Critical current density normal to the tape plane and current-transfer length of (Bi,Pb) 2Sr2Ca2Cu3O10 silver-sheathed tapes

✍ Scribed by B. Hensel; G. Grasso; D.P. Grindatto; H.-U. Nissen; R. Flükiger

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 663 KB
• Volume: 249
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(95)00332-0

✦ Synopsis

We have measured the critical current density parallel (jc) and normal (j~") to the plane of monofilamentary (Bi,Pb)2Sr2Ca2Cu3Olo silver-sheathed tapes prepared on the laboratory scale (l < 10 m) by the powder-in-tube technique with rolling as the only tape-forming process. For the range of critical current densities along the tape jc(T = 77 K, B = 0 T) = 20... 30 kA/cm 2 we obtain jcn= 2... 3 kA/cm 2 normal to the tape plane. We have also directly measured the current-transfer length L~, i.e. the length along the tape that is necessary for the distribution of the current over the filament cross-section. As an upper limit we find L¢ < 2 mm at T --77 K for tapes with jc(T = 77 K, B = 0 T) > 20 kA/cm 2. Transmission electron microscopy of the polycrystalline (Bi,Pb)2Sr2Ca2Cu301o filament confirms the dominant role of the frequent small-angle c-axis tilt grain boundaries ("railway switches") for the current transport, and the observed low anisotropy ratio j¢/jn --10 as well as the magnetic-field dependence jc"(B) agree well with the "railway-switch" model.