Solid-state refrigeration technologies, represented by electrocaloric effect (ECE), are renowned for zero global-warming-potential and high cooling efficiency. Synergistically achieving high electrocaloric effect (ΔT) and wide temperature span (ΔTspan) for EC materials takes a leapfrog toward practical cooling applications, typical for integrated circuits. Guided by phase-field simulation, Ba(Ti, Hf)O3 dubbed as a polar wrench, establishes polar frustration by setting up local stress field and manipulating octahedral oxygen tilt (OOT) in NaNbO3-based relaxor. The resultant P4bm framework entails short-range and highly-polar ferrodistortive nanodomains, i.e., the abundant highly-polar nanodomains facilitate to increase entropy change and robust OOT enables to impede thermal perturbations. Consequently, a large ΔT of 0.85 K and 0.70 K with an ultrawide ΔTspan of 118 K and 130 K is obtained, contributing to an ultrahigh figure of merit of > 90 K2 in NaNbO3-Ba(Ti, Hf)O3, significantly outperforms its counterparts. The local structure responsible for robust EC performances are decrypted through 2D information from atomic-resolution scanning transmission electron microscope, 3D big-box model constructed from neutron total scattering and DFT calculations. These findings highlight that polar frustration strategy in ferrodistortive relaxor enables to pioneer emergent EC performances, and also unearth potential entropy-change-based ferroelectric and ferromagnetic materials beyond.

Sliding ferroelectric (FE) metals provide a practical route to combine switchable out-of-plane polarization with metallicity, yet realizing electrically reversible magnetization and Berry-curvature-driven anomalous transport and magneto-optical effects in a topological system remains challenging. Here, we establish a symmetry-based framework for sliding FE metals with ferrimagnetism. We show that interlayer sliding breaks the combined spin space symmetry, thereby inducing reversible out-of-plane polarization, nonrelativistic spin splitting, and finite net magnetization, namely, triply-coupled switching. Guided by this principle, we identify the MnIn2Se4 bilayer as a realistic sliding FE ferrimagnetic (FiM) metal hosting Weyl points, in which in-plane sliding enables robust triply-coupled switching, while spin-orbit coupling gaps the Weyl points and produces strong Berry curvature around the Fermi level, leading to large and electrically switchable anomalous transport and magneto-optical effects. Our results establish sliding FE FiM metals with topological states as a promising platform for electrically switchable, high-speed, and low-dissipation spintronic devices.

Altermagnetism, the third magnetic phase beyond ferromagnetism and antiferromagnetism, holds great promise for spintronics but also faces challenges in materials discovery and mechanism exploration. Here, through high‐throughput screening of 170 pentagonal 2D materials, 4 altermagnetic semiconductors (MnS 2 , CoS 2 , MnC 2 , and CoPSe) are identified with sizable spin splitting (109–172 meV). It is shown that MnS 2 is the first‐of‐kind altermagnetic second‐order topological insulator (AMSOTI), as evidenced by a nontrivial real Chern number (ν R = 1) and spin‐polarized corner state. Using ab inito quantum transport simulation, a MnS 2 ‐based altermagnetic tunneling junction (AMTJ) is designed and a giant tunneling magnetoresistance (TMR) of 1.5 × 10 5 % at the Fermi level, which surpasses MF 2 (M = Co and Ni)‐based AMTJ by three orders of magnitude. In addition, by applying a twisting angle of 90° to the AMTJ without altering the order, a significant TMR of 1.2 × 10 7 % as driven by the structural changes is observed. This work unveils pentagonal 2D materials as a compelling material platform for exploring the physics and device applications of altermagnets.

