We report on the detection of Fe i −B pairs in heavily B doped silicon using 57Fe emission Mössbauer spectroscopy following implantation of radioactive 57Mn+ parent ions (T 1/2=1.5 min) at elevated temperatures >850 K. The Fe i −B pairs are formed upon the dissociation of Fe i −V pairs during the lifetime of the Mössbauer state (T l/2=100 ns). The resulting free interstitial Fei diffuses over sufficiently large distances during the lifetime of the Mössbauer state to encounter a substitutional B impurity atom, forming Fe i −B pairs, which are stable.up to ∼1,050 K on that time scale.