Manganese(III) oxide

• Dimanganese trioxide
• Mangansesquioxid

Black odorless solid

Fixed

4.50 g · cm -3

940 ° C ( decomposition)

Insoluble in water

Attention

0.5 mg · m-3

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Manganese ( III) oxide is an oxide of manganese.

Production and representation

It arises, for example, in zinc - manganese dioxide cells in their discharge:

Manganese (III ) oxide ( MnO 2, at temperatures over 535 ° C) is also produced by the decomposition of the manganese ( IV) oxide.

When implementing a solution of manganese sulfate tetrahydrate with hydrogen peroxide and ammonia at room temperature, γ -MnO (OH) ( manganite ). From this it can be obtained by careful dehydrating in vacuum at 250 ° C. γ - manganese ( III) oxide.

Properties

Manganese (III ) oxide is a non-flammable black odorless solid that is practically insoluble in water. It decomposes on heating above 940 ° C. The non-naturally occurring γ - Mn2O3 has a tetragonal crystal structure with space group I41/amd (a = 577 pm, c = 944 pm ). It converts at 500 ° C in 48 hours, at room temperature for one year in the α - form. This has at temperatures above 29 ° C a cubic bixbyite structure with space group Ia3 and including an orthorhombic bixbyite structure with space group PCAB. At higher pressures also other modifications exist. So having at pressures above 28 GPa synthesizable δ - Mn2O3 a crystal structure of CaIrO3 type with the space group Cmcm, ε - Mn2O3 crystal structure of corundum type with the space group R3c and ζ - Mn2O3 a distorted triclinic Doppelperovskit structure with space group F1.

Use

Manganese (III ) oxide is used as a starting material for the manufacture of lithium manganate (III, IV) LiMn2O4 ( cathode material of lithium -ion batteries ) and as a pigment in paints ( colors eg brown glass ) is used.