Critical current densities in new high-tc superconductors vary widely with preparation conditions.
For example, in
Y-Ba-Cu-O
,
Jc may be greater than 1 07 A cm-2 in some carefully prepared thini lms
and single crystal s but around 1 03-1 06 A cm-2 in some of the polycrystalline bulk
material (e.g. , sintered bulk samples). In NbsSn, used in superconducting solenoid
magnets, on the other hand, Jc i s close to 1 07 A cm-2 at near 0 K.