Rare-earth-transition-metal intermetallics have attracted considerable attention because of their strong magnetoelastic coupling and potential magnetocaloric applications. This study systematically investigates the magnetovolume effect, critical behavior, and magnetocaloric properties of ThMn12-type RFe10Si2 (R = Er, Ho, Dy) compounds. Below the Curie temperature (TC), these alloys exhibit pronounced positive spontaneous volume magnetostriction. Microstructural analyses (via temperature-dependent synchrotron X-ray diffraction and dilatometry) reveal that this effect originates from local atomic displacements and Wigner-Seitz cell expansion driven by minimization of the total exchange energy. As the de Gennes factor of the rare-earth ions increases, TC increases monotonically from 560 K for ErFe10Si2 to 574 K for DyFe10Si2. Critical behavior analysis confirms a second-order ferrimagnetic-to-paramagnetic transition dominated by long-range exchange interactions. Owing to the broad operating temperature range of this continuous transition, the compounds demonstrate an excellent relative cooling power of up to 249.6 J kg-1 under a magnetic field change of 5 T. These findings clarify the microscopic origin of local magnetoelastic coupling in heavy rare-earth intermetallics and highlight their potential for medium-to-high-temperature solid-state magnetic refrigeration.

Relaxor ferroelectric ceramics are promising energy-storage candidates for high-power electronic systems owing to their high energy density and fast charge-discharge speed. However, achieving ultrahigh energy density still poses challenges due to the inherently inverted coupling relationship between polarization (P) and breakdown electric field (Eb). Here, we propose a high-entropy strategy to decouple polarization from breakdown electric field. The high-entropy design exerts a triple effect, which involves flattening electronic band to restrict the transport of charge carriers, driving the formation of core-shell heterostructure to suppress electrical breakdown, and stabilizing polymorphic polar phases to promote polarization rotation. The triple synergy effect led to an ultrahigh Eb and a maximized polarization disparity (ΔP = Pm - Pr). As a result, the high-entropy ceramics exhibit an ultrahigh recoverable energy density (Wrec) of 10.23 ± 0.99 J/cm3 and a satisfactory efficiency (η) of 85.44% ± 3.34%, alongside good cycling reliability and temperature stability. This work provides an innovative design paradigm for achieving excellent energy storage performance of dielectric capacitors.

Magnesium-sulfur (Mg-S) batteries are promising next-generation energy storage systems due to their high theoretical energy density and the inherent dendrite resistance of magnesium anodes. However, their development is hindered by the polysulfide shuttle effect and sluggish redox kinetics. Herein, we design a copper nanoparticle-decorated MXene composite (MXene@Cu/C-S) as a multifunctional sulfur host. This design leverages an in-situ growth and annealing process to integrate a defective Cu-MOF with MXene, creating a conductive scaffold rich in catalytic sites. Characterization confirms the reduction of Cu2 + to Cu0 nanoparticles, which form strong electronic coupling with the MXene substrate via Cu-O-Ti bonds. This synergy enhances electron transfer and polysulfide adsorption, as evidenced by a high specific capacity of 1130.5 mAh g-1 after 150 cycles and a decay rate of only 0.09 %. Furthermore, the composite significantly lowers the energy barrier for polysulfide conversion and suppresses the shuttle effect. This work provides a novel design strategy for high-performance Mg-S battery cathodes.

We discuss altermagnetic multiferroics, materials hosting distinct advantages for low-power spintronic devices, including a zero net magnetization that eliminates stray fields, a momentum-dependent spin splitting enabling controllable spin currents and an intrinsic strong magnetoelectric coupling originating from the spin space symmetry.

In this work, we introduce a new class of chiral altermagnetic magnetoelectrics in structurally chiral, nonpolar altermagnetic systems and identify the experimentally well-characterized three-dimensional metal-organic framework K[Co(HCOO) 3 ] as a promising material platform. K[Co(HCOO) 3 ] exhibits chirality-locked g-wave altermagnetic spin splitting together with dual-mode switchable electric polarization controlled by Néel-vector reorientation and structural chirality. Specifically, Néel-vector reorientation generates a finite electric polarization and reverses its sign, whereas chirality switching between left- and right-handed enantiomers produces an additional sign reversal. The associated electronic and optical responses provide effective readout channels for these switchable states. Our results establish chiral altermagnetic magnetoelectrics as a promising route to chirality- and Néel-vector-controlled nonvolatile multifunctional spintronics.

