The diffusion coefficients of Li in the NaTl-type Li intermetallic compound of β-LiGa were measured by using a short-lived radioactive diffusion tracer. As the tracer, the α-emitting radioisotope of 8Li delivered as the energetic and pulsed beam from Tokai Radioactive Ion Accelerator Complex (TRIAC) was implanted into the β-LiGa compounds with the composition in the range of about 43 to 54 at.% Li. By analyzing the time-dependent yields of the α-particles measured according to the repetition cycle of the beam, the tracer diffusion coefficients were extracted over the wide range of Li composition. Abnormal composition-dependence of Li diffusion coefficients in β-LiGa was observed; the stoichiometric β-LiGa showed the highest diffusivity of Li. By referring to the composition-dependent diffusivity of Li in the iso-structural β-LiAl and β-LiIn, the abnormal diffusion of Li in very Li-poor composition of β-LiGa could be identified. The anomaly was discussed qualitatively in terms of the formation of defect complex and the interaction between the constitutional defects.

Abnormal Li Diffusion in β-LiGa by the Formation of Defect Complex. S.C.Jeong, I.Katayama, H.Kawakami, Y.Watanabe, H.Ishiyama, N.Imai, Y.Hirayama, H.Miyatake, M.Sataka, H.Sugai, S.Okayasu, S.I.Ichikawa, K.Nishio, S.Mitsuoka, T.Nakanoya, T.Hashimoto, T.Hashimoto, M.Yahagi: Solid State Ionics, 2009, 180[6-8], 626-30