Cobalt phosphate

  (Redirected from Cobalt violet)

Cobalt phosphate is the inorganic compound with the formula Co3(PO4)2. It is a commercial inorganic pigment known as cobalt violet.[1] Thin films of this material are water oxidation catalysts.[2]

Cobalt phosphate
Cobalt(II) phosphate.JPG
Other names
cobalt violet, cobalt(II) phosphate, cobalt orthophosphate, Pigment Violet 14
3D model (JSmol)
ECHA InfoCard 100.033.309
EC Number
  • 236-655-6
Molar mass 366.74231 g/mol
Appearance violet solid
Density 3.81 g/cm3
Melting point 1,160 °C (2,120 °F; 1,430 K)
28,110.0·10−6 cm3/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
A swatch of cobalt violet, popular among the French impressionists.

Preparation and structureEdit

The tetrahydrate Co3(PO4)2•4H2O precipitates as a solid upon mixing aqueous solutions of cobalt(II) and phosphate salts. Upon heating, the tetrahydrate converts to the anhydrous material. According to X-ray crystallography, the anhydrous Co3(PO4)2 consists of discrete phosphate (PO3−
) anions that link Co2+
centres. The cobalt ions occupy both octahedral (six-coordinate) and pentacoordinate sites in a 1:2 ratio.[3][4]

See alsoEdit


  1. ^ Hugo Müller, Wolfgang Müller, Manfred Wehner, Heike Liewald "Artists' Colors" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a03_143.pub2
  2. ^ Matthew W. Kanan, Yogesh Surendranatha, Daniel G. Nocera (2009). "Cobalt–phosphate oxygen-evolving Compound". Chem. Soc. Rev. 38 (1): 109–114. doi:10.1039/B802885K. PMID 19088970.CS1 maint: uses authors parameter (link)
  3. ^ Anderson, J. B.; Kostiner, E.; Miller, M. C.; Rea, J. R. (1975). "Crystal structure of cobalt orthophosphate Co3(PO4)2". Journal of Solid State Chemistry. 14: 372–7.CS1 maint: uses authors parameter (link)
  4. ^ Nord, A. G.; Stefanidis, T. (1983). "Structure of cobalt(II) phosphateStructure refinements of Co3(PO4)2. A Note on the Reliability of Powder Diffraction Studies". Acta Chemica Scandinavica A. 37: 715–p721.CS1 maint: uses authors parameter (link)