Synchrotron X-ray diffraction study on the cation distribution in quaternary Li-Fe-Mn spinel oxides

Single phase spinel solid solutions of LixMn3-x-yFeyO4 series with range of 0.5≤x≤1.0 and 0.2≤y≤1.0, have been synthesized by a solid state reaction. By refining the high-resolution X-ray diffraction patterns with Rietveld profile analysis, the lattice parame- ters, interatomic distances and cation distribution were determined. The Fe-for-Mn substitu- tion increases the spinel unit cell constant from a = 8.27A to a = 8.38A, for the Fe/(Fe+Mn) mole ratio of 0.1 and 0.472, respectively. Evidence is given that the lithium ions occupy the tetrahedral sites exclusively, for the molar ratio 0� Fe/(Mn+Fe) � 0.3.