Hafnium Greatly Improves Nb3Sn Superconductor for High Field Magnets

Published September 20, 2019

Layer critical current density, Jc, in a variety of variants of Nb3Sn monofilament wires fabricated to include Tantalum (Ta), Zirconium (Zr) and Hafnium (Hf) additions, both with and without SnO2 suitable for internal oxidation of the Zr and Hf.

Shreyas Balachandran, Applied Superconductivity Center, National MagLab

Small additions of elemental Hafnium boosts current-carrying capability in Nb3Sn superconductor.

What did researchers discover?

MagLab researchers have found that adding the element Hafnium (Hf) to a Niobium (Nb)-Tantalum (Ta) base alloy and forming a superconductor Nb₃Sn after reaction with Tin (Sn) at high temperatures of 670°C leads to tremendous improvements in the electrical current carrying ability (Layer J_c) of this conductor wire by 60% at operating magnetic fields of 16T at temperatures of 4.2K.

Why is this important?

The high increase in the current carrying capacity of superconducting Nb₃Sn wire is of particular interest to NMR researchers, MRI clinicians, and scientists pursuing next-generation accelerators and nuclear fusion. In particular, this research result specifically indicates that future 16T dipole magnets for the next-generation Future Circular Collider (FCC) planned to be constructed in CERN can be fabricated using this new Nb₃Sn conductor, rather than the riskier high-temperature superconductors.

Who did the research?

Shreyas Balachandran¹, Chiara Tarantini¹, Peter J. Lee¹, Fumitake Kametani^1,2, Yi-Feng Su¹, Benjamin Walker¹, William L. Starch¹, and David C. Larbalestier^1,2

¹National magLab, Florida State University; ²Dept of Mechanical Engineering, Florida State University

Why did this research need the MagLab?

The conductor was developed in-house by researchers at the MagLab. In addition, characterization of the conductors at high fields up to the full superconducting range of Nb₃Sn (26T) would not have been possible elsewhere.