Nanorod Self-Assembly in High Jc YBa2Cu3O7−x Films with Ru-Based Double Perovskites

• Main Authors: Javier F. Baca, Paul H. Tobash, Paul D. Dowden, Yates J. Coulter, Eric D. Bauer, Leonardo Civale, Boris Maiorov, John A. Kennison, Kenneth R. Marken, Terry G. Holesinger, Matthew D. Feldmann
• Format: Article
• Language: English
• Published: MDPI AG 2011-11-01
• Series: Materials
• Subjects: superconductivity; film; pulsed laser deposition; self-assembly; TEM; STEM
• Online Access: http://www.mdpi.com/1996-1944/4/11/2042/

Many second phase additions to YBa2Cu3O7−x (YBCO) films, in particular those that self-assemble into aligned nanorod and nanoparticle structures, enhance performance in self and applied fields. Of particular interest for additions are Ba-containing perovskites that are compatible with YBCO. In this report, we discuss the addition of Ba2YRuO6 to bulk and thick-film YBCO. Sub-micron, randomly oriented particles of this phase were found to form around grain boundaries and within YBCO grains in bulk sintered pellets. Within the limits of EDS, no Ru substitution into the YBCO was observed. Thick YBCO films were grown by pulsed laser deposition from a target consisting of YBa2Cu3Oy with 5 and 2.5 mole percent additions of Ba2YRuO6 and Y2O3, respectively. Films with enhanced in-field performance contained aligned, self-assembled Ba2YRuO6 nanorods and strained Y2O3 nanoparticle layers. A 0.9 µm thick film was found to have a self-field critical current density (Jc) of 5.1 MA/cm2 with minimum Jc(Q, H=1T) of 0.75 MA/cm2. Conversely, Jc characteristics were similar to YBCO films without additions when these secondary phases formed as large, disordered phases within the film. A 2.3 µm thick film with such a distribution of secondary phases was found to have reduced self-field Jc values of 3.4 MA/cm2 at 75.5 K and Jc(min, Q, 1T) of 0.4 MA/cm2.