ABSTRACT

In regard to Maxwel l ' s equations, one of the most significant differences between

granular-type high-Tc and ordinary superconductors is that the former have an

extra level of magnetic structure not possessed by the latter (Figure 11.1). In

ordinary superconductors current can flow freely through crystal grain boundaries

but, as mentioned in the Introduction, in high-Tc materials grain boundaries,

unless the grains are highly oriented, offer an appreciable barrier to current flow.