Anomalous polarization in the antiferroelectric-ferroelectric phase coexistence state in PbZrO₃-Bi(Mg_1/2Ti_1/2)O₃

Abstract

The ferroelectric system (1−x)PbZrO₃-(x)Bi(Mg_1/2Ti_1/2)O₃ has been investigated as a function of composition, temperature, and electric field by x-ray powder diffraction, dielectric, and ferroelectric measurements. Within the solubility limit (x ∼ 0.25), the system evolves from an orthorhombic-antiferroelectric to rhombohedral-ferroelectric state through a phase coexistence region. The highest polarization was found not for the composition exhibiting a pure ferroelectric state, but for a composition x = 0.15 exhibiting ferroelectric + antiferroelectric phase coexistence close to the rhombohedral phase boundary. Electric poling of the equilibrium two-phase state led to irreversible enhancement in the rhombohedral phase fraction suggesting that the enhanced polarization is related to the enhanced polarizability of the lattice due to first order criticality as in ferroelectric-ferroelectric morphotropic phase boundary systems.