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Ceramic Materials

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Articles 571 - 600 of 1347

Full-Text Articles in Materials Science and Engineering

Freeze-Spray Processing Of Layered Ceramic Composites (Preprint), Oratai Jongprateep, Q. Fu, A. Abbott, Fatih Dogan Apr 2006

Freeze-Spray Processing Of Layered Ceramic Composites (Preprint), Oratai Jongprateep, Q. Fu, A. Abbott, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Thermal gradients and associated stresses are critical in designing with ceramic composites having low thermal conductivity. In order to reduce the stresses from thermal gradients, compositional gradients are employed in designing of composite structures. This study addresses development of freeze-spray process to fabricate layered ceramic structures with controlled layer thickness and microstructural development. The composites were processed by spraying of ceramic slurries with low binder content and relatively high solids loadings up to 40 vol on a cooled substrate. The frozen parts were freeze-dried and sintered at elevated temperatures. The relationship between microstructural development and thermal expansion behavior of Al …

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Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix: Quarterly Report, January 2006 To March 2006, Kiel Steven Holliday, Thomas Hartmann, Kenneth Czerwinski Mar 2006

Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix: Quarterly Report, January 2006 To March 2006, Kiel Steven Holliday, Thomas Hartmann, Kenneth Czerwinski

Fuels Campaign (TRP)

This project will examine inert matrix fuels containing ZrO2 and MgO as the inert matrix, with the relative amount of MgO varied from 30% to 70% in ZrO2. Reactor physics calculations will be used to examine suitable quantities of burnable poisons from the candidate elements Gd, Er, or Hf with reactor grade Pu providing the fissile component, with up to 10% of 239Pu. Ceramics will be synthesized and characterized based on the reactor physics results. The solubility of the fuel ceramics, in reactor conditions, reprocessing conditions, and repository conditions, will be investigated in a manner to …

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Characterization Of Compressive Creep Behavior Of Oxide/Oxide Composite With Monazite Coating At Elevated Temperature, Patrick R. Jackson Mar 2006

Characterization Of Compressive Creep Behavior Of Oxide/Oxide Composite With Monazite Coating At Elevated Temperature, Patrick R. Jackson

Theses and Dissertations

The compressive creep behavior of a N610/monazite/alumina composite was investigated in this work. The composite consists of a porous alumina matrix reinforced with NextelTM610 fibers coated with monazite in a symmetric cross-ply (0°/90°/0°/90°)s orientation. Compressive stress-strain behavior was investigated as well. The addition of monazite coating resulted in ~ 35% loss in compressive strength at 900°C and in ~45% loss in compressive strength at 1100°C. Compressive creep behavior was examined at 900 and 1100°C for creep stresses ranging from 50 to 95 MPa. Primary and secondary creep regimes were observed at both temperatures. Minimum creep rate was reached in all …

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Effect Of Hold Times On Fatigue Behavior Of Nextel 720™/Alumina Ceramic Matrix Composite At 1200°C In Air And In Steam Environment, John M. Mehrman Mar 2006

Effect Of Hold Times On Fatigue Behavior Of Nextel 720™/Alumina Ceramic Matrix Composite At 1200°C In Air And In Steam Environment, John M. Mehrman

Theses and Dissertations

The aerospace field requires structural materials that can maintain superior mechanical properties while subjected to high temperatures and oxidizing environments. This research investigated the effect of hold times at maximum load on fatigue performance of a Nextel 720/Alumina ceramic matrix composite at 1200 C, explored the influence of environment on material response to cyclic loading with hold times at maximum load, and assessed the effects of loading history on material behavior and environmental durability. The N720/A composite relies on an oxide/oxide composition for inherent oxidation resistance and a porous matrix with no interphase between the fiber and matrix for damage …

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Creep-Rupture And Fatigue Behaviors Of Notched Oxide/Oxide Ceramic Matrix Composite At Elevated Temperature, Mark A. Sullivan Mar 2006

Creep-Rupture And Fatigue Behaviors Of Notched Oxide/Oxide Ceramic Matrix Composite At Elevated Temperature, Mark A. Sullivan

