| 摘要 |
A superconductor is made by reacting a solid superconductive base member, such as Nb wire or V strip, with an element, or alloy of elements, having a different number of valency electrons, e.g. Sn or Ga as vapour or fused bath, Si vapour, Ga or Al powder, preferably in an inert atmosphere, e.g. A or under vacuum at a temperature below the melting point of the member, to cause the element to diffuse into the member converting at least a portion thereof to an integral, continuous layer of a crystalline reaction product, e.g. Nb3Sn, V3Ga, Nb3Al, SiV3, GaNb3, GeNb3, BeV3, InNb3, SnTa or SnV3, having a b -tungsten structure and superconductive properties superior (higher critical temperature) to either the base member or element. For example, niobium wire may be reacted by (a) diffusing tin vapour into it at 1200 DEG C. in an evacuated chamber, (b) heating it at 1350 DEG C. with powdered aluminium, or (c) immersing it in a fused tin bath containing inert diluents such as Cu or Ag prior to heating the coated wire to 1200 DEG C. in A atmosphere. The diffusion reaction may be conducted by decomposing volatile compounds of the element such as carbonyls or halides. |
