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Synthesis, structure and magnetic properties of Fe-doped tetragonal Li0.95Mn2.05O4

Waldemar Nowicki 1Jolanta Darul 1Fabiano Yokaichiya 2

1. Adam Mickiewicz University, Faculty of Chemistry, Grunwaldzka 6, Poznań 60-780, Poland
2. Hahn-Meitner-Institute (HMI), Glienicker Str. 100, Berlin D-14109, Germany


At room temperature, the lithium deficient sample of the Li0.95Mn2.05O4 obtained by quenching shows a tetragonally distorted spinel lattice, with c/a = 0.98 [1,2]. Partial substitution with very small quantities of Fe3+ ions for Mn3+ depresses the Jahn-Teller effect, reducing the Mn3+/ Mn4+ ratio.

Series of compounds with the Li0.95Mn2.05-xFexO4 stoichiometry have been obtained by solid state reaction of Li2CO3 with the manganese oxide or iron-manganese oxide precursors. The samples underwent a successive thermal treatment in air, at 700°C and 800°C for 4h. After heating, the preparations were either cooled slowly to the room temperature during 24h, or quenched rapidly in the solid CO2. The powder X-ray diffraction patterns of the substituted oxides were obtained using an X-ray diffractometer (Bruker D8 Advance), with copper Kα radiation. Neutron diffraction data were collected in the multicounter high-resolution diffractometer E9 installed at the BER II reactor in Hahn-Meitner-Institute (Berlin). The magnetometric measurements were made with DC-magnetometr/AC-susceptometer MagLab 2000 System (Oxford Instruments Ltd.). The phase identification and phase analysis were performed using the program PowderCell [3]. The structure refinement were performed using the program FullProf [4].

This study examines the effects of important processing parameters, such as composition and cooling condition. The phases obtained by quenching the products of thermal treatment, crystallize in the tetragonal system, space group I41/amd, on the other hand the samples formed as a result of slow cooling technique give nearly stoichiometric LiMn2O4, with the admixture of manganese oxides (bixbyite and hausmannite). A superexchange magnetic interaction between the Mn ions via oxygen atoms alerts, with the Fe3+-content in Li0.95Mn2.05-xFexO4 increasing from x = 0.0-0.1, showing the antiferromagnetic ordering at very low temperature. The Néel point increases from 11 to 27 K.


[1] W. Nowicki, J.Darul, P. Piszora, C. Baehtz, E. Wolska, J. Alloys Comp.,55, 401 (2005)

[2] P. Piszora, Chem. Mater.,4802, 18 (2006)

[3] W. Kraus, G. Nolze, PowderCell 2.3 (1998).

[4] J. Rodriguez-Carvajal, Physica B 159, 55 (1993)


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Submitted: 2008-04-30 13:11
Revised:   2009-06-07 00:48