Competing dynamical and lattice instabilities in RVO4 rare-earth vanadium oxides under high pressure

Uncovering the Effects of Non-Hydrostaticity on Pressure-Induced Phase Transformation in Xenotime-Structured TbPO4

“…Shear can facilitate the plastic deformation involved in phase transformation (i.e., polyhedral rotations and translations) and thereby reduce the hydrostatic pressure required to induce phase transformation. In fact, non-hydrostatic conditions have been suggested to lower the pressure required to induce mechanical instability in other REPO 4 and REVO 4 materials [41,42]. High-pressure dynamical instability (i.e., the softening of Raman-active and silent phonon modes) has also been observed in these materials, but it has less influence on P onset than mechanical instability does [36,41,42].…”

“…In fact, non-hydrostatic conditions have been suggested to lower the pressure required to induce mechanical instability in other REPO 4 and REVO 4 materials [41,42]. High-pressure dynamical instability (i.e., the softening of Raman-active and silent phonon modes) has also been observed in these materials, but it has less influence on P onset than mechanical instability does [36,41,42]. In addition, the TbPO 4 P onset values are marginally (KCl) or significantly (none) lower than those of DyPO 4 in the same PTM.…”

The pressure and temperature evolution of the Ca3V2O8 crystal structure using powder X-ray diffraction

“…The equilibrium volume is 2% larger than in experiments when the Grimme D3 corrections are included and only 0.5% smaller than in experiments when they are not included. Based on this result and the fact that calculations without dispersive corrections usually works well to describe the changes induced by pressure in the crystal structure of vanadates, 39,40 we decided to neglect dispersion corrections in our simulations. Finite temperature calculations are beyond the scope of the present work.…”