Liquid crystal polymers (LCPs) combine the entropic elasticity of polymers with the orderness of LC mesogens, demonstrating outstanding performance across diverse applications, particularly in bionic actuators. In contrast to the organisms that enable multi-stimuli responsibility, most LCP actuators reported thus far exhibit responsiveness to only a single stimulus, hence the fabrication of multi-stimuli responsive LCPs is of pronounced significance. Here, a novel multi-stimuli responsive LCP is developed by integrating ring-opening metathesis polymerization (ROMP) and post-polymerization modification (PPM), which exhibits reversible responsiveness to humidity, light, and pH. By spray-coating the stretched polypropylene with LCP, the bilayer actuator loads exceed 20 times its weight upon exposure to light irradiation and moisture, showcasing exceptional output force. Furthermore, in response to the change in pH and humidity, the actuator exhibits behaviors akin to natural flowers, including blooming, closing, and color-changing. The strategy combining ROMP and PPM has proven to be a versatile strategy for the synthesis of multifunctional LCPs, offering transformative potential for the development of advanced bionic actuators and soft robotic systems.

Two-dimensional transition metal carbides (MXenes) have garnered significant attention due to their distinctive physical and chemical properties. In this study, utilizing density functional theory calculations, we introduce a novel phase of transition metal carbide with the space group of R3m, designated as α-MXene with the chemical formula M₂CX₂ (M = Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn; X = O, F). Notably, α-MXene possesses an ABBCA atomic layer configuration closely resembles the two-dimensional ferroelectric material α-In₂Se₃, distinct from the close packing ABCAB atomic stacking observed in typical MXenes. It is highlighted that α-MXene exhibits adjustable ferroelectric properties with moderate polarization reversal energy barriers, including five rare ferroelectric metals and one Dirac-semimetal. Moreover, α-MXenes not only enable photocatalytic reactions by utilizing infrared light to overcome the band gap restriction of 1.23 eV, but also generate hydrogen and oxygen gases on separate surfaces due to electric field induced by ferroelectric effect. Additionally, ferroelectric tunnel junctions (FTJs) based on α-MXene show exceptionally high tunneling electroresistance ratios (TERs), indicating their suitability for advanced ferroelectric memory device applications. Our research provides a viable strategy for exploring ferroelectric materials within the expansive MXene family and exemplifies the applications of α-MXenes in photocatalysis and spintronics.

Three-dimensional (3D) ultrasounds were applied to the solidification process of multicomponent (FeCoNiCr)₈₅Mo₁₅ eutectic alloy. At the small ultrasonic amplitude of 14 μm, the lamellar (γ+σ) eutectic was significantly refined, and the interface orientation was shifted from [001]_γ//[112]_σ and (-110)_γ//(11-1)_σ to the most stable configuration of [011]_γ//[-110]_σ and (-11-1)_γ//(001)_σ. If ultrasonic amplitude was increased, σ phase transferred from tetragonal to hexagonal close-packed (HCP) structure, while its independent nucleation and growth facilitated the formation of anomalous (γ+σ) eutectics. Once the ultrasonic amplitude reached 16 μm, a metastable μ phase enriched with Cr element was found in the form of lamellar (γ+μ) eutectic structure. These crystallographic structure transitions were attributed to the ultrasound induced high energy and nonlinear cavitation and acoustic streaming effects. The diverse eutectic structures obtained by 3D ultrasonic solidification brought in superior mechanical properties. The maximum yield strength and ductility were enhanced by 1.4 and 2.1 times to 2000 MPa and 21.4 %, respectively. The strengthening mechanism belonged to the refinement of lamellar (γ+σ) eutectics and the stable interface configuration secured by weak ultrasounds, whereas the increased volume fraction of the FCC-structured γ phase in (γ+σ) eutectic and the metastable (γ+μ) eutectic structure formed under strong ultrasounds contributed to enhance alloy ductility.

Photocatalytic water splitting can convert solar energy into hydrogen, which has important implications for reducing dependence on fossil fuels. Constructing heterojunctions is a universal method for facilitating charge transfer, but the poor interface matching limits its charge separation and photocatalytic activity. Here, a metal-nickel bridging (nickel interlayer) NiO-Ni-Zn₂GeO₄ photocatalyst with well interface matching is designed through a partial oxidation strategy. Structure and in situ Raman characterization demonstrate that the nickel interlayer substantially optimizes interface matching and causes the first-order phonon mode transfer from the first-order longitudinal wave to the first-order transverse wave, which implies that NiO acts as the site for hydrogen production and violent surface reaction. Therefore, the nickel interlayer provides a charge transfer channel for carrier separation. Meanwhile, density functional theory calculations prove an optimal hydrogen-oxygen bond-breaking process with 36 % barriers decrease obtained via the effect of nickel interlayer. As a result, NiO-Ni-Zn₂GeO₄ shows the photocatalytic hydrogen production rate of 206.6 μmol g^-1 h^-1, which is over 8 times greater than that of Zn₂GeO₄. This study offers a new approach for designing heterojunctions with well-matched interface and efficient charge separation.