Theses and Dissertations

Oxide/oxide composites are being considered for use in high temperature aerospace applications where their inherent resistance to oxidation provides for better long life properties at high temperature than most other ceramic matrix composites (CMCs). One promising oxide/oxide CMC is Nextel 720/A (N720/A) which uses an 8-harness satin weave (8HSW) of Nextel 720 fibers embedded in a porous alumina matrix. Possible aerospace applications for N720/A will likely require inserting holes into the material for mounting and cooling purposes. The notch characteristics must be understood to ensure designs using the material are sufficient for the desired application. This research effort examined the …

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Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix, Kenneth Czerwinski Jan 2006

Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix, Kenneth Czerwinski

Fuels Campaign (TRP)

This project examines inert fuels containing ZrO2 and MgO as the inert matrix, with the relative amount of MgO varied from 30% to 70% in ZrO2. Reactor physics calculations are used to examine suitable quantities of burnable poisons from the candidate elements Gd, Er, or Hf with reactor grade Pu providing the fissile component, with up to 10% of 239Pu. Ceramics are synthesized and characterized based on the reactor physics results. The solubility of the fuel ceramics, in reactor conditions, reprocessing conditions, and repository conditions, are investigated in a manner to provide thermodynamic data necessary for …

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Effect Of Nozzle Base Material On The Rate Of Clogging During The Continuous Casting Of Aluminum-Killed Steels, Luis Trueba, Kent D. Peaslee, Jeffrey D. Smith, Musa Karakus Jan 2006

Effect Of Nozzle Base Material On The Rate Of Clogging During The Continuous Casting Of Aluminum-Killed Steels, Luis Trueba, Kent D. Peaslee, Jeffrey D. Smith, Musa Karakus

Materials Science and Engineering Faculty Research & Creative Works

One approach to solving the problem of nozzle clogging during the continuous casting of aluminum-killed steels is through careful selection of nozzle materials. in this study, the rate of clogging was measured while casting steel through simulated nozzles produced from alumina, zirconia, magnesia, zirconia-graphite, and alumina-graphite - three common base materials and two common carbon-containing nozzle materials. Spent nozzles were characterized using optical and cathodoluminescence microscopy. Interactions between the nozzles and steel were not observed in the alumina, zirconia, and zirconia-graphite nozzles. Slight interactions were observed in the magnesia nozzles as alumina inclusions within the steel interacted with the nozzle …

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Effect Of Baceo3 And Basno3 Additives On Microstructural Development And Critical Current Density Of Melt Textured Yba2cu3o7-X, Oratai Jongprateep, Fatih Dogan, Michael Strasik, Kevin E. Mccrary Sep 2005

Effect Of Baceo3 And Basno3 Additives On Microstructural Development And Critical Current Density Of Melt Textured Yba2cu3o7-X, Oratai Jongprateep, Fatih Dogan, Michael Strasik, Kevin E. Mccrary

Materials Science and Engineering Faculty Research & Creative Works

Improvement of superconducting properties, such as critical current density Jc and trapped magnetic field, of melt textured YBa2Cu3O7-x (Y123) require introducing of effective pinning sites, e.g., nonsuperconducting inclusions, twin boundaries and other defects. It has been shown that addition of small quantities of BaCeO3 (< 0.5 wt.%) into Y123 results in an increase of the J/sub c/. However, higher cerium concentrations affect the solidification process and inhibit the growth of melt textured Y123 single crystals. In this study, the effect of BaCeO/sub 3/ additions on the growth and microstructural development of melt textured Y123 single crystals were investigated. The relationship between the solidification kinetics, microstructural development and superconducting properties of Y123 melt textured single crystals with cerium additives is discussed.