Two-dimensional materials that combine magnetic order, valley polarization, and piezoelectric response are essential for next-generation low-power electronics. Using first-principles calculations, we predict a new family of two-dimensional rare-earth halides, 2H-LaF X ...

Laser displays are pivotal next-generation technologies for augmented/virtual reality, wearables, and optical communications. To realize full-color patterned lasing displays, we propose an effective‌ photoinduced vapor-solid anion exchange (PVAE) strategy, enabling unprecedented amplified spontaneous emission (ASE) control via precise temporal modulation. It regulates photoswitchable anion exchange in CsPbX3 (X = Cl, Br, I) perovskites, with exchange rates tuned by illumination wavelength and intensity. Under optimized 1561.8 microwatts per square centimeter ultraviolet activation, PVAE drives complete compositional transitions (CsPbIBr2 → CsPbBr3 → CsPbClBr2), inducing linear ASE peak shifts across 470- to 710-nanometer full-color spectra. Spatially modulated multicolor ASE patterns further verify its adaptability. We achieve precise, wide microscale emission wavelength modulation of CsPbX3 films in both temporal and spatial domains. These advantages establish PVAE as a dual-mode platform for high-precision pixelated laser displays, offering practical solutions for cutting-edge photonic applications such as programmable high-resolution lasing displays and dynamic laser anticounterfeiting labels.

ABSTRACT Integrating disparate optoelectronic functionalities—ranging from self‐powered photodetection to neuromorphic computing—within a unified, single‐material architecture is pivotal for the next generation of bias‐programmable intelligent vision systems. Here, we report a voltage‐tunable, monolithic platform based on amorphous Ga 2 O 3 (ITO/GaO x /Al) that achieves bias‐programmable dual‐mode operation, uniting self‐powered solar‐blind photodetection with low‐power optoelectronic synaptic functionalities. The dual‐modality originates from the synergistic coupling between asymmetric interfacial potential barriers and oxygen‐vacancy engineering, which is in situ induced by interfacial redox reactions at the GaO x /Al junction. Benefiting from this precise interface‐defect co‐engineering, the device exhibits exceptional self‐powered solar‐blind detection with high responsivity, a rapid response of ∼100 µs, and a detection limit down to 13 nW. Under a low bias, it emulates bio‐realistic synaptic dynamics—including paired‐pulse facilitation and learning–forgetting–relearning processes—with an ultralow energy footprint of 18 pJ. Reversible voltage modulation enables both single‐pixel and 10 × 10 array devices to bridge the gap between high‐contrast transient imaging and long‐term visual memory. Moreover, a neuromorphic visual system constructed from this platform performs robust “detection–storage–recognition” tasks even under external noise. This study establishes a transformative route for bias‐programmable optoelectronic integration, effectively uniting sensing and cognitive functions within a simplified, high‐performance single‐material system.

The conversion of carbon dioxide (CO2) into usable fuels represents a promising strategy for addressing global energy sustainability and environmental challenges. To achieve this goal, developing efficient and eco-friendly catalytic technologies is imperative. In this study, we introduce a novel catalytic CO2 reduction approach leveraging the synergistic interplay between tribocatalysis and piezocatalysis, utilizing tungsten bronzestructured nanopowder K2NdNb5O15 (KNN) to enhance CO2 reduction efficiency. The experimental design systematically evaluated gas yields under three distinct conditions, incorporating variations in catalyst concentration and solution pH. Results revealed a remarkable CO production rate of 331.85 mu mol/h/g under synergistic conditions, corresponding to a 1.2 fold increase over tribocatalysis alone and a 2.0 fold enhancement compared to piezocatalysis alone. Output charge testing of a vertical contact-separation mode triboelectric nanogenerator (CS-TENG) assessed the material's electron transfer capabilities during friction processes. This work underscores the potential of combining tribocatalysis and piezocatalysis with tungsten bronze-structured nanopowders to significantly boost flammable gas production such as CO, offering a viable pathway to mitigate CO2 emissions and advance sustainable energy solutions.

