Pre-fabricated nanorods in RE-Ba-Cu-O superconductors

摘要

Pre-fabrication of metallic nanorods on biaxially textured templates has been explored in this study to introduce flux pinning centers in RE-Ba-Cu-O (REBCO, RE =rare earth) based superconductors. Pt nanorods were deposited by an electron beam assisted deposition method on LaMnO_3-capped biaxially textured IBAD-(ion beam assisted deposition) substrates. Well-controlled nanorods with varying diameter (50-120 nm), length (up to 1 μm), orientation and unit cell size were grown over an area of 120-150 μm~2. The nanorod-decorated samples were then deposited with Gd-Y-Ba-Cu-O ((Gd, Y)BCO) by metal organic chemical vapor deposition (MOCVD). The Pt nanorods remain in their positions during MOCVD and become embedded in the (Gd, Y)BCO matrix, although they suffer creep-induced shape deformation due to exposure to elevated temperature. Higher unit cell size, longer nanorods, and nanorods oriented at an angle to the substrate normal adversely affect the epitaxy of the (Gd, Y)BCO film due to formation of a-axis grains. The observed current-carrying capacity of the Pt nanorod sample is lower than its corresponding reference sample without any nanorods and processed under identical conditions, but it decreases at a slower rate with increasing magnetic field. Potential routes to improve the performance while retaining the desirable characteristics of controlled nanorod direction and density are discussed.