The mechanism and kinetics of growth of the superconducting compound Nb3Sn

Abstract

A study has been made of the mechanism and kinetics of formation of Nb3Sn from the elemental components. The Nb3Sn forms partly by diffusion and partly by a solution/ deposition mechanism which depends on thermal gradient mass transfer. The effect of this is to modify the growth equation to x = kt0.36 over the temperature range 950 to 1150° C. The temperature dependence of these two processes, given by the difference between the activation energies for diffusion and solution, is −9.7 kcal/g atom (−0.42 eV/atom) so that the thickness of the Nb3Sn layer produced in any given time decreases with increasing temperature.