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Recent studies have shown that layered compound EuCd2As2 could exhibit diverse topological states depending on the different magnetic structures, such as Weyl semimetal, Dirac semimetal, topological insulator, etc. In order to further study the interplay between magnetism and topology of EuCd2As2, it is necessary to figure out its magnetic structure. Here, by magnetization (M) measurements and negative magnetostriction (λ) along the [001] direction measured by scanning tunneling microscope on EuCd2As2 single crystals, we observe field-induced metamagnetic phase transition from A-type antiferromagnetic (AFM) ground state to field-polarized state, with canted AFM (CAFM) state in between. Magnetization and magnetostriction are more sensitive to the in-plane field than the out-of-plane field, indicating the magnetic moments lying in the ab plane. The absence of abrupt jump on M-H and λ-H curves demonstrates the phase transition is a second-order type. In CAFM state, M increases linearly with the field and λ is proportional to M 2 . Tunneling conductance spectra show the field-induced evolution of the electronic density of states. Our results provide experimental evidence for understanding the magnetic structure of EuCd2As2.

High-shear granulation is widely used in many particulate industries for its good capability to improve the size, strength and composition uniformity of powder substances. This work conducted an experimental study to investigate the granulation behavior of iron ore fine in a horizontal high-shear granulator, such as granules size distribution, granules growth rate, and permeability of the granules bed. The results show that the granule size and permeability of packed granules bed increase gradually with increasing the granulation time, and the growth of granules can be divided into three stages: the rapid growth stage, the slow growth stage and the relatively stable stage. Both the higher rotational speed and larger number of impellers increase the kinetic energy and collision frequency of the particles, which causes the increase of average granule size, growth rate and permeability of granules packed bed. On the other hand, the shear damage effect of the impellers on the granules is also enhanced with the increase of rotational speed and impeller number, resulting in significant granule size segregation.

Shale mechanical properties are important for shale gas production, but the magnitudes are difficult to estimate, standard size cores are hard to sample, and secondary interstice generation is inevitable. This paper proposes a method for determining shale macroscale modulus, which is determined at a hierarchy of scales from the nano-to macro-scales. Microscale measurements are upscaled to estimate the corresponding magnitudes at the macroscale. A case study is conducted with Silurian shale samples, using the hierarchy scales, gridding nanoindentation, atomic force microscopy (AFM), mineral liberation analysis (MLA), X-ray diffraction (XRD), and uniaxial compression tests. The mineral compositions are analyzed using MLA and XRD, and the shale composition is described in terms of clay minerals, organic matter, and siliceous and carbonate contents. The variation in the Young's modulus is analyzed based on the recorded indentation depth curves and modulus distributions. The nanoindentation and AFM results are upscaled to the centimeter scale through the Mori–Tanaka method. The upscaled results exhibit satisfactory fitting with the conventional uniaxial compression results, although the fitting of the upscaled AFM results is better than nanoindentation. The proposed approach can be applied to promptly and comprehensively predict the shale mechanical parameters during shale gas exploration.

Electrocatalytic reduction of Cr(VI) to less toxic Cr(III) is deemed as a promising technique. Conventional electrocatalytic reduction is always driven by a constant cathodic potential, which exhibits a repelling action to Cr(VI) oxyanions in wastewater and consequently suppresses reduction kinetics. In order to remarkably accelerate Cr(VI) electrocatalytic reduction, we applied a pulsed potential on an Fe2+-NiFe LDH/NF electrode synthesized by in situ growth of Fe2+-doped NiFe LDH nanosheets on Ni foam using a spontaneous redox reaction. Under anodic potential section, HCrO4– anions are adsorbed on the electrode surface and reduced to Cr(III) by Fe2+. Then, Cr(III) ions are desorbed from the electrode surface under coulombic force. The regeneration of Fe2+ and direct reduction of Cr(VI) are achieved under cathodic potential section. The pulsed potential can achieve complete elimination of Cr(VI) within 60 min at an initial concentration of 10 mg L−1, and the removal efficiency shows a 60% increase with respect to that under constant cathodic potential.

Twinning stress is known to be a critical factor for the actuating performance of magnetic shape memory alloys because of the harmful deterioration of their magnetic field-induced strain effect. However, the intrinsic origin of the high twinning stress is still in debate. In this work, we firstly fill this gap by precisely probing the reorientation behaviors of A-C and A-B two common macro-twin interfaces under the stimulus of uniaxial compression in-situ transmission electron microscope. The grain boundary is proved to be the main reason for large twinning stress. The twinning stress of the A-C and A-B type interfaces quantitatively are ∼0.69 and 1.27 MPa within the plate respectively. The A-C type interface evidently has smaller twinning stress and larger deformation variable than the A-B interface. Under the action of compression, not only the orientations of the crystals have changed, but also the roles of the major and minor lamellae have changed for both interfaces due to the movements of twinning dislocations. Combining in-situ and quasi in-situ electron diffraction data, the reorientation process is clearly and intuitively shown by the stereographic projection. Atomic models and the theory of dislocation motion are proposed to phenomenologically clarify the intrinsic mechanism. This work is believed to not only provide a deeper understanding of the deformation mechanism of magnetic shape memory alloys under uniaxial compression testing, but also discover that compression training is not the mechanical training way to decrease the twinning stress of non-modulated martensite in single crystal shape memory alloys.

