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Poly(lactic acid)-based (PLA) films with biodegradability and ease of processing are promising dielectrics for application in electrostatic capacitors. Nevertheless, the relative low energy storage capability of the PLA film greatly hampers the development of its further application. Herein, a biodegradable polymer of stereocomplex crystals of poly(lactic acid) is prepared utilizing a solution blending method of the co-blended poly-L-lactic acid (PLLA) and poly-D-lactic acid (PDLA) in a 1:1 ratio. The stereocomplex crystals could prominently improve insulation and mechanical properties of PLLA/PDLA blend films, thus achieving an outstanding energy density ( Ud ∼ 13.7 J/cm3) accompanied with high efficiency ( η ∼ 92.8%) at a breakdown electric field of 750 MV/m. Additionally, the PLLA/PDLA blend film also exhibit good high-temperature performance and reliability. This work provides a reasonable tailoring strategy for biodegradable polymer dielectrics and demonstrates a great potential of biodegradable polymers for practical applications in environmentally friendly power electronics and electrical systems.

Polymer dielectric films have been widely used in electronic and power systems due to their unique dielectric properties, processing properties, and excellent cost performance. Although the dielectric constant of dielectric polymers can be improved by adding high contents of ceramic fillers, this approach comes at the expense of the breakdown strength ( Eb). This work is inspired by the idea that high-aspect-ratio fibers can induce a larger electric dipole moment without sacrificing too much Eb compared to zero-dimensional nanoparticles, thereby effectively improving the energy storage performance of the composites. We synthesized antiferroelectric AgNbO3 (ANO) fibers by using an in situ topotactic transition reaction which were then introduced into the polyvinylidene fluoride (PVDF) matrix for energy storage applications. The results show that the nanocomposite film with an ultralow loading of 0.4 wt. % ANO fibers achieves a high discharge energy density of 12.97 J cm−3 at 490 MV m−1. Nanocomposites based on ultralow content ANO fibers show great promise as one-dimensional antiferroelectric fillers for high energy density capacitor applications.

The multilayered composite films combining antiferroelectric (AFE) Pb0.97La0.02(Zr0.95Ti0.05)O3 (PLZT) with paraelectric (PE) SrTiO3 (STO) have been fabricated by the sol–gel method, and their ferroelectric and energy storage performances were carefully investigated. It was revealed that both the dielectric breakdown strength (Eb) and the maximum polarization (Pm) in the multilayered composite films are increased. Consequently, an ultra-high and recoverable energy storage density (Wre) of ∼101 J/cm3 and a high efficiency (η) of ∼62% were achieved in the composite film with an 18 wt. % STO content. The enhanced Wre in the multilayered composite is attributed to the internal-strain release of the PLZT layers and charge blocking by the STO layers with significantly enhanced Eb. The results suggest an effective way of improving the energy storage performances by combining AFE PLZT and PE STO.

Spin configuration, magnetocrystalline anisotropy compensation, and magnetostriction of TbxDy1−x(Fe0.8Co0.2)2 (0.20 ≤ x ≤ 0.40) compounds have been investigated. Experimental evidence for the anisotropy compensation has been observed directly by performing x-ray diffraction on magnetic-field aligned powders and by evaluating the Mossbauer spectra. The easy magnetization direction (EMD) at room temperature rotates from the ⟨100⟩ (x ≤ 0.27) to the ⟨111⟩ axis (x ≥ 0.32), subjected to the anisotropy compensation between Tb3+ and Dy3+ ions. The strong grain-⟨111⟩-oriented pseudo-1–3 epoxy/composite has been fabricated by curing under a moderate magnetic field. A giant low-field magnetostriction, longitudinal λ|| and linear anisotropic λa (=λ|| − λ⊥) up to 550 and 760 ppm at 3 kOe, respectively, is obtained for Tb0.32Dy0.68(Fe0.8Co0.2)2 composite, which can be attributed to anisotropy compensation, a large magnetostriction coefficients λ111, EMD lying along ⟨111⟩ direction, the strong ⟨111⟩-textured orientation, and the chain structure. The good magnetoelastic properties, besides only containing 27 vol. % alloy particles in the insulating epoxy, make it a promising candidate for magnetostriction applications.