Communications Materials最新文献

The chemical and electronic properties of surfaces and interfaces are important for many technologically relevant processes, be it in information processing, where interfacial electronic properties are crucial for device performance, or in catalytic processes, which depend on the types and densities of active nucleation sites for chemical reactions. Quasi-periodic and nonperiodic crystalline surfaces offer new opportunities because of their inherent inhomogeneity, resulting in localisation and properties vastly different from those of surfaces described by conventional Bravais lattices. Here, we demonstrate the formation of a nonperiodic tiling structure on the surface of the frustrated antiferromagnet PdCrO₂ due to hydrogen adsorption. The tiling structure exhibits no long-range periodicity but comprises few-atom hexagonally packed domains covering large terraces. Measurement of the local density of states by tunnelling spectroscopy reveals adsorption-driven modifications to the quasi-2D electronic structure of the surface layer, showing exciting opportunities arising from electron localisation.

Metastable β Ti alloys have potential for vibration damping and actuation applications within the aerospace industry due to thermal and mechanical hysteresis. However, variations in transformation parameters, which are also seen to change following thermal or mechanical cycling, significantly limit industrial acceptance. There is a widespread belief that these variations are a consequence of ⍵ phase formation. However, here we provide evidence to show that this is not necessarily the case. Instead, we show how residual stresses and defect structures are crucial to the transformation of these alloys and present an understanding of the mechanism that governs their behaviour. Importantly, we highlight the consequences for the design of new transforming alloys and component geometries, and how current design theories may need to be employed in conjunction with other methods to effectively prevent longer-term changes in behaviour. To this end, we demonstrate how functional properties could be periodically recovered by introducing short intercycle heat treatments and suggest possible next steps for advancing our understanding of these materials.

Electrically conductive hydrogels can simulate the sensory capabilities of natural skin, such that they are well-suited for electronic skin. Unfortunately, currently available electronic skin cannot detect multiple stimuli in a selective manner. Inspired by the deep eutectic solvent chemistry of the frog Lithobates Sylvaticus, we introduce a double network granular organogel capable of simultaneously detecting mechanical deformation, structural damage, changes in ambient temperature, and humidity. The deep eutectic solvent chemistry adds an additional benefit: Thanks to strong hydrogen bonding, our sensor can recover 97% of the Young's modulus after being damaged. The sensing performance and self-healing capacity are maintained within a temperature range of -20 °C to 50 °C for at least 2 weeks. We exploit the granular nature of this system to direct ink to write a cm-sized frog and e-skin wearables. We realize selective tactile perception by training recurrent neural networks to achieve sensory stimulus classification between the temperature and strain with 98% accuracy.

Light-responsive materials with intrinsic negative feedback enable self-oscillation in non-equilibrium states. Conventional systems rely on self-shadowing in bending modes but fail when shadowing is constrained. Here, we demonstrate that external mechanical forces can bypass this limitation, enabling sustained oscillations without complete shadowing. Using a vertically suspended light-responsive liquid crystal network (LCN) strip under constant irradiation, a transition from static deformation to continuous oscillation arises when a critical load is applied. This system reveals two key phenomena: (1) oscillation amplitude scales with light intensity, reaching an angular displacement of 300°-significantly surpassing bending-mode oscillators; and (2) oscillation frequency decreases with increasing load, reflecting intrinsic mechanical sensitivity. This force-assisted self-oscillation principle generalizes across diverse deformation modes, including bending, twisting, contraction, and off-axis LCN strips. By mimicking biological mechanosensation based on dissipative mechanism, our findings provide a simplified design for non-equilibrium matter capable of dynamic adaptation to mechanical loads.

Dark Field X-ray Microscopy (DFXM) has advanced 3D non-destructive, high-resolution imaging of strain and orientation in crystalline materials, enabling the study of embedded structures in bulk. However, the photon-hungry nature of monochromatic DFXM limits its applicability for studying highly deformed or weakly crystalline structures, and constrains time-resolved studies in industrially relevant materials. Here, we present pink-beam DFXM (pDFXM) at the ID03 beamline of ESRF, achieving a 27-fold increase in diffracted intensity while maintaining 100 nm spatial resolution. We validate pDFXM by imaging a partially recrystallized aluminum grain, confirming sufficient angular resolution for microstructure mapping. The increased flux significantly enhances the diffracted signal, enabling the resolution of subgrain structures. Additionally, we image a highly deformed ferritic iron grain, previously inaccessible in monochromatic mode without focusing optics. Beyond static imaging, pDFXM enables real-time tracking of grain growth during annealing, achieving hundred-millisecond temporal resolution. By combining high photon flux with non-destructive, high-resolution 3D mapping, pDFXM expands diffraction-contrast imaging to poorly diffracting crystals, unlocking new opportunities for studying grain growth, fatigue, and corrosion in bulk materials.

