Title :
Transport and magnetisation measurements of Tl-1223 tapes-the nature of current paths and the role of grain boundaries at high magnetic fields
Author :
Everett, J. ; Johnston, M.D. ; Perkins, G.K. ; Volkozub, A.V. ; Caplin, A.D. ; Moore, J.C. ; Fox, S. ; Hyland, D. ; Grovenor, C.R.M.
Author_Institution :
Centre for High Temp. Supercond., Imperial Coll. of Sci., Technol. & Med., London, UK
fDate :
6/1/1997 12:00:00 AM
Abstract :
The key factors that make the thallium-based 1223 phase conductors attractive candidates for high field applications are a high transition temperature (/spl sim/ 115 K), and an irreversibility line comparable to YBa/sub 2/Cu/sub 3/O/sub 7/. However, a third important factor is the grain boundary behaviour. We have made detailed transport current-voltage (I-V) and magnetic studies of a Ag-0.1%Hf sheathed Tl-1223 tape. For low fields (B<100 mT) its critical current density J/sub c/ performance displays the "weak-link" signatures well-known for polycrystalline YBa/sub 2/Cu/sub 3/O/sub 7/. At high fields however (B>100 mT) there is a plateau region in its J/sub c/(B) characteristics. Possible scenarios for inter-granular transport current conduction and dissipation in this region are discussed.
Keywords :
barium compounds; bismuth compounds; calcium compounds; critical current density (superconductivity); grain boundaries; hafnium alloys; high-temperature superconductors; lead compounds; magnetisation; silver alloys; strontium compounds; superconducting tapes; superconducting transition temperature; thallium compounds; 100 mT; 115 K; Ag-Hf sheathed Tl-1223 tape; I-V studies; J/sub c/; J/sub c/(B) characteristics; Tl-1223 tapes; TlBiPb(SrBa)/sub 2/Ca/sub 2/Cu/sub 3/O-AgHf; critical current density; current paths; grain boundaries; grain boundary behaviour; high field applications; high fields; high magnetic fields; high transition temperature; inter-granular transport current conduction; irreversibility line; magnetic studies; magnetisation measurements; plateau region; thallium-based 1223 phase conductors; transport current-voltage studies; transport measurements; weak-link signatures; Bismuth compounds; Conducting materials; Conductors; Current measurement; Grain boundaries; Magnetic field measurement; Magnetic flux; Magnetization; Superconducting magnets; Temperature;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
