Olivine-type NaCd(AsO4).

The title compound, sodium cadmium orthoarsenate, adopts the olivine [Mg2(SiO4)] structure type in space group Pnma, with Na (site symmetry -1) and Cd (.m.) replacing the two Mg positions, and the AsO4 tetra-hedron (.m.) the SiO4 tetra-hedron. The crystal structure is made up of a nearly hexa-gonal closed-packed arrangement of O atoms stacked along [001]. The Na and Cd atoms occupy one half of the octa-hedral voids in alternate layers stacked along [100], and one eighth of the tetra-hedral voids are occupied by As atoms.