Structural Origin of Morphotropic Phase Boundary in Advanced Perovskite Ferroelectric Oxides

High Resolution Image Download MS PowerPoint Slide Ferroelectric oxides PbZr 1– x Ti x O 3 (PZT) with the ABO 3 perovskite structure exhibit exceptional polarization responses near their morphotropic phase boundary (MPB), yet the chemical origin of this behavior remains unclear. Here, we show that, in a prototypical composition, 0.05Pb(Mn 1/3 Sb 2/3 )O 3 –0.95PbZr 0.52 Ti 0.48 O 3, this origin arises from coupled effects of B-site chemical ordering and multi-ion displacement heterogeneity-related disordering. Pronounced anti-self-clustering of Zr and Ti forms a short-range chemical ordering driven by the mismatch between ionic Zr–O and more covalent Ti–O bonds, generating a soft–hard compatible BO 6 network that reduces local stress, which facilitates polarization rotation and switching. Simultaneously, A-site, B-site, and oxygen ions display significant, directionally distinct off-center displacements, producing continuous local monoclinic polar states (M A –M B ) with coplanar polarization vectors and nanoscale domains with mobile walls. These results show that PZT’s extraordinary response emerges from a unity-of-opposites relationship that balances rigidity and flexibility through compatible bonding and multi-ion displacements, offering guidance for designing high-performance ferroelectrics.