Acta Cryst. (2008). E64, i36  [ doi:10.1107/S1600536808014633 ]

The alluaudite-like arsenate NaCaMg₃(AsO₄)₃

A. Haj Abdallah and A. Haddad

Abstract: The title compound, sodium calcium trimagnesium tris(arsenate), an alluaudite-like arsenate, was prepared by solid-state reaction at high temperature. The structure is built up from edge-sharing MgO₆ octahedra in chains associated with the AsO₄ arsenate groups. The three-dimensional network leads to two different tunnels occupied statistically by Na⁺ and Ca²⁺. One As and one Mg atom lie on twofold rotation axes; one Na and one Ca are disordered over two sites with occupancies of 0.7 and 0.3 and these sites lie on a twofold rotation axis and an inversion centre, respectively.

Online 21 May 2008

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