Abstract
The tetragonal form of is used in a wide range of technologies. In this study, we systematically explore the effect of strain on the relative stability of symmetrically equivalent tetragonal variants of using first-principles density functional theory. We focus, in particular, on the role that strain plays in altering metastability and causing dynamical instabilities as these properties affect the mechanisms of ferroelastic switching. We also discover the emergence of a dynamical instability in tetragonal at its high temperature equilibrium volume. This indicates that the high-temperature thermodynamic properties of tetragonal have important anharmonic vibrational contributions that cannot be captured with the quasiharmonic approximation. Finally, we determine that the instability of tetragonal at large volumes leads to a new orthorhombic phase having a space group.
12 More- Received 14 April 2016
- Revised 4 July 2016
DOI:https://doi.org/10.1103/PhysRevB.94.054108
©2016 American Physical Society