The rich crystal chemistry of the AMM ′(PO 4 ) 2 morphotropic series: NaZnAl(PO 4 ) 2 , the first Na representative with a new structure type

A novel phosphate, sodium zinc aluminium bis(phosphate), NaZnAl(PO 4 ) 2 , was obtained under mild‐temperature hydrothermal conditions at 553 K. The crystal structure has been studied using single‐crystal X‐ray experimental data. The pseudo‐hexagonal phase NaZnAl(PO 4 ) 2 crystallizes in the monoclinic space group P 2 1 / c . Its unique crystal structure is based on a three‐dimensional (3D) framework built by Zn‐, Al‐ and P‐centred tetrahedra sharing vertices. Channels parallel to the [101] and [01] directions are limited by six‐ and eight‐membered windows, and incorporate Na atoms. The new compound is discussed as a member of the morphotropic series AMM ′PO 4 , where A = Na, K, Rb or NH 4 , M  = Cu, Ni, Co, Fe, Zn or Mg and M ′ = Fe, Al or Ga. The title compound is the first Na representative within the series and is characterized by a 3D architecture of tetrahedra populated in an ordered manner by Zn 2+ , Al 3+ and P 5+ ions.