Progress in Nanoengineered Microstructures for Tunable High-Current, High-Temperature Superconducting Wires

• Published in: Advanced materials (Weinheim) 2008-02, Vol.20 (3), p.391-407
• Main Authors: Holesinger, T. G., Civale, L., Maiorov, B., Feldmann, D. M., Coulter, J. Y., Miller, D. J., Maroni, V. A., Chen, Z., Larbalestier, D. C., Feenstra, R., Li, X., Huang, Y., Kodenkandath, T., Zhang, W., Rupich, M. W., Malozemoff, A. P.
• Format: Article
• Language: English
• Subjects: Defect structures; Microstructures; Superconductors
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.200700919

High critical current densities (Jc) in thick films of the Y1Ba2Cu3O7–δ (YBCO, Tc ≈ 92 K) superconductor directly depend upon the types of nanoscale defects and their densities within the films. A major challenge for developing a viable wire technology is to introduce nanoscale defect structures into the YBCO grains of the thick film suitable for flux pinning and the tailoring of the superconducting properties to specific, application‐dependent, temperature and magnetic field conditions. Concurrently, the YBCO film needs to be integrated into a macroscopically defect‐free conductor in which the grain‐to‐grain connectivity maintains levels of inter‐grain Jc that are comparable to the intra‐grain Jc. That is, high critical current (Ic) YBCO coated conductors must contain engineered inhomogeneities on the nanoscale, while being homogeneous on the macroscale. An analysis is presented of the advances in high‐performance YBCO coated‐conductors using chemical solution deposition (CSD) based on metal trifluoroacetates and the subsequent processing to nano‐engineer the microstructure for tuneable superconducting wires. Multi‐scale structural, chemical, and electrical investigations of the CSD film processes, thick film development, key microstructural features, and wire properties are presented. Prospects for further development of much higher Ic wires for large‐scale, commercial application are discussed within the context of these recent advances. High critical current Y1Ba2Cu3O7–δ superconducting films must contain engineered inhomogeneities on the nanoscale within the framework of a uniform, defect‐free macro‐structure. Tailoring of the superconducting properties to application‐specific conditions requires the ability to precisely engineer and control the nanoscale defect structure. This progress report covers the use of chemical solution deposition in achieving this level of control in high‐performance YBCO superconducting films.