In-situ tensile tests were conducted on a chemically corroded third-generation single-crystal superalloy DD9 at 980 and 1100℃.The phase transformation in the surface areas during the tensile process was analyzed usin...In-situ tensile tests were conducted on a chemically corroded third-generation single-crystal superalloy DD9 at 980 and 1100℃.The phase transformation in the surface areas during the tensile process was analyzed using field emission scanning electron microscope,energy dispersive X-ray spectroscope,electron probe X-ray microanalysis,and transmission electron microscope.The phase transformation mechanism on the surface and the influence mechanism were studied through observation and dynamic calculation.During tensile tests at elevated temperatures,chemical corrosion promotes the precipitation of topologically close-packed(tcp)μphase andσphase on the alloy surface.Both the precipitation amount and size of these two phases on the surface at 1100℃are greater than those at 980℃.The precipitation of tcp phase on the alloy surface results in the formation of an influence layer on the surface area,and the distribution characteristics of alloying elements are significantly different from those of the substrate.The depth of the influence layer at 1100℃is greater than that at 980℃.The precipitation of tcp phase prompts the phase transition fromγphase toγ′phase around the tcp phase.展开更多
[Background]High harmonic cavities are widely used in electron storage rings to lengthen thebunch,lower the bunch peak current,thereby reducing the IBS effect,enhancing the Touschek lifetime,as well asproviding Landau...[Background]High harmonic cavities are widely used in electron storage rings to lengthen thebunch,lower the bunch peak current,thereby reducing the IBS effect,enhancing the Touschek lifetime,as well asproviding Landau damping,which is particularly important for storage rings operating with ultra-low emittance or atlow beam energy.[Purpose]To further increase the bunch length without additional hardware costs,the phasemodulation in a dual-RF system is considered.[Methods]In this paper,turn-by-turn simulations incorporating randomsynchrotron radiation excitation are conducted,and a brief analysis is presented to explain the bunch lengtheningmechanism.[Results]Simulation results reveal that the peak current can be further reduced,thereby mitigating IBSeffects and enhancing the Touschek lifetime.Although the energy spread increases,which tends to reduce thebrightness of higher-harmonic radiation from the undulator,the brightness of the fundamental harmonic can,in fact,beimproved.展开更多
A dual-phase synergistic enhancement method was adopted to strengthen the Al-Mn-Mg-Sc-Zr alloy fabricated by laser powder bed fusion(LPBF)by leveraging the unique advantages of Er and TiB_(2).Spherical powders of 0.5w...A dual-phase synergistic enhancement method was adopted to strengthen the Al-Mn-Mg-Sc-Zr alloy fabricated by laser powder bed fusion(LPBF)by leveraging the unique advantages of Er and TiB_(2).Spherical powders of 0.5wt%Er-1wt%TiB_(2)/Al-Mn-Mg-Sc-Zr nanocomposite were prepared using vacuum homogenization technique,and the density of samples prepared through the LPBF process reached 99.8%.The strengthening and toughening mechanisms of Er-TiB_(2)were investigated.The results show that Al_(3)Er diffraction peaks are detected by X-ray diffraction analysis,and texture strength decreases according to electron backscatter diffraction results.The added Er and TiB_(2)nano-reinforcing phases act as heterogeneous nucleation sites during the LPBF forming process,hindering grain growth and effectively refining the grains.After incorporating the Er-TiB_(2)dual-phase nano-reinforcing phases,the tensile strength and elongation at break of the LPBF-deposited samples reach 550 MPa and 18.7%,which are 13.4%and 26.4%higher than those of the matrix material,respectively.展开更多
As electronic technology continues to evolve towards miniaturization and integration,the demand for micro-refrigeration technology in microelectronic systems is increasing.Ferroelectric(FE)refrigeration technology bas...As electronic technology continues to evolve towards miniaturization and integration,the demand for micro-refrigeration technology in microelectronic systems is increasing.Ferroelectric(FE)refrigeration technology based on the electrocaloric effect(ECE)has emerged as a highly promising candidate in this field,due to its advantages of high energy efficiency,simple structure,easy miniaturization,low cost,and environmental friendliness.The EC performance of FE materials essentially depends on the phase transition features under the coupled electric and thermal fields,making the E–T phase diagram a core tool for decoding the underlying mechanism of ECE.This paper reviews the development of EC materials,focusing on the comprehensive study of E–T phase diagrams.By correlating the microscopic phase structure of FE materials with the macroscopic physical properties,it clarifies the manipulation mechanism for enhanced ECE performance,providing theoretical support for the targeted design of high-performance EC materials.In the future,the introduction of data-driven methods is expected to enable the high-throughput construction of FE phase diagrams,thereby accelerating the optimization of high-performance EC materials and promoting the practical application of FE refrigeration technology.展开更多
In the context of the global energy low-carbon transition,phase change energy storage technology becomes a key technology to solve the problem of intermittent renewable energy.Oriented phase change composites(OCPCMs)r...In the context of the global energy low-carbon transition,phase change energy storage technology becomes a key technology to solve the problem of intermittent renewable energy.Oriented phase change composites(OCPCMs)receive widespread attention in practical energy storage applications due to their unique oriented thermally conductive structure,which achieves significant thermal conductivity enhancement in specific directions while retaining the high energy storage capacity of the phase change components.This review systematically summarizes the overall analysis of OCPCMs from synthesis and preparation to application scenarios in recent years.Herein,we introduce the analysis of the heat transfer mechanism of the materials and explore the advantages of the oriented structure in OCPCMs in the heat transfer behavior from a bionic perspective.We then focus on summarizing and generalizing the methods for preparing OCPCMs,giving suggestions for suitable methods according to different scenarios.Besides,we discuss the application of finite element simulation methods to the monitoring of the thermal management behavior of OCPCMs,and look into the potential future application areas of such materials.Finally,it is hoped that this review will provide guidance for the academic community in developing high-performance OCPCMs.展开更多
