Cobalt(II,III) oxide
Chemical compound
From Wikipedia, the free encyclopedia
Cobalt(II,III) oxide is an inorganic compound with the formula Co3O4. Along with cobalt(II) oxide, it is one of two well characterized and stable cobalt oxides.[4] It is a black antiferromagnetic solid. As a mixed valence compound, its formula is sometimes written as Co2+Co3+2O4 and sometimes as CoO·Co2O3.[5] It occurs naturally as the rare mineral guite which is named in honor of Prof. Xiangping Gu (1964-).[6]
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| IUPAC name
cobalt(II) dicobalt(III) oxide | |
Other names
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| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.013.780 |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
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| Molar mass | 240.796 g·mol−1 |
| Appearance | black solid |
| Density | 6.07 g/cm3[2] |
| Melting point | 895 °C (1,643 °F; 1,168 K) |
| Boiling point | 900 °C (1,650 °F; 1,170 K) (decomposes) |
| Insoluble | |
| Solubility | soluble (with degradation) in acids and alkalis |
| 7380×10−6 cm3/mol | |
| Structure | |
| cubic | |
| Fd3m, No. 227[3] | |
| Hazards | |
| GHS labelling:[citation needed] | |
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| Danger | |
| H317, H334, H350, H411 | |
| P261, P273, P284, P304+P340, P342+P311 | |
| NFPA 704 (fire diamond) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Structure
Co3O4 adopts the normal spinel structure, with Co2+ ions in tetrahedral interstices and Co3+ ions in the octahedral interstices of the cubic close-packed lattice of oxide anions.[5]
-oxide-xtal-2006-Co(II)-coord-CM-3D-balls.png) | -oxide-xtal-2006-Co(III)-coord-CM-3D-balls.png) | -oxide-xtal-2006-O-coord-CM-3D-balls.png) |
| tetrahedral coordination geometry of Co(II) | distorted octahedral coordination geometry of Co(III) | distorted tetrahedral coordination geometry of O |
Synthesis
Cobalt(II) oxide, CoO, converts to Co3O4 upon heating at around 600–700 °C (1,112–1,292 °F) in air.[5] Above 900 °C (1,650 °F), CoO is stable.[5][7] These reactions are described by the following equilibrium:
- 2 Co3O4 ⇌ 6 CoO + O2
Applications
Cobalt(II,III) oxide is used as a blue coloring agent for pottery enamel and glass, as an alternative to cobalt(II) oxide.[8]
Cobalt(II,III) oxide is used as an electrode in some lithium-ion batteries, possibly in the form of cobalt oxide nanoparticles.
Cobalt(III) fluoride can be prepared from cobalt(II,III) oxide by sequential treatment with hydrogen fluoride and then fluorine gas, producing a mixture of cobalt(II) fluoride and cobalt oxyfluoride as intermediates, with overall stoichiometry:[4]
- Co3O4 + 4 HF → CoF2 + 2 CoOF + 2 H2O
- 2 CoF2 + 4 CoOF + 5 F2 → 6 CoF3 + 2 O2