Speaker
Adam BOURAIMA
(Mohammed V University, Chemistry department, Rabat, Morocco)
Description
The new silver-, cobalt- and iron-based phosphate, silver cobalt iron tris(orthophosphate),
Ag 1.655 Co 1.64 Fe 1.36 (PO 4 ) 3 , was synthesized by solid-state reactions. Its structure is isotypic to that
of Na 2 Co 2 Fe(PO 4 ) 3 , and belongs to the alluaudite family, with a partial cationic disorder, the
Ag I 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 Co 2+ and Fe 3+ 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) octahedra stacked parallel to [101].
These chains are linked together through PO 4 tetrahedra, forming polyhedral sheets
perpendicular to [010]. The resulting framework displays two types of channels running along
[001], in which the Ag I atoms (coordination number eight) are located as in show figure 1.
Primary author
Adam BOURAIMA
(Mohammed V University, Chemistry department, Rabat, Morocco)
