Spectroscopic characterization of mixed cation diphosphates of the type MI FeIIIP2O7 (with MI¼Li, Na, K, Rb, Cs, Ag)

Abstract

The mixed cation diphosphates of composition MI FeIIIP2O7 have been prepared using the so called co-precipitation method starting with Fe(III) and M(I) nitrate solutions and solid (NH4)H2PO4, and characterized by X-ray powder diffractometry. The infrared and Raman spectra of the compounds were recorded and the results are briefly discussed on the basis of their structural peculiarities. The 57FeMossbauer spectra show that the typical high-spin Fe ¨ IIIO6 octahedra existent in these compounds exhibit almost no distortion. However, the hyperfine parameters are sensitive to some characteristics of the MI cations and to the different structural types.