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Materials Science and Engineering Faculty Research & Creative Works

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Articles 631 - 660 of 1011

Full-Text Articles in Materials Science and Engineering

Experimental And Theoretical Investigation Of Mixing In A Bottom Gas-Stirred Ladle, Jun Aoki, Brian G. Thomas, Jörg Peter, Kent D. Peaslee Sep 2004

Experimental And Theoretical Investigation Of Mixing In A Bottom Gas-Stirred Ladle, Jun Aoki, Brian G. Thomas, Jörg Peter, Kent D. Peaslee

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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Defect Chemistry Of Mixed Ionic/Electronic P-Type Oxides, Harlan U. Anderson, Xiao-Dong Zhou, Fatih Dogan Sep 2004

Defect Chemistry Of Mixed Ionic/Electronic P-Type Oxides, Harlan U. Anderson, Xiao-Dong Zhou, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

The p-type perovskite structure oxides are finding use in a number of energy related applications. In particular they are being used as cathodes in fuel cells as well as dense oxygen separation membranes. The defect concentration and defect mobility determine the electrical properties. Since both of these are dependent upon the operating temperature and oxygen activity, it is important to understand how an oxide equilibrates with its environment. In this paper, a defect chemistry model for the oxidation-reduction behavior of p-type perovskites is reviewed with formulations in the (La,Sr)(Cr,Mn,Co,Fe)03 system being used as examples.

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Novel Yttrium-Stabilized Zirconia Polymeric Precursor For The Fabrication Of Thin Films, Roger M. Smith, X.-D. Zhou, Wayne Huebner, Harlan U. Anderson Sep 2004

Novel Yttrium-Stabilized Zirconia Polymeric Precursor For The Fabrication Of Thin Films, Roger M. Smith, X.-D. Zhou, Wayne Huebner, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

An acetate-based polymeric precursor for producing yttrium-stabilized zirconia (YSZ) was developed. The precursor was prepared under ambient conditions and contains only yttrium and zirconium cations. Dense, crack-free films were fabricated with this precursor on alumina substrates at a rate of 60 nm per deposition, producing polycrystalline YSZ at temperatures as low as 600 °C. Grain growth in thin YSZ films followed Arrhenius equation with an activation energy approximately 0.45 eV. The residual strain in YSZ films decreased with increasing annealing temperature from 600 to 900 °C.

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Pm Manufacturing Research Boosted By Continuous Sintering Furnace, Joseph William Newkirk Sep 2004

Pm Manufacturing Research Boosted By Continuous Sintering Furnace, Joseph William Newkirk

Materials Science and Engineering Faculty Research & Creative Works

University of Missouri-Rolla has recently acquired a Fluidtherm laboratory continuous sintering furnace. Custom designed and built for PM research, the furnace will allow current efforts in sintering development, pressure gas quenching of PM steels, optimisation of toughness and fatigue properties of PM parts, and production of metal matrix composites to be enhanced and extended.

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Anode Supported Single Chamber Solid Oxide Fuel Cell In Ch 4 -Air Mixture, Toshio Suzuki, Piotr Jasinski, Vladimir Petrovsky, Harlan U. Anderson, Fatih Dogan Sep 2004

Anode Supported Single Chamber Solid Oxide Fuel Cell In Ch 4 -Air Mixture, Toshio Suzuki, Piotr Jasinski, Vladimir Petrovsky, Harlan U. Anderson, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

In this study, yttrium-stabilized zirconia (YSZ) thin films 1-2 μm thick electrolyte have been prepared using NiO-YSZ anode as substrates. Fuel cell test was conducted with the single chamber configuration in methane-air gas mixture using (la,Sr)(Co,Fe) O3 (LSCF) as the cathode. Test results showed that the open-circuit voltage to be >0.8 V, with power density as high as 0.12 W cm−2. It was also shown that gas flow rate has a large influence on the performance of the fuel cell, which indicates the importance of the geometrical design for anode support fuel cell system.

