MO observation on YBa2Cu3O7−δ coated conductors obtained by TFA-MOD technique

We have observed the flux penetration into a high-Tc superconducting YBa2Cu3O7−δ (YBCO) tape by a magneto-optical (MO) imaging technique in order to feed back to the R&D of processing. The MO images of YBCO coated conductor prepared by metal organic deposition using trifluoroacetates (TFA-MOD) showed many weak links such as periodic defect and other serious defects, which were corresponding to the dispersion of critical current along to length direction. Since the combination study of MO imaging with TEM observation revealed the reason of such defects, we could feed back to several processes. The new TFA-MOD tapes prepared by using an advanced process after using many innovations showed a homogeneous flux penetration observed by MO imaging, and then it is confirmed that the process went to higher stage rather than previous one.