Stage-III recovery in α-iron studied by means of nuclear magnetic resonance on oriented 131I nuclei

Nuclear magnetic resonance measurements were performed on oriented 131 nuclei implanted into decarburized single crystals of α-Fe. Satellite resonances, centered around 633 MHz, that are well described by an additional quadrupole interaction with a 〈111〉 symmetry appeared both after room-temperature implantation and after low-temperature Frenkel pair production followed by annealing at a temperature corresponding with recovery stage III. The results from a defect-antidefect reaction with mobile stage-I defects strongly indicate that these satellite resonances are caused by trapping of mobile vacancies. Implantation at 20 K and a comparatively low dose resulted in a high-field fraction of 0.9, which is much higher than usually obtained after room-temperature implantation. Two newly discovered satellite patterns, centered around 647 and 660 MHz, are attributed to additional trapping of oxygen and hydrogen impurities, respectivel