In this study,by adjusting the homogenization process,numerous lamellar-shapedγ’phases are generated and uniformly distributed throughout the grain interior within as-extruded Mg-9Gd-4Y-1Zn-0.5Zr(wt.%)alloy,leading ...In this study,by adjusting the homogenization process,numerous lamellar-shapedγ’phases are generated and uniformly distributed throughout the grain interior within as-extruded Mg-9Gd-4Y-1Zn-0.5Zr(wt.%)alloy,leading to a remarkable increase enhancement in both tensile strength and fracture toughness.Notably,as compared to the alloy containing block-shaped long-period stacking-ordered(LPSO)phase,when the lamellar-shapedγ’phase is introduced within theα-Mg matrix,the fracture toughness of 29.7 MPa·m^(1/2)can be achieved with a 27%improvement.This superior fracture resistance is mainly attributed to the delamination toughening derived from the intensive micro-cracks occurring alongγ’phase interfaces oriented perpendicular to the primary fracture surface.Owing to the presence of lamellarshapedγ’phase,the fracture morphology can be significantly changed and characterized with deep dimples and pronounced deflection of main crack,which collectively contribute to the enhanced plastic energy dissipation and fracture toughness.The characteristics of deformed microstructure near the fracture surface demonstrate the activation of kinking and the inhibition of twin propagation due to the interactions with lamellarγ’phase.Such deformation behavior can effectively impede the crack propagation and contribute to the superior fracture resistance.Besides,the X-ray computed tomography analysis of the fractured alloy exhibits the distribution and size of voids,indicating that the prolate voids preferentially nucleate and propagate parallel to the lamellarγ’phase.Accordingly,the deformation mechanisms under a triaxial stress state involve the intricate interplay between lamellarγ’phase-induced delamination,crack deflection as well as void formation.Through the application of tailored pre-treatment heat treatment processes,the control of phase constituents within the microstructure can be achieved to improve the mechanical properties of Mg alloys.It is anticipated to provide a comprehensive understanding of the fracture behavior of Mg-Gd-Y-Zn-Zr,with particular emphasis on the synergistic effects of lamellarγ’phase and LPSO phase in the optimization of overall mechanical performance.展开更多
Optical phase-gradient metasurfaces have garnered significant attention for enabling flexible light manipulation,with applications across diverse domains.In this work,we will demonstrate that the metasurfaces with pha...Optical phase-gradient metasurfaces have garnered significant attention for enabling flexible light manipulation,with applications across diverse domains.In this work,we will demonstrate that the metasurfaces with phase gradient modulation can be used to achieve illusion optics,featuring the advantages of simple geometric structure and feasible implementation compared with the well-known transformation optics method.The underlying mechanism is the anomalous diffraction law caused by the phase gradient,which provides a theoretical basis for freely manipulating the propagation path of light.By considering a specific example,we will demonstrate that the phase gradient can transform spatial coordinates in real space into illusion space,thereby converting a plane in real space into a curved surface structure in illusion space to achieve the illusion effect.This approach provides a viable alternative to transformation optics for designing illusion devices.展开更多
The direct reduction process can reduce carbon emissions by over 50%compared to traditional blast furnace ironmaking.Carbon deposition and carburization are critical for ensuring process stability and economic viabili...The direct reduction process can reduce carbon emissions by over 50%compared to traditional blast furnace ironmaking.Carbon deposition and carburization are critical for ensuring process stability and economic viability.Thermodynamic phase diagrams were developed to intuitively represent carbon deposition and carburization preferences in CH4-CO-H_(2) ternary atmospheres.High carbon potential and low oxygen potential significantly enhance carbon deposition and carburization.Increasing temperature from 500 to 1000℃ shifts the dominant reactions from CO-based to CH_(4)-based,increasing maximum carbon deposition from 0.55 to 0.80 mol and carburization from 0.25 to 0.80 mol per mole of reducing gas.Increasing pressure suppresses CH4-based reactions while promoting CO-based reactions,reducing maximum carbon deposition from 0.8 to~0.7 mol and increasing maximum carburization from 0.80 to 0.85 mol per mole of reducing gas.Equilibrium phase diagrams for various carbides were also developed,revealing preferences for Fe_(3)C_(2),Fe_(7)C_(3),Fe_(5)C_(2),and Fe_(3)C as the Fe/C ratio increases.Higher temperatures and CH_(4) concentrations favor the formation of carbides with higher carbon content.Carburization preferences under typical Energiron ZR and Midrex atmospheres were highlighted,and the higher carbon content in direct reduction iron produced by the Energiron ZR process was thermodynamically confirmed.展开更多
Heterogeneous nucleation,characterized by its low nucleation barrier and controllable nucleation sites,has been widely employed to manipulate the microstructures and properties of metallic materials.In recent years,th...Heterogeneous nucleation,characterized by its low nucleation barrier and controllable nucleation sites,has been widely employed to manipulate the microstructures and properties of metallic materials.In recent years,the dispersion of inclusions,carbides,and microstructure refinement in steel have emerged as one of the key research directions in the development of high-quality steel.The current research status regarding the regulation of inclusions,carbides,and microstructures in steel through heterogeneous nucleation are reviewed.The key points and challenges in refining the second phase and microstructure in steel using inclusion particles are highlighted,aiming to provide inspiration and references for future scholars.Deoxidized inclusions,when refined and dispersed,exhibit favorable lattice matching with second phases(e.g.,nitrides,sulfides,carbides)in steel.This characteristic serves as the fundamental mechanism for achieving refinement of the second phase.Concurrently,the solid-solution alloying effect from deoxidizing metals contributes to second-phase refinement,an aspect that requires prioritized investigation.In addition to the single heterogeneous nucleation refinement effect,the two-stage heterogeneous nucleation refinement of the second phase and microstructure offers a new approach for follow-up research.Notably,second-phase particles added as heterogeneous nucleation sites via external addition often require surface modification to ensure their stable retention in steel at high temperatures,which remains a major challenge restricting the widespread application of this method.Currently,the explanation of heterogeneous nucleation phenomena primarily relies on empirical calculations of lattice mismatch between the substrate and the nucleating phase,which cannot fully elucidate the quantitative relationship on the interface between the substrate and the nucleation phase.On this basis,quantifying the electronic structure and nucleation barrier at the interface between the substrate and the nucleation phase is a critical direction worthy of increased attention in the future.展开更多
Small Baseline Subset Interferometric Synthetic Aperture Radar(SBAS-In SAR)is widely used for deformation monitoring in mining regions.However,phase unwrapping errors often limit its effectiveness in areas with large-...Small Baseline Subset Interferometric Synthetic Aperture Radar(SBAS-In SAR)is widely used for deformation monitoring in mining regions.However,phase unwrapping errors often limit its effectiveness in areas with large-gradient displacements.We propose a novel approach integrating spatiotemporal modeling to address this limitation and improve phase unwrapping.The Simplified Rectangular Dislocation Model(SRDM)simplifies the phase recovery process by reducing model parameters and improving efficiency in large-gradient deformation zones.Subsequently,the Power Exponential Knothe Model(PEKM)is applied to invert the deformation time series and restore the deformation phase from the time dimension.We validated this method using Sentinel-1 and Radarsat-2 data in the Majialiang Coalfield,China.The results demonstrate that the approach achieved 5%(Sentinel-1)and 14%(Radarsat-2)phase range extensions,elevating maximum detectable phase values from 120/100 rad to 160 rad for respective datasets,while the proportions of pixel points with restored phase exceeding 8 rad(-0.035 m)were 17.4%and 32.1%.The proposed method outperformed conventional techniques in resolving phase discontinuities,demonstrating strong adaptability.This approach significantly enhances subsidence monitoring accuracy and supports sustainable mining operations in coal-dependent regions.展开更多
