'''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 Mg<sub>2</sub>TiO<sub>4</sub> and Zn<sub>2</sub>TiO<sub>4</sub>, respectively gives one family of cobalt greens. These materials adopt the spinel structure.<ref name=Ullmann>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}}.</ref>
== Rinman's green== {{Chembox | Name = Rinman's green | ImageFile = | ImageSize = | ImageAlt = | IUPACName = | OtherNames = {{ubl|Cinnabar green|Turquoise green|Rinman's green|Rinmann's green|Zinc green}} |Section2={{Chembox Properties | Formula = Zn<sub>1−x</sub>Co<sub>x</sub>O | MolarMass = | Appearance = | Density = | MeltingPt = | BoilingPt = | Solubility = Insoluble}} |Section3={{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }} }} 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<sub>1−x</sub>Co<sub>x</sub>O 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.<ref>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.</ref>
Cobalt green has been tested for use in "spintronic" devices. Cobalt green is attractive in this application because it is magnetic at room temperature.<ref>{{cite journal|title=Co-Doped ZnO nanoparticles: Minireview |author1=Djerdj, Igor|author2=Jaglicic, Zvonko|author3=Arcon, Denis|author4=Niederberger, Markus|doi=10.1039/c0nr00148a|journal=Nanoscale|year=2010|volume=2|issue=7|pages=1096–1104|pmid=20648333|bibcode=2010Nanos...2.1096D}}</ref>
== See also == * Cobalt blue * List of inorganic pigments
==References== <references/>
== External links == * [http://webexhibits.org/pigments/indiv/overview/cogreen.html Pigments through the Ages]
{{cobalt compounds}} {{zinc compounds}}
Category:Inorganic pigments Category:Cobalt compounds Category:Zinc compounds Category:Transition metal oxides