreement with the results of recently published highly sophisticated theoretical calculations based on LCAO‐type expansions (e.g. PNO‐CEPA) and are also close to precise experimental data (Li, Na, K, Ca). The employed ensemble formalism within LDA allows for the introduction of one‐electron contributions to the total atomic polarizabilities that span the full width from pure atomic orbitals as one‐electron basis to any desired hybrid state. It is shown that the orbital increments to α˜D an be expressed into the form of simple linear relations as a function of the hybridization of the one‐electron wave function. Mean static dipole polarizability increments α˜D the corresponding m = 0 components into the direction of the electric field α˜D(m = 0) as well as m = ± 1 components in the plane perpendicular to the external point charge α0,D(m = ± 1) are tabulated. The relevant numbers depend on the type of the atom and (weakly) on the electronic configuration. Ground state configurations and valence states have been analyzed. The α0,D elements increase linearly with increasing p admixtures in the corresponding hybrid function. The gradient expressing this dependence is largest for the diffuse atoms on the left side of the periodic system. The employed resolution of the α0,D values and the averaging procedure leading to “ensemble states” are a prerequisite for the adaption of the present one‐electron increments in molecular or solid‐state calculations of static dipole polarizabilities on the basis of an atoms‐in‐molecule approach.
On the Order‐Disorder Phase Transition of Anilinium Halides. 127I‐NQR Investigation of the Anilinium Iodides C6H5NHI⊖, C6H5NDI⊖, C6D5NHI⊖, and C6D5NDI⊖. Dilatometric Studies on Anilinium Bromide and Anilinium Iodide Single Crystals
Authors: Feeder Gerhard , Weiss Alarich 
Published: July 2012

Abstract127I‐NQR measurements in the range 77 ≤ T/K ≤ 520 are reported for anilinium iodides C6H5NH⊕3I⊖, C6H5ND⊕3I⊖, C6D5NH⊕3I⊖, and C6D5ND⊕3I⊖. The compound undergoes a ferroelastic phase transition at 240.3 K (C6H5NH⊕3I⊖). The transition temperature changes to 233.6 K (C6H5ND⊕3I⊖) and to 233.4 K (C6D5ND⊕3I⊖) by deuteration. The NQR parameters are thereby influenced too. At 293 K the −NH⊕3 group deuteration influences e2ϕzzQh−1 and η much stronger than the ring deuteration, whereas at 77 K these effects are of comparable magnitude.—The thermal expansion coefficients were measured for C6H5NH⊕3X⊕, X = Br, I, from 120 K to 300 K. by dilatometry and by X‐ray diffraction. In C6H5NH⊕3Br⊖ the three linear expansion coefficients are increasing over the whole temperature range studied, whereas in C6H5NH⊕3I⊖ α[010] increases and both, α[100] and α[001], decrease with increasing temperature. On hand of the known crystal structures the ferroelastic phase transition in the anilinium halides is discussed. The basic mechanism of the transition is the same for C6H5NH⊕3I⊖ and C6H5NH⊕3Br⊖. Freezing in of the −NH⊕3 group hindered rotation is the main process governing the phase transitions, but motions of the phenyl ring are of influence, too.
Topological Aspects of the (1 × 1) ⇌ “Hexagonal” Phase Transition on Pt(100)
Authors: Hösier W. , Ritter E. , Behm R. J. 
Published: July 2012

AbstractWe have investigated the (1 × 1) ⇌ “hexagonal” phase transition on Pt(100) by Scanning Tunneling Microscopy with special emphasis on the density change of the topmost Pt layer correlated to this process. It was found that in both directions extra atoms are accommodated in monolayered islands on top of the flat substrate. The size of the islands mainly depends on the transition temperature, from 25 Å at 375 K to 100 Å at 550 K, which is explained by a stability increase of these islands with increasing size, in agreement with thermodynamic arguments over interface tension.
Structures and Phase Transitions in Physisorption: Molecular‐Axis Orientational Ordering in Nitrogen and Carbon Monoxide Monolayers on Graphite
Authors: Fain Samuel C. 
Published: July 2012

AbstractMolecular axis‐orientational ordering occurs at temperatures below 40 K for monolayers of molecular nitrogen and carbon monoxide physisorbed on the graphite basal plane. The method by which the type of structure has been inferred from the symmetries observed in low‐energy electron diffraction (LEED) measurements is briefly reviewed. The information available about the molecular‐axis orientational order‐disorder transitions from LEED, neutron diffraction, X‐ray diffraction, and heat capacity measurements is reviewed and qualitatively compared with theoretical expectations.
Wetting Phenomena at Domain Boundaries
Authors: Selke Walter 
Published: July 2012

