Diffusion of dilute boron in single-crystal aluminum

Relaxation-time $T_1$ measurements are made on the polarization of diffusing ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ implanted in single-crystal aluminum, as a function of crystal orientation and temperature. A model of uncorrelated random walk from one octahedral interstitial site to another is used to calculate $\eta$, the percentage change in $T_1$ between the [$11\overline{1}$] and [001] directions. At its maximum $\eta$ is three times larger than predicted indicating a clear deviation from uncorrelated-random-walk diffusion.