Vanadium–gallium

Vanadium–gallium (V₃Ga) is a superconducting alloy of vanadium and gallium. It is often used for the high field insert coils of superconducting electromagnets.^{[clarification needed][citation needed]}

Vanadium–gallium tape is used in the highest field magnets (magnetic fields of 17.5 T). The structure of the superconducting A15 phase of V₃Ga is similar to that of the more common Nb₃Sn.^[1]

In conditions where the magnetic field is higher than 8 T and the temperature is higher than 4.2 K, Nb₃Sn and V₃Ga see use.

The main property of V₃Ga that makes it so useful is that it can be used in magnetic fields up to about 18 T, while Nb₃Sn can only be used in fields up to about 15 T.^[2]

The high field characteristics can be improved by doping with high-Z elements such as Nb, Ta, Sn, Pt and Pb.^[3]

Physical properties

Molecular weight	222.55 g/mol
Melting point	1720 °C
Highest magnetic field	18 T

^[4]

V₃Ga has an A15 phase, which makes it extremely brittle. One must be extremely cautious not to over-bend the wire when handling it. ^[2]

Superconducting properties

• Critical temperature (T_c): ~14.2 K^[5]
• Upper critical field (H_c2): over 19 T.

Fabrication of superconductive wires or tapes

V₃Ga wires can be formed using solid-state precipitation.^[6]

• 
  V₃Ga superconducting tape (10 mm × 0.14 mm cross section). A vanadium core is covered with 15 μm V₃Ga layer, then 20 μm bronze (stabilizing layer) and 15 μm insulating layer. Critical current 180 A (19.2 T, 4.2 K), critical current density 20 kA/cm².
• 
  An example of a wire (V₃Ga alloy) used in a superconducting magnet.

History