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Full-Text Articles in Physics

Estimation Of The Free-Charge-Carrier Concentration In Fast-Ion Conducting Na2s-B2s3 Glasses From An Analysis Of The Frequency-Dependent, Ernest F. Hairetdinov, Nikolai F. Uvarov, Hitendra K. Patel, Steve W. Martin Nov 1994

Estimation Of The Free-Charge-Carrier Concentration In Fast-Ion Conducting Na2s-B2s3 Glasses From An Analysis Of The Frequency-Dependent, Ernest F. Hairetdinov, Nikolai F. Uvarov, Hitendra K. Patel, Steve W. Martin

Materials Science and Engineering Publications

ac and dc conductivities of fast-ion conducting xNa2S+(1-x)B2S3 glasses in the composition range 0.001≤x≤0.1 were analyzed using the Almond-West formula σ(ν)=σdc[1+(ν/νH)α]. The hopping frequency for free charge carriers νH, the dc conductivity σdc, and their respective activation energies were determined. The concentration of free charge carriers evaluated from the conductivities and estimated mobilities is in good agreement with the overall content of sodium cations in the glasses and it is proposed that this supports the concept of a strong and not weak electrolyte model for these ...


36th Rocky Mountain Conference On Analytical Chemistry Jul 1994

36th Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Program, abstracts, and information about the 36th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, July 31 - August 5, 1994.


Compositional Short-Range Ordering In Metallic Alloys: Band-Filling, Charge-Transfer, And Size Effects From A First-Principles All-Electron Landau-Type Theory, J. B. Staunton, Duane D. Johnson, F. J. Pinski Jul 1994

Compositional Short-Range Ordering In Metallic Alloys: Band-Filling, Charge-Transfer, And Size Effects From A First-Principles All-Electron Landau-Type Theory, J. B. Staunton, Duane D. Johnson, F. J. Pinski

Duane D. Johnson

Using a mean-field statistical description, we derive a general formalism to investigate atomic short-range order in alloys based on a density-functional description of the finite-temperature, grand potential of the random alloy. This ‘‘first-principles,’’ Landau-type approach attempts to treat several contributions (electronic structure, Fermi surface, electrostatics, magnetism, etc.) to the electronic energy on an equal footing. An important ingredient for the statistical averaging is the replacement of the molecular mean fields (Weiss fields) with Onsager cavity fields, which forces the diagonal part of the fluctuation-dissipation theorem to be obeyed. To show its general applicability and usefulness, we apply the theory to ...


First-Principles All-Electron Theory Of Atomic Short-Range Ordering In Metallic Alloys: D022- Versus L12-Like Correlations, Duane D. Johnson, J. B. Staunton, F. J. Pinski Jul 1994

First-Principles All-Electron Theory Of Atomic Short-Range Ordering In Metallic Alloys: D022- Versus L12-Like Correlations, Duane D. Johnson, J. B. Staunton, F. J. Pinski

Duane D. Johnson

We use a ‘‘first-principles’’ concentration-wave approach based on a finite-temperature, electronic density-functional, mean-field, grand potential of the random alloy to investigate the high-temperature atomic short-range order (ASRO) in Ni75V25 and Pd75V25 solid solutions. Experimentally, these similar alloys both develop D022-type long-range order at low temperatures but different ASRO at high temperatures. Our calculations describe the measured ASRO well. We compare these results with those found for a hypothetical Co75Ti25 solid solution. Since this alloy orders directly from the melt into the L12 phase, it should exhibit strong L12-like ASRO, as we find in our calculations. We analyze the features in ...


Surface-Induced Ordering In Asymmetric Block Copolymers, Y. Liu, W. Zhao, X. Zheng, Alexander H. King, A. Sing, M. H. Rafailovich, J. Sokolov, K. H. Dai, E. J. Kramer, S. A. Schwarz, O. Gebizlioglu, S. K. Sinha Jun 1994

Surface-Induced Ordering In Asymmetric Block Copolymers, Y. Liu, W. Zhao, X. Zheng, Alexander H. King, A. Sing, M. H. Rafailovich, J. Sokolov, K. H. Dai, E. J. Kramer, S. A. Schwarz, O. Gebizlioglu, S. K. Sinha

Alexander H. King

The surface-induced ordering in thin films of asymmetric deuterated polystyrene (dPS)- poly(viny1pyridine) (PVP) diblock and triblock copolymers of comparable polymerization index and PVP volume fraction - 0.25) was studied using transmission electron microscopy, atomic force microscopy, secondary ion massspectrometry, and neutron reflectivity. The morphology of both di- and triblock copolymer films was found to be cylindrical except for the layer adjacent to the silicon oxide surface, which due to the strong interaction of silica with PVP, was lamellar. The spacing between adjacent cylindrical layers was found to be consistent with mean field theory predictions. In the triblock copolymer films ...


Elastic Constants Of Bcc Cu-Al-Ni Alloys, Lluís Mañosa, M. Jurado, Antoni Planes, Jerel L. Zarestky, Thomas A. Lograsso, C. Stassis Apr 1994

Elastic Constants Of Bcc Cu-Al-Ni Alloys, Lluís Mañosa, M. Jurado, Antoni Planes, Jerel L. Zarestky, Thomas A. Lograsso, C. Stassis

Ames Laboratory Publications

We have measured the adiabatic elastic constants of two Cu-Al-Ni martensitic alloys using ultrasonic methods and we have compared the results to recent neutron-scattering experiments. It is shown that the elastic behavior of Cu-Al-Ni alloys follows the same trends exhibited by other Cu-based alloys; in particular, the TA2 long-wavelength acoustic modes are softer than all other modes.


Models For Water Outgassing From Metal Surfaces, Minxu Li Jan 1994

Models For Water Outgassing From Metal Surfaces, Minxu Li

Dissertations, Theses, and Masters Projects

In this study, the outgassing rate from an electropolished stainless steel surface following exposures to H{dollar}\sb2{dollar}O vapor under various conditions was measured. The results of the experiments showed that the outgassing rate is proportional to {dollar}p\sb0\sp{lcub}n{rcub}{dollar}, where {dollar}p\sb0{dollar} is the H{dollar}\sb2{dollar}O exposure pressure and n is about 0.25. The outgassing rate is not as strongly dependent on the system temperature as one would expect if the temperature is kept the same during exposure and pump-down. The outgassing rate is also a ...


Connection Between Nmr And Electrical Conductivity In Glassy Chalcogenide Fast Ionic Conductors , Kyung-Han Kim Jan 1994

Connection Between Nmr And Electrical Conductivity In Glassy Chalcogenide Fast Ionic Conductors , Kyung-Han Kim

Retrospective Theses and Dissertations

Pulsed Nuclear Magnetic Resonance measurements and electric conductivity measurements have been performed in glassy fast ionic conductors, lithium thiogermanates ( xLi2S+(1-x)GeS2) and lithium thioborates ( xLi2S+(1-x)B2S3) in order to investigate the microscopic mechanism of ion dynamics. Both 7Li nuclear spin lattice relaxation rate (NSLR) versus temperature at several resonance frequencies (4 MHz to 135 MHz) and conductivity, [sigma]([omega]) versus temperature, in the frequency range from 1 Hz to 4 MHz have been measured. The 7Li NSLR show BPP-type behavior with strong asymmetry of the bell shaped curve on the two sides of the maximum. A sizable dependence ...