Milling effect on the local structure, site occupation, and site migration in aluminum substituted lithium manganese oxides

Koichi Nakamura, Kosuke Shimokita, Yoichi Sakamoto, Kuniyuki Koyama, Toshihiro Moriga, Naoaki Kuwata, Yoshiki Iwai, Junichi Kawamura

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

7Li and 27Al MAS-NMR, magnetic susceptibility, and complex impedance measurements have been performed to study the local structure and electrical resistivity in Al doped spinel LiMn2−xAlxO4 (x = 0, 0.05) exposed to a ball-milling process. The milling process decreased the effective magnetic moment of the Mn species, arising from the appearance of Mn4+, and lead to the suppression of the antiferromagnetic correlation. A hopping time and an activation energy for hopping charge carrier, estimated from electrical resistivity, relatively became larger above milling time of 2.5 h. 7Li and 27Al MAS-NMR spectra were dependent on milling time, and changes in the spectrum intensities were related to the distribution of Al/Li site occupation. Consequently, we concluded that structural disorder caused by the moderate milling process stimulated a migration of Al3+ ions from the 8a site to the 16d one and the increase of Li+ ions at the 8a site on the diffusion pathway. Such a mutual site migration between the 8a and 16d site for Li+ and Al3+ ions would be favorable to Li+ ion diffusion in the milled samples.

Original languageEnglish
Pages (from-to)214-220
Number of pages7
JournalSolid State Ionics
Volume317
DOIs
Publication statusPublished - 2018 Apr

Keywords

  • Al substitution
  • Electrical resistivity
  • Li ion migration
  • LiMnO
  • NMR

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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