Vortex Dynamics Differences Due To Twin-boundary Pinning Anisotropy In Yba 2cu 3o X At Low Temperatures For H∥ab Planes

We measured the magnetization M of a twin-aligned single crystal of YBa 2Cu 3O x (YBaCuO), with T c =91 K, as a function of temperature T and magnetic field H, with H applied along the ab planes. Isothermal M-vs-H and M-vs-time curves were obtained with H applied parallel (∥) and perpendicular (⊥) to the twin boundary (TB) direction. M-vs-H curves exhibited two minima below 38 K, which resembled similar curves that have been obtained in YBaCuO for H∥c axis. Above 12 K, the field positions of the minima for H∥TB and H⊥TB were quite similar. Below 12 K, the position of the second minimum H min occurred at a higher field value with H∥TB. Below 6 K, only one minimum appeared for both field directions. At low temperatures, these minima in the M-vs-H curves produced maxima in the critical current. It was determined that vortex lines were expelled more easily for H∥TB than for H⊥TB and, therefore, below a certain field value, that J c(H⊥TB) was larger than J c(H∥TB). At T<12 K with H∥TB, the relaxation rate for flux lines leaving the crystal was found to be different from that for flux entering the crystal. We also observed flux jumps at low temperatures, with their sizes depending on the orientation of magnetic field with respect to the TB's. © 2005 The American Physical Society.712Sarikaya, M., Stern, E.A., (1988) Phys. Rev. B, 37, p. 9373Van Bakel, G.P.E.M., Hof, P.A., Van Engelen, J.P.M., Bronsveld, P.M., De Hosson, J.Th.M., (1990) Phys. Rev. B, 41, p. 9502Liu, J.Z., Jia, Y.X., Shelton, R.N., Fluss, M.J., (1991) Phys. Rev. Lett., 66, p. 1354Swartzendruber, L.J., Roitburd, A., Kaiser, D.L., Gayle, F.W., Bennett, L.H., (1990) Phys. Rev. Lett., 64, p. 483Kwok, W.K., Welp, U., Crabtree, G.W., Vandervoort, K.G., Hulscher, R., Liu, J.Z., (1990) Phys. Rev. Lett., 64, p. 966Duran, C.A., Gammel, P.L., Wolfe, R., Fratello, V.J., Bishop, D.J., Rice, J.P., Ginsberg, D.M., (1992) Nature (London), 357, p. 474Gyorgy, E.M., Van Dover, R.B., Schneemeyer, L.F., White, A.E., O'Bryan, H.M., Felder, R.J., Waszczak, J.V., Rhodes, W.W., (1990) Appl. Phys. Lett., 56, p. 2465Oussena, M., De Groot, P.A.J., Porter, S.J., Gagnon, R., Taillefer, L., (1995) Phys. Rev. B, 51, p. 1389Oussena, M., De Groot, P.A.J., Deligiannis, K., Volkozub, A.V., Gagnon, R., Taillefer, L., (1996) Phys. Rev. Lett., 76, p. 2559Vlasko-Vlasov, V.K., Dorosinskii, L.A., Polyanskii, A.A., Nikitenko, V.I., Welp, U., Veal, B.W., Crabtree, G.W., (1994) Phys. Rev. Lett., 72, p. 3246Wijngaarden, R.J., Griessen, R., Fendrich, J., Kwok, W.K., (1997) Phys. Rev. B, 55, p. 3268Duran, C.A., Gammel, P.L., Bishop, D.J., Rice, J.P., Ginsberg, D.M., (1995) Phys. Rev. Lett., 74, p. 3712Pastoriza, H., Candia, S., Nieva, G., (1999) Phys. Rev. Lett., 83, p. 1026Herbsommer, J.A., Nieva, G., Luzuriaga, J., (2000) Phys. Rev. B, 62, p. 3534Jorge, G.A., Rodriguez, E., (2000) Phys. Rev. B, 61, p. 103Bondareko, A.V., (2001) Low Temp. Phys., 27, p. 339(2001) Phys. Rev. B, 27, p. 201Esquinazi, P., Setzer, A., Fuchs, D., Kopelevich, Y., Zeldov, E., Assmann, C., (1999) Phys. Rev. B, 60, p. 12454Mints, R.G., Brandt, E.H., (1996) Phys. Rev. B, 54, p. 12421Muller, K.-H., Andrikidis, C., (1994) Phys. Rev. B, 49, p. 1294Guillot, M., Potel, M., Gougeon, P., Noel, H., Levet, J.C., Chouteau, G., Tholence, J.L., (1988) Phys. Lett. A, 127, p. 363Salem-Sugui Jr., S., Alvarenga, A.D., Friesen, M., Veal, B., Paulikas, P., (2001) Phys. Rev. B, 63, p. 216502Bean, C.P., (1962) Phys. Rev. Lett., 8, p. 250Tinkham, M., (1996) Introduction to Superconductivity, 2nd Ed., , McGraw-Hill, New YorkDe Andrade, M.C., Dilley, N.R., Ruess, F., Maple, M.B., (1998) Phys. Rev. B, 57, pp. R708Abulafia, Y., Shaulov, A., Wolfus, Y., Prozorov, R., Burlachkov, L., Yeshurun, Y., Majer, D., Vinokur, V.M., (1995) Phys. Rev. Lett., 75, p. 2404Maley, M.P., Willis, J.O., Lessure, H., McHenry, M.E., (1990) Phys. Rev. B, 42, p. 2639Shi, D., Salem-Sugui Jr., S., (1991) Phys. Rev. B, 44, p. 7647Beasley, M.R., Labash, R., Weeb, W.W., (1969) Phys. Rev., 181, p. 682Burlachkov, L., (1993) Phys. Rev. B, 47, p. 8056Alvarenga, A.D., Salem-Sugui Jr., S., (1994) Physica C, 235, p. 2811Junod, A., (1989) Physica C, 162-164, p. 482Triscone, G., (1990) Physica C, 168, p. 40Genoud, J.Y., (1991) Physica C, 177, p. 31

