Cobalt green

Cobalt green
Names
Other names cinnabar green, turquoise green, Rinman's green, Rinmann's green, zinc green
Identifiers
Properties
Chemical formula	Zn_1−xCo_xO
Solubility in water	Insoluble
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Chemical compound

Cobalt green is an ambiguous term for either of two families of green inorganic pigments. Both are obtained by doping cobalt(II) oxide into colorless host oxides.

Spinel-based cobalt green

Doping Co(II) into Mg(II) and Zn(II) sites of Mg₂TiO₄ and Zn₂TiO₄, respectively gives one family of cobalt greens. These materials adopt the spinel structure.^[1]

Rinman's green

Rinman's green, also referred to as Rinmann's green, is obtained by doping cobalt(II) oxide into zinc oxide. Sven Rinman, a Swedish chemist, discovered this compound in 1780. Zinc oxide–derived pigments have been used in many industries and processes. It is rarely used because it is a weak chromophore and relatively expensive compared to chromium(III) oxide.

The structure and color of compositions Zn_1−xCo_xO depends on the value of x. For x ≤ 0.3, the material adopts the Wurzite structure (of ZnO) and is intensely green. For x ≥ 0.7, the material has the sodium chloride structure (of CoO) and is pink. Intermediate values of x give a mixture of the two phases.^[2]

Cobalt green has been tested for use in "spintronic" devices. Cobalt green is attractive in this application because it is magnetic at room temperature.^[3]

References

^ Völz, Hans G. et al. "Pigments, Inorganic" in Ullmann's Encyclopedia of Industrial Chemistry, 2006 Wiley-VCH, Weinheim. doi:10.1002/14356007.a20_243.pub2.
^ F. Wagenknecht, and R. Juza "Rinmann's Green" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1092.
^ Djerdj, Igor; Jaglicic, Zvonko; Arcon, Denis; Niederberger, Markus (2010). "Co-Doped ZnO nanoparticles: Minireview". Nanoscale. 2 (7): 1096–1104. Bibcode:2010Nanos...2.1096D. doi:10.1039/c0nr00148a. PMID 20648333.