Manganese(III) oxide
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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
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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
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Thermochemistry | |
Std molar
entropy (S⦵298) |
110 J·mol−1·K−1[2] |
Std enthalpy of (ΔfH⦵298)formation |
−971 kJ·mol−1[2] |
Hazards | |
NFPA 704 (fire diamond) | |
Related compounds | |
Other anions
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manganese trifluoride, manganese(III) acetate
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Other cations
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chromium(III) oxide, iron(III) oxide |
Related compounds
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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).
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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.
Preparation and chemistry
Heating
Manganese(III) oxide is formed by the redox reaction in an alkaline cell:
- 2 MnO2 + Zn → Mn2O3 + ZnO[citation needed]
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]
Structure
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
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]
References
- S2CID 225561660.
- ^ ISBN 978-0-618-94690-7.
- ^ "Bixbyite-(Mn)".
- ^ IMA 21-H: Redefinition of bixbyite and definition of bixbyite-(Fe) and bixbyite-(Mn). CNMNC Newsletter, 64, 2021; Mineralogical Magazine, 85, 2021).
- ^ ISBN 978-0-08-037941-8.
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- ^ ISBN 0-19-855370-6
- ^ High Pressure Phase transition in Mn2O3 to the CaIrO3-type Phase Santillan, J.; Shim, S. American Geophysical Union, Fall Meeting 2005, abstract #MR23B-0050
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- ^ Kim S. H; Choi B. J; Lee G.H.; Oh S. J.; Kim B.; Choi H. C.; Park J; Chang Y. (2005). "Ferrimagnetism in γ-Manganese Sesquioxide (γ−Mn2O3) Nanoparticles". Journal of the Korean Physical Society. 46 (4): 941.
- S2CID 237242460.