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For more than half a century, the morphotropic phase boundary (MPB) has drawn constant interest in developing piezoelectric materials, as the phase instability at the region significantly enhances piezoelectricity. However, the local structure/symmetry at the MPB region is still under controversy. The investigation on morphology and origin of the local structure at MPB is of considerable importance to provide a microstructure basis for high piezoelectricity. In the present study, we thus use high resolution transmission electron microscopy to investigate the microstructure feature of MPB at PMN-PT ceramics. The local structure is shown to be the coexistence of nano-scaled {110}-type rhombohedral (R) twin and {110}-type tetragonal (T) twin. Such nano-scaled coexistence can be due to a nearly vanishing polarization anisotropy and low domain wall energy at MPB, which thus facilitates polarization rotation between 〈001〉T and 〈111〉R states and leads to high properties of MPB compositions.

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Photothermal therapy (PTT), a powerful tool for non-invasive cancer treatment, has been recognized as an alternative strategy for cancer therapy in clinic, and it is promoted by optical absorbing agents...

Quick charge/discharge polymer‐based composites filled with inorganic nanosheets have attracted extensive attention and provided a more efficient way to achieve high energy storage density (U) because of the alleviated agglomeration of fillers and the formation of conduction barriers. However, conductive paths have a chance to extend along out‐of‐plane directions by circumventing the micrometer‐sized nanosheets. Here, large‐sized (111)‐oriented BaTiO3 (BTO) films with outstanding epitaxiality and ferroelectricity are embedded in poly(vinylidene fluoride) (PVDF) using optimal transfer and hot‐pressing processes. The 2D–2D (2–2) type BTO/PVDF composites interlayered by 2‐layer BTO (about 0.2 µm thick of each layer) exhibit the highest U of 20.7 J cm‐3 at 690 MV m‐1, which is 222.6% that of pure PVDF. Phase‐field simulations reveal that high‐resistance PVDF films as outer layers can prevent the charges injection from electrodes and high‐dielectric BTO films as inner layers can effectively suppress the mobile charges across interfaces between layers, leading to a remarkable improvement of breakdown strength. This work puts forward a scalable approach to enhance the U of inorganic/organic composites for advanced energy storage materials and applications.

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Dielectric capacitors are promising for high power energy storage, but their breakdown strength (Eb) and energy density (Ue) usually degrade rapidly at high temperatures. Adding boron nitride (BN) nanosheets can improve the Eb and high‐temperature endurance but with a limited Ue due to its low dielectric constant. Here, freestanding single‐crystalline BaZr0.2Ti0.8O3 (BZT) membranes with high dielectric constant are fabricated, and introduced into BN doped polyetherimide (PEI) to obtain laminated PEI–BN/BZT/PEI–BN composites. At room temperature, the composite shows a maximum Ue of 17.94 J cm−3 at 730 MV m−1, which is more than two times the pure PEI. Particularly, the composites exhibit excellent dielectric‐temperature stability between 25 and 150 °C. An outstanding Ue = 7.90 J cm−3 is obtained at a relatively large electric field of 650 MV m−1 under 150 °C, which is superior to the most high‐temperature dielectric capacitors reported so far. Phase‐field simulation reveals that the depolarization electric field generated at the BZT/PEI–BN interfaces can effectively reduce carrier mobility, leading to the remarkable enhancement of the Eb and Ue over a wide temperature range. This work provides a promising and scalable route to develop sandwich‐structured composites with prominent energy storage performances for high‐temperature capacitive applications.

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