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Mixed Ion-Polaron Transport In Na2o-Pbo-Fe2o3-P2o5 Glasses, A. Moguš-Milanković, A. Šantić, Signo Tadeu Dos Reis, K. Furić, D. E. Day Aug 2004

Mixed Ion-Polaron Transport In Na2o-Pbo-Fe2o3-P2o5 Glasses, A. Moguš-Milanković, A. Šantić, Signo Tadeu Dos Reis, K. Furić, D. E. Day

Materials Science and Engineering Faculty Research & Creative Works

The electrical and dielectric properties of the xNa2O · (100 - x) · [28.3PbO · 28.7Fe2O3 · 43.0P2O5] (0 ≤ x ≤ 30) glasses were measured by impedance spectroscopy in the frequency range from 0.01 Hz to 3 MHz and the temperature range from 303 to 473 K. the conductivity for glasses containing ≤15 mol% Na2O is predominantly electronic and is controlled by electron hopping between Fe(II) and Fe(III) ions. in these glasses the sodium ions have such a low mobility, caused by ion-polaron interaction, that they make no …

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The Structure Of The High-Energy Spin Excitations In A High-Transition-Temperature Superconductor, S. M. Hayden, H. A. Mook, Pengcheng Dal, T. G. Perring, F. Doǧan Jun 2004

The Structure Of The High-Energy Spin Excitations In A High-Transition-Temperature Superconductor, S. M. Hayden, H. A. Mook, Pengcheng Dal, T. G. Perring, F. Doǧan

Materials Science and Engineering Faculty Research & Creative Works

In conventional superconductors, lattice vibrations (phonons) mediate the attraction between electrons that is responsible for superconductivity. The high transition temperatures (high-Tc) of the copper oxide superconductors has led to collective spin excitations being proposed as the mediating excitations in these materials. The mediating excitations must be strongly coupled to the conduction electrons, have energy greater than the pairing energy, and be present at Tc. The most obvious feature in the magnetic excitations of high-Tc superconductors such as YBa 2Cu3O6+x is the so-called 'resonance'. Although the resonance may be strongly coupled to the superconductivity, it is unlikely to be the main …

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Polarized Neutron Measurement Of Magnetic Order In Yba2⁢Cu3⁢O6.45, Herbert A. Mook, Pengcheng Dai, Stephen M. Hayden, Arno Hiess, Sh Lee, Fatih Dogan Apr 2004

Polarized Neutron Measurement Of Magnetic Order In Yba2⁢Cu3⁢O6.45, Herbert A. Mook, Pengcheng Dai, Stephen M. Hayden, Arno Hiess, Sh Lee, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Orbital current order of the d-density-wave type has been postulated to explain the pseudo gap in high temperature superconductors. We have performed neutron scattering experiments to search for this order and show here the results obtained on an YBa2⁢Cu3⁢O6.45 sample using the best neutron spectrometers available. We argue that the data are consistent with a small, largely c-axis-directed moment, found below about 200 K.

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Superplasticity In Cast A356 Induced Via Friction Stir Processing, Z. Y. Ma, Rajiv S. Mishra, M. W. Mahoney Apr 2004

Superplasticity In Cast A356 Induced Via Friction Stir Processing, Z. Y. Ma, Rajiv S. Mishra, M. W. Mahoney

Materials Science and Engineering Faculty Research & Creative Works

Super plasticity was investigated in friction stir processed A356 alloy at temperatures of 470-570 °C and initial strain rates of 3x10 -4-1x10-1 s-1. Maximum superplastic elongation of 650% was obtained at 530 °C and an initial strain rate of 1x10-3 s-1 where a maximum strain rate sensitivity of 0.45 was observed. © 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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Metal Superplasticity Enhancement And Forming Process, Rajiv S. Mishra, Murray W. Mahoney Mar 2004

Metal Superplasticity Enhancement And Forming Process, Rajiv S. Mishra, Murray W. Mahoney

Materials Science and Engineering Faculty Research & Creative Works

A shaped metallic component is formed by friction stirring at least a segment of a single piece of bulk metal to impart superplasticity thereto and thereby yield a single superplastic metal blank from the single piece of bulk metal. The metal blank is then deformed by a metal deformation process such as forging, rolling, drawing, bending, extruding, gas forming, punching, and stamping.

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Bioactive Materials, D. E. Day, Erik M. Erbe, Marina Richard, Joshua A. Wojcik Mar 2004

Bioactive Materials, D. E. Day, Erik M. Erbe, Marina Richard, Joshua A. Wojcik

Materials Science and Engineering Faculty Research & Creative Works

Bioactive substantially silica-free glass material with a hydroxyapatite layer thereon is described, as well as methods for producing hydroxyapatite on a borate glass.

