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in creator/contributor: "Poeppel, R. B."

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Fabrication of ceramic membrane tubes for direct conversion of natural gas

Several perovskite-type oxides that contain transition metals on the B-site show mixed (electronic/ionic) conductivity. These mixed conducting oxides are promising materials for oxygen permeating membranes that can operate without the need of electrodes or external electrical circuitry. SrCo{sub 0.8}Fe{sub 0.2}O{sub x} perovskite is known to exhibit very high oxygen permeabilities and one could use this material for producing value added products by direct conversion of methane, the most abunda… more

Date: May 1, 1992

Creator: Balachandran, U.; Morissette, S. L.; Picciolo, J. J.; Dusek, J. T.; Poeppel, R. B.; Pei, S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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High-temperature superconductor applications development at Argonne National Laboratory

Developments at Argonne National Laboratory of near and intermediate term applications using high-temperature superconductors are discussed. Near-term applications of liquid-nitrogen depth sensors, current leads, and magnetic bearings are discussed in detail.

Date: February 9, 1992

Creator: Hull, J. R. & Poeppel, R. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Sintering of bulk high-{Tc} superconductors: Y-Ba-Cu-O

Sintering of bulk YBa{sub 2}Cu{sub 3}O{sub x} (123) samples has been conducted from 850 to 1010{degrees}C in oxygen partial pressures (P{sub O2}) of 2.5 {times} 10{sup 2} to 10{sup 5} Pa. The final grain sizes of the samples were controlled by selective use of (1) liquid phases and (2) partial decomposition of the 123 phase by sintering in a P{sub O2} that was lower than the minimum needed for 123 stability. In nearly fully dense samples, it was found that the grain size could range from about … more

Date: May 1, 1992

Creator: Goretta, K. C.; Chen, N.; Lanagan, M. T.; Wu, W.; Singh, J. P.; Olson, R. A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Mechanical properties of vacuum-sintered yttria ceramics

Mechanical properties of vacuum sintered dense yttria ceramics have been studied. Values of flexural strength, fracture toughness and thermal shock behavior, better than those reported in the literature, are reported. Microscopic investigations reveal elastic strain energy and cleavage step formation as the major contributors to the fracture energy.

Date: March 1, 1994

Creator: Wagh, A. S.; Roberts, D.; Suratwala, T.; McMann, M. & Poeppel, R. B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Influence of oxygen partial pressure and silver additions on microstructure and related properties of YBCO superconductors

Microstructure has a great influence on the mechanical and superconducting properties of YBCO. Mechanical properties of YBCO can be improved by both modifying the monolithic microstructure and developing composites of YBCO with silver (Ag). When monolithic YBCO was sintered to high densities ({approx} 91%) at a relatively low temperature ({approx} 910{degrees}C) by controlling oxygen partial pressure during sintering, the result was a small-grain microstructure (average grain size {approx} 5 {m… more

Date: February 1, 1992

Creator: Singh, J. P.; Joo, J.; Guttschow, R. & Poeppel, R. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Effects of lithium additions on processing of Bi-Sr-Ca-Cu-O superconducting tapes

Lithium additions to the high-temperature superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x} (2212) increased superconducting transition temperatures and improved resistance to effects of magnetic fields. In addition, these additions lowered the melting point of 2212 and increased reaction kinetics. Ag-clad tapes fabricated from 2212 with and without Li exhibited profound differences. For heating to temperatures less than or equal to 840{degrees}C, grain growth and sintering were much more su… more

Date: January 1, 1994

Creator: Goretta, K. C.; Li, Y. F.; Poeppel, R. B.; Wu, S.; Guo, J. & Schwartz, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Properties of hot isostatically pressed Bi{sub 2}Sr{sub 1.7}CaCu{sub 2}O{sub x}

Dense Bi{sub 2}Sr{sub 1.7}CaCu{sub 2}O{sub x} (2212) superconductor pellets were made by hot isostatic pressing in an inert atmosphere. The pellets exhibited a small amount of preferred orientation of the grains. The transport critical current density (J{sub c}) values were very low for all specimens. Dislocations, planar faults, and intergrowths of the Bi{sub 2}Sr{sub 2}CuO{sub x} phase, which were produced during the pressing, caused the intragranular J{sub c} to increase substantially. 10 re… more

Date: April 1, 1992

Creator: Nash, S.; Goretta, K. C.; Miller, D. J.; Biondo, A. C.; Shi, D.; Sengupta, S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Sintering of bulk high-{Tc} superconductors: Bi-Sr-Ca-Cu-O

Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x} (2212) and (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (2223) superconductors have orthorhombic crystal structures. They form platelike grains that at high temperatures grow primarily in the a-b planes and not in the c direction. The diffusional properties of Bi-Sr-Ca-Cu-O superconductors are so anisotropic that 2212 and 2223 cannot, in general, be densified by solid-state sintering. Improved densification can be achieved by application of pressure or… more

