27 March 2017

Better joints to connect wires of promising superconductor

(Left) Light microscope image of a transverse cross-section of Bi-2212 wire. (Right) Voltage-current (V-I) curves. (Left) Light microscope image of a transverse cross-section of Bi-2212 wire. (Right) Voltage-current (V-I) curves.

The new technique for connecting Bi-2212 round wires is an important step in building better, stronger superconducting magnets.

First, some background

As the only high-temperature superconducting cuprate produced in a practical, round-wire form, the conductor Bi2Sr2CaCu2O8-x (bismuth strontium calcium copper oxide — or Bi-2212 for short) is promising for use in future high-field, high-homogeneity superconducting magnets. But attaching segments of these wires together can be tricky: A bad joint could result in electrical resistance, potentially causing the magnet to malfunction.

What did researchers discover?

MagLab researchers recently invented a practical superconducting joint between two Bi-2212 round wires. The technique connects two wires without introducing any other material. Resulting in near-zero resistance, the procedure is practical and compatible with the coil winding and heat treatments that are standard for Bi-2212 coil manufacturing.

Why is this important?

The joint resistance is sufficiently low to demonstrate the promise of persistent-mode operation of large-inductance Bi-2212 coils for future applications, especially nuclear magnetic resonance (NMR) and particle accelerator magnets.

Who did the research?

P. Chen, U.P. Trociewitz, D.S. Davis, E.S. Bosque, D.K. Hilton, Y. Kim, D.V. Abraimov, W.L. Starch, J. Jiang, E.E. Hellstrom and D.C. Larbalestier

Applied Superconductivity Center, MagLab, Florida State University

Why did this research need the MagLab?

This research relied on the integrated sample preparation and heat treatment processing, as well as the electromagnetic test and metallographic imaging analysis capabilities of the MagLab’s Applied Superconductivity Center.

Details for scientists


This research was funded by the following grants: G.S. Boebinger (NSF DMR-1157490); D.C. Larbalestier (DOE/HEP-DESC0010421), (NIH-R21GM111302).

For more information, contact David Larbalestier.


  • Research Area: Magnet Technology, Superconductivity - Applied
  • Research Initiatives: Materials
  • Facility / Program: ASC
  • Year: 2017
Last modified on 27 March 2017