Optimizing high-temperature energy storage in tungsten bronze-structured ceramics via high-entropy strategy and bandgap engineering.

As a vital material utilized in energy storage capacitors, dielectric ceramics have widespread applications in high-power pulse devices. However, the development of dielectric ceramics with both high energy density and efficiency at high temperatures poses a significant challenge. In this study, we employ high-entropy strategy and band gap engineering to enhance the energy storage performance in tetragonal tungsten bronze-structured dielectric ceramics.

Ultrahigh Energy Storage in Tungsten Bronze Dielectric Ceramics Through a Weakly Coupled Relaxor Design.

Dielectric energy-storage capacitors, known for their ultrafast discharge time and high-power density, find widespread applications in high-power pulse devices. However, ceramics featuring a tetragonal tungsten bronze structure (TTBs) have received limited attention due to their lower energy-storage capacity compared to perovskite counterparts. Herein, a TTBs relaxor ferroelectric ceramic based on the Gd Ba Sr Sm Nb O composition, exhibiting an ultrahigh recoverable energy density of 9 J cm and an efficiency of 84% under an electric field of 660 kV cm is reported.

Polarity Modulation Induced High Electrostrain Performance with Near-Zero Hysteresis in a (SrBi)TiO-Based System.

High-precision piezo actuators necessitate dielectrics with high electrostrain performance with low hysteresis. Polarity-modulated (SrBi)TiO-based ceramics exhibit extraordinarily discrete multiphase coexistence regions: (i) the relaxor phase coexistence (RPC) region with local weakly polar tetragonal () and pseudocubic (Pc) short-range polar nanodomains and (ii) the ferroelectric phase coexistence (FPC) region with long-range domains and Pc nanodomains. The RPC composition features a specially high and pure electrostrain performance with near-zero hysteresis ( ∼ 0.

HISTONE DEACETYLASE 9 transduces heat signal in plant cells.

Heat stress limits plant growth, development, and crop yield, but how plant cells precisely sense and transduce heat stress signals remains elusive. Here, we identified a conserved heat stress response mechanism to elucidate how heat stress signal is transmitted from the cytoplasm into the nucleus for epigenetic modifiers. We demonstrate that HISTONE DEACETYLASE 9 (HDA9) transduces heat signals from the cytoplasm to the nucleus to play a positive regulatory role in heat responses in .

Achieving Ultrahigh Energy-Storage Density with Excellent Thermal Stability in SrBiTiO-Based Relaxors via Polarization Behavior Modulation.

Dielectric capacitors possessing the inherent superiorities of high power density and ultrafast charge-discharge speed make their utilization in energy-storage devices extremely propitious, although the relatively low recoverable energy-storage density () may impede their applications. In this work, unlike the mainstream approach of destroying long-range ferroelectric/antiferroelectric order and inducing relaxor properties to achieve a high value, we have selected end members with a high polarization gene to promote the polarization behavior of the typical relaxor SrBiTiO. Therefore, an ultrahigh ∼ 8 J/cm and a superior efficiency (η) ∼ 91% are accomplished in the 0.

Enhancing Comprehensive Energy Storage Properties in Tungsten Bronze SrBaNbO-Based Lead-free Ceramics by B-Site Doping and Relaxor Tuning.

Dielectric ceramics with relaxor characteristics are promising candidates to meet the demand for capacitors of next-generation pulse devices. Herein, a lead-free Sb-modified (SrBaGd) (NbTaSb)O (SBGNT-based) tungsten bronze ceramic is designed and fabricated for high-density energy storage capacitors. Using a B-site engineering strategy to enhance the relaxor characteristics, Sb incorporation could induce the structural distortion of the polar unit BO and order-disorder distribution of B-site cations as well as the modulation of polarization in the SBGNT-based tungsten bronze ceramic.

Achieving Good Temperature Stability of Dielectric Constant by Constructing Composition Gradient in (Pb,La)(Zr,Ti)O Multilayer Thin Films.

Ferroelectrics with a high dielectric constant are ideal materials for the fabrication of miniaturized and integrated electronic devices. However, the dielectric constant of ferroelectrics varies significantly with the change of temperature, which is detrimental to the working stability of electronic devices. This work demonstrates a new strategy to design a ferroelectric dielectric with a high temperature stability, that is, the design of a multilayer relaxor ferroelectric thin film with a composition gradient.

High Energy Density and Temperature Stability in PVDF/PMMA Polymerization Blending.

