Pressure-Induced Layered Structure in BaWO4

Abstract

We have theoretically investigated the structural stability of the predicted polar phase on the layered Tungsten-based oxide BaWO4 at high pressure. Although the energy vs. volume curves report a non-centrosymetric Cmc21 phase in BaWO4 oxide under pressure, we found that such a phase is dynamically unstable when the phonon-dispersions are considered. Additionally, we have observed that the polar eigendisplacements, related to WO6 octahedral rotations, are destroyed once the internal coordinates are allowed to fully relax. Thus, the symmetry of the crystalline material is transformed into a Cmcm phase, where we found a dynamically stable layered structure.