Corrosion of Epitaxial YBCO Films

•Ermile Gaganidze1, Roland Heidinger1, Juergen Halbritter1, Christian Neumann2, Frank Schnell2 und Tobias Kaesser3
1Forschungszentrum Karlsruhe, IMF I, Postfach 3640, D-76021 Karlsruhe
2Robert Bosch GmbH, FV/FLT, Postfach 106050, 70049 Stuttgart
3Bosch SatCom GmbH, UC-RA/EMD, Gerberstr. 49, 71522 Backnang

Rf superconducting devices are very sensitive to corrosion because of the small penetration depth l £ 200 nm of rf field. Space qualification of the HTS filters requires resistance against corrosion during 3 weeks at 40 C and 93% rel. humidity. To tolerate those severe atmospheric conditions HTS films need a protective layer to avoid electrochemical dissolution [1]. This dissolution has been reduced by a thin BaF2 protective layer produced by soaking YBCO films for 10 min in HF(40%). Results on RS(Hrf, 77 K) of YBCO films of different quality before and after HF-soaking as well as after exposing the films to high humidity atmosphere are presented and explained by weak-link corrosion. [1] M. Regier et al., IEEE Trans. Appl. Superconductivity 9, 2452 (1999).