Ferroelectric materials are highly promising for next-generation electro–optic (EO) modulators because of their ultrafast and efficient light modulation. However, efforts to maximize polarization freedom for large refractive index modulation—through domain engineering, epitaxial strain, and defect engineering—have hit limitations, leaving intrinsic polarization mechanisms largely unexplored. Here, we report a giant effective EO coefficient (~233.5 pm/V) in PbZr_0.52Ti_0.48O₃ (PZT) films, which surpasses all reported values measured under an in-plane electric field and significantly exceeds the theoretical limit (~13 pm/V) as well as the value of LiNbO₃ (~31 pm/V). Beyond conventional domain switching, phase transitions and domain wall variations critically enhance the EO effect. The highly relaxed structure of the PZT film, with mixed [001] and [100] orientations and disordered nanoscale phases, enables unprecedented polarization control. This unique configuration breaks the theoretical EO coefficient limit, bridging the gap between predictions and experimental results. Owing to its high Curie temperature and compatibility with wafer-scale fabrication, PZT has emerged as a promising candidate for next-generation high-performance EO modulators. Our findings not only advance the frontiers of ferroelectric EO materials but also pave the way for exploring other ferroelectric thin-film devices, such as those for energy storage and electrocaloric cooling, by leveraging enhanced polarization modulation mechanisms.

Simultaneously employing light and vibration energy by piezoelectric material to realize environmental remediation is an advanced oxidation method. Silver niobate (AgNbO₃) is a visible light driven photocatalyst for the removal of organic pollutants. However, the high recombination rate of photo-generated electrons and holes suppresses its photocatalytic activity. Piezoelectric potential excited by vibration can facilitate the separation of light induced charges. Unfortunately, AgNbO₃ is an antiferroelectric. In this work, distinct photo-/vibration-bi-catalysis has been achieved in ferroelectric (1−x)AgNbO₃–xLiTaO₃ solid solution. The results show that ~96% Rhodamine B (RhB) can be decomposed under the bi-excitation of ultrasound and visible light within 120 min with 0.95AgNbO₃–0.05LiTaO₃ catalyst. The synergy effect from efficient visible light excitation and enhanced separation of the photo-induced charges from the electric field by the mechanical strain results in the distinct decomposition performance of catalysts.

Ferroelectric thin/thick films with large electrocaloric (EC) effect are critical for solid state cooling technologies. Here, large positive EC effects with two EC peaks in a broad temperature range (~100 K) were obtained in 0.95Pb_0.92La_0.08(Zr_0.70Ti_0.30)_0.98O₃-0.05BiFeO₃ (BFOLa-codoped PZT) epitaxial thin films deposited on the (100), (110) and (111) oriented SrTiO₃ (STO) substrates by a sol-gel method. The thin film deposited on the (111) oriented STO substrate exhibited a stronger EC effect (~20.6 K at 1956 kV/cm) near room temperature. However, the thin films deposited on the (100) and (110) oriented STO substrates exhibited a stronger EC effect (~18.8 K at 1852 kV/cm and ~20.8 K at 1230 kV/cm, respectively) around the peak of the dielectric permittivity (T_m, ~375 K). Particularly, as the direction of the applied electric field was switched (E < 0), the ΔT of the (100)-oriented thin films around T_m was enhanced significantly from 18.8 K to 38.1 K. The self-induced-poling during the preparing process maybe plays a key role on the magic phenomenon. It can be concluded that the BFOLa-codoped PZT epitaxial thin films are promising candidates for application in the next solid-state cooling devices.