The highly alloyed Mg-10Gd-5Y-5Er alloy exhibits high strength, however, the brittle Mg₂₄RE₅ phase accelerates the initiation and development of micro-cracks and significantly deteriorate the plastic deformation ability. Therefore, it is necessary to regulate the type of precipitates to improve the comprehensive mechanical properties of the alloy. In this work, the influence of Zn content on mechanical properties and microstructure evolution of highly alloyed Mg-10Gd-5Y-5Er-xZn alloys (x = 0, 1, 2, 3, and 5 wt%) was investigated. It was found that the tensile strength increases with increasing Zn content, without deterioration of elongation. The maximum tensile yield strength and ultimate tensile strength are achieved to be 298 MPa and 406 MPa, respectively, within the studied concentration range. Thermodynamic calculations and microstructural characterization results indicate that with the increase of Zn content the precipitate transform from Mg₂₄RE₅ phase to long-period-stacking-ordered (LPSO) phase and lamellar structure. This transition will change the solute atom concentration in the matrix and affect the dynamic recrystallization behavior, thereby changing the contributions of solid solution strengthening and grain refinement strengthening to the yield strength of alloy. In particular, the blocky LPSO phase can significantly contribute to the increased strength at relatively high Zn contents (x > 2 wt%) by a mechanism similar to short-fiber strengthening. Moreover, the strategy of improving the mechanical properties by increasing the volume fraction of blocky LPSO phase can be applied to many Mg alloy systems containing LPSO phase.

Dislocation loop is a primary indicator of irradiation, and has a profound impact on the microstructural evolution and thermo-mechanical properties of materials. Although both 1/2<111> and <100> loops are clearly identified in bcc metals after irradiation, the underlying mechanism of <100> loop formation remains elusive especially considering its low stability. Here, we explicitly demonstrate the formation of <100> loops through the interaction of two gliding 1/2<111> loops under uniaxial strain via molecular dynamics simulations, while there is no occurrence of <100> loops under strain-free conditions. Such strain-enhanced formation of <100> loops is different from conventional dislocation reaction mechanisms, which contain rigorous prerequisite conditions on the topology and size of the reactant loops, and thus provide a potential explanation for the frequent occurrence of<100> loops. The microscopic analysis suggests that the generation of <100> dislocation loops via bi-loop reaction is a complicated atomistic process involving the coordinated movement and/or rearrangement of multiple interstitials. The activation energy barriers of each reaction step are determined, and generally decrease with increasing uniaxial strain. Specifically, we develop a predictive model to describe the formation probability of<100> loops under different conditions, which is in good agreement with molecular dynamics simulations. These results shed new light on understanding the <100> loop formation, provide a direct link between simulations and experiments, and enable the accurate assessment of irradiation damage evolution in bcc metals.

Self-powered two-dimensional (2D) polarization-sensitive photodetectors have propelled the advancement of the next-generation optoelectronics. However, currently such devices mainly depend on the stacking of multiple 2D heterojunctions to realize this function, which demands precise operational procedures and strict band alignment. Herein, we present the achievement of self-powered polarization photodetection in 2D GaInS₃ via strain engineering. This primarily depends on the intrinsic in-plane anisotropic structure and internal spontaneous polarization of 2D GaInS₃. Remarkedly, the strained GaInS₃ devices exhibit superior optoelectronic performance with a high on/off ratio (>10⁴), and large anisotropy ratio (~5.4). Furthermore, the strained device can achieve self-powered high-resolution polarization imaging. This work offers a guideline valuable for developing high-performance 2D self-powered polarization photodetectors.

We develop a graphene oxide (GO)@In-Bi alloy composite that exhibits flexibility, leak-proof properties, and efficient interfacial heat transfer. This composite was fabricated using a layer-by-layer strategy for applications in thermal interface materials (TIMs). The incorporation of liquid metal with high thermal conductivity enhances the cross-plane thermal conductivity of the GO film to 1.35 W/(m · K) while reducing the thermal contact resistance to 0.47 ℃ cm²/W. Upon exposure to high-temperature conditions, the In-Bi phase transition occurs, filling the gaps between rough interfaces and facilitating interface wetting, thereby improving heat transfer efficiency. Additionally, due to surface tension effects, the liquid alloy evenly coats the GO surface, providing the composite film with robust mechanical properties and ensuring excellent leak resistance. Overall, this study presents a novel approach for fabricating flexible liquid alloy-based composites with high thermal conductivity and low thermal contact resistance, providing fresh perspectives on the synthesis of TIMs.

