Vacancy trapping by 5sp series impurities in rolled and implanted nickel foils

Nickel foils containing substitutional¹¹⁹Sb,¹²¹Sb and¹²⁵Sb impurities were deformed by rolling at room temperature and subsequently subjected to an isochronal annealing treatment. After each annealing step, a Mössbauer spectrum was measured. In the annealing temperature range from 350 to 800 K, in addition to the component for substitutional impurities, components ascribed to impurity atoms associated with one or more vacancies were observed in all cases. After annealing at 850 K and higher, only the substitutional component remains. Though very similar in general, some of the spectra for deformed¹¹⁹SbNi samples show clear differences from those obtained for implanted¹¹⁹SnNi samples. Additional experiments were performed on implanted sources of¹²¹Te and¹²⁹Te in nickel. Here, substantial vacancy trapping is already present in undeformed and unannealed foils. Rolling of the¹²⁹TeNi sources leads to a considerable increase of trapping after subsequent annealing at intermediate temperatures. For the insoluble Te impurities, a purely substitutional solution can not be recovered by annealing at higher temperatures. The evolution of vacancy trapping at the impurities that serve as probes and the dependence of the hyperfine field and the isomer shift of the impurities on the trapped vacancy configurations are discussed.