Cobalt green

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

Cobalt green

Names
Other names cinnabar green, turquoise green, Rinman's green, Rinmann's green, zinc green
Identifiers
Properties
Chemical formula	Zn1−xCoxO
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

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 Wurtzite 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]

See also

• Cobalt blue
• List of inorganic pigments