Magnetization analysis of sintered Bi2223 using an extended critical state model

The field dependence of the magnetization was measured for sintered Bi2223 high T, superconductor under a field amplitude of 5 T from 10 to 90 K. These data were analysed using our critical state model involving an equilibrium magnetization M-eq and exponential decay of J(c). Some magnetic parameters including the equilibrium critical current density were determined for the intra-grain and inter-grain parts. The temperature dependences of the intra-grain and inter-grain J(c) were also discussed. It was revealed that single vortex pinning was dominant in the intra-grain part, and flux creep caused by collective pinning was confirmed in the inter-grain part.