Preparation, structural and spectroscopical properties of silver terbium diphosphate AgTbP2O7

Abstract Silver terbium diphosphate AgTbP 2 O 7 was prepared by solid state reaction at T=500° and characterized by combining SEM-EDS morphological investigation and semi-quantitative chemical analysis via Scanning Electron Microscopy (SEM) equipped with energy dispersive X-Ray spectroscopy (EDS), structure solution via Rietveld refinement of powder X-ray diffraction (PXRD) data, and Fourier transform infrared (FTIR) spectroscopy. The synthesized compound is monoclinic, P 2 1 / n space group, with cell parameters: a =11.9108(3) Å, b =6.90265(16) Å, c =6.62030(15) Å, β =90.3702(5)° and V=544.28(2) Å 3 . The crystal structure consists of a network of zig-zag chains of TbO 8 polyhedra extending along the b axis, bridged by P 2 O 7 diphosphate groups and by chains of AgO 7 polyhedra running along the c crystallographic direction. MIR (medium infrared) spectrum shows bands typical of P–O modes of diphosphate compounds. Observed band multiplicity is in agreement with the symmetry reduction with respect to orthorhombic rare earth diphosphates with similar stoichiometries reported in the literature.