Stability of FeVO4-II under Pressure: A First-Principles Study

Abstract

In this work, we report first-principles calculations to study FeVO4 in the CrVO4-type (phase II) structure under pressure. Total-energy calculations were performed in order to analyze the structural parameters, the electronic, elastic, mechanical, and vibrational properties of FeVO4-II up to 9.6 GPa for the first time. We found a good agreement in the structural parameters with the experimental results available in the literature. The electronic structure analysis was complemented with results obtained from the Laplacian of the charge density at the bond critical points within the Quantum Theory of Atoms in Molecules methodology. Our findings from the elastic, mechanic, and vibrational properties were correlated to determine the elastic and dynamic stability of FeVO4-II under pressure. Calculations suggest that beyond the maximum pressure covered by our study, this phase could undergo a phase transition to a wolframite-type structure, such as in CrVO4 and InVO4.

Electronic, Vibrational, and Structural Properties of the Natural Mineral Ferberite (FeWO4): A High-Pressure Study

“…This result is due to the stronger compression of the Fe–O distances ( d Fe–O ) than the W–O distances ( d W–O ) (see Figure b). Note that W–O bonds are stronger (more ionic) than Fe–O bonds in terms of the Laplacian of the charge density at the respective bond critical point (∇ 2 ρ). , This is the reason behind the stiffness of W–O bonds in comparison to that of Fe–O bonds. On the other hand, Figure c shows that the polyhedral distortion index Δ d , calculated using the definition established by Baur, decreases with pressure for the WO 6 octahedra, but remains almost constant for FeO 6 .…”

“…For our GGA + U calculations, we chose U = 6 eV and J H = 0.95 eV. Similar values were previously used with success in the study of other iron and ABO 4 compounds. − All properties computed in this study were calculated under the GGA + U approach. For the calculations, we considered nonmagnetic, ferromagnetic, and antiferromagnetic configurations.…”

Dynamical Stability and Physical Properties of Fe Dihalide Nanowires

“…Similar values have been used successfully in the study of Fe-based compounds. [48][49][50][51][52][53][54][55] Calculations are also performed within the DFT-TS approximation to take into account vdW interactions [56] in the systems under study.…”