Transport currents and magnetic properties of textured Bi(2223) tape

Magnetic and transport properties of textured Bi(2223) tape with high critical transport current density (j_c(77 K, 0 T)=2.8*10⁴ A cm^-2) were studied. Magnetic measurements show nongranular behaviour of shielding and transport currents for the magnetic field orientation perpendicular to the tape plane B perpendicular to p at low temperatures and low fields. At high magnetic fields and temperatures, however, quite large differences were observed, which depend on magnetic field sweep rate B and voltage criteria E_c. This is connected with granularity and inhomogeneity of the current flow. It was established that the magnetic field dependence of the critical current has a general scaling behaviour: j_c(B, B, T)=j_c(0, B, T) f(B/B₀(B, T)) where the scaling function f becomes exp(-B/B₀) for B/B₀>or=1. The scaling parameter B₀ is proportional to the irreversibility field B_irr. Both B₀ and B_irr show an exponential temperature dependence.