New layered caesium zinc hydrogen phosphate, CsZn2.5(HPO4)(3)center dot 2H(2)O; synthesis, crystal structure and thermal transformation

The synthesis, crystal structure and thermal transformation of a new caesiu m zinc hydrogen phosphate hydrate, CsZn2.5(HPO4)(3). 2H(2)O, is reported. T his material crystallised from a gel with molar composition 1 ZnO:0.48 P2O5 :0.24 Cs2O:12 H2O:4.8 MeCO2H, and pH of 1.0, after two months at room tempe rature. The crystal structure of CsZn2.5(HPO4)(3). 2H(2)O has layers built from PO4 and ZnO4 tetrahedra and with other zinc atoms forming octahedra by coordination to water molecules. The zinc octahedra are placed across pseu do 12-rings and caesium ions are placed above and below eight-ring openings . Thermal analysis was performed using thermogravimetric (TG) and different ial scanning calorimetric (DSC) measurements. Two weight losses were detect ed and assigned to expulsion of crystal water and water from condensation o f hydrogen phosphate. DSC was used to estimate enthalpy changes from three thermal events.