Manganese(III) oxide
| Manganese(III) oxide | |
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Other names
dimanganese trioxide, manganese sesquioxide, manganic oxide |
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| Identifiers | |
| CAS number | 1317-34-6  |
| PubChem | 14827 |
| RTECS number | OP915000 |
| Properties | |
| Molecular formula | Mn2O3 |
| Molar mass | 157.8743 g/mol |
| Appearance | brown or black crystalline |
| Density | 4.50 g/cm3 |
| Melting point |
940 °C (decomp) |
| Solubility in water | insoluble |
| Solubility | insoluble in alcohol, acetone soluble in acid |
| Structure | |
| Crystal structure | Cubic, cI80[1] |
| Space group | Ia-3, No. 206 |
| Related compounds | |
| Other anions | manganese trifluoride, manganese(III) acetate |
| Other cations | chromium(III) oxide, iron(III) oxide |
| Related compounds | manganese(II) oxide, manganese dioxide |
| Hazards | |
| NFPA 704 |
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 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Manganese(III) oxide is the chemical compound of formula Mn2O3.
[edit] Preparation and chemistry
Heating MnO2 in air at below 800 °C α-Mn2O3 is produced (higher temperatures produce Mn3O4).[2] γ-Mn2O3 can be produced by oxidation followed by dehydration of manganese(II) hydroxide.[2] Many preparations of nano-crystalline Mn2O3 have been reported, for example syntheses involving oxidation of MnII salts or reduction of MnO2.[3][4][5]
Manganese (III) oxide is formed by the redox reaction in an alkaline cell:
- 2 MnO2 + Zn → Mn2O3 + ZnO
Manganese (III) oxide Mn2O3 must not be confused with MnOOH manganese (III) oxohydroxide. Contrary to Mn2O3, MnOOH is a compound that decomposes at about 300 °C to form MnO2.[6]
[edit] Structure
Mn2O3 is unlike many other transition metal oxides in that it does not adopt the corundum (Al2O3) structure.[2] Two forms are generally recognized, α-Mn2O3 and γ-Mn2O3,[7] although a high pressure form with the CaIrO3 structure has been reported too.[8]
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).[9]
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.[7] γ-Mn2O3 is ferrimagnetic with a Neel temperature of 39 K.[10]
[edit] References
- ^ Otto H.H., Baltrasch R., Brandt H.J. (1993). "Further evidence for Tl3+ in Tl-based superconductors from improved bond strength parameters involving new structural data of cubic Tl2O3". Physica C 215: 205. doi:10.1016/0921-4534(93)90382-Z.
- ^ a b c Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0080379419.
- ^ Shuijin Lei, Kaibin Tang, Zhen Fang, Qiangchun Liu, Huagui Zheng (2006). "Preparation of α-Mn2O3 and MnO from thermal decomposition of MnCO3 and control of morphology". Materials Letters 60: 53. doi:10.1016/j.matlet.2005.07.0.
- ^ Zhong-Yong Yuan, Tie-Zhen Ren, Gaohui Du, Bao-Lian Su (2004). "A facile preparation of single-crystalline α-Mn2O3 nanorods by ammonia-hydrothermal treatment of MnO2". Chemical Physics Letters 389: 83. doi:10.1016/j.cplett.2004.03.064.
- ^ Navin Chandra, Sanjeev Bhasin, Meenakshi Sharma and Deepti Pal (2007). "A room temperature process for making Mn2O3 nano-particles and γ-MnOOH nano-rods". Materials Letters 61 (17): 3728. doi:10.1016/j.matlet.2006.12.024.
- ^ Thomas Kohler, Thomas Armbruster, Eugen Libowitzky (1997). "Hydrogen Bonding and Jahn-Teller Distortion in Groutite,α-MnOOH, and Manganite,γ-MnOOH, and Their Relations to the Manganese Dioxides Ramsdellite and Pyrolusite". Journal of Solid State Chemistry 133 (2): 486–500. doi:10.1006/jssc.1997.7516.
- ^ a b Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications 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
- ^ Geller S. (1971). "Structure of α-Mn2O3, (Mn0.983Fe0.017)2O3 and (Mn0.37Fe0.63)2O3 and relation to magnetic ordering". Acta Cryst B27 (4): 821. doi:10.1107/S0567740871002966.
- ^ 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.
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