Abstract
For pt.II see ibid., vol.8, p.1737 (1975). The theory of nuclear spin relaxation by translational diffusion in solids previously developed by Sholl is extended to the case of single crystals. Numerical results are presented over the entire temperature range for FCC, BCC and SC crystal structures enabling the relaxation rates to be determined for polycrystals and for any orientation of magnetic field in single crystals. Some errors in previous work are corrected. The magnitude of the field dependence is quite different for the three crystal structures considered. The validity of the approximation of averaging the relaxation rate rather than the magnetization is examined.