Three new phosphates, Cs8Pb4(P2O7)4, CsLi7(P2O7)2 and LiCa(PO3)3: structural comparison, characterization and theoretical calculation.

Through the high temperature solution method, three new phosphates, Cs8Pb4(P2O7)4, CsLi7(P2O7)2 and LiCa(PO3)3, were obtained. X-ray diffraction analyses suggest that they crystallize in the space group P1[combining macron] of the triclinic crystal system. However, the three-dimensional (3D) structures of Cs8Pb4(P2O7)4 and CsLi7(P2O7)2 consist of various isolated P2O7 groups, while LiCa(PO3)3 is built up by the 1D (PO3)∞ chain. Detailed structural comparison suggests that the different sizes and coordination environments of Ca2+ and Zn2+ cations influence the whole structures of LiX(PO3)3 (X = Ca and Zn). IR spectroscopy and UV/Vis/NIR diffuse reflectance spectroscopy analyses have been performed to investigate their optical properties. First-principles theoretical studies were also carried out to aid the understanding of electronic structures and linear optical properties.