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Annealing-Induced Full Amorphization In A Multicomponent Metallic Film, J. P. Chu, C. T. Liu, T. Mahalingam, S. F. Wang, Matthew O'Keefe, Benedict Y. Johnson, C. H. Kuo Mar 2004

Annealing-Induced Full Amorphization In A Multicomponent Metallic Film, J. P. Chu, C. T. Liu, T. Mahalingam, S. F. Wang, Matthew O'Keefe, Benedict Y. Johnson, C. H. Kuo

Materials Science and Engineering Faculty Research & Creative Works

We present direct experimental evidence that controllable amorphization and nanocrystallization during annealing of metastable films could serve as a precursor for exciting nanomaterials. The interesting discovery is that certain sputtered crystalline films become completely amorphous when annealed in the temperature range between the glass temperature and the crystallization temperature. Unlike other metallic glassy materials that exhibit annealing-induced devitrification, our good glass-forming films are transformed into various nanoscale and amorphous structures due to the annealing process. The formation of an amorphous phase gives rise to notable alterations in the electrical and mechanical properties of the film.

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Optical Characterization Of Ceramic Thin Films: Applications In Low-Temperature Solid Oxide Fuel-Cell Materials Research, Vladimir Petrovsky, Tatiana Petrovsky, Harlan U. Anderson, Brian P. Gorman Feb 2004

Optical Characterization Of Ceramic Thin Films: Applications In Low-Temperature Solid Oxide Fuel-Cell Materials Research, Vladimir Petrovsky, Tatiana Petrovsky, Harlan U. Anderson, Brian P. Gorman

Materials Science and Engineering Faculty Research & Creative Works

Characterization of thin film solid oxide fuel-cell materials can be difficult due to the range of porosities in electrodes and electrolytes as well as the nano-sized pores and particles. In this study, optical characterization techniques such as ultraviolet-visible transmission and reflection spectrophotometry are illustrated as methods for achieving information about the film density from the film refractive index as well as the film thickness. These techniques were used to investigate the sintering process of colloidal CeO2 on sapphire substrates and polymeric precursor-derived ZrO2:16%Y (YSZ) thin films on silicon over the temperature range 400-1000 °C, and the results were compared with …

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Chemical Solution Deposition Of Electronic Oxide Films, Robert W. Schwartz, Theodor Schneller, Rainer Waser Jan 2004

Chemical Solution Deposition Of Electronic Oxide Films, Robert W. Schwartz, Theodor Schneller, Rainer Waser

Materials Science and Engineering Faculty Research & Creative Works

The chemical solution deposition (CSD) technique as a highly flexible method for the fabrication of electronic oxide thin films is reviewed. Various chemical aspects of different approaches are discussed, including sol-gel, hybrid, and metallo-organic decomposition (MOD) routes, which all have been successfully applied for the deposition of this class of materials. Principles of the selection and properties of the educts, the mechanism of film crystallization, and tailoring of microstructure through manipulation of deposition parameters are reported. the role of thermodynamics on the phase transformation process is also reviewed. Finally, some of the applications for chemical solution-derived thin films currently under …

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Thermal Efficiency Of Steel Melting, Kent D. Peaslee, Semen Naumovich Lekakh, Bradley Randall Jan 2004

Thermal Efficiency Of Steel Melting, Kent D. Peaslee, Semen Naumovich Lekakh, Bradley Randall

Materials Science and Engineering Faculty Research & Creative Works

This paper presents the results of energy consumption measurements at steel foundries using induction and/or electric arc furnace melting. Statistical methods, infrared thermography, and numerical investigations were used for analysis of heat losses. The influence of different melting practices on energy losses was examined. Industrial experiments in isothermal holding of liquid steel in induction furnaces under different power inputs were used for evaluation of the real values of heat losses by radiation from liquid steel and conductivity through lining. Average values and statistical distributions of energy consumptions for melting steel are presented in this article.

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Evaluation Of Microstructure And Superplasticity In Friction Stir Processed 5083 Al Alloy, Indrajit Charit, Rajiv S. Mishra Jan 2004

Evaluation Of Microstructure And Superplasticity In Friction Stir Processed 5083 Al Alloy, Indrajit Charit, Rajiv S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

Friction stir processing (FSP) has been developed as a potential grain refinement technique. In the current study, a commercial 5083 Al alloy was friction stir processed with three combinations of FSP parameters. Fine-grained microstructures with average grain sizes of 3.5-8.5 µm were obtained. Tensile tests revealed that the maximum ductility of 590 was achieved at a strain rate of 3 x 10-3 s-1 and 530 °C in the 6.5-µm grain size FSP material, whereas for the material with 8.5-µm grain size, maximum ductility of 575 was achieved at a strain rate of 3 x 10-4 s-1 …

