Observation of a cubic defect in nickel by means of nuclear magnetic resonance on oriented ¹¹⁴In nuclei

^114mIn was implanted at room temperature into nickel single crystals, and nuclear magnetic resonance was detected by observing the destruction of beta -asymmetry in the decay of ¹¹⁴In. After annealing at 400 K, at which temperature indium atoms are known to trap defects of vacancy-type, two single resonance lines were observed, corresponding to hyperfine fields of -3.30(1) T for the substitutional indium atoms, and +5.12(2) T for the defect associated indium atoms. The experiments were carried out with an external magnetic field along the (100), (110) and (111) crystallographic axis, respectively. No significant shift or splitting of the defect associated resonance line was detected. This implies that the defect causes an electric field gradient of at most 10¹⁷ V cm^-2. It is argued that the defect is a cubic vacancy cluster as observed on the system (¹¹¹In to ¹¹¹Cd)Ni with perturbed angular correlations and Mossbauer spectroscopy on (¹¹⁹In to ¹¹⁹Sn)Ni.