AbstractInterfaces between the three physically distinct, but equivalent domains in the (3 × 1) phase of lattice gas models for the adsorbate systems O/Pd(110) and H/Fe(110) are studied. At the wetting transition, the interface or wall between two domains decomposes into two walls of a different type separated by a macroscopically thick region of the third domain. Using mainly Monte Carlo techniques, the characteristic walls are identified and wetting transition lines are determined for phase diagrams in the coverage‐temperature plane.
Phase Transitions in Adsorption Layers on bcc(110) Surfaces: S and O on Mo(110)
Authors: Witt W. , Bauer E. 
Published: July 2012

AbstractThe adsorption of sulfur on Mo(110) was studied by a combination of low energy electron diffraction (LEED), Auger electron spectroscopy (AES) and work function change (ΔΦ) measurements using very fine coverage increments. The evolution of the structures with coverage θ was found to be quite different from that formerly reported for S/Mo(110): discrete commensurate structures exist only for θ ≤ 1/2, whereas for θ > 1/2 a continuous series of incommensurate structures is interrupted by narrow regions of commensurate structures similar to those reported for S/W(110). Thus the “high symmetry hypothesis” is no longer applicable for the interpretation of the structures of S/Mo(110). High resolution LEED diffractometry was used for detailed studies of the S and O/Mo(110)‐p(2 × 2)→(1 × 1) transition. For O this is a single continuous order‐disorder transition contrary to S for which the transition occurs in two steps: a continuous order‐order transition from the p(2 × 2) to a two domain (4 × 1) structure which is followed by an order‐disorder transition. For both adsorbates critical exponents β(θ) and phase diagrams were derived from the data. Finally the kinetics of the domain growth were investigated for S/Mo(110)—p(2 × 2). The time dependence of the average domain size L holds the predicted power law L(t) ∼ tx; x depends on θ. For the ideal p(2 × 2)‐structure x(θ = 1/4) = 0.36 ± 0.03, which is close to the predicted value for Kawasaki dynamics x = 1/3.
Zeolite Supported Iron Oxide as Catalyst or Catalyst Precursor for Hydrocarbon Conversion Reactions
Authors: Bein Thomas , Helen Mia , Jacobs Peter A. 
Published: July 2012

AbstractWhen NaY saturated at room temperature with iron pentacarbonyl, is oxidized at room temperature in a very diluted oxygen flow, a zeolite encaged Fe2O3‐phase is obtained as shown by Mössbauer spectroscopy, electron microscopy and X‐ray diffraction. This catalyst contains 10% by weight of iron and serves as a good precursor of a Fischer‐Tropsch (F.T.) catalyst. Unfortunately, the Fe2O3 phase is unstable under F.T. conditions, since it is shown that the iron phase migrates out of the zeolite matrix during reaction.—This encaged iron oxide phase can be hydrogen reduced giving finely dispersed and zeolite encaged iron, as is shown by physical and chemical methods. This system is a stable and active hydrogenolysis catalyst. Its selectivity is influenced by both particle size and support effects.
Interactions of Hydrophobia Layer Silicates with Alcohol‐Benzene Mixtures I. Adsorption Isotherms
Authors: Dékány I. , Szántó F. , Weiss Armin , Lagaly G. 
Published: July 2012

AbstractA model isotherm is developed that describes the adsorption of methanol and benzene from methanol‐benzene mixtures throughout the whole concentration range (molar fraction of methanol from x1 = 0 to x1 = 1). The clay mineral montmorillonite is used as an adsorbent. The silicate layers are made hydrophobia by exchanging the inorganic gegen ions by alkylammonium ions CncH2nc + 1 NH3+ (nc = 10—18). With increasing alkyl chain length (increasing hydrophobicity) the amounts of benzene adsorbed (ns2) increase, whereas those of methanol (ns1) remain constant. The adsorption potential η1 of methanol decreases and that of benzene (ζ2) increases with the alkyl chain length. The difference η2—η1 changes from positive to negative at nc = 16. Besides the influence of the alkyl chain length, the shape of the excess isotherms and the azeotropic compositions are mainly determined by the bulk‐phase activities.
The Observed and Calculated Vibrational Spectra of DL‐methionine in the Study of the Solid State Phase Transition
Authors: Grunenberg Alfons , Bougeard Daniel 
Published: July 2012

