DIRECT MEASUREMENTS OF IMPURITY AND LATTICE COMPONENTS OF THE NUCLEAR-SPIN-LATTICE RELAXATION IN AL2O3 CRYSTALS

For Al-27 nuclei in Al2O3 crystals, both nominally pure and doped with Cr3+, suppression of the impurity nuclear spin-lattice relaxation und er the condition of additional stationary magnetic saturation of the N MR line has been observed for the first time. Measurements of the latt ice and impurity components of the spin-lattice relaxation time have b een performed. The study was carried out at 77 K for different crystal orientations. Possible mechanisms of the impurity NMR relaxation supp ression are discussed.