Comparative Study Between Similarly Processed rm YBa 2 rm Cu 3 rm O 7 - rm x Films With rm Y 2 rm BaCuO 5 or rm BaSnO 3 Additions

• Published in: IEEE transactions on applied superconductivity 2009-01, Vol.19 (3)
• Main Authors: Varanasi, C V, Burke, J, Brunke, L, Lee, J H, Wang, H, Barnes, P N
• Format: Article
• Language: English
• Subjects: COMPOSITES; COPPER OXIDE; DISLOCATIONS; MICROSTRUCTURES; Nanocomposites; Nanomaterials; Nanoparticles; Nanostructure; PARTICLES; SINGLE CRYSTALS; STACKING FAULTS; SUPERCONDUCTORS; YBCO superconductors; YTTRIUM OXIDE
• ISSN: 1051-8223
• DOI: 10.1109/TASC.2009.2018420

A special YBa sub(2)Cu sub(3)O sub(7- x) (YBCO) target with a thin sector of second phase material, in this case either Y sub(2)BaCuO sub(5) (Y211) or BaSnO sub(3) (BSO), was used to deposit YBCO films with non-layered nanoparticles on single crystal LaAlO sub(3) and biaxially textured Ni-5 at.% W substrates buffered with CeO sub(2) and YSZ layers(coated conductors). Although identical processing conditions were used, TEM images indicated that random Y211 nanoparticles in the case of YBCO + Y211, and evenly spaced BSO nanocolumns in the case of YBCO+BSO, form in the YBCO films. While YBCO plane buckling was observed at many places in the case of YBCO + Y211, a high density of stacking faults and dislocations were observed in the case of YBCO+BSO near the BSO columns. In transport critical current density (Jc) angular dependence measurements, the absence of nanocolumns in YBCO + Y211 films resulted in the absence of a peak at 0deg , Jc(H//c) , in Jc vs. thetas plots, as compared to a clear peak at 0deg observed in YBCO+BSO films with the nanocolumns. The in-field Jc measurements indicated small low-field Jc enhancements at 77 K in YBCO + Y211 films but more than an order of magnitude improvement in high-field Jc in YBCO + BSO films due to the differences in the microstructures.