In this work, supercritical n-decane flowing in ducts with different orientations is thoroughly investigated in terms of secondary flow, wall shear stress, and thermal acceleration. It is known tha...

Although pulse charging strategy has many advantages, it is still controversial. The paradox is that it prolongs the charging time to eliminate the polarization voltage by the pulse interval, and the AC component in pulse current will increase the ohmic losses. In this paper, an optimal charging strategy with complementary pulse current of Lithium-ion is proposed to address and alleviate these issues. For the pulse frequency, the optimization can be achieved through the electrochemical impedance spectroscopy (EIS) analysis to reduce the battery’s AC impedance. For the pulse amplitude, based on the battery’s internal resistance characteristics, minimize the ohmic losses to obtain the optimal amplitude. For the pulse duty cycle, it is adjusted to achieve state of charge (SOC) balancing in the early charging stage, and battery’s terminal voltage balancing in the later stage. Based on the optimized charging strategy, a pulse charger concept is proposed, which can flexibly control the pulse charging currents and use complementary pulses to completely eliminate the prolonged charging time caused by the pulse interval. In the end, an experimental platform for pulse charger of lithium-ion batteries is designed, and the theoretical analysis is verified by the comparative experiments.

Rapid heat loss and fast charge carrier recombination constitute two crucial issues that hinder the development of efficient solar energy utilization and conversion over the semiconductor in a photothermal catalytic system. Inspired by energy production from waste water, we designed an advanced 3D C@TiO2 multishell nanoframe (MNF) photocatalyst. Its unique structural features of heat confinement and vibrant photocarrier kinetics lead to excellent photo-thermal conversion for synchronous superior photocatalytic H2 evolution (503 μmol g-1 h-1) and 98.2% RhB removal without the use of any co-catalyst and sacrificial reagent under simulated sunlight irradiation (AM 1.5G). Mechanism exploration reveals that the difference between the inner and outer gas pressure formed inside C@TiO2 precursor facilitates the selective cleavage of outer TiO2 layers at selected temperatures during calcination. Synergistic effects between residual carbon core and multi-shelled TiO2 framework endow C@TiO2 MNF with excellent heat confinement and vibrant photocarrier kinetics. Such MNF photo-thermocatalyst concept provides a novel strategy for effective utilization of solar energy, and this work may open a novel avenue towards advanced nanostructures for efficient waste-to-energy conversion.

The preparation of MgO-stabilized ZrO2 powders was based on combustion synthesis between Mg powders and CO2 with ZrO2 powders as the diluent. The effects of the diluent content on the combustion process parameters, phase composition, microstructure, and high-temperature stability were systemically investigated. As the diluent content increased, the reaction temperature, propagation velocity, and MgO content decreased. The reactant powders underwent different reaction processes and were transformed into different phase compositions due to the change in diluent content. The obtained MgO-stabilized ZrO2 powders exhibited excellent high-temperature stability up to 1400 °C.

A new method that utilizes theories of thermally activated deformation and repeated transient stress-relaxation tests has been proposed and validated in this study for the characterization and modeling of the stress-relaxation aging (SRA) behavior of aluminum alloys and its dependence on stress and temperature. Using the new method, key deformation-related variables, i.e., stress components, activation volume, and activation energy, of the aerospace grade heat-treatable aluminum alloy AA7B04 have been obtained as a function of aging temperature (388 K, 413 K and 438 K), stress (both elastic and plastic), and SRA time (up to 4 hours). It has been found that the apparent activation energy Qa of the material remains constant in the elastic region but decreases with the increase in strain in the plastic region, and also decreases with the increase in temperature for all initial loading stresses. These characteristics contribute to a much higher degree of stress relaxation in the plastic region and at higher temperatures than in the elastic region and/or at lower temperatures. The obtained changing activation volume V and Qa indicate that the deformation rate is controlled by forest dislocation interactions in the elastic region (V decreases from over 200b3 to less than 100b3), and by a cross-slip mechanism at high stress levels in the plastic region (V decreases to a few tens of b3). Based on these theories and results, a novel and simple constitutive model has been proposed, with which the stress-relaxation behavior of AA7B04 at different aging temperatures (388 K to 448 K), preloaded from elastic to plastic regions for up to 16 hours has been successfully predicted. The proposed model eliminates the limitations of conventional SRA models which mainly deals with elastic loading and isothermal conditions, and provides a foundation to effectively predict the springback after advanced non-isothermal SRA forming of aluminum alloy structures in the aerospace industry.

Solid solutions based on BaAl12-xMxO19 (M = Co2+, Ni2+) showing intense blue shades were successfully synthesized by conventional solid state reaction. Then, novel zirconia ceramic materials with intense blue hues were then prepared upon addition of 5 wt% of the synthesized chromophore to a ZrO2 white matrix containing 5 wt% Y2O3 and sintered at 1400 °C for 6 h. The colors of the BaAl12-xCoxO19 or BaAl12-xNixO19 are due to the d-d transitions of Co2+ or Ni2+ in tetrahedral coordination, respectively. The colored zirconia ceramics were all indexed with tetragonal phase. The coexistence of the chromophore and ZrO2 were observed by scanning electron microscopy and energy dispersive spectrometer. The hardness of the as-synthesized blue zirconia ceramic was slightly higher as compared to the pure undoped sample.

