A new story in the structural chemistry of cerium(IV) phosphate

Two different cerium(IV) phosphates have been prepared by ageing at 95 °C an aqueous solution made from Ce(NO3)6(NH4)2, nitric acid, and phosphoric acid with the following conditions: P/Ce=2, [HNO3]=5.8 M and [Ce4+]=0.1 M. The control over the formed solid was achieved through the ageing time. After 18 h, a metastable compound (A), corresponding to Ce(PO4)1.5(H2O)(H3O)0.5(H2O)0.5, is obtained, while after 5 days a stable one (B), corresponding to Ce(PO4)(HPO4)0.5(H2O)0.5, is recovered. Both solids exhibit a P/Ce ratio of 1.5. Their structures, 31P solid state NMR, and thermal behaviors are compared.