Synthesis, thermal stability and unknown properties of Fe1-xAlxVO4 solid solution

A continuous solid solution Fe1-xAlxVO4 was synthesized by conventional ceramic method and characterized by DTA, XRD, IR, UV-vis/DRS and Mössbauer spectroscopy. Fe1-xAlxVO4 crystallizes in a triclinic system and is isostructural with FeVO4 and AlVO4. With increasing content of Al3+ ions substituted for Fe3+ in the matrix structure of FeVO4 a contraction of crystal lattice was observed, accompanied by shifts of IR absorption bands towards higher wavenumbers and shifts of UV absorption bands towards shorter wavelength. On the basis of the results of UV-vis investigations, the band gap energies were calculated. The solid solution sample of composition Fe0.67Al0.33VO4 was found to have the highest melting point from among all examined samples, which equals to 870 °C. Moreover, the solid product of incongruent melting of Fe1-xAlxVO4 for 0.75 > x ≥ 0.5 is Fe1-xAlxVO4 solid solution, richer in iron. On the grounds of Mössbauer investigation, the partition of iron and aluminum ions over three accessible crystallographic sites was established. Fe0.5Al0.5VO4 sample was successfully used as a reactant for Fe4Al4V10W16O85 preparation.