This work investigated the effect of replacing Zn2+ ions with Cd2+ ions on the microstructure and electromagnetic properties of NiZnCo ferrites. The studies show that the Cd2+ ions substituted for Zn2+ ions at the A sites (tetrahedral sites) of the ferrite lattice. The large ionic radius of the Cd2+ ions can cause lattice distortion. Concurrently, the low melting point of CdO can effectively reduce the sintering temperature of NiZnCo ferrite, thereby significantly changing the magnetoelectric properties of NiZnCo ferrite. These changes are mainly manifested as the decrease in the saturation magnetization (Ms) from 66.6 to 58.5 emu/g and the increase in coercivity (Hc) from 31.2 to 34.8 Oe. The dielectric constant increases considerably, dielectric loss tanδ gradually decreases from 4.71 to 0.83 at 10 kHz, and DC resistivity ρ decreases considerably from 8.0 × 104 to 1.61 × 104 Ω m. Therefore, the substitution of Cd2+ ions in NiZnCo ferrite provides excellent electrical and magnetic properties, which provide a reference for the development of high-frequency miniaturized electronic equipment.

The microstructure of twinning as well as the phase boundary between 1:5H and 2:17R phase in Fe-rich Sm2Co17-type magnets was characterized at atomic scale using nanobeam diffraction and high-resolution STEM-HAADF imaging, and the reason for the dramatic increase of coercivity during slow cooling was investigated based on the microchemistry analysis. The twinning relationship in the 2:17R phase originates from ordered substitution of Sm atoms by Co–Co atomic pairs on every three ( 3 ¯ 033) and (30 3 ¯ 3) planes, leading to formation of two corresponding equivalent twin variants. The basal plane of the 2:17R phase, the 1:3R platelet phase across the 2:17R cell and the 1:5H cell boundary phase between two adjacent 2:17R cells all can act as effective twin boundary. The cell boundary phase is precipitated along the pyramidal habit plane, and a fully coherent phase boundary (PB) is formed between the 1:5H and 2:17R phases with the orientation relationship to be PB//(11 2 ¯ 1)1:5H//(10 1 ¯ 1)2:17R. The phase boundary may either be parallel to or intersect with the pyramidal planes occupied by Co–Co atomic pairs. The substantial increase of coercivity during slow cooling is ascribed to the development of large gradient of the elements concentration within the cell boundary phase, resulting in large gradient of domain wall energy, and thus the pinning strength of the cell boundary phase against magnetic domain wall motion is significantly enhanced.

Poor cycling stability and low volumetric capacity of sulfur cathode prevents practical application of Lithium-sulfur (Li-S) batteries. Herein, we demonstrate a strategy to address the two drawbacks of sulfur cathode by synthesizing a compact and flexible film cathode with bilayer structure using a two-step vacuum filtration method. Two layers make up the sulfur cathode, active layer (sulfur-acethlene black (S C) spheres) and barrier layer (three dimensional MnO2-graphene oxide-multi-walled carbon nanotubes (MnO2-GO-CNTs) composites), which are integrated together by reduced graphene oxide (rGO) through self-binding. The rGO sheets provide an electrical conductive framework and a stable architecture to accommodate volume changes of sulfur. S C spheres stacked orderly between the rGO layers facilitate fast Li+ storage and energy release. Polar MnO2-GO-CNTs composites with large specific surface area have not only afforded efficient sites for chemically binding polysulfides, but also provided fast electron transfer for accelerating polysulfides redox reaction. Consequently, the integrated film cathode exhibits an unprecedented cycling stability of ~0.0279% capacity decay per cycle over more than 600 cycles at 1C and high volumetric capacity of 1021.9 Ah L-1 at 2C. Meanwhile, a foldable Li-S battery based on this flexible cathode is fabricated and shows excellent mechanical and electrochemical properties. The integrated flexible sulfur cathode of this study sheds light on the design strategies for application in flexible high volumetric capacity system.

An Al–Si–Al2O3 composite was prepared with corundum, aluminium powder and silicon powder. A creep test was carried out at 1300°C under 0.2 MPa for 50 h in air. The results show that the Al–Si–Al2O3 composite performs a low constant creep rate and remain until the end of the 50-h test. This is attributed to the in-situ formation of the tough non-oxide reinforcements, whisker-like (AlN)x(Al2OC)1-x solid solution and granular β-SiC, by reactions of Al and Si during creep test. The whisker-like (AlN)x(Al2OC)1-x solid solution and granular β-SiC reinforcements are evenly filled in the pores, which play the role of bridging and pinning reinforcement, forming a strong network structure with corundum aggregates. Moreover, these non-oxide phases are not wetted by the liquid phases, which impel the liquid phase shrinks in the network structure in isolation during creep test. Thus, the adverse effect of the liquid phase on the high-temperature strength of the composites is eliminated, so the composites with strong network structure quickly get a stationary low-creep state. A creep mechanism model is established.

Commercial lithium sulfur batteries are hindered by unstable and unreliable cycling performances due to the dissolution and shuttle of lithium polysulfides. Defect engineering with plentiful active sites and high surface binding energies to restrain polysulfides dissolution and promote the redox conversion polysulfides. Here, we present a nano carbon intercalated by W18O49 nanorods composite materials as functional sulfur host. With high W/O ratio of 0.367 in tungsten oxide famliy (WOx), W18O49 achieves abundant oxygen vacancy in intrinsic atomic structure. These oxygen vacancies not only provide stable active sites to stabilize the Li2S but also immobilize polysulfides by strong coulombic interactions of W-S and Li-O bondings. Accordingly, this cathode achieves stable long cycling performance with decay rate of 0.038 % per cycle at 2 C for 1200 cycles. With high sulfur loading of 6.4 mg·cm−2, the cathode also shows stable cycling at 0.2 C for 150 cycles. This immobilizations of polysulfides by oxygen vacancy engineering in W18O49 is referential for developing commercial useable Li-S batteries.

