Controlled growth and critical currents of bi-textured YBa₂Cu₃O_7-δ films on yttria stabilized zirconia substrate

Bi-textured YBa₂Cu₃O_7-δ films of grains with different ratios of [100] to [110] can be grown controllably on (001) yttria stabilized ZrO₂ substrates using pulsed laser deposition. The grain orientations were studied by X-ray measurements. It was found that the ratio of [100] to [110] grains was determined predominantly by the laser fluence. Both transport and intragranular critical currents were measured and correlated to the texture. It is shown that 45° grain boundaries (GB's) are responsible for only about 18 × reduction in J_c across polycrystalline bi-textured samples. By using a percolation calculation, the relationship between J_c reduction across a single GB and in a polycrystalline thin film sample with many GB's was investigated. The simulation results show that the maximum J_c reduction across a polycrystalline bi-textured sample is ≈ 1 18 even if all the 45° GB's are not conducting.