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Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix: Quarterly Report, April 2005 To June 2005, Earl Wolfram, Thomas Hartmann, Kenneth Czerwinski Jun 2005

Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix: Quarterly Report, April 2005 To June 2005, Earl Wolfram, Thomas Hartmann, Kenneth Czerwinski

Fuels Campaign (TRP)

This project will examine inert matrix fuels containing ZrO2 and MgO as the inert matrix, with the relative amount of MgO varied from 30% to 70% in ZrO2. Reactor physics calculations will be used to examine suitable quantities of burnable poisons from the candidate elements Gd, Er, or Hf with reactor grade Pu providing the fissile component, with up to 10 % of 239Pu. Ceramics will be synthesized and characterized based on the reactor physics results. The solubility the fuel ceramics, in reactor conditions, reprocessing conditions, and repository conditions, will be investigated in a manner to …

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The Wettability Of Titanium Diboride By Molten Aluminum Drops, D. A. Weirauch, W. J. Krafick, G. Ackart, P. D. Ownby May 2005

The Wettability Of Titanium Diboride By Molten Aluminum Drops, D. A. Weirauch, W. J. Krafick, G. Ackart, P. D. Ownby

Materials Science and Engineering Faculty Research & Creative Works

Titanium diboride is widely accepted to be completely wet by liquid aluminum, yet few published wetting studies demonstrate this behavior, and reported contact angles vary widely. Sessile drop substrates from four different sources were selected and their microstructures and chemistries characterized. the results of sessile drop experiments using four techniques to modify oxide film behavior were compared. the Al-TiB2 interfaces were examined in metallographic sections or after chemical removal of the Al drop. Al wets a material containing 5.5 wt% Ni in vacuum experiments before the hold temperature of 1025°C is reached. the other TiB2 substrates are completely wet by …

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High-Temperature Monitoring Of Refractory Wall Recession Using Frequency-Modulated Continuous-Wave (Fm-Cw) Radar Techniques, Bivin Varghese, C. Deconick, G. Cartee, M. Velez, Robert E. Moore, R. Zoughi May 2005

High-Temperature Monitoring Of Refractory Wall Recession Using Frequency-Modulated Continuous-Wave (Fm-Cw) Radar Techniques, Bivin Varghese, C. Deconick, G. Cartee, M. Velez, Robert E. Moore, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Furnaces are among the most crucial components in the glass and metallurgical industry. Nowadays, furnaces are being operated at higher temperatures and for longer periods of time thus increasing the rate of wear on the furnace refractory lining. Consequently, there is a great need for a nondestructive tool that can accurately measure refractory wall thickness at high temperatures. In this paper the utility of a frequency-modulated continuous-wave (FM-CW) radar is investigated for this purpose.

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Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix: Quarterly Report, January 2005 To March 2005, Earl Wolfram, Thomas Hartmann, Kenneth Czerwinski Mar 2005

Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix: Quarterly Report, January 2005 To March 2005, Earl Wolfram, Thomas Hartmann, Kenneth Czerwinski

Fuels Campaign (TRP)

This project will examine inert matrix fuels containing ZrO2 and MgO as the inert matrix, with the relative amount of MgO varied from 30% to 70% in ZrO2. Reactor physics calculations will be used to examine suitable quantities of burnable poisons from the candidate elements Gd, Er, or Hf with reactor grade Pu providing the fissile component, with up to 10% of 239Pu. Ceramics will be synthesized and characterized based on the reactor physics results. The solubility the fuel ceramics, in reactor conditions, reprocessing conditions, and repository conditions, will be investigated in a manner to provide …

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Development, Fabrication And Study Of Fullerene-Containing Carbon Material (Fcc) For Immobilization Of Iodine: Progress Report #1-4, Michael Savopulo, Boris E. Burakov Jan 2005

Development, Fabrication And Study Of Fullerene-Containing Carbon Material (Fcc) For Immobilization Of Iodine: Progress Report #1-4, Michael Savopulo, Boris E. Burakov

Separations Campaign (TRP)

During current reporting period the experiments on synthesis of ceramic-like material by conversion of iodine-doped FCC and activated carbon to SixCy have been completed. Cold pressed granules of FCC and activated carbon were rinsed in water-ethanol solution of tetraethoxysilane (TEOS), Si(OC2H5)4, and then used for further synthesis. All new samples obtained have been studied using precise powder XRD analysis.

