Magnetic characterization of Li1+xMn2-xO4 spinel (0 ≤ x ≤ 1/3)

Li1+xMn2-xO4 spinels have been prepared by wet route technique in the whole concentration range 0 <= x <= 1. Structural analysis has been performed by X-ray diffraction and scanning electron microscopy and Raman spectroscopy. The investigation of impurity phases by magnetic experiments complete the sample characterization, allowing for a comparison with samples obtained by other chemical routes. The analysis of the intrinsic magnetic properties show that the magnetic interactions are Mn3+-O-Mn3+ interactions in a geometrically frustrated lattice, while the Mn4+-Mn4+ interactions are negligible, with the consequence that the paramagnetic Curie temperature vanishes in the limit x similar or equal to 1/3 where only Mn4+ ions remain. A consistent description of both the extrinsic and the intrinsic properties including former investigations of electron paramagnetic resonance has been achieved in relation to the electrochemical properties. (C) 2007 Elsevier Ltd. All rights reserved.