Filamentization of YBCO Coated Conductors by Microcontact Printing

To reduce ac losses of coated conductors (CCs), microcontact printing was employed as an alternative technology for processing striated tapes. All CCs possessed the same basic cross-sectional architecture: stainless steel/ABAD-YSZ/CeO₂/ PLD-YBCO . By magnetron sputtering, thin (100-300 nm) Au layers were deposited on bare (no cover layer on YBCO) tapes. Appropriate SAMs (self-assembled monolayers of alkanethiols) line patterns were printed with elastomeric stamps on the Au layer. A subsequent etching of Au, with ferri/ferrocyanide, and of YBCO, with phosphoric acid, was used to produce the desired filamentary structure. The sample performance was checked by angle-dependent measurements of the critical current density, J_c . Striating the CCs leads to a reduction of hysteretic ac losses of the HTS tapes, which according to E.H. Brandt´s calculations depend on the width of the filaments. This was confirmed by AC SQUID measurements of the complex susceptibility and paves the way for long-length processing of low-loss CCs.