Crystal Structure of a Cerium(IV) Bis(phosphate) Derivative

Microcrystals of (NH 4 ) 2 Ce(PO 4 ) 2 ·H 2 O were hydrothermally obtained from a CeO 2 −CO(NH 2 ) 2 −H 3 PO 4 −H 2 O system ( T = 180 °C). The structure [orthorhombic, Imma, a = 6.8940(9), b = 6.8860(9), c = 17.723(2) Å] consists of CeO 8 distorted dodecahedra and PO 4 tetrahedra joined together to form a three-dimensional framework with small four-sided and larger six-sided tunnels in quasi-equivalent directions. Ammonium ions and water molecules are situated inside the larger tunnels. Also, the thermal decomposition is discussed.