Investıgatıon Of Superconductıvıty Propertıes Of Ybco Tapes Whıch Have Artıfıcıal Pınnıng Centers Formed By Laser

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Thesis Type: Doctorate

Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, FİZİK ANABİLİM DALI, Turkey

Approval Date: 2018

Thesis Language: Turkish

Student: NESLİHAN TURAN

Supervisor: ŞÜKRÜ ÇAVDAR

Open Archive Collection: AVESIS Open Access Collection

Abstract:

In order for superconducting materials to be used in technology, it is important that they have a high critical current density. Many studies have been carried out on increasing the critical current density in superconducting materials. In these studies, random artificial pinning centers were formed by adding partial displacements, adding effects or non-superconducting secondary structures of rare earth elements to increase the critical current density. Studies have shown that the creation of artificial pinning centers is the important parameter for increasing the critical current density. In this study, YBCO tapes were prepared using sol-gel and dip coating techniques. The Ni-5%W tapes of 75 μm thickness were coated with (Gd0,9Ho0,1)2O3 buffer layer and characterized. Then YBCO superconductor layer was coated and characterized on the buffer layer. Regular defects were formed on the YBCO thin films with ns-IR and ps-UV lasers to determine which laser is suitable to defect formation. Regular pulse, line, and circular defects were created with the ps-UV laser to check that the deformations created could not be artificial pinning centers and/or where they could be. Magnetization measurements of defective samples were taken between 0-5 T. Jc values were calculated from the obtained M-H cycles. The most important difference between the work presented and the studies in the literature is the detailed examination of the laser-controlled artificial pinning centers on the superconducting surface