Crystal structure of disodium dicobalt(II) iron(III) tris-(orthophosphate) with an alluaudite-like structure

• Published in: Acta crystallographica. Section E, Crystallographic communications Vol. 71; no. Pt 5; pp. 558 - 560
• Main Authors: Bouraima, Adam, Assani, Abderrazzak, Saadi, Mohamed, Makani, Thomas, El Ammari, Lahcen
• Format: Journal Article
• Language: English
• Published: England International Union of Crystallography 01.05.2015
• Subjects: alluaudite-like structure; crystal structure; Na2Co2Fe(PO4)3; Research Communications; solid-state reaction synthesis; transition metal phosphates; crystal structure; alluaudite-like structure; Na2Co2Fe(PO4)3; transition metal phosphates; solid-state reaction synthesis
• ISSN: 2056-9890; 2056-9890
• DOI: 10.1107/S2056989015007926

The title compound, Na2Co2Fe(PO4)3, was synthesized by a solid-state reaction. This new stoichiometric phase crystallizes in an alluaudite-like structure. In this structure, all atoms are in general positions except for four atoms which are located at the special positions of the C2/c space group. One Co atom, one P and one Na atom are all located on Wyckoff position 4e (2), while the second Na atom is located on an inversion centre 4a (-1). The other Co and Fe atoms occupy a general position with a statistical distribution. The open framework results from [(Co,Fe)2O10] units of edge-sharing [(Co,Fe)O6] octa-hedra, which alternate with [CoO6] octa-hedra that form infinite chains running along the [10-1] direction. These chains are linked together through PO4 tetra-hedra by the sharing of vertices so as to build layers perpendicular to [010]. The three-dimensional framework is accomplished by the stacking of these layers, leading to the formation of two types of tunnels parallel to [010] in which the Na(+) cations are located, each cation being surrounded by eight O atoms.