Grain boundaries (GBs) in high-temperature superconductors suppress the critical current density (J c) dramatically, with the J c decreasing exponentially with GB angle, especially when GB misorientation exceeds 4°. To reduce the number of high-angle GBs, fabrication of biaxially textured, superconducting wires via heteroepitaxial growth on cube-textured metals was widely investigated worldwide. Such wires exhibit very high Jc in applied magnetic fields despite having a majority of GBs with total misorientations in the range 4-8°. Here, it was shown that GB networks in these wires have numerous GBs with out-of-plane misorientations greater than 4° but few boundaries having in-plane misorientations greater than 4°. Transport measurements on bicrystal GBs show that GBs with out-of-plane tilts between 4° and 8° were well linked. Together, these results explain the high performance of superconducting films on cube-textured metals.

Grain Boundary Networks in High-Performance, Heteroepitaxial, YBCO Films on Polycrystalline, Cube-Textured Metals. A.Goyal, D.P.Field, R.Held, J.Mannhart: Philosophical Magazine Letters, 2011, 91[4], 246-55