Anisotropic characteristics of the energy dissipation in Bi(2223) ceramics and tapes in weak magnetic fields

摘要

For practical application of HTSC tapes as current leads, their behavior in realistic conditions, in the presence of magnetic field, becomes crucially important. We have investigated in detail the resistivity transition and the excess resistivity induced by low magnetic fields (1-750 Oe) in highly aligned composite structures of Bi(2223) based tapes and also, for comparison, in bulk ceramics of the same composition. We demonstrate the strong dependence of the electrical and magnetic properties on the microstructure of the composite ceramics. We observed also a dependence of the energy dissipation on the direction of the transport current with respect to the grain orientation. Percolation theory and the effective medium approximation are applied to analyze the anisotropy in the resistive transition of these systems.