Received 20 November 2013
The title compound, sodium potassium trialuminium tetrakis(orthoarsenate), was prepared by solid-state reactions. The anionic framework consists of corrugated layers parallel to (010) and is made up of corner-sharing AlO6 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.
Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WM2786 ).
Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany.
Brown, I. D. (2002). In The Chemical Bond in Inorganic Chemistry: The Bond Valence Model. Oxford University Press.
Enraf-Nonius (1994). CAD-4 EXPRESS. Enraf-Nonius, Delft, The Nether- lands.
Friaa, B. B., Boughzala, H. & Jouini, T. (2003). J. Solid State Chem. 173, 273-279.
Haj Abdallah, A. & Haddad, A. (2012). Acta Cryst. E68, i29.
Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.
North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351-359.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.