Influence of simultaneous doping of Li+ and Fe3+ ions in the LiMn2O4 spinel structure

A series of compounds LixMn3-x-yFeyO4 (x = 1.0125; 0 <= y <= 0.05) were synthesized by solid state reaction of Li2CO3 with the manganese oxide or iron-man-ganese oxide precursors. Investigations of the structure transformation effect of double substitution with Li+ and Fe3+ ions in LiMn2O4, in the temperature range of 10-300 K, were undertaken using high-resolution X-ray powder diffraction at the HASYLAB (DESY) synchrotron. The Li1.0125Mn1.9625Fe0.025O4 transforms from cubic (FOm) to orthorhombic (Fddd) below 250 K, and is stable to 10 K. Whereas in the Li1.0125Mn1.9375Fe0.05O4 oxide no phase transition was observed, this spinel remains in cubic structure down to the temperature of 10 K.