The motion of O in samples which contained 0.26 to 3.40at%O was studied by making 51V and 93Nb nuclear spin relaxation measurements at 300 to 1400K. The Zeeman nuclear spin relaxation rate was determined, over the entire temperature range, by fluctuations in the conduction electron-nucleus interaction. However, the rotating-frame nuclear spin relaxation rates exhibited 3 distinct maxima at high temperatures in addition to the conduction electron-induced contribution. These nuclear spin relaxation peaks were shown to be caused by fluctuations in the nuclear quadrupole interaction of the probe nuclei, due to the migration of interstitial O atoms. It was found that the atomic jump rates differed with regard to their pre-exponential factors, while the activation energies were almost identical (about 1eV) for all 3 relaxation mechanisms.

B.Michel, O.Kanert, B.Günther: Acta Metallurgica et Materialia, 1994, 42[10], 3409-15