Lead iron phosphate Pb3Fe2(PO4)4 was synthesized by solid state method and characterized by X-ray powder and electron diffraction, differential scanning calorimetry, Mössbauer and infrared spectroscopy. A structural model for Pb3Fe2(PO4)4 was proposed and was refined by the Rietveld method. The compound crystallizes in the monoclinic space group P21/c with a = 9.0065Å, b = 9.0574Å, c = 9.3057Å, β = 116.880°, V = 677.10Å3, Z = 2, Rwp = 3.52%, Rp = 2.66%. It exhibited a structure with a 3-dimensional open framework. The 3D framework was formed by PO4 tetrahedra and FeO6 octahedra connected via common vertices. Some ¾ of cavities in the framework were occupied by lead and ¼ were vacant.

Layered Ordering of Vacancies of Lead Iron Phosphate, Pb3Fe2(PO4)4. A.P.Malakho, V.A.Morozov, K.V.Pokholok, B.I.Lazoryak, G.Van Tendeloo: Solid State Sciences, 2005, 7[4], 397-404