Structure cristalline de type alluaudite KNa 5 Mn 3 (MoO 4 ) 6

Abstract

The new phase potassium pentasodium trimanganese hexakis(molybdate), KNa 5 Mn 3 Mo 6 O 24 , has been synthesized using solid-state methods. The structure is composed of M 2 O 10 ( M = Mn, Na) dimers and MoO 4 tetrahedra (point group symmetry 2) sharing corners and forming layers parallel to (100), which are linked via common corners of another type of M O 4 tetrahedra, forming a three-dimensional structure with two types of large channels along [001] in which two types of Na + cations (one with site symmetry 2, one with -1) and K + cations (site symmetry 2, half-occupation) are located. Mn 2+ and the third type of Na + cations are located at the same site M with occupancies of 0.75 and 0.25, respectively. A comparative structural description is provided between the structure of the title compound and those of the related phases Cu 1.35 Fe 3 (PO 4 ) 3 and NaAgFeMn 2 (PO 4 ) 3 .