Electric and magnetic properties of LiMn2O4- and Li2MnO3-type oxides

XRD measurements proved the coexistence of spinel, lithium-rich spinel, and rock-salt phases in the Li-Mn-O system. An investigation of the electrical properties, carried out on polycrystalline samples, shows that Li2MnO3 has insulating behavior while the spinel phases provide an example of hopping conduction mechanism. The negative Seebeck coefficient suggests that electrons constitute the charge carriers and their number is consistent with the fraction of Mn3+ over the total number of Mn3+ and Mn4+ sites in the spinel structure. The static magnetic susceptibility results agree with the presence of the Mn3+ ions in high spin configuration. (C) 1997 Academic Press.