Synthesis of (Li,Mn) ferrites by reaction of ultrafine γ-Fe2O3 with LiMn2O4 spinel at 650°C

(Li,Mn) ferrites (LMFs; LiyMn2yFe3−3yO4+δ, y = 0.27–0.75, δ = 0.01–0.04) were synthesized by solid-state reaction of ultrafine maghemite (γ-Fe2O3) with lithium manganese spinel (LiMn2O4) at 650°C. For y ≤ 0.5, the LMFs were synthesized in a He gas stream; for y > 0.5, the LMFs were formed in an air stream at 650°C. In the formation of LMF (y = 0.44), release of oxygen gas was observed at 460 and 650°C in a He gas stream. The oxygen release at 460°C was accompanied by the reaction of LiMn2O4 with γ-Fe2O3, and the release at 650°C was due to the reaction of the formed LMF and α-Fe2O3. The deviation of lattice constant from Vegard’s Law was largest at y = 0.5, where all Mn ions were trivalent.