Structural and magnetic characterization of mixed oxides: a study of Li-Ni-O and Li-Mn-O systems

The present paper details the way to determine the cation distribution in mixed oxides with transition ions from the diffraction and magnetic susceptibility data. This approach allows one to determine phase abundances and phase compositions by two combined procedures. By X-ray diffraction Rietveld profile refinement and magnetic susceptibility data analysis it is possible to estimate the ratio and the occupancy factor of paramagnetic ions in different oxidation states. A brief discussion of practical cases is reported. In the Li-Ni-O system the lithium cationic fraction of the ordered phase Li2xNi2-2xO2 increases monotonically with the total lithium fraction x1 for 0.31 ≤ x1 ≤ 0.46. In the Li-Mn-O system for 0.36 ≤ x1 ≤ 0.53 the Li2MnO3 fraction has been determined, and for the coexistent Li [LiyMn2-y]O4 spinel phase the dependence of y on x1 has been evaluated.