Argonne National Laboratory: High-Temperature Superconductivity R&D in Brief

     Since the discovery of superconductivity at temperatures exceeding the boiling point of liquid nitrogen in 1986, the Argonne National Laboratory has been actively engaged in research aimed at exploiting high critical-temperature superconducting (HTS) materials for electric power applications. With sustained funding from the Department of Energy’s (DOE’s) Office of Energy Efficiency and Renewable Energy (dating back to the late 1980’s), Argonne has conducted forefront scientific investigations that have strongly contributed to the resolution of progress-limiting issues and to the discovery of improved methodologies for fabricating and implementing composite wire and thin film HTS embodiments. The program at Argonne involves scientists and engineers from four divisions of the Laboratory—the Energy Technology Division, the Chemical Technology Division, the Materials Science Division, and the Energy Systems Division. In conjunction with the research and development activities, Argonne staff continuously monitor and assess worldwide progress in the development of HTS technology.

      In the course of its superconductor research, Argonne has forged scores of collaborations with industries, universities, and other national laboratories. Through a cooperative research and development agreement with American Superconductor, in place for over ten years now, Argonne has participated in the highly regarded Wire Development Group (WDG), which also includes Los Alamos National Laboratory and the University of Wisconsin. The WDG pioneered the fabrication of long-length, silver-sheathed Bi-2223 (Ag/Bi-2223) composite conductors suitable for cables, motors, generators, fault current limiters, etc. In particular, aspects of the heat treatment used by American Superconductor to manufacture Ag/Bi-2223 wire benefited significantly from research done at Argonne. Since 1992, Argonne has collaborated with Intermagnetics General Corp. (IGC) in establishing the processing science and technology that is needed to manufacture Bi-2223 tapes. Long-length Bi-2223 tapes fabricated by IGC are used in a prototype fault-current limiter (FCL). Vacuum-calcination for synthesizing phase-pure superconductor powders, an R&D-100-Award-winning technique developed at Argonne, was transferred to Superconductive Components, Inc., who uses it to manufacture superconductor powders and market them worldwide.

    In recent years, the emphasis of Argonne’s HTS technology effort has shifted to YBa₂Cu₃O₇(YBCO) -coated conductors. This work focuses primarily on the development of the inclined substrate deposition method for producing suitably textured templates on which continuous, biaxially textured YBCO films can be grown. The objective of this research is to develop a fabrication method that is adaptable to the efficient and economical manufacturing of long-length coated conductors. Test specimens carrying over 0.5 MA/cm² have been produced by methods that have the potential to meet DOE’s cost/performance goals. In the area of coated conductors, Argonne collaborates with AMSC, IGC-SuperPower, and Universal Energy Systems, Inc. Our industrial partners have made lengths (>1 m) of coated conductors that carry >100 amps/cm-width of tape.

      In addition to Argonne's research into the optimization of conductor performance and the fabrication of superconducting devices, it has made strong contributions over the past decade in the area of conductor characterization. These contributions have made excellent use of unique Argonne facilities, such as the Electron Microscopy Center, the Advanced Photon Source, and the Intense Pulsed Neutron Source. Raman microspectroscopy methods that were developed and utilized by Argonne staff have contributed seminal insights about phase evolution during the synthesis of HTS ceramics. Magneto-optic imaging, another R&D-100-Award-winning technique, was developed at Argonne to map the current distribution in HTS and provided valuable feedback for the optimization of conductor performance. Argonne staff have also investigated critical factors that influence current transport across individual grain boundaries in HTS. Argonne’s characterization studies have produced seminal information about the chemical and mechanical properties of HTS materials, the relationships between microstructure and conductor performance, and the effects of processing conditions on the quality of fully fabricated conductors.

     In collaboration with industrial partners, Argonne is developing a flywheel energy storage system and an FCL that are based on HTS materials. Argonne continues to collaborate with industry, utilities, universities, and other national laboratories in the development and application of HTS materials.