AbstractThe ir and Raman spectra of α and β‐DL‐methionine and three isotopomers have been recorded and assigned with the help of normal coordinate analyses. The vibrational intensities of three conformers (χ1 = gauche II; χ2 = trans; χ3 = gauche I, trans, and gauche II) have been calculated for the free molecule with a MNDO program including a finite field perturbation. Except for the vibrations including the S atom, the CO−2 and NH+3 group the calculations agree with experimental data and confirm the change of χ3 from trans to gauche I at the 326 K transition. The lattice vibrations confirm the conservation of the overall structure of the double layers through the transition.
Defects and Cation Diffusion in Magnetite (VI): Point Defect Relaxation and Correlation in Cation Tracer Diffusion
Authors: Dieckmann R. , Schmalzried H. 
Published: July 2012

AbstractChemical diffusion coefficients have been derived from experiments on the point defect relaxation in magnetite. Based on data from preceding studies on the nonstoichiometry of magnetite and on the iron tracer diffusion of this oxide, the chemical diffusion coefficients are analyzed with regard to elementary diffusion processes and the correlated motion of tracer cations.
Cationic Motions Involving Self‐Diffusion and Structural Phase Transitions in Solid Dimethyl‐ and Trimethylammonium Nitrates as Studied by Differential Thermal Analysis and 1H NMR Techniques
Authors: Ishida Hiroyuki , Ikeda Ryuichi , Nakamura Daiyu 
Published: July 2012

AbstractDifferential thermal analysis and the temperature dependence of broad‐line 1H NMR absorptions and of 1H spin‐lattice relaxation times in both laboratory and rotating frames were observed for (CH3)2NH2NO3, (CH3)ND2NO3, and (CH3)3NHNO3. A solid‐solid phase transition was located at 297 K for (CH3)2NH2NO3. while two phase transitions at 359 and 407 K were found for (CH3)3NHNO3. The 1H spin‐lattice relaxation times in the laboratory frame at different Larmor frequencies and those in the rotating frame at the rf field of 8 G observed for the above salts were analyzed by referring to the 1H NMR second moments determined. The motional parameters of the cations in each solid phase of the salts were evaluated by a fitting calculation to the relaxation times observed. In the highest‐temperature solid phase of (CH3)3NHNO3, the cation was found to perform self‐diffusion as well as overall rotation with the relatively low activation energy of 29 kJ mol−1. The motions of the cations in each newly found solid phase are characterized.
In Situ Studies of Intercalation Reactions Via Nuclear Quadrupole Interactions
Authors: Butz T. , Lerf A. 
Published: July 2012

AbstractWe report on the in situ measurement of the nuclear quadrupole interaction of radioactive 181Ta labels in 2H‐TaS2 during (i) electrochemical intercalation of lithium, hydrated potassium, hydrogen and (ii) thermal intercalation of indium (at 670 K), gallium (850 K), and the eutectic In0.17Ga0.83 (300 K!). The measurements were performed by time differential perturbed angular correlation (TDPAC) on the 133–482 keV γ‐γ‐cascade in 181Ta. Information on the reaction pathways, on non‐equilibrium phenomena and their equilibration, on intercalate mobilities, and on the thermal stability of the compounds is presented.
Zur Stabilität olivinischer Silikate im Sauerstoffpotentialgradienten. II. Das Kobaltsilikat Co2SiO4
Authors: Brinkmann U. , Laqua W. 
Published: July 2012

AbstractThe decomposition of Co2SiO4 in oxygen potential gradients is studied at T = 1.600 K. The critical ratio of the two oxygen partial pressures, at which the compound can be found decomposed into CoO and SiO2, depends strongly on the location of the acting oxygen potential field within the single phase region of Co2SiO4. The results can be explained by po2‐dependent Co‐ and Si‐diffusivities via vacancies and interstitials respectively.
Chemical Diffusion in CuInS2 in the Temperature Range of 20°C to 100°C
Authors: Kleinfeld M. , Wiemhöfer H.‐D. 
Published: July 2012

AbstractMeasurements of steady state current voltage relation and transient resistance with point electrodes on CuInS2 showed effects of ionic mobility at low temperature due to mobile copper ions. From the form of the steady state current voltage relation it was concluded that increasing copper concentration leads to a change from p‐ to n‐type conduction in CuInS2 at the contact with the point electrode. From transient measurements, chemical diffusion coefficients of copper were derived which increase with decreasing electrical conductivity of CuInS2. At 20°C, 1.1 · 10−7 cm2/s was measured on a sample with a conductivity of 0.64 (Ω cm)−1, another sample with 21 (Ω cm)−1 gave 2.1 · 10−1 cm2/s.