Low angle grain boundary transport in YBa2Cu3O7-δ coated conductors

Second generation, high-temperature superconducting wires are based on buffered, metallic tape substrates of near single crystal texture. Strong alignment of adjacent grains was found to be necessary from previous work that suggested large angle, YBa2Cu3O7-delta [001]-tilt boundaries reduce J(c) exponentially with increasing misorientation angle (theta). We pursue the low-theta regime by evaluating single grain boundaries (GB) and biaxially aligned polycrystalline films utilizing both the rolling-assisted biaxially textured substrates and ion-beam assisted deposition coated conductor architectures. Analysis concludes that an exponential dependence on J(c) is applicable for theta greater than or similar to 4 degrees, where the spacing between the periodic disordered regions along the GB become smaller than a coherence length. (C) 2000 American Institute of Physics. [S0003-6951(00)02713-3].