Mössbauer studies of low‐temperature radiation damage in α‐iron

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Abstract
The Mössbauer effect has been used to study radiation damage in α‐iron, doped with 0.6 at% Os and 4 at% Pt. The samples were irradiated in a nuclear reactor at 4.6 K. The Mössbauer nuclei of Ir193 and Au197 were produced by capture of thermal neutrons in Os192 or Pt196, a process which simultaneously could lead to radiation damage. Compared with annealed samples, the average magnetic field was reduced after the irradiation by about 2% and the line width was increased by approximately 30%. Isochronal annealing processes were studied. The annealing of the irradiation effects took place primarily between 90 and 140 K with activation energies in the range between 0.30 and 0.40 eV. These effects are interpreted as mainly due to a vacancy as nearest or next nearest neighbour of the displaced Mössbauer atom combined with an interstitial several lattice sites away from the vacancy. The Mössbauer atom does not come to rest as an interstitial atom. These results are in good agreement with results from computer experiments of Vineyard's group.