|Title||8 Li $\beta$-NMR study of epitaxial Li x CoO 2 films|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||Sugiyama, J, Harada, M, Oki, H, Shiraki, S, Hitosugi, T, Ofer, O, Salman, Z, Song, Q, Wang, D, Saadaoui, H, Morris, GD, Chow, KH, MacFarlane, WA, Kiefl, RF|
|Journal||J. Phys.: Conf. Ser.|
In order to investigate the diffusive motion of Li + in a thin film electrode material for Li-ion batteries, we have measured β -NMR spectra of 8 Li + ions implanted into epitaxial films of Li 0.7 CoO 2 and LiCoO 2 in the temperature range between 10 and 310 K. Below 100 K, the spin-lattice relaxation rate (1/ T 1 ) in the Li 0.7 CoO 2 film increased with decreasing temperature, indicating the appearance and evolution of localized magnetic moments, as observed with μ + SR. As temperature is increased from 100 K, 1/ T 1 starts to increase above 200 K, where both Li- NMR and μ + SR also sensed an increase in 1/ T 1 due to Li-diffusion. Interestingly, such diffusive behavior was found to depend on the implantation energy, possibly because the surface of the film is decomposed due to chemical instability of the Li 0.7 CoO 2 phase in air. Such diffusive behavior was not observed for the LiCoO 2 film up to 310 K.