Practical superconductor development for electrical power applications - quarterly report for the period ending December 31, 2000

This is a multiyear experimental research program focused on improving relevant material properties of high-T{sub c} superconductors (HTSs) and on development of fabrication methods that can be transferred to industry for production of commercial conductors. The development of teaming relationships through agreements with industrial partners is a key element of the Argonne National Laboratory (ANL) program. Recent results are presented on YBa{sub 2}Cu{sub 3}O{sub x} (Y-123) coated conductors, including fabrication by pulsed laser deposition (PLD) and sol-gel techniques. An approach to understanding the critical current density (J{sub c}) of grain boundaries is also presented and a technique is identified for increasing J{sub c}

Practical superconductor development for electrical power applications

Development of useful high-critical-temperature (high-[Tc]) superconductors requires synthesis of superconducting compounds; fabrication of wires, tapes, and films from these compounds; production of composite structures that incorporate stabilizers or insulators; and design and testing of efficient components. This report describes the technical progress of research and development efforts aimed at producing superconducting components that are based on the Y-Ba-Cu, Bi-Sr-Ca-Cu, Bi-Pb-Sr-Ca-Cu, and (TI,Pb)-(Ba,Sr)-Ca-Cu oxide systems. Topics discussed are synthesis and heat treatment of high-[Tc] superconductors, formation of monolithic and composite wires and tapes, superconductor/metal connectors, characterization of structures and superconducting and mechanical properties, fabrication and properties of thin films, and development of prototype components. Collaborations with industry and academia are documented

Improved fracture toughness for copper oxide superconductors

An oxide-based strengthening and toughening agent, such as tetragonal Zro{sub 2} particles, has been added to copper oxide superconductors, such as superconducting YBa{sub 2}Cu{sub 3}O{sub x} (123) to improve it fracture toughness (K{sub IC}). A sol-gel coating which is non-reactive with the superconductor, such as Y{sub 2}BaCuO{sub 5} (211) on the ZrO{sub 2} particles minimized the deleterious reactions between the superconductor and the toughening agent dispersed therethrough. Addition of 20 mole percent ZrO{sub 2} coated with 211 yielded a 123 composite with a K{sub IC} of 4.5 MPa(m){sup 0.5}

Plastic deformation of alumina reinforced with SiC whiskers

Addition of small amounts of stiff reinforcement (SiC whiskers) to a polycrystalline AL{sub 2}O{sub 3} matrix partially inhibits grain boundary sliding because of an increase in threshold stress. When the concentration of whiskers is high enough, a pure diffusional mechanism takes over the control of plastic deformation of the composites. For higher whisker loadings, the materials creep properties depend on a microstructural feature different from the nominal grain size. A tentative correlation of this effective microstructural parameter with the spacing between the whiskers was established through a model

Improvement of critical current density in thallium-based (Tl, Bi)Sr{sub 1.6}Ba{sub 0.4}Ca{sub 2}Cu{sub 3}O{sub 9-{delta}} superconductors

Epitaxial (Tl,Bi)Sr{sub 1.6}Ba{sub 0.4}Ca{sub 2}Cu{sub 3}O{sub x} ((Tl, Bi)-1223) thin films on (100) single crystal LaAlO{sub 3} substrates were synthesized by a two-step procedure. Phase development, microstructure, and relationships between film and substrate were studied by x-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Resistance versus temperature, zero-field-cooled and field-cooled magnetization, and transport critical current density (J{sub c}) were measured. The zero-resistance temperature was 105--111 K. J{sub c} at 77 K and zero field was >2 {times} 10{sup 6} A/cm{sup 2}. The films exhibited good flux pinning properties

Solid-particle erosion of an Al{sub 2}O{sub 3}-SiC-TiC composite

An electrodischarge-machinable Al{sub 2}O{sub 3}-SiC-TiC composite developed by Industrial Ceramic Technology, Inc., has a high fracture toughness, 9.6{+-}0.6 MPm{sup 1/2}, as measured by indentation, and a Vickers hardness of 20.3{+-}0.6 GPa. The composite`s resistance to solid-particle erosion was measured for 143-{mu}m dia SiC particles impacting at 20-90{degree} angles and 50-100 m/s velocities. Erosion rate exhibited a maximum for normal incidence, and the erosion resistance was better than that of commercial Al{sub 2}O{sub 3}. SEM indicated that material wastage was by a combination of brittle fracture and microplasticity