Nano-composite (RE)-Ba-Cu-O bulk superconductors containing non-superconducting phase inclusions of composition RE 2 Ba 4 CuMO y (the '2411' phase), where M = W, Nb, Ag and Bi, embedded in the REBa 2 Cu 3 O 7-d (RE-123) superconducting matrix have been fabricated successfully. The 2411-phase has typical dimensions in the range 10-300 nm and is stable under the substitution of any rare earth element on the Y site for all M elements. The 2411-phase is paramagnetic in nature and is characterized by a double perovskite cubic crystallographic structure. All phases within the (RE)-2411 family are chemically inert within the RE-123 matrix and do not coarsen appreciably at elevated temperatures during processing. Most significantly, the (RE)-2411 phase forms effective flux pinning sites within the superconducting matrix, since their size is comparable to that of the coherence length of RE-Ba-Cu-O. A direct correlation between the RE 2 Ba 4 CuMO y phase inclusions content in the RE-123 matrix and increased magnetic flux pinning has been observed. The flux pinning force and the current densities increase by an order of magnitude for the nano-composites compared to that of bulk, melt processed RE-Ba-Cu-O without inclusions, confirming their potential for improved current carrying performance when processed in the form of bulk, thin-film or coated conductors.
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Copyright Akadémiai Kiadó AKJournals is the trademark of Akadémiai Kiadó's journal publishing business branch.
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