The volume change behavior of natural gas hydrate-bearing sediment is essential as it influences settlement,strength,and stiffness,which directly affect the stability of hydrate reservoirs during hydrate extraction or...The volume change behavior of natural gas hydrate-bearing sediment is essential as it influences settlement,strength,and stiffness,which directly affect the stability of hydrate reservoirs during hydrate extraction or in response to environmental changes.The volume change is influenced not only by stress but also by the formation and dissociation of hydrates.This study adopted a customized apparatus for one-dimensional compression tests,allowing independent control of gas pressure and effective stress.Tests were conducted on samples with different hydrate saturations along various temperature-gas pressure-effective stress paths,yielding some conclusions related to compressibility and creep.An unusual phenomenon was observed under low-stress conditions:hydrate formation led to shrinkage rather than expansion.Three potential mechanisms behind this occurrence were discussed.As hydrate saturation increases,the yield stress rises while the compression and swelling indexes remain minimally affected.After hydrate dissociation,the compression curve of hydrate-bearing sediment drops to that of hydrate-free sediment.Once hydrate is formed,the compression curve of hydrate-free sediment gradually approaches that of hydrate-bearing sediment during the subsequent loading.Under low-stress conditions,the creep of both hydrate-free and hydrate-bearing sediments is very weak.However,when stress increases,significantly beyond the yield stress,the creep of both sediments increases significantly,with hydrate-bearing sediment exhibiting much greater creep than hydrate-free sediment.展开更多
Material phase-transition represents a significant phenomenon and mechanism in the context of hypervelocity protection.This study presents a thorough analysis of the phase-transition phenomena induced by shock pressur...Material phase-transition represents a significant phenomenon and mechanism in the context of hypervelocity protection.This study presents a thorough analysis of the phase-transition phenomena induced by shock pressure as the shock wave propagates initially to the rear of the projectile.The shock wave that induces a phase-transition is commonly referred to as a macroscopic phase-transition wave,whereas the interface that separates the distinct phases is referred to as macroscopic phase-boundary.The contact interface between the spherical projectile and the thin plate,characterized by its curved surface,plays a significant role in the nonlinear propagation and evolution of wave systems.The pressure distribution along the central axis of a spherical projectile is derived in accordance with the linear decay law observed for axial pressure.On this basis,a quadratic function is employed to characterize the trend of changes in wave front pressure,thereby facilitating the establishment of a model for wave front pressure distribution.Using the phase-transition pressure criterion for materials,the wave front phase evolution process is derived,and the macroscopic phase-boundary is determined.Based on the geometric propagation model(GPM)and the pressure distribution of the wave front,a phase geometric propagation model(PGPM)is proposed.The phase distribution of a spherical projectile impacting a thin plate is obtained by theoretical methods.The accuracy of the PGPM is subsequently validated through a comparison of its results with those obtained from numerical simulations.展开更多
Interferometry is a crucial investigative technique used across diverse fields to achieve highprecision measurements.It works by analyzing the phase difference between two interfering waves,which results from variatio...Interferometry is a crucial investigative technique used across diverse fields to achieve highprecision measurements.It works by analyzing the phase difference between two interfering waves,which results from variations in optical path lengths within an interferometer.We introduce a novel method for directly measuring changes in the phase difference within an optical interferometer,importantly,with the added advantage of a controllable enhancement factor.This approach is achieved through a two-step process:first,the optical phase difference is encoded into a sub-GHz radiofrequency(RF)signal using microwave-photonic manipulation;then,RF interferometry-assisted phase amplification is implemented at the destructive interference point.In our experiments,we demonstrate a phase sensitivity of 2.14 rad∕nm operating at 140 MHz using a miniature in-fiber Fabry-Pérot interferometer for sub-nanometer displacement sensing,which reveals a sensitivity magnification factor of 258.6.With further refinement,we anticipate that even higher enhancement factors can be achieved,paving the way for the development of cost-effective,ultrasensitive interferometry-based instruments for high-precision optical measurements.展开更多
In recent years,acoustic logic gates has attracted growing interest in acoustics due to their promising applications in acoustic communication and signal processing.For practical implementation,these logic gates must ...In recent years,acoustic logic gates has attracted growing interest in acoustics due to their promising applications in acoustic communication and signal processing.For practical implementation,these logic gates must operate over a certain bandwidth to ensure reliable performance.However,current experimental realizations have predominantly been confined to single-frequency or narrowband operation,leaving their broadband capabilities largely unverified.To address this gap,we present both numerical and experimental demonstrations of three basic acoustic logic gates(OR,NOT,and AND)using a phased unit cell composed of a central channel flanked by two arrays of semicircular cavities.By leveraging phase modulation of the unit cells and linear interference of sound,we achieve these logic operations with a uniform threshold of I_(t)=0.25.Remarkably,the measured fractional bandwidths(bandwidth relative to center frequency)reach approximately 111.5%(OR),37.2%(NOT),and 48.5%(AND),demonstrating ultra-broadband functionality.The proposed logic gates combine exceptional bandwidth with structural simplicity,offering significant potential for applications in acoustic computing,information processing,and integrated acoustic systems.展开更多
High-performance lead-free piezoelectric single crystals are urgently needed for next-generation actuators and transducers.In this study,we reveal that a compositionally driven tetragonal-pseudocubic(T-PC)phase bounda...High-performance lead-free piezoelectric single crystals are urgently needed for next-generation actuators and transducers.In this study,we reveal that a compositionally driven tetragonal-pseudocubic(T-PC)phase boundary,in conjunction with an octahedral order-disorder tilting transition,significantly enhances the piezoelectric response in Nb^(5+)-substitution(Bi_(0.48)Na_(0.425)K_(0.055)Ba_(0.04))(Ti_(0.98)Nb_(0.02))O_(3)(BNKBT-2Nb)single crystals.The crystal achieves an outstanding piezoelectric coefficient of d33=662 pC/N at room temperature.In situ X-ray diffraction confirms an electric field-induced transition from the PC to T phase.Atomic-resolution HADDF-STEM analysis reveals an increase in the c/a ratio(c/a>1.01)on the local scale and ordered octahe-dral tilting of the a^(0)a^(0)c+type driven by the poling field.The single crystals exhibit excellent piezoelectric per-formance over a broad temperature range,achieving a peak d_(33) of 920 pC/N at approximately 92℃.Furthermore,the polar states exhibit a pronounced frequency dependence near the depolarization temperature.These findings provide critical insight into the structure-property relationship and offer a promising pathway for designing advanced lead-free piezoelectric crystals for functional electromechanical applications.展开更多
