Defect-engineering to probe attainable flux-pinning in coated conductors
Abstract
High Temperature Superconductors (HTS) wires or coated conductors based on REBa2Cu3O7- (REBCO) hold promise to revolutionize the electric grid of the 21st century. The superconducting wire is processed in the form of an epitaxial film deposited by different methods on a near single-crystal, flexible template comprising a metal substrate and epitaxial oxide buffer layers. The template is manufactured using two major technologies: the rolling assisted biaxially textured substrate (RABiTS) technology and the LMOe-enabled, IBAD-MgO process. Although such coated conductor, superconducting wires can carry several orders of magnitude more power than copper wires of the same cross section, further performance improvements are necessary for the supercpetitive, especially in the presence of high-applied magnetic fields. This objective can be achieved by introducing and controllingnano-sized defects and non-superconducting phases within the superconducting films matrix to pin the flux-lattice. The Goyal group was the first to demonstrate that strain-driven, self-assembled columnar defects can address this need and result in stellar vortex-pinning at high operating temperatures (65K-77 K) as well as at low operating temperatures (4.2K-30 K) in high-applied magnetic fields. At 65K-77 K, incorporation of nanoscale BZO columns provides strong correlated pinning as expected. BZO nanocolumn incorporation also significantly enhances critical current density, Jc, and mitigates the Jc anisotropy at lower temperatures (4.2-30 K) and magnetic fields at up to 16 T (with no sign of decreasing at higher fields), via weak uncorrelated pinning created by oxygen point defects around the nanoscale columnar defects. This weak uncorrelated pinning, shows at 5 K, a record high flux pinning force density,Fp > 1.5 TN/m3 in 1.4 m thick films and a Jc ~20% of depairing current density Jd was achieved. This Jc value is more than 100 times higher than the optimized NbTi superconductors. In addition, Jc keeps rising with BZO concentration up to 4 vol %. This work hasguided developments in the field world-wide in the area of coated conductors. The resent project seeks to further enhance performance of coated conductors to guide long-length coated conductor developments. Specific objectives include:A)Explore the limits of performance in coated conductors obtained using PLD films with simultaneous BZO additions and rare-earth dopants such as Gd. Perform depositions as a function of rare-earth and BZO additions. Perform detailed transport measurements, structural characterizations using advanced X-ray techniques and atomic-resolution characterization of the defect structures. B)Explore Ca doping in both YBCO +BZO films made using PLD and also in (Gd,Y)Ba2Cu3Ox + BZO films as a function of Ca doping to determine if Tc (zero) can be increased while retaining the excellent pinning. Perform depositions as a function of rare-earth and BZO additions. Perform detailed transport measurements, structural characterizations using advanced X-ray techniques and atomic-resolution characterization of the defectstructures.C)Explore BaHfO3 additions and compare with BaZrO3 additions. Using advanced structural and microstructural characterizations using HRTEM and EELS mapping, determine fundamental reasons for any observed differences in properties and determine the limits of performance.Future Naval Relevance: This proposal fully meets Topic 1.5 of the Special Notice N00014-18-R-SN02, Special Program Announcement for Office of Naval Research Basic and Applied Research Opportunity: Enhanced Superconductors for Future Naval Applications.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 09, 2021
- Source ID
- N000142112534
Entities
People
- Amit Goyal
Organizations
- Office of Naval Research
- Research Foundation for the State University of New York
- United States Navy