Synthesis and characterization of compounds LixMn1+xFe2–2xO4 with spinel structure in the quasiternary system „LiO0,5 – MnOx

Crystal Research and Technology

Cryst. Res. Technol. 41, 18 (2006) - Abstract -

Synthesis and characterization of compounds Li_xMn_1+xFe_2–2xO₄ with spinel structure in the quasiternary system „LiO_0,5 – MnO_x – FeO_x“

C. Wende and H. Langbein

Institute of Inorganic Chemistry, Dresden University of Technology, 01062 Dresden, Germany

Keywords	thermal analysis, spinel phases Li_xMn_1+xFe_2–2xO₄, freeze drying, XRD
PACS	61.10.Nz, 61.66.Fn, 75.50.Gg
DOI	10.1002/crat.200410523

The thermal decomposition of freeze-dried Li-Mn(II)-Fe(III)-formate precursors was investigated by means of DTA, TG and mass spectroscopy. By the thermal treatment of the prefired precursors between 400 and 1000°C, single phase solid solutions Li_xMn_1+xFe_2–2xO₄ (0 ≤ x ≤ 1) with cubic spinel structure were obtained. To get single phase spinels, special conditions concerning the temperature T and the oxygen partial pressure p(O₂) during the synthesis are required. Because of the high reactivity of the freeze-dried precursors, in comparison with the conventional solid state reaction, the reaction temperature can be lowered by 200°C. The cation distribution and the properties of the Li-Mn-ferrites were studied by chemical analysis, X-ray powder diffraction and magnetization measurements. It was found that for high substitution rates, almost all lithium occupies the tetrahedral coordinated A-sites of the spinel lattice AB₂O₄, while at small x-values, lithium ions are distributed over the tetrahedral and octahedral sites.

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