Surface passivation via two-dimensional(2D)perovskite has emerged as a promising strategy to enhance the performance of perovskite solar cells(PSCs)due to the effective compensation of interfacial states.However,the i...Surface passivation via two-dimensional(2D)perovskite has emerged as a promising strategy to enhance the performance of perovskite solar cells(PSCs)due to the effective compensation of interfacial states.However,the in situ grown 2D perovskite passivation layers typically comprise a mixture of multiple dimensionalities at the interface,where band alignment has only been portrayed qualitatively and empirically.Herein,the interface states for precisely phase-tailored 2D perovskite passivated PSCs are quantitatively investigated.In comparison to traditional passivation molecules,2D perovskite layers based on 4-trifluoromethyl-phenylethylammonium iodide(CF3PEAI)exhibit an increased work function,introducing desirable downward band bending to eliminate the Schottky Barrier.Furthermore,precisely phase-tailored 2D layers could modulate the interface trap density and energetics.The n=1 film delivers optimal performance with a hole extraction efficiency of 95.1%.The optimized n-i-p PSCs in the two-step method significantly improve PCE to 25.40%,along with enhanced photostability and negligible hysteresis.It highlights that tailoring in the composition and phase distribution of the 2D perovskite layer could modulate the interface states at the 2D/3D interface.展开更多
Understanding the complex deformation mechanisms of non-equimolar multi-principal element alloys(MPEAs)requires high-fidelity atomic-scale simulations.This study develops a deep potential(DP)model to enable molecular ...Understanding the complex deformation mechanisms of non-equimolar multi-principal element alloys(MPEAs)requires high-fidelity atomic-scale simulations.This study develops a deep potential(DP)model to enable molecular dynamics simulations of the Ta_(0.4)Ti_(2)Zr(Ta_(0.4))alloy.Monte Carlo simulations using this potential reveal Ta atom precipitation in the Ta_(0.4)alloy.Under uniaxial tensile loading along the[100]direction in the NPT ensemble,the alloy undergoes a remarkable sequence of phase transformations:an initial body-centered cubic(BCC_(1))to face-centered cubic(FCC)transformation,followed by a reverse transformation from FCC to a distinct BCC phase(BCC_(2)),and finally a BCC_(2) to hexagonal close-packed(HCP)transformation.Critically,the reverse FCC to BCC_(2) transformation induces significant volume contraction.We demonstrate that the inversely transformed BCC_(2) phase primarily accommodates compressive stress.Concurrently,the reorientation of BCC_(2) crystals contributes substantially to the observed high strain hardening.These simulations provide atomic-scale insights into the dynamic structural evolution,sequential phase transformations,and stress partitioning during deformation of the Ta_(0.4)alloy.The developed DP model and the revealed mechanisms offer fundamental theoretical guidance for accelerating the design of high-performance MPEAs.展开更多
MoTe_(2) has emerged as a promising candidate in the field of integrated circuits,memristive devices,and catalysts,owing to its polymorphic nature across different phases.Experimentally,strain engineering has been dem...MoTe_(2) has emerged as a promising candidate in the field of integrated circuits,memristive devices,and catalysts,owing to its polymorphic nature across different phases.Experimentally,strain engineering has been demonstrated as an effective approach for manipulating the phase transition of MoTe_(2),but the mechanism remains unclear.The strain-dependent phase transition and its micro-mechanisms have been investigated based on first principle calculations.As demonstrated,critical strain and phase transition path from H→T'phases are strongly governed by the applied strain's orientation,magnitude,and triaxiality.At the atomic level,nonzero movements of Te atoms within the phase transition domain with mechanical unloading have been clarified,together with an advanced understanding on the impact of strain on Te-vacancies migration.These insights advanced the knowledge of MoTe_(2) phase transition behavior and demonstrated the large space to explore potential applications through strain,defect,and phase engineering.展开更多
The dissolvable polysulfides and sluggish Li_2S conversion kinetics are acknowledged as two significant challenges in the application lithium-sulfur(Li-S)batteries.Herein,we introduce a dual-doping strategy to modulat...The dissolvable polysulfides and sluggish Li_2S conversion kinetics are acknowledged as two significant challenges in the application lithium-sulfur(Li-S)batteries.Herein,we introduce a dual-doping strategy to modulate the electronic structure of MoS_(2),thereby obtaining a multifunctional catalyst that serves as an efficient sulfur host.The W/V dual single-atomdoped MoS_(2)grown on carbon nanofibers(CMWVS)demonstrates a strong adsorption ability for lithium polysulfides,suppressing the shuttle effects.Additionally,the doping process also results in the phase transition from 2H-MoS_(2)to 1T-MoS_(2)and generates sufficient edge sulfur atoms,promoting the charge/electron transfer and enriching the reaction sites.All these merits contribute to the superior conversion reaction kinetics,leading to the outstanding Li-S battery performance.When fabricated as cathodes by compositing with sulfur,the CMWVS/S cathode delivers a high capacity of 1481.7 mAh g^(-1)at 0.1 C(1 C=1672 mAh g^(-1))and maintains 816.3 m Ah g^(-1)after 1000 cycles at 1.0 C,indicating outstanding cycling stability.Even under a high sulfur loading of 7.9 mg cm^(-2)and lean electrolyte conditions(E/S ratio of 9.0μL mg^(-1)),the cathode achieves a high areal capacity of 8.2 m Ah cm^(-2),showing great promise for practical Li-S battery applications.This work broadens the scope of doping strategies in transition-metal dichalcogenides by tailoring their electronic structures,providing insightful direction for the rational development of high-efficiency electrocatalysts for advanced Li-S battery applications.展开更多
文摘In-situ tensile tests were conducted on a chemically corroded third-generation single-crystal superalloy DD9 at 980 and 1100℃.The phase transformation in the surface areas during the tensile process was analyzed using field emission scanning electron microscope,energy dispersive X-ray spectroscope,electron probe X-ray microanalysis,and transmission electron microscope.The phase transformation mechanism on the surface and the influence mechanism were studied through observation and dynamic calculation.During tensile tests at elevated temperatures,chemical corrosion promotes the precipitation of topologically close-packed(tcp)μphase andσphase on the alloy surface.Both the precipitation amount and size of these two phases on the surface at 1100℃are greater than those at 980℃.The precipitation of tcp phase on the alloy surface results in the formation of an influence layer on the surface area,and the distribution characteristics of alloying elements are significantly different from those of the substrate.The depth of the influence layer at 1100℃is greater than that at 980℃.The precipitation of tcp phase prompts the phase transition fromγphase toγ′phase around the tcp phase.
