Hydrothermal Synthesis, Crystal Structure, and Characterization of Tetrasodium Tricobalt(II)-bis-Phosphate-bisHydrogenophosphate Octahydrate, Na4Co3H2(PO4)4·8H2O, with a New Structure Type

The luminescence of silver(I) ions was investigated in diphosphate of compositions Na2-xAgxZnP2O7. The [P2O7] groups share corners with [ZnO4] tetrahedra in a layer arrangement. The Na/Ag atoms are located between layers in distorted oxygenated cubic sites sharing faces––with short intermetallic distances––or edges. Two luminescent centers were detected and attributed, respectively, to single Ag+ and Ag+–Ag+ pairs. The luminescent parameters are discussed with respect to the symmetry of the silver sites and of the ionocovalent character of the silver oxygen bonds