Material for resistive barriers in Bi-2223/Ag tapes

The reactivities of several oxide materials (OM) in direct contact with BSC CO powder has been tested at a temperature of approximately 845 degreesC in air. The OM such as BaZrO3, SrCO3, MgO and ZrO2 showing little or no react ivity with BSCCO were mixed (10 wt%) with a BSCCO precursor powder and used for monocore tapes made by a standard powder-in-tube technique. The micros tructure of the BSCCO+OM cores was analysed by SEM and XRD and the transpor t current properties-critical current, pinning force and resistance up to 1 6 T-were measured as a function of the magnetic field for various orientati ons with respect to the ab plane. The OM used influenced the electrical pro perties of the Bi-2223 phase in different ways. This is because the oxides react with BSCCO during the heat treatment and simultaneously affect the 22 12 --> 2223 phase transformation as well as the Bi-2223 grain growth and gr ain connectivity. Submicrometre commercial SrCO3 powder was evaluated as th e best material from all those tested, for resistive barriers in Bi-2223/Ag tapes.