基金National Natural Science Foundation of China(12405168)The Fundamental Research Funds for the Central Universities,China(2024CDJXY004)。
文摘[Background]High harmonic cavities are widely used in electron storage rings to lengthen thebunch,lower the bunch peak current,thereby reducing the IBS effect,enhancing the Touschek lifetime,as well asproviding Landau damping,which is particularly important for storage rings operating with ultra-low emittance or atlow beam energy.[Purpose]To further increase the bunch length without additional hardware costs,the phasemodulation in a dual-RF system is considered.[Methods]In this paper,turn-by-turn simulations incorporating randomsynchrotron radiation excitation are conducted,and a brief analysis is presented to explain the bunch lengtheningmechanism.[Results]Simulation results reveal that the peak current can be further reduced,thereby mitigating IBSeffects and enhancing the Touschek lifetime.Although the energy spread increases,which tends to reduce thebrightness of higher-harmonic radiation from the undulator,the brightness of the fundamental harmonic can,in fact,beimproved.
基金Shaanxi Province Qin Chuangyuan“Scientist+Engineer”Team Construction Project(2022KXJ-071)2022 Qin Chuangyuan Achievement Transformation Incubation Capacity Improvement Project(2022JH-ZHFHTS-0012)+8 种基金Shaanxi Province Key Research and Development Plan-“Two Chains”Integration Key Project-Qin Chuangyuan General Window Industrial Cluster Project(2023QCY-LL-02)Xixian New Area Science and Technology Plan(2022-YXYJ-003,2022-XXCY-010)2024 Scientific Research Project of Shaanxi National Defense Industry Vocational and Technical College(Gfy24-07)Shaanxi Vocational and Technical Education Association 2024 Vocational Education Teaching Reform Research Topic(2024SZX354)National Natural Science Foundation of China(U24A20115)2024 Shaanxi Provincial Education Department Service Local Special Scientific Research Program Project-Industrialization Cultivation Project(24JC005,24JC063)Shaanxi Province“14th Five-Year Plan”Education Science Plan,2024 Project(SGH24Y3181)National Key Research and Development Program of China(2023YFB4606400)Longmen Laboratory Frontier Exploration Topics Project(LMQYTSKT003)。
文摘A dual-phase synergistic enhancement method was adopted to strengthen the Al-Mn-Mg-Sc-Zr alloy fabricated by laser powder bed fusion(LPBF)by leveraging the unique advantages of Er and TiB_(2).Spherical powders of 0.5wt%Er-1wt%TiB_(2)/Al-Mn-Mg-Sc-Zr nanocomposite were prepared using vacuum homogenization technique,and the density of samples prepared through the LPBF process reached 99.8%.The strengthening and toughening mechanisms of Er-TiB_(2)were investigated.The results show that Al_(3)Er diffraction peaks are detected by X-ray diffraction analysis,and texture strength decreases according to electron backscatter diffraction results.The added Er and TiB_(2)nano-reinforcing phases act as heterogeneous nucleation sites during the LPBF forming process,hindering grain growth and effectively refining the grains.After incorporating the Er-TiB_(2)dual-phase nano-reinforcing phases,the tensile strength and elongation at break of the LPBF-deposited samples reach 550 MPa and 18.7%,which are 13.4%and 26.4%higher than those of the matrix material,respectively.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U25A20232,52325208,52173217,52202128)the Interdisciplinary Research Project for Young Teachers of USTB(Grant No.FRF-IDRY24-002)。
文摘As electronic technology continues to evolve towards miniaturization and integration,the demand for micro-refrigeration technology in microelectronic systems is increasing.Ferroelectric(FE)refrigeration technology based on the electrocaloric effect(ECE)has emerged as a highly promising candidate in this field,due to its advantages of high energy efficiency,simple structure,easy miniaturization,low cost,and environmental friendliness.The EC performance of FE materials essentially depends on the phase transition features under the coupled electric and thermal fields,making the E–T phase diagram a core tool for decoding the underlying mechanism of ECE.This paper reviews the development of EC materials,focusing on the comprehensive study of E–T phase diagrams.By correlating the microscopic phase structure of FE materials with the macroscopic physical properties,it clarifies the manipulation mechanism for enhanced ECE performance,providing theoretical support for the targeted design of high-performance EC materials.In the future,the introduction of data-driven methods is expected to enable the high-throughput construction of FE phase diagrams,thereby accelerating the optimization of high-performance EC materials and promoting the practical application of FE refrigeration technology.
基金financially supported by the Fundamental Research Funds for the Central Universities(No.FRF-KST-25-001)the Beijing Natural Science Foundation(No.L253029)。
文摘In the context of the global energy low-carbon transition,phase change energy storage technology becomes a key technology to solve the problem of intermittent renewable energy.Oriented phase change composites(OCPCMs)receive widespread attention in practical energy storage applications due to their unique oriented thermally conductive structure,which achieves significant thermal conductivity enhancement in specific directions while retaining the high energy storage capacity of the phase change components.This review systematically summarizes the overall analysis of OCPCMs from synthesis and preparation to application scenarios in recent years.Herein,we introduce the analysis of the heat transfer mechanism of the materials and explore the advantages of the oriented structure in OCPCMs in the heat transfer behavior from a bionic perspective.We then focus on summarizing and generalizing the methods for preparing OCPCMs,giving suggestions for suitable methods according to different scenarios.Besides,we discuss the application of finite element simulation methods to the monitoring of the thermal management behavior of OCPCMs,and look into the potential future application areas of such materials.Finally,it is hoped that this review will provide guidance for the academic community in developing high-performance OCPCMs.
基金supported by National Natural Science Foundation of China(No.U21A2047,No 52071115,No 52401140,No U22A20187 and No 51971076)the China Postdoctoral Science Foundation(No.2024M760878)the Science Fund of State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle(No.32465004).
