Double polarization hysteresis loops associated with field-induced antiferroelectric-ferroelectric (AFE-FE) phase transitions, which underpin many antiferroelectric functionalities, are rarely observed in PbZrO₃ polycrystals at ambient conditions because the required critical field often approaches the dielectric breakdown strength. Here, dense PbZrO₃ ceramics fabricated by hot pressing reach 97.8% relative density and exhibit an orthorhombic Pbam average structure, as confirmed by high-energy X-ray diffraction. A sharp paraelectric-antiferroelectric anomaly is observed at 235 °C, with a peak permittivity of 5387 at 10 kHz and negligible frequency dispersion. Room-temperature polarization measurements demonstrate a field-induced AFE-FE transition can be triggered at 27 kV/mm, yielding well-defined double hysteresis loops with forward and backward critical fields of 26.5 kV/mm and 19.1 kV/mm, respectively. The ceramics deliver a recoverable energy density of 3.6 J/cm³ with an efficiency of 73.5%, accompanied by a large field-induced strain of 0.49%. Large-signal dielectric measurement reveals a non-monotonic field dependence of permittivity, featuring a pronounced enhancement as the forward transition is approached. Atomistic-resolution electron microscopy and polarization mapping directly resolve the commensurately modulated antipolar “↑↑↓↓” order and quantify an average Pb displacement of ~24 pm with dipoles aligned along <110> directions. These results establish a room-temperature experimental benchmark for pristine bulk PbZrO₃, linking atomistic-scale antipolar order to macroscopic transition and providing a quantitative baseline for evaluating phase competition and transition pathways in antiferroelectric perovskites.

Complex lead-based perovskites with the general formula Pb(B_x'B_1-x")O₃, represent an important class of antiferroelectrics beyond the prototypical PbZrO₃ and NaNbO₃. Depending on the combination of B-site species and the degree of cationic ordering, these materials exhibit a wide range of ferroic behaviors, spanning from antiferroelectric to (relaxor) ferroelectric responses. In this study, we investigate (Pb_1-xBa_x)(Yb_1/2Nb_1/2)O₃ polycrystals synthesized via a two-step processing route. Despite displaying antiferroelectric, ferroelectric, or nearly linear dielectric behavior at room temperature, all compositions exhibit double polarization hysteresis loops in proximity to a lower-temperature dielectric anomaly. This dielectric anomaly originates from the competition between antipolar and nanoscale polar regions, and shifts towards lower temperature with increasing Ba content, reflecting the suppression of long-range antiferroelectric ordering. Notably, a composition-invariant temperature scale, T*, is identified and associated with the onset of static correlations among nanoscale polar entities, consistent with behavior reported in other complex Pb-based relaxor ferroelectrics. Superlattice reflections arising from antiparallel Pb²⁺ displacements persist above T*, suggesting an intricate cation-ordering landscape requiring further investigation. These findings underscore the coexistence and competition of polar and antipolar instabilities in complex lead-based perovskites, and their pronounced sensitivity to chemical substitution, thermal fluctuations, and external electric fields.

Understanding the atomic-scale structural dynamics that enable ultrahigh piezoelectric responses in lead-free piezoceramics remains a central challenge in materials science. Here, we employ in situ electric field pair distribution function (PDF) analysis to elucidate the local structural origin of a KNN-based piezoceramic with a nominal composition of 0.964K_0.5Na_0.5Nb_0.965Sb_0.035O₃–0.03(Bi_0.5Na_0.5)_0.9(Ga_0.5Li_0.5)_0.1ZrO₃–0.006BiFeO₃ that has an exceptional piezoelectricity coefficient (d₃₃ > 500 pC/N). Combined Rietveld refinement, PDF fitting, and reverse Monte Carlo simulations revealed the coexistence of long-range tetragonal and orthorhombic phases with local c-type monoclinic symmetry. In situ electric field PDF analyses indicated a reversible polarization rotation between the <001>_PC and <110>_PC directions via a monoclinic plane, with a critical switching field of approximately 0.4 kV/mm. These findings establish polarization rotation, rather than abrupt phase transitions, as the governing mechanism for the enhanced piezoresponse, providing a structural design principle for next-generation lead-free piezoelectrics.