title: Crystal structure of disodium dicobalt(II) iron(III) tris-(orthophosphate) with an alluaudite-like structure.
abstract: 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.
authors.affiliation: Laboratoire de Chimie du Solide Appliquée, Faculté des Sciences, Université Mohammed V, Avenue Ibn Battouta, BP 1014, Rabat, Morocco ; Département de chimie, Faculté des Sciences, Université des Sciences et Techniques de Masuku, BP 943, Franceville, Gabon.
authors.forename: Adam
authors.initials: A
authors.lastname: Bouraima
authors.affiliation: Laboratoire de Chimie du Solide Appliquée, Faculté des Sciences, Université Mohammed V, Avenue Ibn Battouta, BP 1014, Rabat, Morocco.
authors.forename: Abderrazzak
authors.initials: A
authors.lastname: Assani
authors.affiliation: Laboratoire de Chimie du Solide Appliquée, Faculté des Sciences, Université Mohammed V, Avenue Ibn Battouta, BP 1014, Rabat, Morocco.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Saadi
authors.affiliation: Département de chimie, Faculté des Sciences, Université des Sciences et Techniques de Masuku, BP 943, Franceville, Gabon.
authors.forename: Thomas
authors.initials: T
authors.lastname: Makani
authors.affiliation: Laboratoire de Chimie du Solide Appliquée, Faculté des Sciences, Université Mohammed V, Avenue Ibn Battouta, BP 1014, Rabat, Morocco.
authors.forename: Lahcen
authors.initials: L
authors.lastname: El Ammari
keywords: Na2Co2Fe(PO4)3; alluaudite-like structure; crystal structure; solid-state reaction synthesis; transition metal phosphates