Pressure-induced phase transformations in Nb2O5 from ab initio molecular dynamics simulations

Abstract

The equations of state for the H−, L– and T–Nb2O5 polymorphs were investigated with density functional theory. The shock Hugoniot curves were predicted from ab initio molecular dynamics simulations along 300–2500 K isotherms. Enthalpies derived from simulations at 300 K show that the H → L transition occurs at 6.2 GPa, in agreement with the measured value of ∼5.9 GPa, and is more favorable than the H → T transition. Pressure-induced amorphization (PIA) of L–Nb2O5 is in the range ∼18–25 GPa, consistent with experiments reporting PIA above 21.4 GPa. The simulated PIA of T–Nb2O5 between ∼16 and 26 GPa reproduces PIA observed above 19.2 GPa.