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Amorphous/crystalline high-entropy-alloy (HEA) composites show great promise as structural materials due to their exceptional mechanical properties. However, there is still a lack of understanding of the dynamic nanoindentation response of HEA composites at the atomic scale. Here, the mechanical behavior of amorphous/crystalline HEA composites under nanoindentation is investigated through a large-scale molecular dynamics simulation and a dislocation-based strength model, in terms of the indentation force, microstructural evolution, stress distribution, shear strain distribution, and surface topography. The results show that the uneven distribution of elements within the crystal leads to a strong heterogeneity of the surface tension during elastic deformation. The severe mismatch of the amorphous/crystalline interface combined with the rapid accumulation of elastic deformation energy causes a significant number of dislocation-based plastic deformation behaviors. The presence of surrounding dislocations inhibits the free slip of dislocations below the indenter, while the amorphous layer prevents the movement or disappearance of dislocations towards the substrate. A thin amorphous layer leads to great indentation force, and causes inconsistent stacking and movement patterns of surface atoms, resulting in local bulges and depressions at the macroscopic level. The increasing thickness of the amorphous layer hinders the extension of shear bands towards the lower part of the substrate. These findings shed light on the mechanical properties of amorphous/crystalline HEA composites and offer insights for the design of high-performance materials. [ABSTRACT FROM AUTHOR]

A novel strategy is proposed in this work to accelerate proton-coupled electron transfer via phase-engineered amorphous/crystalline interface for advancing overall water splitting. [Display omitted] • Co/Co 2 C crystals have been assembled on amorphous N, S co-doped porous carbon through hydrothermal and calcination process. • The stable biphase structure and amorphous/crystalline interface enhances the conductivity and intrinsic activity. • The adsorption ability of water molecules and intermediates is improved significantly. • This work has pioneered the crystalline/amorphous phase in electrocatalysts and provided new insights into phase engineering. Traditional phase engineering enhances conductivity or activity by fully converting electrocatalytic materials into either a crystalline or an amorphous state, but this approach often faces limitations. Thus, a practical solution entails balancing the dynamic attributes of both phases to maximize an electrocatalyst's functionality is urgently needed. Herein, in this work, Co/Co 2 C crystals have been assembled on the amorphous N, S co-doped porous carbon (NSPC) through hydrothermal and calcination processes. The stable biphase structure and amorphous/crystalline (A/C) interface enhance conductivity and intrinsic activity. Moreover, the adsorption ability of water molecules and intermediates is improved significantly attributed to the rich oxygen-containing groups, unsaturated bonds, and defect sites of NSPC, which accelerates proton-coupled electron transfer (PCET) and overall water splitting. Consequently, A/C-Co/Co 2 C/NSPC (Co/Co 2 C/NSPC with amorphous/crystalline interface) exhibits outstanding behavior for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), requiring the overpotential of 240.0 mV and 70.0 mV to achieve 10 mA cm−2. Moreover, an electrolyzer assembled by A/C-Co/Co 2 C/NSPC-3 (anode) and A/C-Co/Co 2 C/NSPC-2 (cathode) demonstrates a low drive voltage of 1.54 V during overall water splitting process. Overall, this work has pioneered the coexistence of crystalline/amorphous phases in electrocatalysts and provided new insights into phase engineering. [ABSTRACT FROM AUTHOR]

Although XLPE cables are widely used in power transmission and distribution systems, their insulating properties are susceptible to degradation due to thermal aging. In order to clarify the influence law of the thermal aging process on the structural and dielectric properties of XLPE cables, this paper investigates the thermal aging characteristics of XLPE cables by using polarization and depolarization current measurement. Results show that when the XLPE cable is aged at 140 °C, the crystallinity of the insulation layer appears to increase and then decrease. With the increase in aging time, micron-sized microvoids appear on the surface of the XLPE. At the same time, the DC conductivity and 0.1 Hz dielectric loss factor of the insulating layer increase with the aging time. The average DC conductivity increased from 2.26 × 10−16 S/m for new cables to 4.47 × 10−16 S/m after aging for 432 h, while the dielectric loss increased from 0.11% to 0.42%. The polarization characteristics of thermal-aged cables were further analyzed using the extended Debye model. Results indicate that the time constant of the third branch of the model increased significantly with increasing aging time. A correspondence between this parameter and the thermal aging time of the cable was established. Thermal aging can damage the crystalline structure of XLPE, so that the number of interfaces between the crystalline and amorphous regions of the material increases, resulting in structural damages and a decline in the dielectric properties of the cable insulation. [ABSTRACT FROM AUTHOR]

