7Li NMR measurements were performed to study milling effects on ionic diffusion

in lithium cobalt oxide, LiCoO2 and piezoelectric compound, LiNbO3 prepared by

mechanical milling method. The milling process gives quite different effects on

NMR spectra of these compounds. Both 7Li MAS and static NMR spectra of the

milled LiCoO2 showed the line broadening with increasing milling time. 59Co static

spectra also showed specific changes in the line shape with increasing milling time.

These results would be attributed to the change in an electronic state of Co 3d

orbitals because of charge compensation associated with oxygen vacancies and/or

defects. 7Li static NMR spectrum of milled LiNbO3 exhibited complicated line

shape with increasing milling time. It was explained by superposition of two

spectra arising from mobile Li+ ions and non-mobile ones settled on the fixed site.

It was shown that the ratio of mobile Li+ ions increased up to a maximum of 9.4%

with increasing milling time. Milling effects on the Li+ ionic diffusion in LiCoO2

and LiNbO3 were discussed in connection with changes in local structure.

Ionic Diffusion and Structural Changes in Lithium Compounds. K.Nakamura,

H.Hirano, D.Nishioka, S.Endou, K.Itsuki, Y.Michihiro, T.Moriga, N.Kuwata,

J.Kawamura: Solid State Ionics, 2009, 180[6-8], 621-5