Dielectric ceramics with outstanding energy-storage performances are nowadays in great demand for pulsed power electronic systems. Here, we propose a synergistic design strategy to significantly enhance the energy-storage properties of (1 - x)(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-xCaTi0.75Ta0.2O3 solid solution ceramics through introducing polar nanoregions, shifting rhombohedral to tetragonal phase transition below room temperature (stable antiferroelectric characteristic), as well as increasing the band gap in the system. Ultrahigh energy-storage properties with a record value of recoverable energy-storage density Wrec ∼ 9.55 J/cm3 and a high efficiency η ∼ 88% are achieved in Na0.5Bi0.5TiO3-based bulk ceramics with x = 0.24. Moreover, high Wrec (>3.4 J/cm3) and η (>90%) with a variation of less than 6% can be observed in a wide frequency and temperature frequency range of 5-200 Hz and 25-140 °C. Our research result not only indicates the great possibility of Na0.5Bi0.5TiO3-based lead-free compositions to replace lead-based energy-storage ceramics but also gives an effective strategy to design ultrahigh energy-storage performances for eco-friendly ceramics.

Ultrahigh Energy-Storage Performances in Lead-free Na0.5Bi0.5TiO3-Based Relaxor Antiferroelectric Ceramics through a Synergistic Design Strategy.

Although relaxor ferroelectrics have been widely investigated owing to their various advantages, there are still impediments to boosting their energy-storage density (Wrec) and energy-storage efficiency (η). In this paper, we propose a cooperative optimization strategy for achieving comprehensive outstanding energy-storage performance in (Na0.5Bi0.5)0.7Sr0.3TiO3 (NBST)-based ceramics by triggering a nonergodic-to-ergodic transformation and optimizing the forming process. The first step of substituting NaNbO3 (NN) for NBST generated an ergodic state and induced polar nanoregions under the guidance of a phase-field simulation. The second step was to apply a viscous polymer process (VPP) to the 0.85NBST-0.15NN ceramics, which reduced porosity and increased compactness, resulting in a significant polarization difference and high breakdown strength. Consequently, 0.85NBST-0.15NN-VPP ceramics optimized by this cooperative two-step strategy possessed improved energy-storage characteristics (Wrec = 7.6 J/cm3, η = 90%) under 410 kV/cm as well as reliable temperature adaptability within a range of 20-120 °C, outperforming most reported (Na0.5Bi0.5) TiO3-based ceramics. The improved energy-storage performance validates the developed ceramics' practical applicability as well as the advantages of implementing a cooperative optimization technique to fabricate similar high-performance dielectric ceramics.

Enhanced Energy Storage Properties in Lead-Free (Na0.5Bi0.5)0.7Sr0.3TiO3-Based Relaxor Ferroelectric Ceramics through a Cooperative Optimization Strategy.

Heterogeneous N-doped carbon composite NiSe2–FeSe double-shell hollow nanorods for tunable and high-efficient microwave attenuation

High‐efficiency electromagnetic (EM) functional materials are the core building block of high‐performance EM absorbers and devices, and they are indispensable in various fields ranging from industrial manufacture to daily life, or even from national defense security to space exploration. Searching for high‐efficiency EM functional materials and realizing high‐performance EM devices remain great challenges. Herein, a simple solution‐process is developed to rapidly grow gram‐scale organic–inorganic (MAPbX3, X = Cl, Br, I) perovskite microcrystals. They exhibit excellent EM response in multi bands covering microwaves, visible light, and X‐rays. Among them, outstanding microwave absorption performance with multiple absorption bands can be achieved, and their intrinsic EM properties can be tuned by adjusting polar group. An ultra‐wideband bandpass filter with high suppression level of −71.8 dB in the stopband in the GHz band, self‐powered photodetectors with tunable broadband or narrowband photoresponse in the visible‐light band, and a self‐powered X‐ray detector with high sensitivity of 3560 µC Gyair−1 cm−2 in the X‐ray band are designed and realized by precisely regulating the physical features of perovskite and designing a novel planar device structure. These findings open a door toward developing high‐efficiency EM functional materials for realizing high‐performance EM absorbers and devices.

