Cationic distribution and oxidation kinetics of divalent manganese ions in iron manganite spinels Mn 3 − xFe xO 4 (0 < x < 1.50)

Abstract

A quantitative analysis by derivative thermogravimetry based on the difference of reactivity in oxygen of Mn 2+ ions of iron manganite spinels Mn 3 − x Fe x O 4 with 0 < x < 1.50 in relation to the occupied site (octahedral B site or tetrahedral A site) permits a cation distribution to be proposed. Kinetics studies on the oxidation process of Mn 2+ ions show that the oxidation proceeds by way of a diffusion-controlled reaction for Mn 2+ ions located at B sites and by a nucleation-growth mechanism for Mn 2+ ions located at A sites. The difference in the kinetics behavior has been attributed to a structural change cation-deficient spinel into multi-phase oxides induced by oxidation temperature.