Diffusion of radiation damage in Fe-P systems

The dimer method has been applied to determine the transition energy barriers for defect motion in α-Fe containing a phosphorus impurity. The principal defects analysed were those that were found to exist after a classical molecular dynamics (MD) simulation of the collisional phase of a cascade. We have found two different diffusion mechanisms when the P is in an interstitial site. The P interstitial can diffuse through the lattice by hopping between 〈1 1 0〉 dumbbell and tetrahedral sites, taking a few nanoseconds per transition at 300 K. This is much slower than the transition times found in previous studies of Fe self-interstitial defects, in which transitions can be observed over normal MD time scales of a few tens of picoseconds at 300 K.