CHARGE ORDER TRANSITION IN LiMn2O4

Stoichiometric LiMn2O4 undergoes a structural phase transition around room temperature from cubic to orthorhombic, induced by a partial charge ordering on the manganese sites, similar to the Verwey transition occurring in Fe3O4. We Studied the charge ordering transition of LiMn2O4 by means of anelastic spectroscopy, measuring the Young's modulus, E, and the elastic energy loss function, Q(-1). Our measurements confirm the occurrence of a phase transition at 292 K on cooling, showing a large hysteresis on heating. The anelastic spectroscopy results also indicate that the transformation is characterised by the coexistence of two phases. In addition, the Young's modulus reveals presence of an additional anomaly, on cooling, around the onset of the phase transformation.