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Cobalt(II) phosphate

Names
Other names cobalt violet, cobalt(II) phosphate, cobalt orthophosphate, Pigment Violet 14
Identifiers
CAS Number	(tetrahydrate: 10294-50-5) 13455-36-2 (tetrahydrate: 10294-50-5)
3D model (JSmol)	Interactive image
ChemSpider	55523
ECHA InfoCard	100.033.309
EC Number	236-655-6
PubChem CID	61615
UNII	0B5M38T47H
CompTox Dashboard (EPA)	DTXSID20893875
InChI InChI=1S/3Co.2H3O4P/c;;;2*1-5(2,3)4/h;;;2*(H3,1,2,3,4)/q3*+2;;/p-6Key: ZBDSFTZNNQNSQM-UHFFFAOYSA-H InChI=1/3Co.2H3O4P/c;;;2*1-5(2,3)4/h;;;2*(H3,1,2,3,4)/q3*+2;;/p-6Key: ZBDSFTZNNQNSQM-CYFPFDDLAU
SMILES P(=O)().P(=O)()...
Properties
Chemical formula	Co3(PO4)2
Molar mass	366.74231 g/mol
Appearance	violet solid
Density	3.81 g/cm
Melting point	1,160 °C (2,120 °F; 1,430 K)
Solubility in water	insoluble
Solubility product (Ksp)	2.05×10
Magnetic susceptibility (χ)	28,110.0·10 cm/mol
Refractive index (nD)	1.7
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references

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

Preparation and structure

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 (PO
₄) anions that link Co
centres. The cobalt ions occupy both octahedral (six-coordinate) and pentacoordinate sites in a 1:2 ratio.

See also

• List of inorganic pigments

References

1. John Rumble (June 18, 2018). CRC Handbook of Chemistry and Physics (99th ed.). CRC Press. pp. 5–188. ISBN 978-1138561632.
2. 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
3. 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.
4. Donaldson, John Dallas; Beyersmann, Detmar (2005). "Cobalt and Cobalt Compounds". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a07_281.pub2. ISBN 9783527303854.
5. Sankar, Selvasundarasekar Sam; Rathishkumar, Arumugam; Geetha, Kathiresan; Kundu, Subrata (2020-10-15). "A Simple Route for the Synthesis of Cobalt Phosphate Nanoparticles for Electrocatalytic Water Oxidation in Alkaline Medium". Energy & Fuels. 34 (10): 12891–12899. doi:10.1021/acs.energyfuels.0c02809. ISSN 0887-0624. S2CID 224960926.
6. 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 (4): 372–377. Bibcode:1975JSSCh..14..372A. doi:10.1016/0022-4596(75)90058-4.
7. Nord, A. G.; Stefanidis, T. (1983). "Structure refinements of Co₃(PO₄)₂. A Note on the Reliability of Powder Diffraction Studies". Acta Chemica Scandinavica A. 37: 715–721. doi:10.3891/acta.chem.scand.37a-0715.

• Phosphates
• Cobalt(II) compounds
• Inorganic pigments