Pressure Dependence of Instabilities in Perovskite PbZrO3
Eric J. Cockayne, K M. Rabe
We have computed the frequencies of selected normal modes in perovskite PbZrO3 (PZ) as a function of lattice parameter using local density functional theory variational linear response. The most significant instabilities that freeze in to give the orthorhombic antiferroelectric phase in PZ and the low-temperature rhombohedral ferroelectric phase in PbZr1-xTixO3 (PZT) all become more unstable under pressure. The most unstable antiferroelectric ς3 mode destabilizes more rapidly than the unstable zone center polar mode. This provides and explanation for the observed ferroelectric-antiferroelectric transition in (modified) Zr-rich PZT under applied pressure.
Journal of Physics and Chemistry of Solids
DFT, first-principles calculations, LDA, lead zirconate, lead zirconate titanate, phonons, PZT