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High Gradient Multilayer Insulator Technology, Harlan U. Anderson, Stephen E. Sampayan, G. J. Caporaso, W. C. Nunnally, D. M. Sanders, J. A. Watson, Mike L. Krogh Jan 2004

High Gradient Multilayer Insulator Technology, Harlan U. Anderson, Stephen E. Sampayan, G. J. Caporaso, W. C. Nunnally, D. M. Sanders, J. A. Watson, Mike L. Krogh

Materials Science and Engineering Faculty Research & Creative Works

We are investigating a novel insulator concept that involves the use of alternating layers of conductors and insulators with periods less than 1 mm. These structures perform 1.5 to 4 times better than conventional insulators in long pulse, short pulse, and alternating polarity applications. We have surveyed our ongoing studies by investigating the performance under long pulse electron beam, short pulse, and full reversing conditions.

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Optical Characterization Of Ceramic Thin Films: Applications In Low-Temperature Solid Oxide Fuel-Cell Materials Research, B. P. Gorman, V. Petrovsky, Harlan U. Anderson, T. Petrovsky Jan 2004

Optical Characterization Of Ceramic Thin Films: Applications In Low-Temperature Solid Oxide Fuel-Cell Materials Research, B. P. Gorman, V. Petrovsky, Harlan U. Anderson, T. Petrovsky

Materials Science and Engineering Faculty Research & Creative Works

Characterization of thin film solid oxide fuel-cell materials can be difficult due to the range of porosities in electrodes and electrolytes as well as the nano-sized pores and particles. in this study, optical characterization techniques such as ultraviolet-visible transmission and reflection spectrophotometry are illustrated as methods for achieving information about the film density from the film refractive index as well as the film thickness. These techniques were used to investigate the sintering process of colloidal CeO2 on sapphire substrates and polymeric precursor-derived ZrO2:16%Y (YSZ) thin films on silicon over the temperature range 400-1000 °C, and the results …

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Superplastic Forming Of Micro Components, Rajiv S. Mishra Dec 2003

Superplastic Forming Of Micro Components, Rajiv S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

A method for forming a miniaturized shaped component. Bulk superplastic material is contacted with a flat rotating surface of a rotating tool to frictionally heat the bulk superplastic material with the bulk superplastic material positioned between the flat rotating surface of the tool and a micro fabricated tool die. The bulk superplastic material is forced into the microfabricated die once the bulk superplastic material is heated to a temperature between a glass transition temperature and a crystallization temperature.

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Self-Consistent Modification To The Electron Density Of States Due To Electron-Phonon Coupling In Metals, Fatih Dogan, Frank Marsiglio Oct 2003

Self-Consistent Modification To The Electron Density Of States Due To Electron-Phonon Coupling In Metals, Fatih Dogan, Frank Marsiglio

Materials Science and Engineering Faculty Research & Creative Works

The "standard" theory of a normal metal consists of an effective electron band which interacts with phonons and impurities. The effects due to the electron-phonon interaction are often delineated within the Migdal approximation; the properties of many simple metals are reasonably well described with such a description. On the other hand, if the electron-phonon interaction is sufficiently strong, a polaron approach is more appropriate. The purpose of this paper is to examine to what degree the Migdal approximation is self-consistent, as the coupling strength increases. We find that changes in the electron density of states become significant for very large …

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Neodymium Oxide Doped Melt Textured Yba2cu3o7-X Single Crystals, Fatih Dogan, Stephen W. Sofie, William C. Hicks, Michael Strasik, Kevin E. Mccrary, Arthur C. Day Jun 2003

Neodymium Oxide Doped Melt Textured Yba2cu3o7-X Single Crystals, Fatih Dogan, Stephen W. Sofie, William C. Hicks, Michael Strasik, Kevin E. Mccrary, Arthur C. Day

Materials Science and Engineering Faculty Research & Creative Works

Processing, microstructure and property relationships in neodymium oxide doped high temperature superconducting YBa2Cu3O7-x were investigated. It has been observed that a small amount (0.25–1 mol%) of Nd2O3 results in the formation of nanosized secondary phases which may have a significant effect on the superconducting properties of melt textured Y123 single crystals. It was further observed that addition of Nd2O3 greater than 1 mol% leads to multiple nucleation during solidification of Y123 and results in polycrystalline samples. Melt textured single crystals of Y123 with 1 mol% were successfully grown and …