The discovery of unconventional superconductivity often triggers significant interest in associated electronic and structural symmetry breaking phenomena. For the infinite-layer nickelates, structural allotropes are investigated intensively. Here, using high-energy grazing-incidence x-ray diffraction, we demonstrate how in-situ temperature annealing of the infinite-layer nickelate PrNiO_2+x (x ≈ 0) induces a giant superlattice structure. The annealing effect has a maximum well above room temperature. By covering a large scattering volume, we show a rare period-six in-plane (bi-axial) symmetry and a period-four symmetry in the out-of-plane direction. This giant unit-cell superstructure-likely stemming from ordering of diffusive oxygen-persists over a large temperature range and can be quenched. As such, the stability and controlled annealing process leading to the formation of this superlattice structure provides a pathway for novel nickelate chemistry.

Piezoelectric energy harvesting, i.e. the interconversion of electrical and mechanical energy, has the potential to revolutionise how we generate sustainable power for electronic devices. Currently the majority of research into maximising the electrical output of piezoelectrics focuses on the material itself i.e. modulating the electromechanical properties via stoichiometry, crystal engineering, deposition technique, etc. Here we take a different approach, demonstrating that for direct force harvesting the base layer onto which piezoelectrics are mounted has a huge impact on the voltage output of commercial piezoelectric transducers. We almost triple the open-circuit voltage output of a small piezoelectric array from 2.8 to 7.5 Volts by changing the flexibility of the material they are adhered to. As well as conventional base layer materials we use a variety of 3D-printed geometries, which offer a low-cost and efficient method for controlling the dynamics of a piezoelectric-based interface. The goal is that by demonstrating this phenomenon using widely used lead-based piezoelectrics, that it can be utilised for increasing the power output of sustainable alternatives.

Understanding polymer-surfactant interactions is essential for regulating phase transition and polymer aggregation, enabling the design of functional materials with tailored properties. Here, we introduce programmable dextran-based thermoresponsive polysaccharide condensates that exhibit reversible phase transitions with tunable lower critical solution temperatures. Photo-initiated radical polymerization permits hydrogel crosslinking, harnessing phase separation to generate hydrogels with distinct microstructures and mechanical heterogeneity. We systematically investigate the impact of anionic sodium dodecyl sulfate (SDS), cationic hexadecyltrimethylammonium bromide (CTAB), nonionic Pluronic F-127, and zwitterionic 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS) surfactants on phase transition dynamics. Surfactant charge density, hydrophilic-lipophilic balance (HLB), and critical micelle concentrations (CMC) collectively govern temperature-triggered phase separation. The resulting photo-crosslinked gels demonstrate surfactant-specific microstructures, including core-shell domains, interconnected elongated micelles, and dual emulsions. Micromechanical characterization exhibits structurally coordinated stiffness and adhesion, where Pluronic forms core-shell structures with reduced adhesion, while CTAB presents elongated structures and lowered modulus. These findings provide a framework for tailoring surfactant-polysaccharide interactions to direct microstructure-property-performance relationships in biocomposite materials design.

Hydrogels are frequently used in regenerative medicine due to their hydrated, tissue-compatible nature, and tuneable mechanics. While many strategies enable bulk mechanical modulation, little attention is given to tuning surface tribology, and its impact on cellular behavior under mechanical stimuli. Here, we demonstrate that photocrosslinking hydrogels on hydrophobic substrates leads to significant, long-lasting reductions in surface friction, ideal for cartilage tissue regeneration. Gelatin methacryloyl and hyaluronic acid methacrylate hydrogels photocrosslinked on polytetrafluoroethylene possess more hydrated, lubricious surfaces, with lower friction coefficients and crosslinking densities than those crosslinked on glass. This facilitated self-lubrication via water exudation, limiting shear during biaxial stimulation. When subject to intermittent biaxial loading mimicking joint movement, low-friction chondrocyte-laden neo-tissues formed superior hyaline cartilage, confirming the benefits of reduced friction on tissue development. Finally, in situ photocrosslinking enabled precise hydrogel formation in a full-thickness cartilage defect, highlighting the clinical potential and emphasizing the importance of crosslinking substrate in regenerative medicine.

Perovskites at the crossover between ferroelectric and relaxor are often used to realize dielectric capacitors with high energy and power density and simultaneously good efficiency. Lead-free Bi_0.5Na_0.5TiO₃ is gaining importance in showing an alternative to lead-based devices. Here we show that (1-x)Bi_0.5Na_0.5TiO₃ - xBaZr _y Ti _1-y O₃ (best: 0.94Bi_0.5Na_0.5TiO₃ -0.06BaZr_0.4Ti_0.6O₃) shows an increase of recoverable energy density and electric breakdown upon chemical substitution. In thin films derived from Chemical Solution Deposition, we observed that polarization peaks at the morphotropic phase boundary at x = 0.06. While Zr substitution results in reduced polarization, it enhances both efficiency and electric breakdown strength, ultimately doubling the recoverable energy density and the metallization interface by lowering surface roughness. Our dielectric capacitor shows <3% deviation of energy properties over 10⁶ cycles. A virtual device model of a multilayer thin film capacitor (7.25 mJ recoverable energy) was used to compare its performance to already in use multilayer ceramic capacitors.