Tuning porosity of YBa2Cu3O7−δ vicinal films by insertion of Y2BaCuO5 nanoparticles

High critical current density (Jc) is the most critical specification for high-temperature-superconductor-coated conductors as required by numerous electric power-related applications. This has motivated an intensive research effort on the effects of microstructure on Jc. By growing YBa2Cu3O7−δ (YBCO) films at a small vicinal angle [R. L. S. Emergo, J. Z. Wu, T. Aytug, and D. K. Christen, Appl. Phys. Lett. 85, 618 (2004)] we have recently obtained a highly porous structure in these films accompanied with a significantly enhanced Jc. This result raises a challenging question on whether the porosity can be tailored in YBCO films to allow a higher Jc. In this study, we have explored the insertion of Y2BaCuO5 (211) nanoparticles in vicinal YBCO thick films to alter the strain at the nanometer scale; a nearly doubled pore density was obtained. A further improved Jc as the consequence of the enhanced pore density in these films suggests a direct correlation between microstructure and Jc and projects an even higher Jc in YBCO films with microstructure engineered optimally at a nanometer scale.