Date: May 1, 1992

Creator: Goretta, K. C.; Lanagan, M. T.; Kaufman, D. Y.; Biondo, A. C.; Wu, C. T.; Loomans, M. E. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Calcination and solid state reaction of ceramic-forming components to provide single-phase ceramic product having fine particle size

The invention consists of an improved method for the preparation of single phase, fine grained ceramic materials from precursor powder mixtures where at least one of the components of the mixture is an alkali earth carbonate. The process consists of heating the precursor powders in a partial vacuum under flowing oxygen and under conditions where the partial pressure of CO{sub 2} evolved during the calcination is kept to a very low level relative to the oxygen. The process has been found particu… more

Date: September 28, 1990

Creator: Balachandran, U.; Poeppel, R. B.; Emerson, J. E. & Johnson, S. A.

Item Type: Patent

Partner: UNT Libraries Government Documents Department

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Sodium Heat Engine Development Program. Phase 1, Final report

The Sodium Heat Engine (SHE) is an efficient thermoelectric conversion device which directly generates electricity from a thermally regenerative electrochemical cell that relies on the unique conduction properties of {beta}{double_prime}-alumina solid electrolyte (BASE). Laboratory models of a variety of SHE devices have demonstrated the feasibility and efficiency of the system, engineering development of large prototype devices has been slowed by a series of materials and fabrication problems.… more

Date: January 1, 1992

Creator: Singh, J. P.; Kupperman, D. S.; Majumdar, S.; Dorris, S.; Gopalsami, N.; Dieckman, S. L. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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The variability residual stresses of thick superconductor films during orthorhombic to tetragonal transformation

YBa{sub 2}Cu{sub 3}O{sub x} thick films have been deposited by spray pyrolysis of a sol-gel on 10 cm diameter polycrystalline MgO wafers. The film thickness was built up in layers of approximately 1 {mu}m thick. The in-plane residual stresses were measured by an optical interferometry (shadow moire) method as a function of film structure. In-plane residual stress maps over the area of the wafer have been obtained. The average stress of the 5 {mu}m orthorhombic phase was 0.84 GPa. As the film tr… more

Date: April 1, 1992

Creator: Wu, W.; Danyluk, S.; Lanagan, M. T. & Poeppel, R. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Processing method for superconducting ceramics

A process for preparing a superconducting ceramic and particularly YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}, where {delta} is in the order of about 0.1--0.4, is carried out using a polymeric binder which decomposes below its ignition point to reduce carbon residue between the grains of the sintered ceramic and a nonhydroxylic organic solvent to limit the problems with water or certain alcohols on the ceramic composition.

Date: May 7, 1990

Creator: Bloom, I. D.; Poeppel, R. B. & Flandermeyer, B. K.

Item Type: Patent

Partner: UNT Libraries Government Documents Department

open access

Mechanical properties of vacuum-sintered equimolar CaO-Y{sub 2}O{sub 3} system

Dense composite material was fabricated aimed at pyrochemical container applications by vacuum-sintering an equimolar mixture of CaO and Y{sub 2}O{sub 3}. Its mechanical and physical properties were characterized: flexural strength, fracture toughness, thermal shock resistance, microstructure, density.

Date: April 1, 1991

Creator: Wagh, A. S.; Maiya, P. S.; Poeppel, R. B.; Russell, R.; Suratwala, T. & Roberts, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Processing and properties of silver-clad Tl-Ba-Ca-Cu-O wires and tapes

TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} and Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} powders were synthesized, loaded into Ag tubes, and worked into wires and tapes by drawing and rolling. All processing outside of furnaces was in a dry-N{sub 2} glovebox. All heat treatments were performed in O{sub 2}. The Ag-clad wires fabricated from these powders exhibited onset of superconductivity at {approx}118 K and critical current densities at 77K of 2{times}10{sup 3} to 4{times}10{sup 3} A/cm{sup 2}. more

Date: March 1, 1992

Creator: Goretta, K. C.; Wu, C. T.; Lanagan, M. T.; Boling, M. A.; Shi, D.; Miller, D. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Microstructure and associated properties of YBa{sub 2}Cu{sub 3}O{sub x} superconductors prepared by melt-processing techniques

From the standpoint of applications, melt-processed bulk YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) superconductors are of considerable interest. We have studied the microstructure and levitation force of melt-processed YBCO, YBCO plus Y{sub 2}BaCuO{sub 5}, and YBCO plus Pt samples. Large single crystalline samples, grown using a seeding technique, were also studied. The levitation force is highest in melt-processed samples made by the seeding technique. 6 figs, 24 refs.

