In situ lithium diffusion measurement in solid ionic conductors using short-lived radiotracer beam of 8Li

Bi-Arrhenius Diffusion and Surface Trapping of Li+8 in Rutile Chatzichristos1, McFadden2, Dehn3 et al. 2019Phys. Rev. Lett.

“…The information on Li diffusion comes from the time evolution of the α-signal. The absolute α-to-β ratio, i.e., the baseline ratio of Y α , in the absence of diffusion, depends on experimental factors such as detector efficiencies, therefore in order to account for these systematics, each α-spectrum is self-normalized to start from unity at time zero, i.e., Y n α (t) = Y α (t)/Y α (0) [26]. In order to extract the Li diffusion rate, the experimentally acquired normalized Y n α (t) was compared to a library of simulated Y n α (t) signals.…”

“…A technique similar to the one discussed here has been developed by Jeong et al [29] for Li + diffusion on micrometer and, recently, by Ishiyama et al [21] on a nanometer length scales; however, the experiment reported here differs in a few key ways. In particular, the 8 Li implantation rates accessible at TRIUMF (typically 10 6 -10 7 8 Li + /s) are 1-2 orders of magnitude larger [21], which allows the α-detector to be placed at a grazing angle θ (≤4.4°versus 10(1) o [26]). This detector configuration significantly decreases the α-counts, but greatly enhances the sensitivity to the near-surface region.…”

“…This detector configuration significantly decreases the α-counts, but greatly enhances the sensitivity to the near-surface region. In addition, the ZnS:Ag ring detector used in the present setup is much simpler and easier to install close to the sample in UHV compared to a Si detector [26], although it has less energy resolution.…”