Neutron radiography was used to study a Li ion-conducting spinel-type oxide, Li1.33Ti1.67O4, and thus visualize the movement of Li ions. When a direct current was passed through samples with various 6Li/7Li isotope ratios, neutron radiographic images were obtained which revealed Li ion conduction in the oxide. An analysis of these images indicated that the transport number of Li ions was equal to 0.99 at 900C. This was almost the same value as that which was obtained by using an O concentration cell. A more detailed analysis was carried out in order to investigate which type of Li ion (tetrahedral A-site, octahedral B-site, or both) in the spinel-type structure contributed to electrical conduction. The involvement of A-site Li ions in conduction was confirmed.

M.Kamata, T.Esaka, N.Kodama, S.Fujine, K.Yoneda, K.Kanda: Journal of the Electrochemical Society, 1996, 143[6], 1866-71