• Al matrix composite reinforced by deformable metallic-glass particles was prepared. • Al matrix composite with the interfacial interlayer had a strength-ductility synergy. • Distinct Al-B bond in interfacial interlayer facilitated strong interfacial bonding. • Co-deformation of metallic-glass nanoparticles and matrix rendered high ductility. Metal matrix composites (MMCs) are the materials-of-choice for a large range of important applications under harsh service conditions. However, owing to the high phase contrast between the matrix and the reinforcements, the strength-ductility conflict of MMCs is still outstanding. Here we fabricated a novel aluminum (Al) matrix composite reinforced by deformable, cobalt-zirconium-boron (CoZrB) metallic glass nanoparticles. The amorphous CoZrB/Al composite with only 2.0 vol.% particle reinforcements possessed a uniaxial tensile strength of 387.0 ± 1.2 MPa, showing over 80 % improvement over the unreinforced pure Al matrix at a similar uniform elongation. The strength-ductility synergy of the composite was also significantly superior to that of the composite reinforced by fully crystallized nanoparticles. These findings were rationalized by the unique multi-functionality of the amorphous particle/matrix interfaces, which effectively transferred the load from the matrix to the particles, coordinated the co-deformation of the nanoparticles and the matrix, and imparted a transgranular fracture mode in the composite with extensive matrix plastic deformation. The methodology developed in this study was shown to be generally effective for other matrix and metallic glass nanoparticle compositions, and our work may shed new light on the development of high-performance metal matrix composites for advanced structural applications. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The heterostructure was induced to enhance triple-functional electrocatalysis. • The surface reconstruction was revealed to enhance electrocatalytic oxidation. • The favorable adsorption of intermediates led to the improved electrocatalysis. Rational design of non-precious metal-based catalysts for value-added chemicals production is crucial but still challenging. Herein, a trifunctional electrocatalyst with heterostructures is developed via phosphating and NaBH 4 pretreatment of the pristine ZIF-L for overall water splitting and urea oxidation. The as-prepared CoBO x /NiCoP catalyst exhibits superior electrocatalytic performance with only overpotentials of 100, 283 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) to reach the current density of 10 and 100 mA cm−2, respectively, and the low potential of 1.35 V to achieve a current density of 100 mA cm−2 for urea oxidation reaction (UOR). Theoretical calculations show that the construction of amorphous/crystalline heterostructure can accelerate the charge transfer between the active site and intermediate, thus enhance the intermediates adsorption and reduce the kinetic barrier toward HER/OER process for enhancing electrocatalytic activity. Importantly, the in-situ Raman spectroscopy discloses that the rapid formation of oxidation-state transition metal oxyhydroxide species would provide more active sites for the oxidation reaction. This multiple electrocatalysis demonstrates the great potential of amorphous/crystalline heterogeneous interfaces for high-performing electrocatalytic conversions. [ABSTRACT FROM AUTHOR]

• Based on the Euler-Lagrange framework, a three-dimensional transient heat-mass transfer model of silicon particle melting/migration coupled with turbulent heat transfer in the silicon melt during CCZ monocrystalline silicon growth was developed using large eddy simulation method. • The heat exchange between silicon particles and their own melt, as well as the changes in particle size during their melting/migration were considered. • The influences of key feeding particles parameters such as the feeding temperature, feeding particle size, and feeding speed on the melting/migration characteristics of silicon particles and the melt temperature were firstly revealed in detail. The Continuous Czochralski (CCZ) is a promising approach for preparing low-cost high-quality monocrystalline silicon in the photovoltaic field. To investigate the coupled mechanism of silicon particles melting/migration and melt turbulent heat transfer during the CCZ monocrystalline silicon growth, based on the Euler–Lagrange framework, a three-dimensional transient heat-mass transfer model is developed using the LES method considering the heat exchange between the silicon particles and the silicon melt as well as the particles size change. In addition, we investigated the effects of key silicon particle parameters such as feeding temperature, particle size and feeding speed, on the silicon particles melting/migration and melt turbulent heat transfer. The results show that appropriately increasing the feeding temperature and speed contributes to achieve more concentrated particles distribution and weaken the movement of silicon particles towards the crystalline interface simultaneously, which conduce to eliminate the adverse impact of continuous feeding on monocrystalline silicon growth. And the feeding temperature has a great effect on the temperature fluctuation near the crystalline interface. In addition, when the feeding speed exceeds 1.5m/s, increasing feeding speed has no significant effect on the particles distribution and melting process. Besides, the feeding particle size has a significant effect on the maximum penetration depth of particles. The small silicon particles prefer moving to the crystalline interface driven by thermophoretic force, which is detrimental to the high-quality CCZ monocrystalline silicon growth. [ABSTRACT FROM AUTHOR]