Multifunctional Organic–Inorganic Hybrid Perovskite Microcrystalline Engineering and Electromagnetic Response Switching Multi‐Band Devices

Transparent ceramic capacitors have broad application prospects in electronic devices due to their excellent optical transparency and energy storage properties. However, the low polarizability and high remnant polarization of the existing transparent dielectric ceramics limit the promotion of energy storage performance. Here, Bi(Li0.5Nb0.5)O3 (BLN) was chosen to modify the (K0.5Na0.5)NbO3 (KNN)-based ceramics to optimize the optical transmittance and energy storage characteristics simultaneously. On the one hand, the grain growth is inhibited, contributing to the improved breakdown strength and transmittance. On the other hand, the doping BLN could reduce the polar nanoregions size, which makes them respond more quickly to the external electric field and, thus, improves the energy storage efficiency. As a consequence, 0.95KNN–0.05BLN ceramic possesses the excellent Wrec of 4.39 J/cm3, η of 81.4%, and transparency of 77.9% with an average grain size of ∼109 nm. This work opens up a paradigm to develop a transparent pulse capacitor. 

Amelioration on energy storage performance of KNN–based transparent ceramics by optimizing the polarization and breakdown strength

The multirelaxation behavior is promising for high-performance dielectric materials based on polarization-controllable high-efficiency electromagnetic attenuation. However, a single polar unit is the main problem that restricts the development of dielectric materials in the field. Herein, by constructing multiple polar units based on nanodomain engineering, enhanced electromagnetic attenuation properties are achieved in La doping BiFeO3 ferroelectric ceramics. A dual-band attenuation with a maximum reflection loss of -43.4 dB together with a wide effective bandwidth (<-10 dB) of 3.3 GHz in X-band, is acquired in Bi0.85 La0.15 FeO3 which just has a thickness of 1.54 mm. A systematic experimental analysis coupled with potential well modeling suggests that the miniaturization of the ferroelectric domain, from micron to nanoscale, induces an additional interface polarization that is capable of responding to microwave frequency, leading to the formation of dual dielectric relaxation. The way that intrinsic polar unit induces another polar unit through size effect to obtain multiple contributions of electromagnetic loss provides a feasible and universal strategy to design high-performance electromagnetic attenuation materials based on the ferroelectric family.

High-Performance Ferroelectric Electromagnetic Attenuation Materials with Multiple Polar Units Based on Nanodomain Engineering.

Efficient Ultraviolet-Visible-Near Infrared Self-Powered Photodetector Based on Hexagonal YMnO3-Based Ferroelectric Thin Film by Multiscale Polarity Structure Optimization

In this paper, high-velocity impact resistance of lightweight laminates with multi-layers of carbon-fibre/epoxy laminates sandwiched by two titanium alloy skins and aluminium alloy skins was extensively investigated by experiments with a total of 48 impact tests conducted. The ballistic limit of the titanium-based carbon-fibre/epoxy laminate was estimated to be between 241.6 m/s and 257.1 m/s. Impact velocity governed energy absorption and the corresponding damage modes were characterised and identified. The influence of fibre metal laminates configuration on the impact resistance was then experimentally investigated at a fixed impact velocity with full penetration in ten types of laminates. The results also showed that thicker skin and higher number of fibre layers favoured the specific energy absorption in the tested matrix. 

Ballistic impact experiments of titanium-based carbon-fibre/epoxy laminates

The utilization of ferroelectric materials is believed to be a viable way to construct self-powered photodetectors based on ferroelectric photovoltaic effect. However, low photocurrent density of ferroelectric materials is a...

https://pubs.rsc.org/en/content/articlepdf/2022/qi/d2qi01774a

Ao Gong

Papers

High-Performance Ferroelectric Electromagnetic Attenuation Materials with Multiple Polar Units Based on Nanodomain Engineering.

Efficient Ultraviolet-Visible-Near Infrared Self-Powered Photodetector Based on Hexagonal YMnO3-Based Ferroelectric Thin Film by Multiscale Polarity Structure Optimization

Ballistic impact experiments of titanium-based carbon-fibre/epoxy laminates

Ultrahigh-Performance Self-Powered Photodetector Based on Hexagonal YbMnO3 Ferroelectric Thin Film by Polarization-Induced Ripple Effect

Broadband, high-sensitivity self-powered ferroelectric LuMnO3-based photodetector with large photocurrent output