Bi-2212/Ag superconducting ceramics were grown using the electrically assisted laser floating zone (EALFZ) technique. The main goal was improving the superconducting properties by applying an electrical current through the sample during the solidification process. The effect of a 100 mA current intensities in two configurations were studied: (i) direct current (connecting the seed rod to the positive pole and the feed to the negative one) and (ii) reverse current (positive pole connected to the feed rod and negative to the seed one). The resulting textured cylindrical bars were annealed in order to obtain the superconducting phases. A strong correlation between current polarity, grain alignment and superconducting properties was observed. The rods grown under direct current exhibit higher critical current density (-3000 A/cm2) than the ones grown under conventional method (-2300 A/cm2) or under reverse current condition (-35 A/cm2). The superior value obtained for the direct current results from a better grain alignment and fewer amount of second phases.

The authors are thankful to FCT for the project PEst-C/CTM/LA0025/2011. The Spanish MICINN-FEDER (Projects MAT2008-00429 and AIB2010-PT-00247), MINECO-FEDER (Project MAT2011-22719), the Universidad de Zaragoza (UZ2011-TEC-03), and the Gobierno of Aragón (research consolidate groups T12 and T87) are acknowledged for financial support. Sh. Rasekh acknowledges a JAE-PreDoc2010 grant from the MICINN-CSIC.

Peer Reviewed