文摘In this study,by adjusting the homogenization process,numerous lamellar-shapedγ’phases are generated and uniformly distributed throughout the grain interior within as-extruded Mg-9Gd-4Y-1Zn-0.5Zr(wt.%)alloy,leading to a remarkable increase enhancement in both tensile strength and fracture toughness.Notably,as compared to the alloy containing block-shaped long-period stacking-ordered(LPSO)phase,when the lamellar-shapedγ’phase is introduced within theα-Mg matrix,the fracture toughness of 29.7 MPa·m^(1/2)can be achieved with a 27%improvement.This superior fracture resistance is mainly attributed to the delamination toughening derived from the intensive micro-cracks occurring alongγ’phase interfaces oriented perpendicular to the primary fracture surface.Owing to the presence of lamellarshapedγ’phase,the fracture morphology can be significantly changed and characterized with deep dimples and pronounced deflection of main crack,which collectively contribute to the enhanced plastic energy dissipation and fracture toughness.The characteristics of deformed microstructure near the fracture surface demonstrate the activation of kinking and the inhibition of twin propagation due to the interactions with lamellarγ’phase.Such deformation behavior can effectively impede the crack propagation and contribute to the superior fracture resistance.Besides,the X-ray computed tomography analysis of the fractured alloy exhibits the distribution and size of voids,indicating that the prolate voids preferentially nucleate and propagate parallel to the lamellarγ’phase.Accordingly,the deformation mechanisms under a triaxial stress state involve the intricate interplay between lamellarγ’phase-induced delamination,crack deflection as well as void formation.Through the application of tailored pre-treatment heat treatment processes,the control of phase constituents within the microstructure can be achieved to improve the mechanical properties of Mg alloys.It is anticipated to provide a comprehensive understanding of the fracture behavior of Mg-Gd-Y-Zn-Zr,with particular emphasis on the synergistic effects of lamellarγ’phase and LPSO phase in the optimization of overall mechanical performance.
基金supported by the National Natural Science Foundation of China (Grant Nos.12274313 and 62375234)the Gusu Leading Talent Plan for Scientific and Technological Innovation and Entrepreneurship (Grant No.ZXL2024400)。
文摘Optical phase-gradient metasurfaces have garnered significant attention for enabling flexible light manipulation,with applications across diverse domains.In this work,we will demonstrate that the metasurfaces with phase gradient modulation can be used to achieve illusion optics,featuring the advantages of simple geometric structure and feasible implementation compared with the well-known transformation optics method.The underlying mechanism is the anomalous diffraction law caused by the phase gradient,which provides a theoretical basis for freely manipulating the propagation path of light.By considering a specific example,we will demonstrate that the phase gradient can transform spatial coordinates in real space into illusion space,thereby converting a plane in real space into a curved surface structure in illusion space to achieve the illusion effect.This approach provides a viable alternative to transformation optics for designing illusion devices.
基金the financial support from the National Key R&D Program of China(No.2024YFC2910800)National Natural Science Foundation of China(52404336)+6 种基金China Postdoctoral Science Foundation(2024M750176)Postdoctoral Fellowship Program of CPSF(GZC20240109)the Young Elite Scientist Sponsorship Program by CAST(YESS20210090)Beijing Natural Science Foundation(J210017)the Project of SKLAM(No.KF24-14)China Baowu Low Carbon Metallurgical Technology Innovation Fund under Grant No.20210901Anhui Major Industrial Innovation Program under Contract No.AHZDCYCX-LSDT2023-01.
文摘The direct reduction process can reduce carbon emissions by over 50%compared to traditional blast furnace ironmaking.Carbon deposition and carburization are critical for ensuring process stability and economic viability.Thermodynamic phase diagrams were developed to intuitively represent carbon deposition and carburization preferences in CH4-CO-H_(2) ternary atmospheres.High carbon potential and low oxygen potential significantly enhance carbon deposition and carburization.Increasing temperature from 500 to 1000℃ shifts the dominant reactions from CO-based to CH_(4)-based,increasing maximum carbon deposition from 0.55 to 0.80 mol and carburization from 0.25 to 0.80 mol per mole of reducing gas.Increasing pressure suppresses CH4-based reactions while promoting CO-based reactions,reducing maximum carbon deposition from 0.8 to~0.7 mol and increasing maximum carburization from 0.80 to 0.85 mol per mole of reducing gas.Equilibrium phase diagrams for various carbides were also developed,revealing preferences for Fe_(3)C_(2),Fe_(7)C_(3),Fe_(5)C_(2),and Fe_(3)C as the Fe/C ratio increases.Higher temperatures and CH_(4) concentrations favor the formation of carbides with higher carbon content.Carburization preferences under typical Energiron ZR and Midrex atmospheres were highlighted,and the higher carbon content in direct reduction iron produced by the Energiron ZR process was thermodynamically confirmed.
基金supported by the National Natural Science Foundation of China(No.52304358)Young Elite Scientists Sponsorship Program by CAST(No.YESS20230462).
文摘Heterogeneous nucleation,characterized by its low nucleation barrier and controllable nucleation sites,has been widely employed to manipulate the microstructures and properties of metallic materials.In recent years,the dispersion of inclusions,carbides,and microstructure refinement in steel have emerged as one of the key research directions in the development of high-quality steel.The current research status regarding the regulation of inclusions,carbides,and microstructures in steel through heterogeneous nucleation are reviewed.The key points and challenges in refining the second phase and microstructure in steel using inclusion particles are highlighted,aiming to provide inspiration and references for future scholars.Deoxidized inclusions,when refined and dispersed,exhibit favorable lattice matching with second phases(e.g.,nitrides,sulfides,carbides)in steel.This characteristic serves as the fundamental mechanism for achieving refinement of the second phase.Concurrently,the solid-solution alloying effect from deoxidizing metals contributes to second-phase refinement,an aspect that requires prioritized investigation.In addition to the single heterogeneous nucleation refinement effect,the two-stage heterogeneous nucleation refinement of the second phase and microstructure offers a new approach for follow-up research.Notably,second-phase particles added as heterogeneous nucleation sites via external addition often require surface modification to ensure their stable retention in steel at high temperatures,which remains a major challenge restricting the widespread application of this method.Currently,the explanation of heterogeneous nucleation phenomena primarily relies on empirical calculations of lattice mismatch between the substrate and the nucleating phase,which cannot fully elucidate the quantitative relationship on the interface between the substrate and the nucleation phase.On this basis,quantifying the electronic structure and nucleation barrier at the interface between the substrate and the nucleation phase is a critical direction worthy of increased attention in the future.
基金Open Research Fund of Guangxi Key Laboratory of Culture and Tourism Smart Technology,Guilin Tourism UniversityGuangxi University young and middle-aged teachers research basic ability improvement project(2025KY0961)。
文摘Small Baseline Subset Interferometric Synthetic Aperture Radar(SBAS-In SAR)is widely used for deformation monitoring in mining regions.However,phase unwrapping errors often limit its effectiveness in areas with large-gradient displacements.We propose a novel approach integrating spatiotemporal modeling to address this limitation and improve phase unwrapping.The Simplified Rectangular Dislocation Model(SRDM)simplifies the phase recovery process by reducing model parameters and improving efficiency in large-gradient deformation zones.Subsequently,the Power Exponential Knothe Model(PEKM)is applied to invert the deformation time series and restore the deformation phase from the time dimension.We validated this method using Sentinel-1 and Radarsat-2 data in the Majialiang Coalfield,China.The results demonstrate that the approach achieved 5%(Sentinel-1)and 14%(Radarsat-2)phase range extensions,elevating maximum detectable phase values from 120/100 rad to 160 rad for respective datasets,while the proportions of pixel points with restored phase exceeding 8 rad(-0.035 m)were 17.4%and 32.1%.The proposed method outperformed conventional techniques in resolving phase discontinuities,demonstrating strong adaptability.This approach significantly enhances subsidence monitoring accuracy and supports sustainable mining operations in coal-dependent regions.