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Neodymium Oxide Doped Melt Textured Yba2cu3o7-X Single Crystals, Fatih Dogan, Stephen W. Sofie, William C. Hicks, Michael Strasik, Kevin E. Mccrary, Arthur C. Day Jun 2003

Neodymium Oxide Doped Melt Textured Yba2cu3o7-X Single Crystals, Fatih Dogan, Stephen W. Sofie, William C. Hicks, Michael Strasik, Kevin E. Mccrary, Arthur C. Day

Materials Science and Engineering Faculty Research & Creative Works

Processing, microstructure and property relationships in neodymium oxide doped high temperature superconducting YBa2Cu3O7-x (Y123) were investigated. It has been observed that a small amount (/spl sim/ 0.25 - 1 mol%) of Nd2O3 results in the formation of nanosized secondary phases which may have a significant effect on the superconducting properties of melt textured Y123 single crystals. It was further observed that addition of Nd2O3 greater than 1 mol% leads to multiple nucleation during solidification of Y123 and results in polycrystalline samples. Melt textured single crystals of Y123 with < 1 mol% were successfully grown and characterized with respect to microstructural development and superconducting properties.

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Optical And Electrical Properties Of Pr0.8sr0.2mno3 Thin Films, Toshio Suzuki, Piotr Z. Jasinski, Vladimir Petrovsky, Xiao Dong Zhou, Harlan U. Anderson May 2003

Optical And Electrical Properties Of Pr0.8sr0.2mno3 Thin Films, Toshio Suzuki, Piotr Z. Jasinski, Vladimir Petrovsky, Xiao Dong Zhou, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The optical and electrical properties of Pr0.8Sr0.2MnO3 thin films were discussed. It was found that the results of optical measurements were correlated with the annealing temperatures of the films and the shape of the optical spectra was found to change as the structure changed from an amorphous to crystalline structure. the electrical conductivity was found to be observed to be about three orders of magnitude higher for specimens which were crystalline as compared to amorphous.

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Electron Microscopy Studies On Platinum-Ceramics Nanocomposites Synthesized By Spray Process, X.-D. Zhou Feb 2003

Electron Microscopy Studies On Platinum-Ceramics Nanocomposites Synthesized By Spray Process, X.-D. Zhou

Materials Science and Engineering Faculty Research & Creative Works

The platinum-ceramics nanocomposites synthesized by spray process were discussed using electron microscopy. It was found that the nanocomposites of Pt-ceramics were synthesized by spray process with a controllable distribution of Pt primary particles. the analysis showed that the nanometer Pt primary particles encapsulating YSZ nanocomposites were derived when ethanol was used as solvent.

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In-Plane Anisotropy And Temperature Dependence Of Oxygen Phonon Modes In Yba2⁢Cu3⁢O6.95, J-H Chung, Takeshi Egami, Rj Mcqueeney, Mohana Yethiraj, Masatoshi Arai, Tetsuya Yokoo, Y. Petrov, Herbert A. Mook, Yasuo Endoh, Setsuko Tajima, C. Frost, Fatih Dogan Jan 2003

In-Plane Anisotropy And Temperature Dependence Of Oxygen Phonon Modes In Yba2⁢Cu3⁢O6.95, J-H Chung, Takeshi Egami, Rj Mcqueeney, Mohana Yethiraj, Masatoshi Arai, Tetsuya Yokoo, Y. Petrov, Herbert A. Mook, Yasuo Endoh, Setsuko Tajima, C. Frost, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Inelastic pulsed neutron scattering measurements on YBa2⁢Cu3⁢O6.95 single crystals indicate that the sample has a distinct a-b plane anisotropy in the oxygen vibrations. The Cu-O bond-stretching-type phonons, which are suspected to interact strongly with charge, are simultaneously observed along the a and b directions due to a 7-meV splitting arising from the orthorhombicity, even though the sample is twinned. The bond-stretching LO branch with the polarization along a (perpendicular to the chain) loses intensity beyond the middle of the zone, indicating branch splitting as seen in doped nickelates, with the second branch being located at …

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Dynamics Of Bulk And Adsorbed Poly(Vinyl Acetate), Frank D. Blum, Robert D. O'Connor Jan 2003

Dynamics Of Bulk And Adsorbed Poly(Vinyl Acetate), Frank D. Blum, Robert D. O'Connor

