Crystal Structure and Cation Exchanging Properties of A Novel Open Framework Phosphate of Ce (IV)

Herein we report preparation, crystal structure and ion exchanging properties of a new phosphate of tetravalent cerium, K2Ce(PO4)(2). A monoclinic structure having framework type arrangement of Ce(PO4)(6) units formed by CeO8 square-antiprism and PO4 tetrahedra is assigned for K2Ce(PO4)(2). The K+ ions are occupied in the channels formed by the Ce(PO4)(6) and provide overall charge neutrality. The unique channel type arrangements of the K+ make them exchangeable with other cations. The ion exchanging properties of K2Ce(PO4)(2) has been investigated by equilibrating with solution of Sr-90 followed by radiometric analysis. In optimum conditions, significant exchange of K+ with Sr2+ with K-d similar to 8000 mL/g is observed. The details of crystal structure and ion exchange properties are explained and a plausible mechanism for ion exchange is presented.