Preparation of a new crystal form of manganese dioxide: λ-MnO 2
Abstract
Treatment of the spinel-type material LiMn 2O 4 with aqueous acid was found to result in conversion of the LiMn 2O 4 to nearly pure MnO 2, while preserving the structural framework of the LiMn 2O 4. The resulting material, designated λ-MnO 2, thus has a structure related to spinel, but with most of the lithium removed from the tetrahedral sites. The conversion of LiMn 2O 4 to λ-MnO 2 results in some contraction of the lattice, as evidenced by a reduction in the lattice constant a0 from 8.24 to 8.03 Å. A mechanism for the conversion of LiMn 2O 4 to λ-MnO 2 is proposed, which involves solid state diffusion of lithium in the structure, in a manner analogous to the proton diffusion which occurs during the cathodic reduction of γ-MnO 2.
- Publication:
-
Journal of Solid State Chemistry France
- Pub Date:
- September 1981
- DOI:
- 10.1016/0022-4596(81)90323-6
- Bibcode:
- 1981JSSCh..39..142H