Diffusion experiment with the accelerated, shorot-lived radioactive beam of Li

Jeong, S.-C.*; Sugai, Hiroyuki; Yahagi, Masahito*

We have demonstrated a non-destructive and on-line radiotracer method for diffusion studies in lithium ionic conductors, by using, as a tracer, the short-lived alpha-emitting radioisotope of Li from TRIAC (Tokai Radioactive Ion Accelerator Complex). The method has been successfully applied to measure the lithium diffusion coefficients in a typical defect-mediated lithium ionic conductor of LiGa, well demonstrating that the method is very effective to measure the diffusion in the micrometer regime per second. Anomalous composition-dependence of Li diffusion coefficients in LiGa was observed. The anomaly was discussed qualitatively in terms of the formation of defect complex and the interaction between the constituent defects. The ordering of the Li vacancies in the Li-deficient LiGa was observed for the first time in terms of the Li diffusion by the present method, and its thermodynamic aspect was discussed.