This study presents a comprehensive computational investigation of magnetite nanoparticles, systematically evaluating a range of force fields against experimental results. We analyze the influence of particle size, temperature, and surface-adsorbed water molecules on the structural and dynamic properties of the nanoparticles. We performed classical molecular dynamics simulations of nanoparticles and bulk magnetite and utilized density functional theory calculations for bulk magnetite for comparison. Our results reveal that nanoparticle size and the presence of adsorbed water molecules have a pronounced impact on the vibrational density of states. Specifically, as the nanoparticle size is decreased, phonon modes exhibit significant broadening and softening, which is attributable to reduced phonon lifetimes resulting from enhanced boundary scattering. The incorporation of water further broadens the density of states and extends the spectra to higher energy regions. Temperature variations result in a slight broadening and softening of the phonon density of states, particularly in the oxygen-dominated region, which is attributed to phonon anharmonicity. Our results close a gap by providing a systematic phonon density of states study on magnetite nanoparticles and outline a reusable framework for characterizing similar nanomaterials.

Piezocatalytic hydrogen evolution enables the conversion of mechanical energy into chemical fuels, but its efficiency is constrained by a trade-off between piezoelectric polarization and electronic conductivity. Strong piezoelectric polarization is essential for sufficient driving force, yet highly polar materials typically suffer from poor conductivity, which limits bulk-to-surface charge transport. Conversely, enhancing conductivity often compromises piezoelectric performance, resulting in a bottleneck in piezocatalysis. Herein, we decouple piezoelectricity and conductivity using atomically dispersed nickel single atoms on amino-functionalized UiO-66 (Ni SAs@UiO-66-NH2). Introducing polar amino groups and asymmetric Ni─N coordination significantly enhances the piezoelectric response, increasing the piezoelectric coefficient d33 from 48 to 242 pm V-1. Simultaneously, hydrogen adsorption at Ni sites under mechanical stress triggers a pressure-induced semiconductor-to-metal transition, creating transient metallic conduction pathways that facilitate efficient electron extraction without sacrificing bulk polarization. As a result, hydrogen adsorption sites shift from framework carbons to Ni centers, yielding near-optimal H* adsorption energetics (ΔGH * approximately 0.12 eV at 100 MPa), and enabling rapid polarization-driven hydrogen evolution. Consequently, the Ni SAs@UiO-66-NH2 catalyst achieves exceptional hydrogen evolution rate of 1871 µmol g-1 h-1 in deionized water and 17 613 µmol g-1 h-1 in methanol-containing media, surpassing reported MOF-based piezocatalysts and competing with leading photo-piezocatalytic and photocatalytic systems.

Ferroelectric switching provides a nonvolatile way to control electronic structures, but a general symmetry rule connecting the full Bloch bands of two switchable polarization states is still lacking. Here, we introduce ferroelectric band twinning, a pair-state relation in which the bands of two opposite-polarization states are mapped onto each other by a non-inversion state-exchange symmetry. Using dichromatic groups, we derive the band-twinning rule and identify 11 ferroelectric band-twinning point-group classes. Screening the Ferroelectric Materials Database yields 16 candidate compounds, of which the two lattice-metric-preserving candidates, bulk gamma-Ag3SI and BaAl2O4, are selected for first-principles validation. For gamma-Ag3SI, we further show that the same pair-state symmetry controls the transformation of shift-current tensor components under polarization reversal. These results establish ferroelectric band twinning as a general symmetry framework for nonvolatile control of momentum-dependent electronic structures in ferroelectrics.

