The exceptional breakdown field strength of polymers, combined with the large spontaneous polarization exhibited by inorganic ferroelectric materials, has led to continuous advancements in the records for the giant electrocaloric effect (ECE) in polymer composites enhanced by ferroelectric inorganic components. This study aims to investigate the ECE properties of P(VDF-TrFE-CFE)/Ba_0.67Sr_0.33TiO₃ (BST67) composites by analyzing the aspect ratio, composition ratio, and orientation of BST67 nanoparticles in conjunction with the P(VDF-TrFE-CFE) matrix. The results of the P–E loop calculations indicate that all three factors related to the BST67 nanoparticles enhance the ferroelectric polarization value of the composite material. This enhancement is attributed to the longer aspect ratio, higher composition ratio, and improved orientation, which enable the BST67 nanoparticles to achieve a greater electric field strength. The calculation of ΔT using the LGD method reveals that these three factors of BST67 can independently increase ΔT, and they exhibit a synergistic effect on the ECE performance of the ferroelectric polymer. Our conclusions provide valuable insights for future research on ECE in polymer/inorganic ferroelectric composites.

Antiferroelectric materials represented by PbZrO₃(PZO) have excellent energy storage performance and are expected to be candidates for dielectric capacitors. It remains a challenge to further enhance the effective energy storage density and efficiency of PZO-based antiferroelectric films through domain engineering. In this work, the effects of three variables, misfit strain between the thin film and substrate, defect dipoles doping, and film thickness, on the domain structure and energy storage performance of PZO-based antiferroelectric materials are comprehensively investigated via phase-field simulations. The results show that applying tensile strain to the films can effectively increase the transition electric field from antiferroelectric to ferroelectric. In addition, the introduction of defect dipoles while applying tensile strain can significantly reduce the hysteresis and improve energy storage efficiency. Ultimately, a recoverable energy density of 38.3 J/cm³ and an energy storage efficiency of about 89.4% can be realized at 1.5% tensile strain and 2% defect dipole concentration. Our work provides a new idea for the preparation of antiferroelectric thin films with high energy storage density and efficiency by domain engineering modulation.

To meet the expectation set by Moore’s law on transistors, the search for thickness-scalable high dielectric constant (k) gate layers has become an emergent research frontier. Previous investigations have failed to solve the “polarizability–scalability–insulation robustness” trilemma. In this work, we show that this trilemma can be solved by using a gate layer of a high k ferroelectric oxide in its superparaelectric (SPE) state. In the SPE, its polar order becomes local and is dispersed in an amorphous matrix with a crystalline size down to a few nanometers, leading to an excellent dimensional scalability and a good field-stability of the k value. As an example, a stable high k value (37±3) is shown in ultrathin SPE films of (Ba_0.95,Sr_0.05)(Zr_0.2,Ti_0.8)O₃ deposited on LaNiO₃-buffered Pt/Ti/SiO₂/(100)Si down to a 4 nm thickness, leading to a small equivalent oxide thickness of ~0.46 nm. The aforementioned characteristic microstructure endows the SPE film a high breakdown strength (~10.5 MV·cm⁻¹ for the 4 nm film), and hence ensures a low leakage current for the operation of the complementary metal oxide semiconductor (CMOS) gate. Lastly, a high electrical fatigue resistance is displayed by the SPE films. These results reveal a great potential of superparaelectric materials as gate dielectrics in the next-generation microelectronics.

Bi_0.5Na_0.5TiO₃–BaTiO₃ (BNT–100xBT) ceramics are promising candidates for piezoelectric applications. The correlation between their structure and piezoelectric properties has attracted considerable interest. Herein, the structures of 6BT and 7BT with distinct piezoelectricity are investigated via in-situ synchrotron X-ray diffraction and transmission electron microscopy. It is found that although both compositions present morphotropic phase boundary (MPB) features with coexisting R3c and P4bm phases, their refined structures are significantly different. 6BT is composed of the R3c phase with a small P4bm fraction after electrical poling, while 7BT presents comparable fractions of the two phases. Less pronounced structure distortion and oxygen octahedral tilting occur in 7BT, which favor the phase transformation, resulting in an enhanced piezoelectricity. This enhancement driven by structural flexibility is elucidated by phenomenological analysis. These results demonstrate that the design of high piezoelectricity at MPBs should consider not only the phase-coexisting states but also the refined crystal structure.