A New Cadmium-Based Pb2Cd3(PO4)2(P2O7) with Two Types of Isolated P-O Groups

Introduction transition metal with d(10) electrons and lone pair cations with large radius into phosphate systems are helpful to get new crystal structure configuration. Guided by the above method, the first lead cadmium phosphate, Pb2Cd3(PO4)(2)(P2O7), was synthesized. Pb2Cd3(PO4)(2)(P2O7) features a three-dimensional (3D) structure, in which Pb(1)(2)O-8 dimer and Pb(2)O-5 polyhedra are filled between the two-dimensional (2D) layers, which are composed of unique [Cd6P8O30] groups. In the (PbMPO)-M-II-P-II (M-II = without or divalent metal ions) systems, the title compound is the first phosphate containing two different P-O groups simultaneously. The ratios of cation/phosphorus (C/P) and polymerization modes of P-O anions have a close relationship by many structural comparisons. Thermal analysis shows that Pb2Cd3(PO4)(2)(P2O7) melts congruently and is thermally stable. In addition, the UV/Vis-IR diffuse reflectance spectrum and infrared (IR) spectrum have been reported. The relationship between electronic structure and optical properties was clarified by first-principles studies.