Dielectrics with improved energy density have long-standing demand for miniature and lightweight energy storage capacitors for electrical and electronic systems. Recently, polyvinylidene fluoride (PVDF)-based ferroelectric polymers have shown attractive energy storage performance, such as high dielectric permittivity and high breakdown strength, and are regarded as one of the most promising candidates. However, the non-negligible energy loss and inferior temperature stability of PVDF-based polymers deteriorated the energy storage performance or even the thermal runaway, which could be ascribed to vulnerable amorphous regions at elevated temperatures.

Enhanced charge separation in LaNiO nanoplates by coupled piezocatalysis and photocatalysis for efficient H evolution.

Photocatalytic hydrogen evolution is one promising method for solar energy conversion, but the rapid charge recombination limits its efficiency. To this end, in this work, grain size, and hence the charge carrier migration path, is reduced by lowering the synthesis temperature of two-dimensional visible light-responsive LaNiO perovskite. Interestingly, the hydrogen yield for the piezoelectric response of LaNiO under only 40 kHz ultrasonic vibration is as high as 680 μmol h g, which is 80 times that under only 600 mW cm visible light irradiation.

New Degree of Freedom in Determining Superior Piezoelectricity at the Lead-Free Morphotropic Phase Boundary: The Invisible Ferroelectric Crossover.

The morphotropic phase boundary (MPB) in lead-free ferroelectrics, starting from a quadruple point (QP), often displays large piezoelectric responses due to the flattened free-energy profiles. In this work, we found that the QP composition rendering most flattened energy profiles could also exhibit abnormally low piezoelectric constants in Hf-doped BaTiO. Such an anomaly in the strength of piezoelectricity can be ascribed to the progressive influence of additional strain heterogeneity induced by the substitution of Hf for Ti in BaTiO, which was overlooked previously.

Atomic-scale fatigue mechanism of ferroelectric tunnel junctions.

Ferroelectric tunnel junctions (FTJs) are promising candidates for next-generation memories due to fast read/write speeds and low-power consumptions. Here, we investigate resistance fatigue of FTJs, which is performed on Pt/BaTiO/Nb:SrTiO devices. By direct observations of the 5–unit cell–thick BaTiO barrier with high-angle annular dark-field imaging and electron energy loss spectroscopy, oxygen vacancies are found to aggregate at the Pt/BaTiO interface during repetitive switching, leading to a ferroelectric dead layer preventing domain nucleation and growth.

Domain Engineered Lead-Free Ceramics with Large Energy Storage Density and Ultra-High Efficiency under Low Electric Fields.

Dielectric energy storage materials are becoming increasingly popular due to their potential superiority, for example, excellent pulse performance as well as good fatigue resistance. Although numerous studies have focused on lead-free dielectric materials which possess outstanding energy storage characteristics, the results are still not satisfying in terms of achieving both large discharging energy density () and high discharging efficiency (η) under low electric fields, which is crucial to be conducted in miniatured electronic components. Here, we adopt the strategy of domain engineering to develop sodium bismuth titanate (BiNaTiO)-based ceramics employed in the low-field situation.

Flexoelectric Thin-Film Photodetectors.

The flexoelectric effect, which manifests itself as a strain-gradient-induced electrical polarization, has triggered great interest due to its ubiquitous existence in crystalline materials without the limitation of lattice symmetry. Here, we propose a flexoelectric photodetector based on a thin-film heterostructure. This prototypical device is demonstrated by epitaxial LaFeO thin films grown on LaAlO substrates.

Giant Electrocaloric Effect and Ultrahigh Refrigeration Efficiency in Antiferroelectric Ceramics by Morphotropic Phase Boundary Design.

Electrocaloric effect (ECE) in ferroelectric (FE)/antiferroelectric (AFE) materials offers a promising high-efficient and zero-emission solid-state cooling technology, whose materials design is usually focused on the morphotropic phase boundary (MPB) between two FE phases. This work constructs an MPB between an orthorhombic AFE and a rhombohedral FE phase in PbBaLaZrTiO (PBLZT100, = 0-0.08) ceramics and achieves a superior ECE performance.

The Role of Ferroelectric Polarization in Resistive Memory Properties of Metal/Insulator/Semiconductor Tunnel Junctions: A Comparative Study.

Recently, tunnel junction devices adopting semiconducting Nb:SrTiO electrodes have attracted considerable attention for their potential applications in resistive data storage and neuromorphic computing. In this work, we report on a comparative study of Pt/insulator/Nb:SrTiO tunnel junctions between ferroelectric BaTiO and nonferroelectric SrTiO and LaAlO barriers to reveal the role of polarization in resistance switching properties. Although hysteretic behaviors appear in current-voltage measurements of all devices regardless of the barrier character, significantly improved current ratios by more than three orders of magnitude are observed in the Pt/BaTiO/Nb:SrTiO tunnel junctions due to the dominance of polarization in modulation of junction barrier profiles between the low and high resistance states.