Date: March 1993

Creator: Balachandran, U.; Zhong, W.; Youngdahl, C. A. & Poeppel, R. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Recent results in characterization of melt-grown and quench-melt- grown YBCO superconductors

From the standpoint of applications, melt-grown (MG) and quench-melt-grown (QMG) bulk YBCO superconductors are of considerable interest. In this paper, we studied the intragranular critical current density (J{sub c}), the apparent pinning potential (U{sub o}), and the irreversibility temperature (T{sub irr}) of MG and QMG samples and compared the results to those for conventionally sintered YBCO. A systematic increase in U{sub o} and a slower drop in J{sub c} with temperature indicate a systema… more

Date: February 1, 1992

Creator: Balachandran, U.; Poeppel, R. B. & Gangopadhyay, A. K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

YBa{sub 2}Cu{sub (3-x)}Co{sub x}O{sub y}: A substrate material for YBCO superconductors

The physical properties of the ceramic YBa{sub 2}Cu{sub (3-x)}Co{sub x}O{sub y} have been investigated in order to evaluate its usefulness as a substrate material for YBCO superconductors. YBa{sub 2}Cu{sub (3-x)}Co{sub x}O{sub y} has been found to be thermally and chemically compatible with 123 and displays adequate electrical properties for a substrate material. A material with the nominal composition of YBa{sub 2}Cu{sub 2.2}Co{sub 0.8}O{sub 7} was investigated, extensively. The mechanical pro… more

Date: April 1, 1992

Creator: Vienna, J. D.; Balachandran, U.; Poeppel, R. B.; Cermignani, W. & Taylor, J. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Mechanical properties of fiber-reinforced YBa{sub 2}Cu{sub 3}O{sub x} and Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x} bars

Strength in four-point bending and fracture toughness of YBa{sub 2}Cu{sub 3}O{sub x} (123) and Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x} (2212) were examined at room temperature. The 123 was reinforced with 15 vol.% Y{sub 2}BaCuO{sub 5} (211) fibers and was processed to 90--91% density by cold pressing and sintering. The 2212 was reinforced with 15 vol.% 2212 fibers and was processed to {approx}90% density by sinter forging. The 123/211 composites had a fracture toughness of 1.9 MPa(m){sup 0.5}, wh… more

Date: July 1, 1993

Creator: Goretta, K. C.; Martin, L. J.; Singh, D.; Poeppel, R. B.; Chen, Nan; Chu, C. Y. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Fabrication and microstructural development of Ag-clad TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} tapes

Three different 1223 powders with varied phase distributions were used to fabricate tapes by the powder-in-tube process. It was found that powders consisting primarily of phase pure 1223 were superior to a phase assemblage of Ca{sub 2}CuO{sub 3}, BaCuO{sub 2}, and Tl{sub 2}O{sub 3} powders. No texturing in the microstructure was observed for any of the annealing times or temperatures. Critical current densities over 5,000A/cm{sup 2} were measured at 77 K, and J{sub c} degraded as the number of … more

Date: July 1, 1993

Creator: Biondo, A. C.; Lanagan, M. T.; Goretta, K. C.; Hu, J.; Miller, D. J.; Wu, C. T. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Energy Technology Division research summary addendum.

No Description Available.

Date: May 18, 2004

Creator: Poeppel, R. B. & Shack, W. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Energy Technology Division research summary 2004.

The Energy Technology (ET) Division provides materials and engineering technology support to a wide range of programs important to the US Department of Energy (DOE). The Division's capabilities are generally applied to technical issues associated with energy systems, biomedical engineering, transportation, and homeland security. Research related to the operational safety of commercial light water nuclear reactors (LWRs) for the US Nuclear Regulatory Commission (NRC) remains another significant … more

Date: May 6, 2004

Creator: Poeppel, R. B. & Shack, W. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Transient Swelling Studies with the GRASS Code

No Description Available.

Date: March 1, 1973

Creator: Dias, J. W. & Poeppel, R. B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Processing and properties of superconductor wires

Variables in fabrication of superconductor wires by extrusion and by powder-in-tube processing are discussed. Decomposition of plastically extruded YBCO is minimized by firing at reduced total pressure. Extruded wires of YBCO were densified with fine-grained microstructures by sintering at an oxygen partial pressure of 10{sup {minus}3} MPa. A reduction in average grain size from 23 to 4 {mu}m increased strength from 83 to 191 MPa. Addition of 15 vol. % Ag particles further increased the strengt… more

Date: October 1, 1991

Creator: Singh, J. P.; Dorris, S. E.; Lanagan, M. T.; Wu, C. T.; Goretta, K. C.; Joo, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Degradation of properties of YBa sub 2 Cu sub 3 O sub x superconductors sintered in CO sub 2 -containing atmosphere

Stability of the YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) superconductor toward reacting with CO{sub 2} in CO{sub 2}/O{sub 2} gas mixtures during sintering was investigated as a function of the partial pressure of CO{sub 2} and temperature. The transport critical current density, J{sub c}, of the superconductor decreased drastically with increasing partial pressure of CO{sub 2} was increased, J{sub c} became zero (at 77 K) even though the major phase of the sample was still a superconductor as determ… more

Date: September 1, 1990

Creator: Balachandran, U.; Zhang, C.; Xu, D.; Gao, Y.; Merkle, K. L.; Mundy, J. N. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department