Versatile electronic behavior of the LixMn3-x-yFeyO4 spinels

The detailed structural and electronic characterization of microcrystalline powders of new spinels Lix-Mn3-x-yFeyO4 (0.4 <= x <= 1.33; 0 <= y <= 1.30), obtained by the liquid mix method, is reported. Compositional characterization was carried out by means of thermogravimetric analysis, energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy, and their structure was refined from neutron and Xray diffraction showing a cubic symmetry between 5 and 550 K, Space Group Fd (3) over barm. However, at temperatures above ca. 950 K, a reversible transformation, probably implying the formation of an ordered vacant phase, has been detected. The magnetic behavior, analyzed from neutron diffraction data and magnetization measurements, is interpreted considering an incomplete ferrimagnetic response, due to magnetic frustration in the B sites. Potential applications have been evaluated from the magnetocaloric, electrochemical and dielectric behavior in selected compositional ranges. (C) 2013 Elsevier B.V. All rights