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

Milling effect on the local structure, site occupation, and site migration in aluminum... 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. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Solid State Ionics Elsevier

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

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Publisher
Elsevier
Copyright
Copyright © 2018 Elsevier B.V.
ISSN
0167-2738
eISSN
1872-7689
D.O.I.
10.1016/j.ssi.2018.01.019
Publisher site
See Article on Publisher Site

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.

Journal

Solid State IonicsElsevier

Published: Apr 1, 2018

References

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