Raman spectroscopic studies of lithium manganates with spinel structure

Raman scattering spectra of a set of lithium manganospinels Li_1−x+zMn_2−zO₄ with 0 ^≤ x^≤ 1 and 0 ^≤ z^≤ 0.33 are reported and analysed. Structural changes have been investigated following the evolution of Raman spectra with the concentration of lithium cations. The local structure was characterized as a function of the mean oxidation state of manganese cations. The trigonal distortion of MnO₆ octahedra is evidenced by insertion of lithium ions into the [B₂]O₄ spinel framework. A comparison with tetragonal Mn₃O₄ and Fe₃O₄ spinels shows the influence of the Jahn–Teller effect on the Raman features for this class of materials.