Acta Cryst. (2013). E69, i53
[ doi:10.1107/S1600536813020151 ]
Abstract: The title compound, heptasodium trialuminium tetrakis(diarsenate), has been isolated as single crystals from a solid-state reaction. Its structure, which is isotypic with that of the Na7Fe3(X2O7)4 (X = As, P) family of compounds, consists of AlO6 octahedra sharing their vertices with As2O7 groups, forming a three-dimensional [Al3(As2O7)4] framework incorporating channels occupied by the sodium ions. One of the aluminium ions lies on a crystallographic twofold axis. The sodium ions are situated over ten positions (one with site symmetry 2), all but one of which are partially occupied.
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