基金supported by the National Natural Science Foundation of China(Grant No.42171135)the Science and Technology Program of CNOOC Research Institute(Grant No.2023OTKK03)the“CUG Scholar”Scientific Research Funds at China University of Geosciences(Project No.2022098).
文摘The volume change behavior of natural gas hydrate-bearing sediment is essential as it influences settlement,strength,and stiffness,which directly affect the stability of hydrate reservoirs during hydrate extraction or in response to environmental changes.The volume change is influenced not only by stress but also by the formation and dissociation of hydrates.This study adopted a customized apparatus for one-dimensional compression tests,allowing independent control of gas pressure and effective stress.Tests were conducted on samples with different hydrate saturations along various temperature-gas pressure-effective stress paths,yielding some conclusions related to compressibility and creep.An unusual phenomenon was observed under low-stress conditions:hydrate formation led to shrinkage rather than expansion.Three potential mechanisms behind this occurrence were discussed.As hydrate saturation increases,the yield stress rises while the compression and swelling indexes remain minimally affected.After hydrate dissociation,the compression curve of hydrate-bearing sediment drops to that of hydrate-free sediment.Once hydrate is formed,the compression curve of hydrate-free sediment gradually approaches that of hydrate-bearing sediment during the subsequent loading.Under low-stress conditions,the creep of both hydrate-free and hydrate-bearing sediments is very weak.However,when stress increases,significantly beyond the yield stress,the creep of both sediments increases significantly,with hydrate-bearing sediment exhibiting much greater creep than hydrate-free sediment.
基金supported by National Natural Science Foundation of China(Nos.12432018,12372346)the Innovative Research Groups of the National Natural Science Foundation of China(No.12221002)National Natural Science Foundation of China(No.12302493)。
文摘Material phase-transition represents a significant phenomenon and mechanism in the context of hypervelocity protection.This study presents a thorough analysis of the phase-transition phenomena induced by shock pressure as the shock wave propagates initially to the rear of the projectile.The shock wave that induces a phase-transition is commonly referred to as a macroscopic phase-transition wave,whereas the interface that separates the distinct phases is referred to as macroscopic phase-boundary.The contact interface between the spherical projectile and the thin plate,characterized by its curved surface,plays a significant role in the nonlinear propagation and evolution of wave systems.The pressure distribution along the central axis of a spherical projectile is derived in accordance with the linear decay law observed for axial pressure.On this basis,a quadratic function is employed to characterize the trend of changes in wave front pressure,thereby facilitating the establishment of a model for wave front pressure distribution.Using the phase-transition pressure criterion for materials,the wave front phase evolution process is derived,and the macroscopic phase-boundary is determined.Based on the geometric propagation model(GPM)and the pressure distribution of the wave front,a phase geometric propagation model(PGPM)is proposed.The phase distribution of a spherical projectile impacting a thin plate is obtained by theoretical methods.The accuracy of the PGPM is subsequently validated through a comparison of its results with those obtained from numerical simulations.
基金support from the Roy A.Wilkens Professorship Endowment。
文摘Interferometry is a crucial investigative technique used across diverse fields to achieve highprecision measurements.It works by analyzing the phase difference between two interfering waves,which results from variations in optical path lengths within an interferometer.We introduce a novel method for directly measuring changes in the phase difference within an optical interferometer,importantly,with the added advantage of a controllable enhancement factor.This approach is achieved through a two-step process:first,the optical phase difference is encoded into a sub-GHz radiofrequency(RF)signal using microwave-photonic manipulation;then,RF interferometry-assisted phase amplification is implemented at the destructive interference point.In our experiments,we demonstrate a phase sensitivity of 2.14 rad∕nm operating at 140 MHz using a miniature in-fiber Fabry-Pérot interferometer for sub-nanometer displacement sensing,which reveals a sensitivity magnification factor of 258.6.With further refinement,we anticipate that even higher enhancement factors can be achieved,paving the way for the development of cost-effective,ultrasensitive interferometry-based instruments for high-precision optical measurements.
基金Project supported by the National Natural Science Foundation of China(Grant No.12174159)。
文摘In recent years,acoustic logic gates has attracted growing interest in acoustics due to their promising applications in acoustic communication and signal processing.For practical implementation,these logic gates must operate over a certain bandwidth to ensure reliable performance.However,current experimental realizations have predominantly been confined to single-frequency or narrowband operation,leaving their broadband capabilities largely unverified.To address this gap,we present both numerical and experimental demonstrations of three basic acoustic logic gates(OR,NOT,and AND)using a phased unit cell composed of a central channel flanked by two arrays of semicircular cavities.By leveraging phase modulation of the unit cells and linear interference of sound,we achieve these logic operations with a uniform threshold of I_(t)=0.25.Remarkably,the measured fractional bandwidths(bandwidth relative to center frequency)reach approximately 111.5%(OR),37.2%(NOT),and 48.5%(AND),demonstrating ultra-broadband functionality.The proposed logic gates combine exceptional bandwidth with structural simplicity,offering significant potential for applications in acoustic computing,information processing,and integrated acoustic systems.
基金supported by the National Natural Science Foundation of China(Grant No.11704301)the Natural Science Basic Research Plan in Shaanxi Province of China(Program No.2022JM212)supported by the Ministry of Science and Higher Education of the Russian Federation(FSEG-2023-0016).
文摘High-performance lead-free piezoelectric single crystals are urgently needed for next-generation actuators and transducers.In this study,we reveal that a compositionally driven tetragonal-pseudocubic(T-PC)phase boundary,in conjunction with an octahedral order-disorder tilting transition,significantly enhances the piezoelectric response in Nb^(5+)-substitution(Bi_(0.48)Na_(0.425)K_(0.055)Ba_(0.04))(Ti_(0.98)Nb_(0.02))O_(3)(BNKBT-2Nb)single crystals.The crystal achieves an outstanding piezoelectric coefficient of d33=662 pC/N at room temperature.In situ X-ray diffraction confirms an electric field-induced transition from the PC to T phase.Atomic-resolution HADDF-STEM analysis reveals an increase in the c/a ratio(c/a>1.01)on the local scale and ordered octahe-dral tilting of the a^(0)a^(0)c+type driven by the poling field.The single crystals exhibit excellent piezoelectric per-formance over a broad temperature range,achieving a peak d_(33) of 920 pC/N at approximately 92℃.Furthermore,the polar states exhibit a pronounced frequency dependence near the depolarization temperature.These findings provide critical insight into the structure-property relationship and offer a promising pathway for designing advanced lead-free piezoelectric crystals for functional electromechanical applications.
