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Names | |
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Other names
dimanganese trioxide, manganese sesquioxide, manganic oxide, manganous oxide
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Identifiers | |
3D model (
JSmol)
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ChemSpider | |
ECHA InfoCard | 100.013.878 |
PubChem
CID
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RTECS number |
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UNII | |
CompTox Dashboard (
EPA)
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Properties | |
Mn2O3 | |
Molar mass | 157.8743 g/mol |
Appearance | brown or black crystalline |
Density | 4.50 g/cm3 |
Melting point | 888 °C (1,630 °F; 1,161 K) (alpha form) 940 °C, decomposes (beta form) |
0.00504 g/100 mL (alpha form) 0.01065 g/100 mL (beta form) | |
Solubility | insoluble in
ethanol,
acetone soluble in acid, ammonium chloride |
+14,100·10−6 cm3/mol | |
Structure [1] | |
Bixbyite, cI80 | |
Ia3 (No. 206) | |
a = 942 pm
| |
Thermochemistry | |
Std molar
entropy (S⦵298) |
110 J·mol−1·K−1 [2] |
Std enthalpy of
formation (ΔfH⦵298) |
−971 kJ·mol−1 [2] |
Hazards | |
NFPA 704 (fire diamond) | |
Related compounds | |
Other
anions
|
manganese trifluoride, manganese(III) acetate |
Other
cations
|
chromium(III) oxide, iron(III) oxide |
Related compounds
|
manganese(II) oxide, manganese dioxide |
Except where otherwise noted, data are given for materials in their
standard state (at 25 °C [77 °F], 100 kPa).
|
Manganese(III) oxide is a chemical compound with the formula Mn2O3. It occurs in nature as the mineral bixbyite (recently changed to bixbyite-(Mn) [3] [4]) and is used in the production of ferrites and thermistors.
Heating MnO2 in air at below 800 °C produces α-Mn2O3 (higher temperatures produce Mn3O4). [5] γ-Mn2O3 can be produced by oxidation followed by dehydration of manganese(II) hydroxide. [5] Many preparations of nano-crystalline Mn2O3 have been reported, for example syntheses involving oxidation of MnII salts or reduction of MnO2. [6] [7] [8]
Manganese(III) oxide is formed by the redox reaction in an alkaline cell:
Manganese(III) oxide Mn2O3 must not be confused with MnOOH manganese(III) oxyhydroxide. Contrary to Mn2O3, MnOOH is a compound that decomposes at about 300 °C to form MnO2. [9]
Mn2O3 is unlike many other transition metal oxides in that it does not adopt the corundum ( Al2O3) structure. [5] Two forms are generally recognized, α-Mn2O3 and γ-Mn2O3, [10] although a high pressure form with the CaIrO3 structure has been reported too. [11]
α-Mn2O3 has the cubic bixbyite structure, which is an example of a C-type rare earth sesquioxide ( Pearson symbol cI80, space group Ia3, #206). The bixbyite structure has been found to be stabilised by the presence of small amounts of Fe3+, pure Mn2O3 has an orthorhombic structure ( Pearson symbol oP24, space group Pbca, #61). [12] α-Mn2O3 undergoes antiferromagnetic transition at 80 K. [13]
γ-Mn2O3 has a structure related to the spinel structure of Mn3O4 where the oxide ions are cubic close packed. This is similar to the relationship between γ-Fe2O3 and Fe3O4. [10] γ-Mn2O3 is ferrimagnetic with a Néel temperature of 39 K. [14]
ε-Mn2O3 takes on a rhombohedral ilmenite structure (the first binary compound known to do so), wherein the manganese cations divided equally into oxidation states 2+ and 4+. ε-Mn2O3 is antiferromagnetic with a Néel temperature of 210 K. [15]
![]() | |
Names | |
---|---|
Other names
dimanganese trioxide, manganese sesquioxide, manganic oxide, manganous oxide
| |
Identifiers | |
3D model (
JSmol)
|
|
ChemSpider | |
ECHA InfoCard | 100.013.878 |
PubChem
CID
|
|
RTECS number |
|
UNII | |
CompTox Dashboard (
EPA)
|
|
| |
| |
Properties | |
Mn2O3 | |
Molar mass | 157.8743 g/mol |
Appearance | brown or black crystalline |
Density | 4.50 g/cm3 |
Melting point | 888 °C (1,630 °F; 1,161 K) (alpha form) 940 °C, decomposes (beta form) |
0.00504 g/100 mL (alpha form) 0.01065 g/100 mL (beta form) | |
Solubility | insoluble in
ethanol,
acetone soluble in acid, ammonium chloride |
+14,100·10−6 cm3/mol | |
Structure [1] | |
Bixbyite, cI80 | |
Ia3 (No. 206) | |
a = 942 pm
| |
Thermochemistry | |
Std molar
entropy (S⦵298) |
110 J·mol−1·K−1 [2] |
Std enthalpy of
formation (ΔfH⦵298) |
−971 kJ·mol−1 [2] |
Hazards | |
NFPA 704 (fire diamond) | |
Related compounds | |
Other
anions
|
manganese trifluoride, manganese(III) acetate |
Other
cations
|
chromium(III) oxide, iron(III) oxide |
Related compounds
|
manganese(II) oxide, manganese dioxide |
Except where otherwise noted, data are given for materials in their
standard state (at 25 °C [77 °F], 100 kPa).
|
Manganese(III) oxide is a chemical compound with the formula Mn2O3. It occurs in nature as the mineral bixbyite (recently changed to bixbyite-(Mn) [3] [4]) and is used in the production of ferrites and thermistors.
Heating MnO2 in air at below 800 °C produces α-Mn2O3 (higher temperatures produce Mn3O4). [5] γ-Mn2O3 can be produced by oxidation followed by dehydration of manganese(II) hydroxide. [5] Many preparations of nano-crystalline Mn2O3 have been reported, for example syntheses involving oxidation of MnII salts or reduction of MnO2. [6] [7] [8]
Manganese(III) oxide is formed by the redox reaction in an alkaline cell:
Manganese(III) oxide Mn2O3 must not be confused with MnOOH manganese(III) oxyhydroxide. Contrary to Mn2O3, MnOOH is a compound that decomposes at about 300 °C to form MnO2. [9]
Mn2O3 is unlike many other transition metal oxides in that it does not adopt the corundum ( Al2O3) structure. [5] Two forms are generally recognized, α-Mn2O3 and γ-Mn2O3, [10] although a high pressure form with the CaIrO3 structure has been reported too. [11]
α-Mn2O3 has the cubic bixbyite structure, which is an example of a C-type rare earth sesquioxide ( Pearson symbol cI80, space group Ia3, #206). The bixbyite structure has been found to be stabilised by the presence of small amounts of Fe3+, pure Mn2O3 has an orthorhombic structure ( Pearson symbol oP24, space group Pbca, #61). [12] α-Mn2O3 undergoes antiferromagnetic transition at 80 K. [13]
γ-Mn2O3 has a structure related to the spinel structure of Mn3O4 where the oxide ions are cubic close packed. This is similar to the relationship between γ-Fe2O3 and Fe3O4. [10] γ-Mn2O3 is ferrimagnetic with a Néel temperature of 39 K. [14]
ε-Mn2O3 takes on a rhombohedral ilmenite structure (the first binary compound known to do so), wherein the manganese cations divided equally into oxidation states 2+ and 4+. ε-Mn2O3 is antiferromagnetic with a Néel temperature of 210 K. [15]