Manganese(II,III) oxide is the chemical compound with formula Mn₃O₄. Manganese is present in two oxidation states +2 and +3 and the formula is sometimes written as MnO.Mn₂O₃. Mn₃O₄ is found in nature as the mineral hausmannite.

Preparation

Mn₃O₄ formed when any manganese oxide is heated in air above 1000°C. Considerable research has centred on producing nano-crystalline Mn₃O₄ and various syntheses that involve oxidation of Mn^II or reduction of Mn^VI.

Reactions

Mn₃O₄ has been found to act as a catalyst for a range of reactions e.g. the oxidation of methane and carbon monoxide ; the decomposition of NO, the reduction of nitrobenzene and the catalytic combustion of organic compounds

Structure

Mn₃O₄ has the spinel structure, where the oxide ions are cubic close packed and the Mn^II occupy tetrahedral sites and the Mn^III octahedral sites. The structure is distorted due to a Jahn-Teller effect. At room temperature Mn₃O₄ is paramagnetic, below 41-43 K, it is ferrimagnetic. although this has been reported as reducing in nano-crystalline samples to around 39 K

Uses

Mn₃O₄ is sometimes used as a starting material in the production of soft ferrites e.g. manganese zinc ferrite, and lithium manganese oxide, used in lithium batteries.

References