Solid State Ionics, Vol.338, 134-137, 2019
Synthesis, crystal structure and possible proton conduction of Fe(H2PO4)(2)F
A new iron fluorophosphate compound, Fe(H2PO4)(2)F, was synthesized by a solvent-less method at low temperatures. Its structure was determined from single crystal X-ray diffraction. Fe(H2PO4)(2)F was found to have a 3-dimensional structure built up by parallel chains of corner-sharing octahedra. This novel compound crystallizes in a tetragonal 14/mcm space group with the following lattice parameters: a = b = 9.01870(10) angstrom and c = 7.8058(2) angstrom. Further characterization of the material was conducted by TGA and Mossbauer spectroscopy. Proton conductivity measurements under dry condition revealed activation energies of E-a = 0.43 eV (along c-axis) and E-a = 0.41 eV (along a-axis) with corresponding room-temperature conductivities 2.6 x 10(-7) S cm(-1) and 5.8 x 10(-8) S cm(-1).