Elongated grains in textured substrate tapes and their effect on transport currents in superconductor layers

摘要

The development of cube textured flexible metallic substrate tapes is of basic interest for the economic production of YBa_2Cu_3O_x (YBCO) coated superconductors. Nickel tapes microalloyed with silver were prepared with the specific feature of an elongated grain structure. Cube textured NiO films were grown by surface oxidation epitaxy on these tapes retaining the elongated grains. Further, buffer layers and YBCO were deposited thereon. The YBCO layer transports an up to four times higher critical current density (J_c=2.35 MA/cm~2) in the direction of grain elongation compared to the transversal one (J_c=0.55 MA/cm~2).