Bouhassine M.A.,Laboratoire Des Materiaux Et Of Cristallochimie |
Boughzala H.,Laboratoire Des Materiaux Et Of Cristallochimie
Acta Crystallographica Section E: Structure Reports Online | Year: 2014
The title compound, sodium potassium trialuminium tetra-kis(orthoarsenate), was prepared by solid-state reactions. The anionic framework consists of corrugated layers parallel to (010) and is made up of corner-sharing AlO 6 octahedra (site symmetries.2. and 2/m.) that are connected to isolated AsO4 tetrahedra (site symmetries.2. and m.) through edge-and corner-sharing. The alkali cations are occupationally disordered. The two K+ cations [site symmetries.2. and m.; occupancies 0.314(7) and 0.035(12)] are situated in the interlayer space, whereas the smaller Na + cations [both with site symmetry m.; occupancies = 0.725(14) and 0.112(14)] are located in the cavities of the anionic framework. The K + cations are surrounded by six and seven O atoms, the Na+ cations by seven and nine O atoms. The resulting coordination polyhedra of the two types of cations are highly distorted.