Manganese(III) oxide

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Manganese(III) oxide
Other names dimanganese trioxide, manganese sesquioxide, manganic oxide
Identifiers
CAS number [1317-34-6]
Properties
Molecular formula Mn2O3
Molar mass 157.874 g/mol
Appearance brown or black
Density 5.00 g/cm3
Melting point

940°C
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and 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).[1] γ-Mn2O3 can be produced by oxidation followed by dehydration of manganese(II) hydroxide.[1] Many preparations of nano-crystalline Mn2O3 have been reported, for example syntheses involving oxidation of MnII salts or reduction of MnO2.[2][3][4]

[edit] Structure

Mn2O3 is unlike many other transition metal oxides, M2O3, as the Al2O3, corundum structure is not adopted.[1] Two forms are generally recognised, , α-Mn2O3 and γ-Mn2O3 [5], although a high pressure form with the CaIrO3 structure has been reported.[6]
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 ).[7]
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.[5] γ-Mn2O3 has been reported to be ferrimagnetic with a Neel temperature of 39 K.[8]

[edit] References

  1. ^ a b c Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4. 
  2. ^ Preparation of α-Mn2O3 and MnO from thermal decomposition of MnCO3 and control of morphology Shuijin Lei, Kaibin Tang, Zhen Fang, Qiangchun Liu, Huagui Zheng, Materials Letters 60, 1, (2006), 53-56 doi:10.1016/j.matlet.2005.07.0
  3. ^ A facile preparation of single-crystalline α-Mn2O3 nanorods by ammonia-hydrothermal treatment of MnO2 Zhong-Yong Yuan, Tie-Zhen Ren , Gaohui Du, Bao-Lian Su Chemical Physics Letters,389,1-3,(2004), 83-86, doi:10.1016/j.cplett.2004.03.064
  4. ^ A room temperature process for making Mn2O3 nano-particles and γ-MnOOH nano-rods Navin Chandra, Sanjeev Bhasin, Meenakshi Sharma and Deepti Pal Materials Letters 61, 17, (2007), 3728- -3732 doi:10.1016/j.matlet.2006.12.024
  5. ^ a b Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
  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
  7. ^ Structure of α-Mn2O3, (Mn0.983Fe0.017)2O3 and (Mn0.37Fe0.63)2O3 and relation to magnetic ordering , Geller S., Acta Cryst. (1971). B27, 821-828 doi:10.1107/S0567740871002966
  8. ^ Ferrimagnetism in γ-Manganese Sesquioxide (γ−Mn2O3) Nanoparticles, Kim S. H, Choi B. J ,Lee G.H., Oh S. J., Kim B., Choi H. C., Park J, Chang Y., Journal of the Korean Physical Society, 46, 4, (2005), 941∼944