Structures of Quenched Li_xMn_3-xO₄ Spinels

Abstract

The pseudo-ternary Li−Mn−O phase diagram at 20 °C has been extended by three new phases. The lithium-deficient orthorhombic phase (Fddd), isostructural with low-temperature LiMn2O4, has for the first time been obtained by the steering of manganese occupancy and valence on tetrahedral sites. The influence of lithium deficiency on the formation of various crystal structures is shown, accompanied by their structural parameters resulting from the Rietveld refinement. Valence of manganese at tetrahedral sites has been proven as playing a key role in the phase transitions of the lithium-deficient lithium−manganese oxides.