In the present work, we have investigated the crystal structure, magnetic, and magnetocaloric properties of the ordered monoclinic polycrystalline double perovskite Nd2BMnO6 (B = Co and Ni). A study of the magnetization dynamics employing temperature and magnetic field shows a powerful spin frustration state with freeing temperature of Tf ~154 K (for Nd2CoMnO6) and Tf ~ 194 K (for Nd2NiMnO6). The ac susceptibility measurements show exhibit frequency- and field-dependent behavior. Both the magnetic relaxation effects and related analysis indicate a typical spin-glass (SG) behavior in Nd2BMnO6. Furthermore, Nd2CoMnO6 (NCMO) and Nd2NiMnO6 (NNMO) show remarkable magnetocaloric effect (MCE) and relative cooling power (RCP) near the paramagnetic (PM) to ferromagnetic (FM) transition. Moreover, the critical behavior is investigated by different theoretical, such as modified Arrott plot (MAP) and Kouvel-Fisher (KF). The critical exponents (β, γ, and δ) of Nd2BMnO6 are obtained from the different methods, which are close to the mean-field model. The detailed analysis on the critical behavior in Nd2BMnO6, which suggests that the long-range FM interaction in the Nd2BMnO6.

Ni-rich layered oxides have been demonstrated to be promising cathode materials for high-energy–density batteries. However, most of them suffer from sluggish kinetics and structural instability, severely impeding their practical applications. Herein, the surface of LiNi0.8Co0.1Mn0.1O2 cathode is modified with ionic, conducting zinc phosphate (Zn3(PO4)2) nanolayers. The nanolayers are autogenously formed from the reaction of NH4H2PO4 with ZnO assisted with citric acid. The as-prepared 3 wt% Zn3(PO4)2 coated sample exhibits a first discharge capacity of 203.4 mAh g-1and excellent capacity retention for 100 cycles. The surface Zn3(PO4)2 nanolayers positively impact the cell performance by scavenging HF and H2O in the electrolyte, leading to less formation of byproducts on the surface of the cathodes, which lowers the cell resistance and polarization voltage. Our study provides a simple and efficient strategy to design and optimize promising layer-structural cathodes for LIBs.

This work presents a study of the granulation of iron fines in a horizontal high shear granulator. Both experiments and DEM simulations were conducted to investigate the effect of water content, impeller rotational speed and particle sizes on granulation performance. The experimental results showed that the granule size increased with increasing water content, but the granules had the most uniform size at 8% of water content. The DEM model was developed to understand the inter-particle force, particle motion and adhesion during granulating. The results show that the liquid bridge force and the amount of bonded small particles increased with increasing water content, resulting in larger granules with wider granule size distributions. Increasing impeller speed also increased granulation efficiency due to increased collisions between particles. The simulation of the granulation of particles with different size ratios showed that granulation efficiency increased with increasing size ratios of nucleating and adhesive particles.

The design of artificial photocatalytic devices that simulates the ingenious and efficient photosynthetic systems in nature is promising. Herein, a metal-organic cage [Pd6(NPyCzPF)12]12+ (MOC-PC6) integrating 12 organic ligands NPyCzBP and 6 Pd2+ catalytic centers is designed, which is well defined to include organic dye fluorescein (FL) for constructing a supramolecular photochemical molecular device (SPMD) FL@MOC-PC6. Photoinduced electron transfer (PET) between MOC-PC6 and the encapsulated FL has been observed by steady-state and time-resolved emission spectroscopy. FL@MOC-PC6 is successfully heterogenized with TiO2 by a facile sol-gel method to achieve a robust heterogeneous FL@MOC-PC6-TiO2. The close proximity between the Pd2+ catalytic site and FL included in the cage enables PET from the photoexcited FL to Pd2+ sites through a powerful intramolecular pathway. The photocatalytic hydrogen production assessments of the optimized 4 wt % FL@MOC-PC6-TiO2 demonstrate an initial H2 production rate of 2402 μmol g-1 h-1 and a turnover number of 4356 within 40 h, enhanced by 15-fold over that of a homogeneous FL@MOC-PC6. The effect of the MOC content on photocatalytic H2 evolution (PHE) is investigated and the inefficient comparison systems, such as MOC-PC6, MOC-PC6-TiO2, FL-sensitized MOC-PC6/FL-TiO2, and analogue FL/MOC-PC6-TiO2 with free FL, are evaluated. This study provides a creative and distinctive approach for the design and preparation of novel heterogeneous SPMD catalysts based on MOCs.

Spark-assisted chemical engraving (SACE) is suitable to machine hard and brittle insulating materials such as quartz glass; however, the processing efficiency is quite low for achieving good machin...