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Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix, Kenneth Czerwinski Jan 2005

Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix, Kenneth Czerwinski

Fuels Campaign (TRP)

This project examines inert fuels containing ZrO2 and MgO as the inert matrix, with the relative amount of MgO varied from 30% to 70% in ZrO2. Reactor physics calculations are used to examine suitable quantities of burnable poisons from the candidate elements Gd, Er, or Hf with reactor grade Pu providing the fissile component, with up to 10% of 239Pu. Ceramics are synthesized and characterized based on the reactor physics results. The solubility of the fuel ceramics, in reactor conditions, reprocessing conditions, and repository conditions, are investigated in a manner to provide thermodynamic data necessary for …

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Continuous Solidification Of Yba2cu3o7−X By Isothermal Undercooling, Fatih Dogan Jan 2005

Continuous Solidification Of Yba2cu3o7−X By Isothermal Undercooling, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Growth kinetics and microstructural development of single crystal YBa2Cu3O7−x (Y123) superconductors, prepared by a melt texturing method under isothermal undercooling conditions, were investigated. At small undercooling, ΔT = 6 K, the initial growth of Y123 crystal was terminated at a size of ∼8 mm × 8 mm in the semisolid phase before the entire sample was fully solidified through the peritectic reaction. With incremental increase of ΔT, the growth of the crystal continued so that the whole sample (22 mm diameter and 8 mm thickness) solidified as a single crystal. Termination of the crystal growth …

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Single Chamber Electrolyte Supported Sofc Module, Toshio Suzuki, Piotr Jasinski, Harlan U. Anderson, Fatih Dogan Nov 2004

Single Chamber Electrolyte Supported Sofc Module, Toshio Suzuki, Piotr Jasinski, Harlan U. Anderson, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

An electrolyte supported single chamber solid oxide fuel cell (SOFC) module consisting of two cells has been proposed. The module consists of one Sm-doped CeO2 (SDC) electrolyte substrate (0.5 mm thick with the size of 5 3 10 mm), two Ni-SDC anodes on one side, and two SDC-(La,Sr)(Co,Fe)O3 cathodes on the other side. Two modules with different electrode areas were prepared and tested using an air-propane mixture. The electrode area had a strong influence on the performance of the module. It was shown that the two-cell module generated 1.5 V open-circuit voltage and about 17 mW maximum power …

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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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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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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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Monotonic, Creep-Rupture, And Fatigue Behavior Of Carbon Fiber Reinforced Silicon Carbide (C/Sic) At An Elevated Temperature, John M. Engesser Mar 2004

Monotonic, Creep-Rupture, And Fatigue Behavior Of Carbon Fiber Reinforced Silicon Carbide (C/Sic) At An Elevated Temperature, John M. Engesser

Theses and Dissertations

The main objective of this research effort was to examine the impact that cyclic loading frequency has on the life of a C/SiC composite at an elevated temperature of 550°C. Cyclic loading of C/SiC was investigated at frequencies of 375 Hz, 10 Hz, 1 Hz, and 0.1 Hz. Creep-Rupture tests and tests that were combinations of creep-rupture and fatigue were also accomplished. A monotonic tensile test was performed at 550°C and compared to a room temperature monotonic test. This study showed that an elevated temperature of 550°C has very little effect on the Ultimate Tensile Strength (UTS) of C/SiC. The …

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Preparation Of (Pb,Ba)Tio3 Powders And Highly Oriented Thin Films By A Sol-Gel Process, Stacey Boland, Suresh Pillai, Wein-Duo Yang, Sossina Haile Jan 2004

Preparation Of (Pb,Ba)Tio3 Powders And Highly Oriented Thin Films By A Sol-Gel Process, Stacey Boland, Suresh Pillai, Wein-Duo Yang, Sossina Haile

Articles

Solid solution Pb1-xBaxTiO3, with particular emphasis on Pb0.5Ba0.5TiO3, was prepared
using a sol-gel process incorporating lead acetate trihydrate, barium acetate, and
titanium isopropoxide as precursors, acetylacetone (2,4 pentanedione) as a chelating
agent, and ethylene glycol as a solvent. The synthesis procedure was optimized by
systematically varying acetylacetone: Ti and H2O:Ti molar ratios and calcination
temperature. The resulting effects on sol and powder properties were studied using
thermogravimetric analysis/differential scanning calorimetry, Fourier transform infrared
spectroscopy, Brunauer-Emmett-Teller analysis, and x-ray diffraction (XRD).
Crystallization of the perovskite structure occurred at a temperature as low as 450 °C.
Thin films were prepared by spin …

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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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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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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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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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