Tests were performed in alkali halide in the extrinsic region where vacancies created due to divalent impurity dominate in undeformed material while the additional athermal vacancies formed during deformation resulted in enhanced vacancy diffusion. Both NaCl and NaF single crystals yielded similar results, while phonon and paramagnetic impurities respectively dominated at a low temperatures in undeformed condition. Skin effect problems encountered in metals precludes use of macroscopic samples and thus thin (25 µm) foils of pure aluminium are tested. At very low temperatures (below about 300 K) in the undeformed aluminium, NMR relaxation was due mainly to the conduction electrons (Korringa relaxation) with the relaxation rate proportional to the temperature. Diffusion dominated relaxation (motional narrowing) was noted at elevated temperatures. As in alkali halides, in-situ annealing of strain-induced excess vacancies is noted at high temperatures thereby delineating the low and high temperature regimes. The excess vacancy concentration during deformation is found to be,

C_v l_{low T} = 9.7 and C_v l_{high T} = 3.6×10³/_v{1 - [exp(-43)/(1 - 1.53×10⁴/_v)]}

where _v is the vacancy jump rate { exp(-0.62eV/kT)}

These studies clearly reveal the power and utility of these NMR techniques in the determination of deformation induced vacancies in-situ in a non-invasive fashion.