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arXiv · 1810.12537

Bi-Arrhenius diffusion and surface trapping of $^{8}$Li$^{+}$ in rutile TiO$_2$

A. Chatzichristos·R. M. L. McFadden·M. H. Dehn·S. R. Dunsiger·D. Fujimoto·V. L. Karner·I. McKenzie·G. D. Morris·M. R. Pearson·M. Stachura·J. Sugiyama·J. O. Ticknor·W. A. MacFarlane·R. F. Kiefl
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Abstract

We report measurements of the diffusion rate of isolated ion-implanted $^{8}$Li$^{+}$ within $\sim$120 nm of the surface of oriented single-crystal rutile TiO$_2$ using a radiotracer technique. The $α$-particles from the $^{8}$Li decay provide a sensitive monitor of the distance from the surface and how the depth profile of $^{8}$Li evolves with time. The main findings are that the implanted Li$^{+}$ diffuses and traps at the (001) surface. The T-dependence of the diffusivity is described by a bi-Arrhenius expression with activation energies of 0.3341(21) eV above 200 K, whereas at lower temperatures it has a much smaller barrier of 0.0313(15) eV. We consider possible origins for the surface trapping, as well the nature of the low-T barrier.

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A. Chatzichristos, R. M. L. McFadden, M. H. Dehn, S. R. Dunsiger, D. Fujimoto, V. L. Karner, I. McKenzie, G. D. Morris, M. R. Pearson, M. Stachura, J. Sugiyama, J. O. Ticknor, W. A. MacFarlane, R. F. Kiefl. 2019-03-01. Bi-Arrhenius diffusion and surface trapping of $^{8}$Li$^{+}$ in rutile TiO$_2$. https://doi.org/10.1103/physrevlett.123.095901

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