In this study, a vertical twin-roll cast (TRC) thermal-fluid coupling model was established to determine a suitable roll-casting velocity. A slab of 0.9mm thick roll-cast Al-50 wt.% Si alloy with a two-phase zone width of 473°C was prepared at a velocity of 20m/min for the first time. In addition, the finite element simulation showed that the average heat transfer rate had a positive correlation with the roll-casting velocity. When the roll-casting velocity increased to 20m/min, the average heat transfer rate reached 1260K/s, at which point, the average size of the primary Si was merely 16.5μm. This was a decrease of approximately 90% when compared with the size of alloys cast with conventional methods. After carrying out semi-solid heating, an observation on the distribution of alloy elements identified a novel phenomenon of solute redistribution, i.e., inverse segregation. This inverse segregation process was highly significant in further controlling solute redistribution in the alloy. Additionally, it provided a new concept for improving roll-cast segregation.

Lithium carbon fluorides (Li/CFx) primary batteries are of highly interests due to their high specific energy and power densities. The shelf life is one of the major concerns when they are used as backup power, emergency power and storage power in landers, manned spacecraft or military applications. In this work, real-time storage tests are carried out for both energy-type and power-type Li/CFx pouch batteries at 25 oC. Accelerated storage tests are performed at elevated temperature of 55 oC. The electrochemical tests are conducted throughout the aging period of 0−365 days for various batteries to study the effects of temperature on both type of batteries. The observed electrochemical behaviors are explained with the evidences from multiple characterizations for post-tested samples.

The novel Al4O4C–(Al2OC)1-x(AlN)x–Zr2Al3C4–Al2O3 refractories with ultra-low carbon content have been successfully prepared by constructing the core-shell structure of aluminum at 1300–1700°C in nitrogen. The phase composition, microstructure, and properties of the novel refractories are deeply investigated. The cracking temperature on the core-shell structure of aluminum is further explored and the reaction mechanism of Zr2Al3C4 has also added explanation. The results show that the novel refractories have excellent physical properties and cannot be corroded by molten iron. There exist two different Al2OC solid solutions in the novel refractories, Al2OC-rich (Al2OC)1-x(AlN)x and AlN-rich (Al2OC)1-x(AlN)x. The temperatures affect their relative content. When temperatures are less than 1600°C, the relative content of Al2OC-rich (Al2OC)1-x(AlN)x is more than that of AlN-rich (Al2OC)1-x(AlN)x. When temperatures are above 1700°C, the relative content of AlN-rich (Al2OC)1-x(AlN)x is more than that of Al2OC-rich (Al2OC)1-x(AlN)x. The core-shell structure of aluminum fully ruptures at about 1200°C. Zr2Al3C4 begins to form at about 1000°C and generates in large at 1200°C.

Adopting the sidewall-insulated hollow electrode (SIHE) is an ideal approach to achieve electrolyte-refresh and stray corrosion inhibition functions in micro electrochemical machining (ECM) processes. Most of the traditional SIHEs are made of metal substrate and non-metal thin films. The insulating film has poor durability, and the preparation approach of the traditional SIHE is complex and has limited repeatability. This research presents a novel structure of a SIHE with an insulated substrate and an internal conductive film. The machining performance of the novel SIHE is primarily verified by a potential distribution analysis in the numerical simulation. According to the concept of the novel SIHE, a silver-plated glass tube electrode (SPGTE) is presented: the glass tube acts as the insulated substrate, and the plated silver layer acts as the working cathode. Then, a fabrication process for the SPGTE is proposed. Silver layers are tightly bonded on the glass tube surface by electroless plating. The thickness of the silver layer is approximately 3.5 μm, and its electrical resistivity is approximately 5 × 10−5 Ω cm. In micro ECM experiments, microstructures with steep sidewalls with taper angles of

Na3V2(PO4)3 is a very prospective sodium-ion batteries (SIBs) electrode material owing to its NASICON structure and high reversible capacity. Conversely, on account of its intrinsic poor electronic conductivity, Na3V2(PO4)3 electrode materials confront with some significant limitations like poor cycle and rate performance which inhibit their practical applications in the energy fields. Herein, a simple two-step method has been implemented for the successful preparation of carbon-coated Na3V2(PO4)3 materials. As synthesized sample shows a remarkable electrochemical performance of 124.1 mAh/g at 0.1 C (1 C = 117.6 mA/g), retaining 78.5 mAh/g under a high rate of 200 C and a long cycle-performance (retaining 80.7 mAh/g even after 10000 cycles at 20 C), outperforming the most advanced cathode materials as reported in literatures.

Conductive carbon structure has been considered as a promising sulfur-hosting material as the cathode of lithium-sulfur batteries. However, the issue of polysulfide shuttling requires an additional component to help restrict and convert sulfur substances. Herein, in this work, hollow and porous carbon nanospheres (HCS) are synthesized by a template method and a high-temperature carbonization treatment. A thin layer of ZnS coating is then deposited on the HCS-based sulfur (ZnS@HCS/S) cathode with controlled thickness, and the overall electrochemical properties are systematically evaluated. Results show that with 30 nm -thick ZnS coating, the cathode reveals an improved capacity of 1411 mA h g−1, and higher capacities from 0.2 to 3 C rate compared with bare HCS/S cathode. Moreover, the ZnS coating also enhances the cycling stability of ZnS@HCS/S cathode over 280 cycles at 0.5 C, with only 0.2% capacity decay per cycle. This work demonstrates potential applications for high-performance lithium-sulfur batteries.

