Abstract
The new silver-, cobalt- and iron-based phosphate, silver cobalt iron tris(ortho-phosphate), Ag1.655Co1.64Fe1.36(PO4)3, was synthesized by solid-state reactions. Its structure is isotypic to that of Na2Co2Fe(PO4)3, and belongs to the alluaudite family, with a partial cationic disorder, the AgI atoms being located on an inversion centre and twofold rotation axis sites (Wyckoff positions 4a and 4e), with partial occupancies of 0.885 (2) and 0.7688 (19), respectively. One of the two P atoms in the asymmetric unit completely fills one 4e site while the Co and Fe atoms fill another 4e site, with partial occupancies of 0.86 (5) and 0.14 (5), respectively. The remaining Co2+ and Fe3+ cations are distributed on a general position, 8f, in a 0.39 (4):0.61 (4) ratio. All O atoms and the other P atoms are in general positions. The structure is built up from zigzag chains of edge-sharing [MO6] (M = Fe/Co) octa-hedra stacked parallel to [101]. These chains are linked together through PO4 tetra-hedra, forming polyhedral sheets perpendicular to [010]. The resulting framework displays two types of channels running along [001], in which the AgI atoms (coordination number eight) are located.
Highlights
The new silver, cobalt- and iron-based phosphate, silver cobalt iron tris(orthophosphate), Ag1.655Co1.64Fe1.36(PO4)3, was synthesized by solid-state reactions
Its structure is isotypic to that of Na2Co2Fe(PO4)3, and belongs to the alluaudite family, with a partial cationic disorder, the AgI atoms being located on an inversion centre and twofold rotation axis sites (Wyckoff positions 4a and 4e), with partial occupancies of 0.885 (2) and 0.7688 (19), respectively
The remaining Co2+ and Fe3+ cations are distributed on a general position, 8f, in a 0.39 (4):0.61 (4) ratio
Summary
Compounds belonging to the large alluaudite structural family (Moore, 1971; Moore & Ito, 1979; Hatert et al, 2000, 2004). Have been of continuing interest owing to their open-framework architecture, with hexagonal-shaped channels, and their physical properties. This fact is amply justified by their practical applications, for example as corrosion inhibitors, passivators of metal surfaces, and catalysts (Korzenski et al, 1999). Our attention is mostly focused on the elaboration and structural characterization of new alluaudite-type phosphates within the. Most recently, the hydrothermal investigation of the Na2O–MO–P2O5 pseudo-ternary system has allowed the isolation of the sodium- and magnesium-based alluaudite phosphate NaMg3(PO4)(HPO4) (Ould Saleck et al, 2015). Silver-, cobalt- and iron-based alluaudite-type phosphate, namely Ag1.655Co1.64Fe1.36(PO4), has been synthesized by means of solid-state reactions and characterized by single crystal X-ray diffraction
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