Low angle grain boundary transport in YBa2Cu3O7-delta coated conductors

Second generation, high-temperature superconducting wires are based on buff ered, metallic tape substrates of near single crystal texture. Strong align ment of adjacent grains was found to be necessary from previous work that s uggested large angle, YBa2Cu3O7-delta [001]-tilt boundaries reduce J(c) exp onentially with increasing misorientation angle (theta). We pursue the low- theta regime by evaluating single grain boundaries (GB) and biaxially align ed polycrystalline films utilizing both the rolling-assisted biaxially text ured substrates and ion-beam assisted deposition coated conductor architect ures. Analysis concludes that an exponential dependence on J(c) is applicab le for theta greater than or similar to 4 degrees, where the spacing betwee n the periodic disordered regions along the GB become smaller than a cohere nce length. (C) 2000 American Institute of Physics. [S0003-6951(00)02713-3] .