基金supported by the National Natural Science Foundation of China(Nos.62304111,62304110,22579136)the National Key Research and Development Program of China(2024YFE0201800)+6 种基金the China Postdoctoral Science Foundation(No.2024M761492)the Project of State Key Laboratory of Organic Electronics and Information Displays(Nos.GDX2022010009,GZR2023010046)the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(No.NY223053)the Science and Technology Project of Jiangsu(Science and Technology Cooperation Project of HongKong,Macao and Taiwan,No.BZ2023059)Shaanxi Fundamental Science Research Project for Mathematics and Physics(No.22jSY015)Young Talent Fund of Xi'an Association for Science and Technology(No.959202313020)Guangdong Provincial Key Laboratory of Semiconductor Optoelectronic Materials and Intelligent Photonic Systems(No.2023B1212010003).
文摘Surface passivation via two-dimensional(2D)perovskite has emerged as a promising strategy to enhance the performance of perovskite solar cells(PSCs)due to the effective compensation of interfacial states.However,the in situ grown 2D perovskite passivation layers typically comprise a mixture of multiple dimensionalities at the interface,where band alignment has only been portrayed qualitatively and empirically.Herein,the interface states for precisely phase-tailored 2D perovskite passivated PSCs are quantitatively investigated.In comparison to traditional passivation molecules,2D perovskite layers based on 4-trifluoromethyl-phenylethylammonium iodide(CF3PEAI)exhibit an increased work function,introducing desirable downward band bending to eliminate the Schottky Barrier.Furthermore,precisely phase-tailored 2D layers could modulate the interface trap density and energetics.The n=1 film delivers optimal performance with a hole extraction efficiency of 95.1%.The optimized n-i-p PSCs in the two-step method significantly improve PCE to 25.40%,along with enhanced photostability and negligible hysteresis.It highlights that tailoring in the composition and phase distribution of the 2D perovskite layer could modulate the interface states at the 2D/3D interface.
基金supported by the National University of Defense Technology Research Fund Projectthe National Natural Science Foundation of China(Grant No.12534013)the Science and Technology Innovation Program of Hunan Province(Grant Nos.2025ZYJ001 and 2021RC4026)。
文摘Understanding the complex deformation mechanisms of non-equimolar multi-principal element alloys(MPEAs)requires high-fidelity atomic-scale simulations.This study develops a deep potential(DP)model to enable molecular dynamics simulations of the Ta_(0.4)Ti_(2)Zr(Ta_(0.4))alloy.Monte Carlo simulations using this potential reveal Ta atom precipitation in the Ta_(0.4)alloy.Under uniaxial tensile loading along the[100]direction in the NPT ensemble,the alloy undergoes a remarkable sequence of phase transformations:an initial body-centered cubic(BCC_(1))to face-centered cubic(FCC)transformation,followed by a reverse transformation from FCC to a distinct BCC phase(BCC_(2)),and finally a BCC_(2) to hexagonal close-packed(HCP)transformation.Critically,the reverse FCC to BCC_(2) transformation induces significant volume contraction.We demonstrate that the inversely transformed BCC_(2) phase primarily accommodates compressive stress.Concurrently,the reorientation of BCC_(2) crystals contributes substantially to the observed high strain hardening.These simulations provide atomic-scale insights into the dynamic structural evolution,sequential phase transformations,and stress partitioning during deformation of the Ta_(0.4)alloy.The developed DP model and the revealed mechanisms offer fundamental theoretical guidance for accelerating the design of high-performance MPEAs.
基金supported by NSFC Grants(Nos.12032004,11872114,and 11502150)Natural Science Foundation of Hebei Province of China(No.A2016210060)+1 种基金The Higher Education Youth Talents Program of Hebei Province of China(No.BJ2017052)Science and Technology Project of Hebei Education Department(No.QN2020204)。
文摘MoTe_(2) has emerged as a promising candidate in the field of integrated circuits,memristive devices,and catalysts,owing to its polymorphic nature across different phases.Experimentally,strain engineering has been demonstrated as an effective approach for manipulating the phase transition of MoTe_(2),but the mechanism remains unclear.The strain-dependent phase transition and its micro-mechanisms have been investigated based on first principle calculations.As demonstrated,critical strain and phase transition path from H→T'phases are strongly governed by the applied strain's orientation,magnitude,and triaxiality.At the atomic level,nonzero movements of Te atoms within the phase transition domain with mechanical unloading have been clarified,together with an advanced understanding on the impact of strain on Te-vacancies migration.These insights advanced the knowledge of MoTe_(2) phase transition behavior and demonstrated the large space to explore potential applications through strain,defect,and phase engineering.
基金supported by the National Natural Science Foundation of China(52402166)the Science and Technology Development Fund+2 种基金Macao SAR(0065/2023/AFJ,0116/2022/A3)the Australian Research Council(DE220100154)the Natural Science Foundation of Guangdong Province(2025A1515011120)。
文摘The dissolvable polysulfides and sluggish Li_2S conversion kinetics are acknowledged as two significant challenges in the application lithium-sulfur(Li-S)batteries.Herein,we introduce a dual-doping strategy to modulate the electronic structure of MoS_(2),thereby obtaining a multifunctional catalyst that serves as an efficient sulfur host.The W/V dual single-atomdoped MoS_(2)grown on carbon nanofibers(CMWVS)demonstrates a strong adsorption ability for lithium polysulfides,suppressing the shuttle effects.Additionally,the doping process also results in the phase transition from 2H-MoS_(2)to 1T-MoS_(2)and generates sufficient edge sulfur atoms,promoting the charge/electron transfer and enriching the reaction sites.All these merits contribute to the superior conversion reaction kinetics,leading to the outstanding Li-S battery performance.When fabricated as cathodes by compositing with sulfur,the CMWVS/S cathode delivers a high capacity of 1481.7 mAh g^(-1)at 0.1 C(1 C=1672 mAh g^(-1))and maintains 816.3 m Ah g^(-1)after 1000 cycles at 1.0 C,indicating outstanding cycling stability.Even under a high sulfur loading of 7.9 mg cm^(-2)and lean electrolyte conditions(E/S ratio of 9.0μL mg^(-1)),the cathode achieves a high areal capacity of 8.2 m Ah cm^(-2),showing great promise for practical Li-S battery applications.This work broadens the scope of doping strategies in transition-metal dichalcogenides by tailoring their electronic structures,providing insightful direction for the rational development of high-efficiency electrocatalysts for advanced Li-S battery applications.
