Computer Modeling Study of the Lithium Ion Distribution in Quaternary Li–Mn–Fe–O Spinels

✍ Scribed by S.M. Woodley; C.R.A. Catlow; P. Piszora; K. Stempin; E. Wolska

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 173 KB
• Volume: 153
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2000.8770

✦ Synopsis

Computational and experimental techniques have been used to investigate the structural properties, especially the cation distribution, of spinel solid solutions formed between LiMn 2 O 4 and LiFe 5 O 8 . The series of solid solutions of composition (1؊x)LiMn 2 O 4 ؊xLi 0.5 Fe 2.5 O 4 are single-phase products with the cubic spinel structure, with the lattice parameter increasing from 8.21 to 8.33 A > as x varies from 0 and 1. The variation of the unit cell parameter with x shows a distinct departure from Vegard:s law, which is most pronounced for samples with the Fe : Mn molar ratio close to 1 : 1. With higher Fe content, the ordering of lithium ions in the octahedral spinel sites leads to the reduction of the crystal symmetry and to a strongly marked preference of Li ؉ ions to occupy the octahedral positions. Our lattice energy minimization results make clear predictions as to the Li ؉ ion content and distribution in these materials and thereby resolve confusions in the experimental data.