Sodium ion batteries (SIBs) have garnered more and more attentions owing to the uneven distribution and increasing price of lithium mineral. Herein, BiVO 4 –V 2 C endogenous heterostructures as anode for SIBs are synthesized via one-step in situ hydrothermal method. The designed hydrangea-like heterostructure ensures a wide contact surface for the interaction of anode material with the electrolyte, and endows stable heterojunction interfaces between BiVO 4 and V 2 C MXene, the synergistic effect of which significantly improves the electrical conductivity, pseudo-capacitance and alleviates the volumetric change of BiVO 4 during charge/discharge process. Density functional theory (DFT) calculations ulteriorly demonstrate that the electric field at the BiVO 4 –V 2 C interface contributes to the excellent Na ion diffusion kinetics and impressive sodium storage capacity. As a result, the BiVO 4 –V 2 C anode achieved outstanding performance with a high discharge capacity (480 mAh g−1 after 600 cycles at 0.2 A g−1), and impressive long-term lifespan (303 mAh g−1 over 2000 cycles at 1 A g−1). This work reveals a new design of novel V 2 C MXene heterojunctions which coupling with BiVO 4 combined with the analysis of amorphous/crystalline interface, developing a proper strategy for the effective energy storage of sodium. An endogenous heterostructure of BiVO 4 coupled with V 2 C MXene (BiVO 4 –V 2 C) is developed via a one-step hydrothermal method. The designed hydrangea-like heterostructure provides a large surface area for the contact of the electrode material with electrolyte, and endows stable heterojunction interfaces between BiVO 4 and V 2 C, which significantly improves the reaction kinetics. [Display omitted] • Hydrangea-like endogenous BiVO 4 –V 2 C heterostructure is firstly reported. • Internal micro-electric field for improving Na+ migration and reaction kinetics. • The electrode delivers superior specific capacity and excellent cycle stability. • Endogenous heterostructure offers new insights for MXenes heterojunctions design. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anthracene-appended poly(ʟ-lactide)s (AAP) were synthesized by ROP of ʟ-lactide. • The excimer emission was observed in the low molecular weight AAP. • The monomeric emission is observed in amorphous and single crystals of AAP. • In crystallized AAP, fluorescence arises from anthracene excimers and monomers. • In the gel state AAP (e form), only the excimer emission was observed. The design and development of solid-state excimer-emitters bear great potential for attaining efficient solid-state luminescent materials. In this study, we have synthesized anthracene-appended poly(ʟ-lactide)s (AAPs) to regulate the arrangement of anthracene moieties by controlling the crystallization and polymorphic form of covalently linked poly(ʟ-lactide) (PLLA). In the high molecular weight AAP, the fluorescence intensity mainly arises from the monomeric anthracene moieties, whereas in the low molecular weight AAP, the excimer emission was observed depending on the structure and morphology of covalently-linked PLLA. The monomeric emission is predominantly observed in amorphous polymer due to the molecular level dispersion of covalently-linked anthracene moieties throughout the polymer matrix. When the polymer was crystallized under different conditions, covalently-linked anthracene moieties were excluded from polymer crystals or crystalline lamellae and are located on the surface or at the interface, which is advantageous for regulating the geometry of anthracene moieties. In the case of single crystals of PLLA, covalently-linked anthracene moieties assemble on the surface and emit mainly in their monomeric state due to the lack of π-stacking. In the melt-crystallized sample (α form), covalently-linked anthracene moieties reside at the interface of crystalline and amorphous domains by either dipolar interactions or π-stacking and fluorescence arising from anthracene excimers and monomers. In the gel state (ε form), only the excimer emission was observed due to the effective interactions between the anthracene moieties in the presence of excess solvent in the amorphous domains. In this way, polymer crystallization played a significant role in determining the arrangement of covalently-linked anthracene moieties in AAP. This study reveals the role of polymer crystallization on the excimer evolution in fluorophore-appended semicrystalline polymers and provides new insight into the design and development of fluorophore-appended polymers for optoelectronic devices. [ABSTRACT FROM AUTHOR]