Cobalt phosphate is the

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

with the formula Co₃(PO₄)₂. It is a commercial inorganic

pigment A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...

known as cobalt violet.Hugo Müller, Wolfgang Müller, Manfred Wehner, Heike Liewald "Artists' Colors" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. Thin films of this material are

water oxidation catalyst Water oxidation catalysis (WOC) is the acceleration (catalysis) of the conversion of water into oxygen and protons: :2 H2O → 4 H+ + 4 e− + O2 Many catalysts are effective, both homogeneous catalysts and heterogeneous catalysts. The oxygen ev ...

s. :

Preparation and structure

The tetrahydrate Co₃(PO₄)₂•4H₂O precipitates as a solid upon mixing aqueous solutions of

cobalt(II) Cobalt is a chemical element; it has symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, pr ...

and phosphate salts. Upon heating, the tetrahydrate converts to the anhydrous material. According to

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

, the anhydrous Co₃(PO₄)₂ consists of discrete phosphate () anions that link centres. The cobalt ions occupy both

octahedral In geometry, an octahedron (: octahedra or octahedrons) is any polyhedron with eight faces. One special case is the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at each vertex. Many types of i ...

(six-coordinate) and pentacoordinate sites in a 1:2 ratio.

References

{{Phosphates Phosphates Cobalt(II) compounds Inorganic pigments

Preparation and structure

See also

References