Coupling between phase transitions and glassy magnetic behaviour in Heusler alloy NiMnInGa.

The transition sequence in the Heusler alloy NiMnInGahas been determined from measurements of elasticity, heat flow and magnetism to be paramagnetic austenite → paramagnetic martensite → ferromagnetic martensite at ∼335 and ∼260 K, respectively, during cooling. The overall pattern of elastic stiffening/softening and acoustic loss is typical of a system with bilinear coupling between symmetry breaking strain and the driving structural/electronic order parameter, and a temperature interval below the transition point in which ferroelastic twin walls remain mobile under the influence of external stress. Divergence between zero-field-cooling and field-cooling determinations of DC magnetisation below ∼220 K indicates that a frustrated magnetic glass develops in the ferromagnetic martensite.

Interface-Charge Induced Giant Electrocaloric Effect in Lead Free Ferroelectric Thin-Film Bilayers.

Conventional refrigeration methods based on compression-expansion cycles of greenhouse gases are environmentally threatening and cannot be miniaturized. Electrocaloric effects driven by electric fields are especially well suited for implementation of built-in cooling in portable electronic devices. However, most known electrocaloric materials present poor cooling performances near room temperature, contain toxic substances, and require high electric fields.

Remarkably Enhanced Negative Electrocaloric Effect in PbZrO Thin Film by Interface Engineering.

The electrocaloric effect in ferroelectric materials has drawn much attention due to its potential applications in integrated circuit cooling and novel cooling devices. In contrast to the widely researched positive electrocaloric effect, the negative electrocaloric effect has received much less attention due to the lack of any effective methods for significant enhancement. In this work, we fabricated PbZrO thin film on a Pt/Si substrate by the sol-gel method.

Nano-Ferroelectric for High Efficiency Overall Water Splitting under Ultrasonic Vibration.

Piezocatalysis, converting mechanical vibration into chemical energy, has emerged as a promising candidate for water-splitting technology. However, the efficiency of the hydrogen production is quite limited. We herein report well-defined 10 nm BaTiO nanoparticles (NPs) characterized by a large electro-mechanical coefficient which induces a high piezoelectric effect.

All-Inorganic Flexible Embedded Thin-Film Capacitors for Dielectric Energy Storage with High Performance.

As passive components in flexible electronics, the dielectric capacitors for energy storage are facing the challenges of flexibility and capability for integration and miniaturization. In this work, the all-inorganic flexible dielectric film capacitors have been obtained. The flexible capacitors show a desirable recoverable energy density ( W) of 40.

Developing a ferroelectric nanohybrid for enhanced photocatalysis.

We develop a ferroelectric nanohybrid that improves photocatalytic efficiency by reducing the recombination of holes and electron charge carriers. In particular, the size of uniformly dispersed ferroelectric BaTiO in the nanohybrid reaches the critical size of a monodomain, which avoids the need for a poling process for switching the ferroelectric polarization.

Large Energy Density, Excellent Thermal Stability, and High Cycling Endurance of Lead-Free BaZrTiO Film Capacitors.

A large energy storage density (ESD) of 30.4 J/cm and high energy efficiency of 81.7% under an electrical field of 3 MV/cm was achieved at room temperature by the fabrication of environmentally friendly lead-free BaZrTiO epitaxial thin films on Nb-doped SrTiO (001) substrates by using a radio-frequency magnetron sputtering system.

Ultrahigh Energy Storage Performance of Lead-Free Oxide Multilayer Film Capacitors via Interface Engineering.

Ultrahigh energy storage density of 52.4 J cm with optimistic efficiency of 72.3% is achieved by interface engineering of epitaxial lead-free oxide multilayers at room temperature.

Novel lead-free ferroelectric film by ultra-small BaSrTiO nanocubes assembled for a large electrocaloric effect.

A giant electrocaloric effect (ECE) can be achieved in ferroelectric thin films, which demonstrates the applications of thin films in alternative cooling. However, electrocaloric thin films fabricated by conventional techniques, such as the pulsed laser deposition or sol-gel methods, may be limited by high costs, low yield and their dependence on substrates. In this study, we present a new bottom-up strategy to construct electrocaloric BaSrTiO thin films by assembling precisely designed building blocks of ferroelectric nanocubes, which is supported by detailed structural characterization.

Metamaterials: A New Ba0.6 Sr0.4 TiO3 -Silicon Hybrid Metamaterial Device in Terahertz Regime (Small 19/2016).

A giant terahertz modulation based on a Ba0.6 Sr0.4 TiO3 -silicon hybrid metamaterial is reported by L.