Lead-free relaxor ferroelectric ceramics are promising for pulsed-power systems due to their ultrafast discharge and high-power density, yet their practical use remains limited by low breakdown strength and insufficient energy-storage density. Here, we report Ba2La1-xBixTi2Nb3O15 ceramics with a tetragonal tungsten bronze structure, which achieve a recoverable energy density of 14.39 J/cm3 and an efficiency of 87.69% under an ultrahigh field of 1400 kV/cm-one of the highest recoverable energy density values reported for bulk tetragonal tungsten bronze structured ceramics. By combining experiments, first-principles calculations, and finite-element simulations, we unravel a multiscale structural optimization mechanism. Bi3+ incorporation induces oxygen-octahedral distortion that disrupts long-range order and enhances relaxation behavior. Concurrent grain refinement and band gap widening substantially raise the breakdown strength, leading to superior energy-storage properties. Moreover, the material exhibits excellent stability against variations in temperature, frequency, and fatigue cycles. This work establishes a generally applicable multiscale structural-engineering strategy for tetragonal-tungsten-bronze dielectrics with high energy storage performance.

ABSTRACT 2D inorganic electrides have attracted extensive interdisciplinary interest due to their unique physicochemical properties, which arise from the presence of non‐nuclear‐bound interstitial anionic electrons (IAEs). Nevertheless, the stringent design criteria for realizing 2D IAEs have limited viable candidates to only a few categories, thereby constraining the expansion of the candidate pool and further exploration of related applications. Here, based on the electronegativity differences of elements and combined with the design principles of 2D inorganic electrides, we constructed eight negative‐valence transition metal‐based AB‐type 2D inorganic electrides (A = Ca/Sr/Ba, B = Cu/Ag/Au). These materials exhibit a typical layered structure, forming an ordered alternating arrangement of atomic layers and IAE layers along the kz direction. Interestingly, despite the absence of conventional magnetic atoms, their monolayer structures display distinct magnetic ordering—originating from surface‐floating IAEs. Furthermore, these electrides exhibit diverse topological phases and ultralow work functions. Leveraging their ability to mitigate hydrogen poisoning, we demonstrate that Ru supported on these electrides can serve as an efficient catalyst for ammonia (NH3) synthesis. These findings not only establish a new material platform for exploring 2D inorganic electrides but also open avenues for designing and modulating their multifunctional properties toward applications in spintronics, topological electronics, and energy conversion.

Machinable layered ternary carbides and nitrides (MAX phases) are a class of multifunctional materials combining the advantages of both ceramics and metals, making them of vital technological importance. Understanding their mechanical behavior is critical for practical applications and failure analysis. However, there is still no in situ investigation on their strength and plastic deformation under high pressure/stress. In this study, we investigate the strength and texture development of Ti3AlC2 under nonhydrostatic pressure up to 41 GPa. Clear strength anisotropy was observed and the lattice stress states of different planes were determined. At 41 GPa, the highest differential stresses supported by the (10-10) plane and (0008) plane are approximately 13.7 GPa and 4.5 GPa, respectively. The average strength exceeds that of stishovite, one of the strongest oxides. A strong 0001 deformation texture developed under ultra-high stress. This work clearly reveals the lattice-stress states and deformation behavior of Ti3AlC2 under high stress, offering direct experimental insights for the design and processing of MAX phase materials.

Lead-free relaxor ferroelectric ceramics are promising for pulsed-power systems due to their ultrafast discharge and high power density, yet their practical use remains limited by low breakdown strength and insufficient energy-storage density. Here, we report Ba 2 La 1 − x Bi x Ti 2 Nb 3 O 15 (BLBTN- x ) ceramics with a tetragonal tungsten bronze structure, which achieve a recoverable energy density of 14.39 J/cm 3 and an efficiency of 87.69% under an ultrahigh field of 1400 kV/cm—the highest performance reported in this material family. By combining experiments, first-principles calculations, and finite-element simulations, we unravel a multiscale structural optimization mechanism. Bi 3+ incorporation induces oxygen-octahedral distortion that disrupts long-range order and enhances relaxation behavior. Concurrent grain refinement and bandgap widening substantially raise the breakdown strength, leading to superior energy-storage properties. Moreover, the material exhibits excellent stability against variations in temperature, frequency, and fatigue cycles. This work establishes a viable design strategy for tetragonal-tungsten-bronze dielectrics with superior energy-storage performance.