Nanostructured high-temperature superconductors: Creation of strong-pinning columnar defects in nanorod/superconductor composites

A chemical approach to the formation of columnar defects involving the growth and incorporation of MgO nanorods into high temperature superconductors (HTS's) has been developed. MgO nanorods were incorporated into Bi₂Sr₂CaCu₂O_z, Bi₂Sr₂Ca₂Cu₃O_z, and Tl₂Ba₂Ca₂Cu₃O_z superconductors at areal densities up to 2 × 10¹⁰/cm². Microstructural analyses of the composites demonstrate that the MgO nanorods create a columnar defect structure in the HTS matrices, form a compositionally sharp interface with the matrix, and self-organize into orientations perpendicular and parallel to the copper oxide planes. Measurements of the critical current density demonstrate significant enhancements in the MgO nanorod/HTS composites at elevated temperatures and magnetic fields compared with reference samples.