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Influence of Defects on Critical Parameters in High Temperature Superconductors

Kisa, Predrag (2006) Influence of Defects on Critical Parameters in High Temperature Superconductors. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Bismuth cuprate high temperature superconductors are currently the only ceramic material that can be successfully processed in kilometer length wires. Bismuth cuprates form three compositions that can be represented with the generic formula Bi2Sr2CanCun+1O8+d n = 0, 1, 2 (with critical temperatures Tc = 20K, 85-94K and 110K respectively). With critical temperatures above 77K (liquid nitrogen boiling point) the only property inhibiting a widespread use is the infield performance, that is, insufficient critical current densities in high magnetic fields. The infield critical current is intimately related to the pinning of the flux vortices that form under the influence of a magnetic field. The intrinsic pinning of flux vortices, is still not well understood in these quaternary systems. The influence of SrCuO2 second phase additions as well as internal cation nonstoichiometry was investigated as a viable way to control the flux pinning properties in the Bi2Sr2CaCu2O8+d (Bi-2212) system. The compositions of Bi2Sr2+xCaCu2+xO8+y (x = 0.0001-0.6) as well as Nd substituted Ca samples were prepared via freeze-drying. Phase pure stoichiometric Bi-2212 was synthesized via freeze-drying in a reduced oxygen atmosphere. It was further determined that up to 20mol% additions of SrCuO2 can be accommodated in the Bi-2212 structure and that the additions increase critical current. The incorporation of SrCuO2 into Bi-2212 results in change of both lattice parameters and modulation vector.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Kisa, Predragprkst5@pitt.eduPRKST5
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairEror, Nicholas G
Committee MemberNettleship, Ian
Committee MemberBlachère, Jean R
Committee MemberMcHenry, Michael E
Date: 2 June 2006
Date Type: Completion
Defense Date: 8 April 2006
Approval Date: 2 June 2006
Submission Date: 26 March 2006
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Materials Science and Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: freeze-drying; Superconductor; BSCCO; incomensurate modulation
Other ID:, etd-03262006-183151
Date Deposited: 10 Nov 2011 19:32
Last Modified: 15 Nov 2016 13:37


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