Spectroscopic characterization of mixed cation diphosphates of the type MIFeIIIP2O7 (with MI=Li, Na, K, Rb, Cs, Ag) Original Research Article

The mixed cation diphosphates of composition MIFeIIIP2O7 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 57Fe-Mössbauer spectra show that the typical high-spin FeIIIO6 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.