Nuclear Spin Relaxation Studied by β-NMR of 12N Implanted in TiO2

The β-NMR of short-lived β-emitter 12N(I π = 1+, T 1/2 = 11ms) in a rutile TiO2 single crystal has been measured as functions of temperature and external magnetic field. Atomic motion induced spin lattice relaxation was observed for two known sites, O substitutional and interstitial sites. The data were analyzed in terms of the thermal atomic jump, which suggests that the motion of defects around the substitutional 12N atom for O, and of the interstitial 12N atom are attributed to the spin lattice relaxation. The electric field gradients have shown temperature dependence for both sites, which is probably due to the thermal expansion of rutile.