Materials Science and Engineering Faculty Research & Creative Works

We have recently completed a series of experiments on methyl-labeled poly(vinyl acetate)-d3, (PVAc-d3)1 and poly(methyl acrylate)-d3 (PMA-d3).234 the systems have been studied as a function of the adsorbed amount, molecular weight, and presence of a protonated overlayer. Using deuterium line shape analysis, we have found that around the glass transition temperature, the adsorbed polymers show the presence of a motional gradient. Polymer segments near the silica-polymer interface have less mobility than the bulk polymer and those near the polymer-air interface are more mobile than those of the bulk polymer. A schematic representation of the motional gradient is shown in Figure …

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Influence Of Nanocrystalline Grain Size On The Breakdown Strength Of Ceramic Dielectrics, Yang Ye, Fatih Dogan, E. Schamiloglu, J. Gaudet, P. Castro, M. Roybal, M. Joler, C. Christodoulou, Shi C. Zhang Jan 2003

Influence Of Nanocrystalline Grain Size On The Breakdown Strength Of Ceramic Dielectrics, Yang Ye, Fatih Dogan, E. Schamiloglu, J. Gaudet, P. Castro, M. Roybal, M. Joler, C. Christodoulou, Shi C. Zhang

Materials Science and Engineering Faculty Research & Creative Works

In an effort to develop transmission lines with higher energy storage capabilities for compact pulsed power applications, the University of Missouri-Rolla (UMR) and the University of New Mexico (UNM) have undertaken a collaborative approach to developing and studying ceramic dielectrics. At UMR, the electrical breakdown strength (BDS) of TiO2-based materials is investigated for high energy density applications. The results of research to-date show that dense titania ceramics with nanocrystalline grain size (~200 nm) exhibit significantly higher BDS as compared to ceramics made using coarse grain materials. Processing-microstructure-property relationships in TiO2 systems are found to play a role with respect to …

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Comparison Of Anode And Electrolyte Support Configuration Of Single-Chamber Sofc, Piotr Jasinski, Toshio Suzuki, Zach Byars, Fatih Dogan, Harlan A. Anderson Jan 2003

Comparison Of Anode And Electrolyte Support Configuration Of Single-Chamber Sofc, Piotr Jasinski, Toshio Suzuki, Zach Byars, Fatih Dogan, Harlan A. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The single-chamber solid oxide fuel cell (SOFC) has recently received considerable attention. This type of fuel cell operates in the mixed reactant gas and therefore does not require separation of the fuel and oxidant gases. In this paper we report the anode- and electrolyte-supported configurations of the single chamber SOFC that we have studied. The system based on typical fuel cell composition has been examined: yttrium stabilized zirconia (YSZ) as an electrolyte, nickel/YSZ cermet as an anode, lanthanum strontium manganese oxide (LSM) as a cathode. The cells were prepared by tape-casting and screen-printing techniques. The cathode processing parameters have been …

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Phase Diagram For Stripes In Yba2cu3o6+X Superconductors, Herbert A. Mook, Fatih Dogan Dec 2002

Phase Diagram For Stripes In Yba2cu3o6+X Superconductors, Herbert A. Mook, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Neutron scattering has been used to measure the charge and spin structure in the YBa2Cu3O6+x superconductors. Incommensurate static charge ordering is found at low doping levels while only charge fluctuations are found at higher doping. The spin structure is complex with both a commensurate resonance and incommensurate structure observed at low temperatures. The scattering results are used to construct a phase diagram for stripes in the YBa2Cu3O6+x system.

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Nonstoichiometry And Electrical Transport In Sc-Doped Zirconia, Igor Kosacki, Harlan U. Anderson, Yasunobu Mizutani, Kenji Ukai Dec 2002

Nonstoichiometry And Electrical Transport In Sc-Doped Zirconia, Igor Kosacki, Harlan U. Anderson, Yasunobu Mizutani, Kenji Ukai

Materials Science and Engineering Faculty Research & Creative Works

The results of electrical conductivity measurements on ZrO2: Sc (ScSZ) ceramics as a function of oxygen activity and temperature are presented. The influence of the microstructure on electrical transport is discussed and the experimental data for dense microcrystalline specimens have been compared with those obtained for dense nanocrystalline thin films. From these results the electronic and ionic contribution to the electrical transport has been determined and correlated with microstructure. It has been found that nanocrystalline ScSZ films possess quite different nonstoichiometry compared with that observed for microcrystalline specimens in the fact that the electronic conductivity is enhanced so …

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