THE PUZZLE OF TWO DIFFERENT SUB-MICROMETER TUNGSTEN-RICH DEPOSITS IN BULK YBCO: ONE ACTS AS PINNING CENTERS AND THE OTHER DOES NOT

Journal Article · Thu Apr 08 00:00:00 EDT 2010 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3402330· OSTI ID:21371746

Sawh, Ravi-Persad; Weinstein, Roy; Parks, Drew; Gandini, Alberto ^[1]

---

1. Beam Particle Dynamics Laboratory, Department of Physics, and Texas Center for Superconductivity, University of Houston, Houston, Texas, 77204 (United States)

Two types of large grain YBCO samples doped with tungsten oxide, one with platinum and the other without, were produced using a slow cooling process. Observations of the trapped magnetic flux density showed that the flux density of the W-doped, Pt-free samples did not change with W doping levels of up to 2.1 mol%. In contrast, the (W+Pt)-doped samples resulted in a monotonic improvement in trapped magnetic flux density as a function of W doping. Microstructure studies indicate that both types of samples contain profuse sub-micrometer deposits of a W-rich compound. The Pt-free samples contain (W{sub 0.4}Y{sub 0.6})BaO{sub 3} deposits while the (W+Pt)-doped samples contain deposits of a (W{sub 0.5}Pt{sub 0.5})YBa{sub 2}O{sub 6} compound. Both types of deposits are of essentially the same size and have comparable number density. The results are strikingly similar to an earlier experiment in which uranium doped, Pt-free, large grain YBCO also did not show any improvement in trapped magnetic flux density. The U-doped, Pt-free samples contain profuse sub-micrometer deposits of a (U{sub 0.4}Y{sub 0.6})BaO{sub 3} compound, which have been shown to be ferromagnetic. The inability of both the (W{sub 0.4}Y{sub 0.6})BaO{sub 3} and (U{sub 0.4}Y{sub 0.6})BaO{sub 3} sub-micrometer deposits to act as pinning centers in self-field, suggest that this behavior is systematic.

• OSTI ID: 21371746
• Journal Information: AIP Conference Proceedings, Vol. 1219, Issue 1; Conference: International cryogenic materials conference (ICMC) on advances in cryogenic engineering materials, Tucson, AZ (United States), 28 Jun - 2 Jul 2009; Other Information: DOI: 10.1063/1.3402330; (c) 2010 American Institute of Physics; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
BARIUM OXIDES
COPPER OXIDES
CRITICAL CURRENT
CRYSTAL STRUCTURE
CUPRATES
DOPED MATERIALS
FLUX DENSITY
HIGH-TC SUPERCONDUCTORS
MAGNETIC FLUX
MICROSTRUCTURE
PLATINUM COMPOUNDS
TRAPPING
TUNGSTEN OXIDES
URANIUM COMPOUNDS
X-RAY DIFFRACTION
YTTRIUM OXIDES
ACTINIDE COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COHERENT SCATTERING
COPPER COMPOUNDS
CURRENTS
DIFFRACTION
ELECTRIC CURRENTS
MATERIALS
OXIDES
OXYGEN COMPOUNDS
REFRACTORY METAL COMPOUNDS
SCATTERING
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS
TYPE-II SUPERCONDUCTORS
YTTRIUM COMPOUNDS