ZONE-MELTING REFINING IN BI-PB-SR-CA-CU-O SUPERCONDUCTOR PREPARED THROUGH THE SOL-GEL METHOD

A zone melting-refining technique, with a horizontal sample-holding pa ttern for incorporating grain orientation in sintered bismuth-based su perconductor (BPSCCO) is presented. Acrylate precursor-derived BPSCCO powder was uniaxially compacted into strips of 60 mm x 10 mm x 2 mm an d sintered at 845-degrees-C for 20 h to obtain 90% density. These stri ps were zone melted in a three-zone furnace which had an independent t emperature control system for each zone. The grain orientation in the sample was studied by scanning electron microscopy and X-ray diffracti on. In the case of a BPSCCO-Ag (5%) composite, the silver was seen to flow along the intergrannular boundaries of the BPSCCO grains. The pre sent technique is an easy and fast method to introduce orientation of grains with large aspect ratio into sintered BPSCCO or Ag-BPSCCO compo site under partial melting-refining conditions. The possibility of ext ending the present technique to silver-sheathed wire and tapes is also indicated.