Cobalt(II,III) oxide explained

Cobalt(II,III) oxide is an inorganic compound with the formula Co₃O₄. It is one of two well characterized cobalt oxides. It is a black antiferromagnetic solid. As a mixed valence compound, its formula is sometimes written as Co^IICo^III₂O₄ and sometimes as CoO•Co₂O₃.

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.

Synthesis

Cobalt(II) oxide, CoO, converts to Co₃O₄ upon heating at around 600–700 °C in air. Above 900 °C, CoO is stable.^[1] 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.^[2]

Cobalt(II,III) oxide is used as an electrode in some lithium-ion batteries, possibly in the form of cobalt oxide nanoparticles.

Safety

Cobalt compounds are potentially poisonous in large amounts.^[3]

Notes and References

Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. p. 1520.
Frank Hamer, Janet Hamer (2004): The Potter's Dictionary of Materials and Techniques. University of Pennsylvania Press; 437 pp.
http://www.mallbaker.com/americas/msds/english/c4961_msds_us_default.pdf MSDS