Tape Development: Microstructure and Critical Current Densities

R. Flukiger (1, 2) , G. Grasso (1, 2) , A. Jérémie (2) , B. Hensel (2) , R. Gladyshevskii (2) , J.-C. Grivel (2) , F. Marty (1, 2) , Christine Opagiste (1) , A. Perrin (2) , M. Däumling (2)

1 GAP - Group of Applied Physics [Geneva]
2 DPMC - Département de Physique de la Matière Condensée

The formation of the textured Bi,Pb(2223) in mono- and multifilamentary tapes is described as a result of several reactions, involving an intermediate phase Bi,Pb(2212), which is formed as a solid solution of the initial phase Bi(2212), the latter having a monoclinic superstructure. For Bi,Pb(2223) tapes, a direct correlation between the degree of texturing of the initial Bi(2212) grains after rolling (before reaction) and of the current carrying Bi,Pb(2223) platelets (after reaction) is shown. The difference between the critical current densities of pressed and rolled tapes is discussed by comparing the maximum applicable uniaxial pressure with the local pressure exerted by the rolls. The optimization of the complex preparation process leading to long rolled Bi,Pb(2223) tapes is discussed. The lateral distribution of the transport critical current densities in monofilamentary Bi,Pb(2223) tapes with jc(77K, 0T) = 28000A/cm2 shows a marked minimum at the center and a maximum at the sides, the highest value reaching 54000A/cm2. At 4.2K and 14T, the same tape reached the value jc=75000A/cm2. For long (>1m), rolled multifilamentary Bi,Pb(2223) tapes with 7 and 19 cores, critical current densities up to 23000A/cm2 have been obtained. The field dependance of jc is essentially the same as for monofilamentary tapes. The variation of the critical current density in Bi,Pb(2223) tapes as a function of B and T is presented and discussed within the "railway switch" model.

Mots clés: High Tc superconductors; critical current density; current distribution; crystal structure

Domaines: Supraconductivité [cond-mat.supr-con]

R. Flukiger, G. Grasso, A. Jérémie, B. Hensel, R. Gladyshevskii, et al.. Tape Development: Microstructure and Critical Current Densities. 8th International Symposium on Superconductivity, ISS'95, Oct 1995, Hamamatsu, Shizuoka, Japan. pp.781. ⟨hal-00587240⟩