New FeVTaO6 compound—synthesis, structure and selected properties

A new ceramic compound of the chemical formula FeVTaO6 was obtained in polycrystalline form, as a result of a high-temperature reaction between Fe2O3, Ta2O5 and VO2 mixed at the molar ratio 1:1:2 as well as in the reaction of equimolar mixture of FeTaO4 with VO2. The synthesis of this new compound has also been carried out by mechanochemical method realized by high-energy ball milling of some mixture of reactants. FeVTaO6, in both cases, was obtained under an atmosphere of deoxygenated argon. The new compound was characterized by XRD, DTA-TG, IR, SEM/EDX, TEM, XRF and UV–vis-DRS methods. Using X-ray powder diffraction, the lattice parameters of the unit cell and the parameters of the positioning of atoms (Rietveld analysis) were determined, and grain sizes were obtained on the basis of diffraction line broadening. The results showed that FeVTaO6 crystallizes in the tetragonal system with rutile-type structure. As shown in the DTA results, regardless of the synthesis method, FeVTaO6 is stable in argon atmosphere up to 1225 °C and in air up to 925 °C. Based on the UV–Vis-DR spectra, it was also established that the obtained compound is a semiconductor. The energy gap value determined for the compound obtained by the solid-state method is Eg 1.75 eV, and for the compound obtained by the mechanochemical method Eg 2.10 eV.