Crystal chemistry and polymorphism of an iron-tungsten mixed oxide

Among the complex metal oxides, the crystal chemistry of the iron-tungsten oxide Fe2WO6 is of interest because of the existence of several crystal structures with different organizations of the FeO6 and WO6 octahedra. The conditions of polymorphism are still unclear: structures were reported in the literature for only two of the three polymorphs (α and γ) and very little is known about the third polymorph (β). For the first time, we could synthesize a complete set of the three polymorphs as single-phase products by spray-drying. We proposed a new structural model for α-polymorph. We confirmed the existence of β-polymorph and solved its structure. With this procedure of synthesis, we were also able to control and tune the Fe/W ratio and investigate the possibility for a solid solution domain. The final products were characterized by means of X-Ray Diffraction (synchrotron data), Rietveld refinement, Scanning Electron Microscopy and 57Fe Mossbauer spectroscopy.