Grain Boundaries Versus Vortex Pinning In Critical Current Enhancement Of Bi-Based High Temperature Superconductor Tape

Lau, Kok Tee and Agus Setyo, Budi and Mohamad Nizam, Ayof and Safarudin Ghazali, Herawan (2005) Grain Boundaries Versus Vortex Pinning In Critical Current Enhancement Of Bi-Based High Temperature Superconductor Tape. Project Report. UTeM, Melaka, Malaysia. (Submitted)

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Abstract

Regardless of numerous studies have been done on the HTSc grain boundaries, the role of the grain boundaries on its vortex pinning mechanism still largely unknown. Therefore, this research will try to gain insight into the interplay of the grain boundaries and vortex pinning in the enhancement of high temperature superconductor (HTSc) tapes's transport critical current density Jc using Ag-sheathed Bi(Pb)-Sr-Ca-Cu-0 HTSc tapes with nanopowder CoFe20 4 addition. We have prepared five sample groups of superconductor tapes labelled as S835, S845, S855, S845Pl and S845P2 prepared by co-precipitation and powder-in-tube method which then went through different thermo-mechanical treatment. Jc of the samples at temperature of 77 K and in applied magnetic fields (B) from 0-0.75 T were studied using four point probe method. Phase composition of the core of the samples was identified by powder X-ray diffraction method. Cross-sectional area of tapes' core and surface microstructure of the tapes were observed using scanning electron microscopy (SEM). Nominal chemical composition (nominal composition) for one of the samples was identified using EDS apparatus integrated to SEM. The sample with better pinning strength will have a lower number of weak links and strong links which indicates the links may be not act effectively as flux-pinning centres to pin magnetic fluxes penetrating the samples. The results show no interplay between grain boundaries and pinning mechanism of the samples was observed.

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