Anomalous properties of antiferroelectric PbZrO 3 under hydrostatic pressure
Résumé
First-principles calculations are performed to investigate several low-enthalpy phases of the prototype PbZrO 3 antiferroelectric material under hydrostatic pressure. They are the orthorhombic P bam and P nma states, the monoclinic P 2 1 /c and rhombohedral R3c phases, and possess different ionic degrees of freedom (e.g., antipolar motions, oxygen octahedral tilting, and polarization). Several anomalous features are discovered, including a change in pressure behavior of the polarization in the R3c state, which renders such ferroelectric phase the ground state of PbZrO 3 (PZO) (along with the nearly degenerate P 2 1 /c phase) for pressure ranging between 30 and 85 GPa. Another example is the strong first-order isostructural transition exhibited by P bam at 70 GPa, which results in the reentrance of this phase as the ground state of PZO for pressure above 85 GPa. Another more continuouslike isostructural transition is also predicted for the P nma phase at 50 GPa. Experiments are conducted to confirm some of these predictions.