At room temperature, the lithium deficient sample of the Li_0.95Mn_2.05O₄ 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 Li_0.95Mn_2.05-xFe_xO₄ 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 K_α 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 Li_0.95Mn_2.05-xFe_xO₄ 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)

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/15375 must be provided.

1. Structural properties and compressibility of spinels: More questions than answers
2. Synchrotron X-ray diffraction studies of products of the steel pipe corrosion measured in the native aqueous suspension
3. Effect of Zn doping on the tetragonally distorted CuFe₂O₄ structure
4. Phase transitions in the spinel Li_xMn_3-xO₄ intercalation compounds. Synchrotron X-ray diffraction studies.