To investigate the differences in densification effects and oxidation resistance of curved samples subjected to gaseous and liquid Si infiltration, HfB₂-SiC-MoSi₂-Si/SiC-Si coated C/C composites are prepared using gaseous and liquid Si infiltration (G-HSM and L-HSM), respectively. The mass change rates of G-HSM and L-HSM after thermal shock from 1700 ℃ to room temperature are -2.52 % and 0.07 %. After isothermal oxidation at 1700 ℃ for 200 h, the mass change rate of L-HSM is -0.12 %, while that of G-HSM reaches -0.60 % after 124 h. The high content of HfB₂ and MoSi₂ in L-HSM improves the coating stability, which effectively avoids droplet shedding. In addition, the lower roughness and narrower original cracks reduce oxygen adsorption sites and diffusion channels of L-HSM during oxidation. Thus, L-HSM exhibits better thermal shock resistance and oxidation resistance than G-HSM. This study provides a strategy for the coating design of curved components above 1700 ℃.

A new integrated filler metal/base metal manufacturing method by cold spray additive manufacturing is proposed. The integrated CuTi filler metal/GH3536 and CuTi + W composite filler metal/GH3536 are prepared by cold spray additive manufacturing techniques. The large plastic deformation of Cu and Ti particles and the tamping effect of W particles promote the interfacial bonding of particles, which improves the weldability of cold sprayed CuTi + W composite filler metals. Based on the cold sprayed CuTi + W composite filler metal, the C_f/SiC composites and GH3536 are successfully brazed, and the typical microstructure and brazing mechanism are investigated. As a result, the shear strength of C_f/SiC-GH3536 joint brazed by cold sprayed CuTi + W composite filler metal reaches 77 MPa. This study highlightes the great potential of cold spray additive manufacturing for integrated filler metal/base metal manufacturing in brazing.

Commercialization of MoS₂ electrode materials has been severely limited due to low electrical conductivity and significant volume variations during their cycling. Meanwhile, bottom-up modification strategies require precise experimental conditions and control techniques, which further restrict the industrial application of MoS₂ materials. Herein, the changes in the electronic structure of MoS₂ surfaces due to carbon coating and N-doped carbon coating are compared through theoretical calculations. Based on this, a top-down modification strategy is proposed, involving mechanical pulverization and N-doped carbon layer coating of commercial MoS₂ through high-energy ball milling and ultrasound-assisted in situ coating technology, and carbonization. This strategy effectively improves the electronic structure of the surface of MoS₂ particles, enhancing the ion transport kinetics and cycling stability of molybdenum disulfide. Thanks to the elemental and structural advantages, the coated MoS₂ exhibits excellent electrochemical performance, with outstanding specific capacity and cyclic stability (specific capacity of 753.9 mAh g^-1 at a current density of 500 mA g^-1 after 200 cycles, with a capacity retention percentage of 92.2%) as well as excellent rate performance (specific capacity of 302.9 mAh g^-1 after 500 cycles at a current density of 5 A g^-1). This study not only establishes a detailed scheme for enhancing the lithium storage performance of MoS₂ but also provides new insights for its industrial research.

To achieve strength improvement while ensuring a certain degree of plasticity of titanium matrix composites (TMCs) by selective laser melting (SLM), minor TiB₂ particles were used to fabricate in situ TiB whiskers (TiBw) reinforced Ti6.5Al2.5Zr1Mo1V composites in this work. It is found that pore defects in the as-printed TMCs reduce with the decreasing energy density. The porosity of as-printed TMCs decreases to 0.0005% under an optimized energy density of 61 J·mm^-3. To establish the relationship between porosity and SLM parameters, a systematic investigation of the influence of SLM parameters on the microstructure of TMCs is conducted, and the microstructure evolution is clarified during complex thermal cycling. The nano TiBw effectively hinders the coarsening of hierarchical martensite during the complex thermal cycles. As a result, the martensite plate thickness is approximately 60% in comparison with the as-printed Ti6.5Al2.5Zr1Mo1V alloy. A remarkable strengthening effect is achieved with minor TiBw, resulting in an impressive tensile strength of 1432 MPa and yield strength of 1320 MPa, while an elongation rate of 4.0% is maintained.

We employ the unified heat capacity model to predict thermal expansion in the temperature range from several Kelvin to melting temperature. A generic method is first established to get thermal expansion only by the experimental heat capacity in a series of materials, which is well in agreement with the experimental results of thermal expansion. The method is important to predict the temperature-dependent thermal expansion, and is helpful for further understanding the physical nature of thermal properties in solids.

We systematically elaborate the thermal stability mechanism of MgAgSb-based materials through thermodynamic and kinetic analysis of grain boundary characterizations. By proposing the general strategy of grain boundary segregation engineering (GBSE) to improve the stability of nanostructured bulk thermoelectric materials, it is found that excessive Cu doping can modify the microstructure to enhance stability as both Ag and Cu segregation coexist at the grain boundary. After annealing at elevated temperature, the final performance is almost unchanged with a high room-temperature dimensionless figure-of-merit zT of around 0.7, in contrast to property deterioration of pure MgAgSb. As revealed by atom probe tomography (APT) measurements, Cu segregation inhibits grain boundary migration and hinders grain growth, due to the additional reduced grain boundary energy and mobility. Our work provides new insights into the critical role of grain boundary segregation in the properties optimization and thermal stability enhancement, which opens up alternative perspectives for designs of highly stable and high-performance nanostructured thermoelectric materials.