Magnesium alloy sheets have an increasing proportion of applications in automobiles due to their high specific strength. The usability of traditional welding processes and mechanical joining processes is restricted by the characteristic of magnesium alloy sheets. In order to improve the plasticity of magnesium alloy sheets and realize the reliable joining of magnesium alloy sheets with dissimilar sheets, researchers have conducted a lot of research. In this paper, the existing joining processes of friction stir spot welding, friction stir blind riveting, hybrid self-piercing riveting, and friction self-piercing riveting for magnesium alloy sheets are reviewed; the latest advances of joining process are introduced; and the principle, development, advantages, and shortcomings of each process for improving the plasticity of magnesium alloy sheets are systematically described. Several unaddressed issues in the joining of magnesium alloy sheets are identified. The hybrid of mechanical and solid-state joining processes will be a trend in future development.

Lithium-sulfur (Li-S) batteries are recognized as one of the most promising next-generation energy storage devices, but their practical application is greatly limited by several obstacles, such as the highly insulating nature and sluggish redox kinetics of sulfur and the dissolution of lithium polysulfides. Herein, three-dimensional carbon nanosheet frameworks anchored with Ni@Ni3N heterostructure nanoparticles (denoted Ni@Ni3N/CNS) are designed and fabricated by a chemical blowing and thermal nitridation strategy. It is demonstrated that the Ni@Ni3N heterostructure can effectively accelerate polysulfide conversion and promote the chemical trapping of polysulfides. Meanwhile, the carbon nanosheet frameworks of Ni@Ni3N/CNS establish a highly conductive network for fast electron transportation. The cells with Ni@Ni3N heterostructures as the catalyst in the cathode show excellent electrochemical performance, revealing stable cycling over 600 cycles with a low-capacity fading rate of 0.04% per cycle at 0.5 C and high-rate capability (594 mAh g-1 at 3 C). Furthermore, Ni@Ni3N/CNS can also work well in room-temperature sodium-sulfur (RT-Na/S) batteries, delivering a high specific capacity (454 mAh g-1 after 400 cycles at 0.5 C). This work provides a rational way to prepare the metal-metal nitride heterostructures to enhance the performance both of Li-S and RT-Na/S batteries.

Ferroelectric is thought to be one of the most promising energy-storage materials due to its high polarization. However, large energy loss and low breakdown strength (BDS) are the main drawbacks that hinder high energy-storage performances of ferroelectric materials. Here, excellent energy-storage performances are achieved in 0.85(0.55Na0.5Bi0.5TiO3-0.45Sr0.7La0.2TiO3)-0.15Bi(Mg2/3Nb1/3)O3 (NBT-SLT-BMN) relaxor ferroelectric ceramic by optimizing sintering temperatures, which leads to a high recoverable energy-storage density (Wrec) of 3.88 J/cm3 together with a high energy efficiency (η) of 85% at the optimal sintering temperature of 1170 °C. The microstructural analysis suggests that the softened B-O vibrations and the formation of polar nanorgeions give rise to the enhanced relaxation behavior that is responsible for the decrease of energy loss. Meanwhile, the optimal sintering temperature has an effective role in decreasing grain size, resulting in a large increase of the BDS. Moreover, the ceramic sintered at 1170 °C exhibits excellent energy-storage stability in the range of 20–180 °C and 1-125 Hz. Based on the pulse charge-discharge measurement, a high-power density of 68.47 MW/cm3 and a fast charge-discharge speed of 72 ns are acquired. These results show that the appropriate sintering temperature can optimize the microstructure and improve the energy-storage performance of ferroelectric ceramics.

The microstructure and elevated-temperature mechanical properties of dispersoid-strengthened Al-Mg-Si-Mn alloys produced by twin roll casting (TRC) and conventional mold casting (MC) were studied. A specific heat treatment at 430 ​°C for 6 ​h was applied, followed by rolling. Tensile tests were carried out at 300 ​°C. The results show that in the as-cast microstructures, equiaxed grains formed in the MC sample while elongated grains with substructures formed in the TRC sample. The eutectics in the TRC sample were much finer than those in the MC sample. Upon heat treatment, large numbers of α-Al(Fe, Mn)Si dispersoids precipitated, and the TRC sample had a greater number density of dispersoids than those in the MC sample. During the tensile test after rolling, the TRC samples exhibited higher strength than the MC samples, which resulted from the combination of the strengthening effect of the stronger dispersoids and the greater substructure hardening effect in the TRC sample; the TRC sample exhibited better ductility due to its finer initial eutectic than that in the MC sample, which depressed the stress concentration and delayed the occurrence of microcracks and fracture in the TRC sample.

Based on laboratory direct shear tests and discrete element theory, the crack propagation mechanism and numerical simulation of rock-like specimens with preexisting flaws considering combined actions of internal hydraulic pressure and shear force were carried out in this paper. We completed the filling of the internal hydraulic pressure in the rock-like specimens with preexisting flaws, and performed direct shear tests on the specimens. Furthermore, we explored the crack propagation process of rock-like specimens with flaws under internal hydraulic pressure and shear load. In the numerical analysis, the pipe domain model in the two-dimensional particle flow code (PFC2D) was modified owing to the high brittleness and low permeability of the cement mortar particles in the numerical model. We modified the calculation rules of the interaction between the fluid and cement mortar particles, and proposed an improved fluid–solid coupling model which is more suitable for the crack propagation analysis in the high brittle cement mortar specimens. Under the action of internal hydraulic pressure, a tensile region existed at the tip of the preexisting flaws of the cement mortar specimen, which can also explain the crack initiation and propagation along the horizontal shear direction during the stage of crack initiation. When cracks progressively propagated, concentrated tensile stress and internal hydraulic pressure were released, leading to the appearance of a large number of tensile cracks, and the release of transverse shear force and internal hydraulic pressure resulted in the appearance of a large number of shear cracks. In the presence of internal hydraulic pressure, the increased number of pre-existing flaws would reduce the shear strengths of cement mortar specimens. Compared with the shear strength of the specimen with single flaw, the shear strength of the specimen with double flaws was reduced by 7.6%, and the specimen with triple flaws was reduced by 10.2%.

