Microstructures and superconducting properties of V doped Bi2223 tapes

We prepared Ag-sheathed tapes by the powder-in-tube method using V doped Bi2223 powder. We found that V doping into Bi oxide superconductors greatly enhances the Bi2223 phase formation of the tapes without any degradation of the superconducting critical temperature T-c. The doped V is not included in the Bi2223 (or Bi2212) grains, but instead exists as Sr6V2O11 particles with diameters of 0.1 to several micrometers, in which the larger plate-like particles play an important role to promote the formation of the Bi2223 phase. With V doping, the optimum critical current density J(c) value is obtained for a short time heat treatment. (C) 1998 Published by Elsevier Science Ltd. Ali rights reserved.