Niobium-tin superconducting wire for ITER tokamak. (Source: Charlie Sanabria, Wikipedia.org)

A niobium-tin alloy that has superconducting properties at temperatures below 4 kelvin and magnetic fields up to 30 tesla. It is a superconductor usable in strong magnetic fields but very difficult to manufacture. Niobium-tin is very brittle and cannot be wound. The producer therefore creates coils separately from niobium and tin and then applies heat to make the tin diffuse into niobium and create a brittle superconductor. Magnetically confined plasma research requires superconducting coils capable of keeping their properties even in very strong magnetic fields, and the niobium-tin material is suitable for that.