Double-transition-metal MXenes (D-MXenes) have been widely pursued in the advancement of the renewable energy storage technology in recent years. In this work, the hydrogen evolution reaction (HER) catalytic mechanism of several oxygen-terminated D-MXenes with the chemical formula of M'2M″C2O2 (M' = Mo, Cr; M″ = Ti, V, Nb, Ta) is theoretically studied. For comparison, the corresponding monometallic MXenes (M-MXenes, M'3C2O2) are fairly compared by means of the density functional theory calculations. Based on our theoretical results, the HER performance of M-MXenes can be improved by constructing a "sandwich-like" ordered D-MXene configuration. Moreover, the HER performance of Mo-based D-MXenes (Mo2M″C2O2) is superior to that of Cr-based D-MXenes (Cr2M″C2O2), which highlights that the HER activity of Mo2VC2O2 and Mo2NbC2O2 is better than that of Pt(111). This work not only unravels the HER mechanism of D-MXenes (M'2M″C2O2) but also paves the way in designing emergent MXene-based HER electrocatalysts with high efficiency.

The monolayer VN as well as multilayer VN/C coatings were obtained on 316 L steel via physical vapor deposition (PVD) technology. Structure, mechanical property and tribo-corrosion behavior of monolayer VN and multilayer VN/C coatings under simulated seawater were estimated by corresponding detection equipment. After analysis, C nanolayer could break the grain growth of VN phase, which would enhance the coating toughness and inhibit the source of crack. At the same time, the multilayer structure interface could suppress the dislocation movement. In tribo-corrosion process, the corrosion current density (icorr) of VN/C coating was 2.71 × 10−6 A/cm2, which was 70.47% lower than that of VN coating (9.18 × 10−6 A/cm2), implying that the nano-multilayer structure of VN/C coating showed a strong barrier effect on corrosion medium. Moreover, the C nanolayer not only suppressed the permeation of simulated seawater, but also formed the transfer film to protect the substrate. Thus, the multilayer VN/C coating revealed stronger anti-wear and anti-corrosion abilities than the monolayer VN coating.

In this study, we developed a novel method for synthesising Al2OC-AlNss using a solid nitrogen source: a Si3N4 mesophase. The two-step sintered Al–Al2O3 and Si3N4–Al–Al2O3 samples were prepared under an atmosphere of nitrogen to investigate the effect of Si3N4 on the formation of Al2OC-AlNss in resin-bonded Al–Al2O3 composites. The samples were investigated via XRD and SEM. The results indicated that the synthesis of Al2OC-AlNss with different morphologies was achieved via the Si3N4 mesophase, and its morphology was influenced by the source of AlN. Both Al2OC-AlNss and Al4O4C were formed in the two-step sintered Al–Al2O3 sample, whereas only Al2OC-AlNss was formed in the two-step sintered Si3N4–Al–Al2O3 sample. Induced by the AlN formed by the nitridation of Al, needle-like Al2OC-AlNss was generated. Compared to that formed by the nitridation of Al, more AlN nuclei were provided by the reaction between Si3N4 and Al. Subsequently, columnar and granular Al2OC-AlNss were formed. Furthermore, fibre-like Al2OC-AlNss was also generated via the VS and VLS mechanism. The reaction model was established in this study.

The solid-state magnetic cooling (MC) method based on the magnetocaloric effect (MCE) is recognized as an environmentally friendly and high-energy-efficiency technology. The search or design of suitable magnetic materials with large MCEs is one of the main targets at present. In this work, we apply the chemical and hydrostatic pressures in the Ni35Co15Mn35−xFexTi15 all-d-metal Heusler alloys and systematically investigate their crystal structures, phases, and magnetocaloric performances experimentally and theoretically. All the alloys are found to crystallize in an ordered B2-type structure at room temperature and the atoms of Fe are confirmed to all occupy at sites Mn(B). The total magnetic moments decrease gradually with increasing Fe content and decreasing of volume as well. The martensitic transformation temperature decreases with the increase of Fe content, whereas increases with increasing hydrostatic pressure. Moreover, obviously enhanced magnetocaloric performances can also be obtained by applied pressures. The maximum values of magnetic entropy change and refrigeration capacity are as high as 15.61(24.20) J (kg K)−1 and 109.91(347.26) J kg−1 with ΔH = 20(50) kOe, respectively. These magnetocaloric performances are superior to most of the recently reported famous materials, indicating the potential application for active MC.

