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

Abstract

The β-NMR of short-lived β-emitter $^{{12}} {\text{N}}{\left( {I^{\pi } = 1^{ + } ,T_{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} = 11{\text{ ms}}} \right)}$ 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.