Multi-level granular structure in high-Tc superconductors

This paper reports on a way to study quantitatively the relationship between low-field magnetic properties and microstructure of high-Tc superconductors which is introduced. Our treatments lead to the concept of effective grains, that could be understood as either grains grain clusters, or even subgrains n different sintered high-Tc superconductors. The intergranular supercurrents are then inter effective grains in nature. The existence of grain clusters suggests a potentiality to increase the transport Jc