Phosphorylated-oligo [poly(ethylene glycol)fumarate] (Pi-OPF) was combined with functionalized clays to facilitate the extrusion 3D printing of Pi-OPF. Acrylated montmorillonite (Ac-MMT) was synthesized for the covalent crosslinking of MMT with the Pi-OPF. The incorporation of Ac-MMT was observed to improve the rheological properties of Pi-OPF, enabling a high-fidelity extrusion printing. A well-dispersed exfoliated MMT phase was observed within the polymer matrix after the crosslinking. This leveraged improved mechanical properties of the Pi-OPF hydrogels evident through the compressive analysis. Additionally, a unique bioink combining chitosan methacrylate (ChiMA) and gelatin was developed with a primary goal of depositing the cells on the 3D printed Pi-OPF scaffolds for uniform cell distribution and for facilitating a spatial interaction between cells and Ac-MMT particles. This bioink was shown to support the encapsulation and proliferation of the printed pre-osteoblasts by the live/dead cell assay results. This excellent cell responses were unaltered when the cell laden was deposited on 3D printed Pi-OPF scaffolds. Furthermore, the spatial interaction between cells and Ac-MMT elicited improved osteoblast responses indicated by the spreading of encapsulated cells and higher intracellular alkaline phosphatase (ALP) expression. Taken together, the results of this study present the combinatorial application of 3D printing and bioprinting to achieve desirable biological responses through the interaction between cells and biomaterials.

Heteroclusters constructed by tethering dissimilar nanoclusters using organic linkers resemble lipids and self-assemble into cubosomes, namely, microparticles of soft crystals composed of unique nanochannel lattices with a defined symmetry and topology. The internal porous crystal structures can be accurately characterized using transmission electron microscopy. We herein describe twin boundaries and five-fold twin boundaries in cubosomes with a double-diamond Pn3m structure. Our analysis indicates a clear distinction in the conformation of the skeletal unit: a centrosymmetric staggered conformation with point group D3d for the normal skeletal unit and a mirror-symmetric eclipsed one with point group D3h for the skeletal unit on the twin boundary. This symmetry distinction causes the channels to change direction and elongate slightly as they pass through the twin boundary, but the topology is maintained. For cubosomes containing five-fold twin boundaries, one of the channels is in the center of the particles seamlessly connecting the five blocks. Our conclusion is that the two distinct channel systems are still continuous. This fundamental understanding will contribute to the development of soft crystals with defined shapes and special inner nanostructures for advanced applications.

Small biomolecules (m/z < 500) are the material basis of organisms and participate in life activities, but their comprehensive and accurate detection in complex samples remains a challenge. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a powerful detection tool for molecular analysis with high throughput. The development of a new matrix is essential to improve the efficiency of the MALDI-MS for molecular compound detection. In this work, the sandwich-like gold nanoparticles@mesoporous silica nanocomposite@silver nanoparticles (Au@MSN@Ag) nanospheres were prepared by layer-by-layer super-assembly strategy, and can be used as a novel matrix for the quantitative detection and enrichment of small biomolecules by LDI-MS. The sandwich-like nanospheres form a unique plasma resonant cavity that effectively absorbs the laser energy, while the homogeneous mesoporous structure of MSN can lock the analyte, which is essential for efficient LDI of small molecules. Compared to traditional matrices, Au@MSN@Ag shows the advantages of low background, wide application range, high sensitivity, super high salt and protein tolerance, and good stability. For example, the detection limit of glucose was as low as 5 fmol, and showed a good linear relationship in the range of 1–750 µg/mL. Au@MSN@Ag assisted LDI-MS allows the enrichment and detection of small molecules in traditional Chinese medicine (TCM) without derivatization and purification, classification of herbs using the accurate quantitative results oligosaccharides, and identification of gelatin by amino acid content. This research could help in designing more efficient nanostructure matrices and further explored the application of LDI-MS.

This work reports strategies for improving the power conversion efficiency (PCE) by capitalizing on temporal changes through the storage effect and immediate improvements by interface passivation. It is demonstrated that both strategies can be combined as shown by PCE improvement in passivated perovskite solar cells (PSCs) upon ambient storage because of trap density reduction. By analyzing the dominant charge recombination process, we find that lead-related traps in perovskite bulk, rather than at the surface, are the recombination centers in both as-fabricated and ambient-stored passivated PSCs. This emphasizes the necessity to reduce intrinsic defects in the perovskite bulk. Furthermore, storage causes temporal changes in band alignment even in passivated PSCs, contributing to PCE improvement. Building on these findings, composition engineering was employed to produce further immediate PCE improvements because of defect reduction in the bulk, achieving a PCE of 22.2%. These results show that understanding the dominant recombination mechanisms within a PSC is important to inform strategies for producing immediate and temporal PCE enhancements either by interface passivation, storage, composition engineering, or a combination of them all to fabricate highly efficient PSCs.

To power large-scale energy storage systems, sodium-ion batteries (SIBs) must have not only high-energy density but also high performance under a low-temperature (LT) environment. P2-type manganese oxides with high specific capacity are promising cathode candidates for SIBs, but their LT applications are limitedly explored. We proposed a P2-type Na0.67Ni0.1Co0.1Mn0.8O2 material with outstanding LT performance prepared through reasonable structure modulation. The material offers an excellent Na+ diffusion coefficient (approximately 10−9–10−7.5 cm2 s−1) at −20°C, a superior LT discharge capacity of 147.4 mA h g−1 in the Na half-cell system, and outstanding LT full cell performance (energy density of 358.3 W h kg−1). Various characterisations and density function theory calculations results show that the solid solution reaction and pseudocapacitive feature promote the diffusion and desolvation of Na+ from the bulk electrode to interface, finally achieving superior electrochemical performance at LT.