Temperature-dependent properties of the antiferroelectric model PbZrO3 : An effective Hamiltonian study

Abstract

A novel atomistic effective Hamiltonian scheme, incorporating an original and simple bilinear energetic coupling, is developed and used to investigate the temperature-dependent physical properties of the prototype antiferroelectric PbZrO 3 (PZO) system. This scheme reproduces very well the known experimental hallmarks of the complex Pbam orthorhombic phase at low temperatures and the cubic paraelectric state of Pm 3m symmetry at high temperatures. Unexpectedly, it further predicts a novel intermediate state also of Pbam symmetry, but in which antiphase oxygen octahedral tiltings have vanished with respect to the Pbam ground state. Interestingly, such a new state exhibits a large dielectric response and thermal expansion that remarkably agrees with previous experimental observations and the x-ray experiments we performed. We also conducted direct first-principles calculations at 0 K, which further support such a low-energy phase. Within this fresh framework, a reexamination of the properties of PZO is thus called for.