Effect of quenching process on the microstrucmre and mechanical properties of a kind of seamless tubes of steel 28CrMnMoV was investigated. Then, an investigation on the influence of two different quenching processes ...Effect of quenching process on the microstrucmre and mechanical properties of a kind of seamless tubes of steel 28CrMnMoV was investigated. Then, an investigation on the influence of two different quenching processes on the ductile-brittle transition behavior of this steel was undertaken. The ductile-brittle transition temperatures of the steel by two different quenching processes were also determined. The results show that a good combination of mechanical properties can be obtained through austenitizing experimental steel at 800 ℃ or 890 ℃ followed by tempering at 630 ℃. Ductile-to-brittle transition temperature of 28CrMnMoV steel austenitized at 800 ℃ followed by tempering at 640 ℃ is about -73 ℃, which is much lower than the value -37 ℃ when the steel was austenitized at 890℃ and then tempered at 650 ℃. This indicates that subcritical quenching process could decrease largely the ductile-to-brittle transition temperature of 28CrMnMoV steel.展开更多
Based on the crack tip structure a new model of ductile -brittle transition was proposed. Using this new model we calculated the dependence of the transition temperature-strain rate over a wide range of strain rate. F...Based on the crack tip structure a new model of ductile -brittle transition was proposed. Using this new model we calculated the dependence of the transition temperature-strain rate over a wide range of strain rate. Finally the significance of this new model is discussed in detail.展开更多
Brittleness is a dominant issue that restricts potential applications of Mg_2Si intermetallic compounds(IMC). In this paper, guided by first-principles calculations, we found that Al doping will enhance the ductility ...Brittleness is a dominant issue that restricts potential applications of Mg_2Si intermetallic compounds(IMC). In this paper, guided by first-principles calculations, we found that Al doping will enhance the ductility of Mg_2Si. The underlying mechanism is that Al doping could reduce the electronic exchange effect between Mg and Si atoms, and increase the volume module/shear modulus ratio, both of which are beneficial to the deformation capability of Mg_2Si. Experimental investigations were then carried out to verify the calculation results with Al doping contents ranging from Al-free to 10 wt%. Results showed that the obtained ductile-brittle transition temperature of the Mg_2Si–Al alloy decreased and the corresponding ductility increased. Specifically, the ductile-brittle transition temperature could be reduced by about 100℃. When the content of Al reached 6 wt%, α-Al phase started to precipitate, and the ductile-brittle transition temperature of the alloy no longer decreased.展开更多
The dynamic fracture toughness of a mild steel has been studied at different loading rates and temperatures.The material exhibits a transition from tough to brittle fracture with the chang- ing loading rate alone.Anal...The dynamic fracture toughness of a mild steel has been studied at different loading rates and temperatures.The material exhibits a transition from tough to brittle fracture with the chang- ing loading rate alone.Analysis of the fracture process by the theory of thermal activation suggests that the fracture activation energy approximates to the bond energy of the{100}of a unit cell.The toughness can be resolved into two parts,J-(fd)=J_a+J_l,where J_a is the athermal part,being independent on temperature and loading rate,while J_l=(K/K_o)^(1/n)exp(Q_f/nkT),which controls the fracture process is temperature and load- ing rate dependent.The transition of fracture mechanism caused by both temperature and loading rate is associated with the thermal movement of atoms.展开更多
Transition metal phosphides(TMPs)have been regarded as alternative hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts owing to their comparable activity to those of noble metal-based catalysts...Transition metal phosphides(TMPs)have been regarded as alternative hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts owing to their comparable activity to those of noble metal-based catalysts.TMPs have been produced in various morphologies,including hollow and porous nanostructures,which are features deemed desirable for electrocatalytic materials.Templated synthesis routes are often responsible for such morphologies.This paper reviews the latest advances and existing challenges in the synthesis of TMP-based OER and HER catalysts through templated methods.A comprehensive review of the structure-property-performance of TMP-based HER and OER catalysts prepared using different templates is presented.The discussion proceeds according to application,first by HER and further divided among the types of templates used-from hard templates,sacrificial templates,and soft templates to the emerging dynamic hydrogen bubble template.OER catalysts are then reviewed and grouped according to their morphology.Finally,prospective research directions for the synthesis of hollow and porous TMP-based catalysts,such as improvements on both activity and stability of TMPs,design of environmentally benign templates and processes,and analysis of the reaction mechanism through advanced material characterization techniques and theoretical calculations,are suggested.展开更多
Magneto-plasticity occurs when a weak magnetic field alters material plasticity and offers a viable solution to enhance ductile-mode cutting of brittle materials.This study demonstrates the susceptibility of non-magne...Magneto-plasticity occurs when a weak magnetic field alters material plasticity and offers a viable solution to enhance ductile-mode cutting of brittle materials.This study demonstrates the susceptibility of non-magnetic single-crystal calcium fluoride(CaF_(2))to the magneto-plastic effect.The influence of magneto-plasticity on CaF_(2) was confirmed in micro-deformation tests under a weak magnetic field of 20 mT.The surface pile-up effect was weakened by 10-15 nm along with an enlarged plastic zone and suppressed crack propagation under the influence of the magnetic field.Micro-cutting tests along different crystal orientations on the(111)plane of CaF_(2) revealed an increase in the ductile-brittle transition of the machined surface with the aid of magneto-plasticity where the largest increase in ductile-brittle transition occurred along the[112]orientation from 512 nm to a range of 664-806 nm.Meanwhile,the subsurface damage layer was concurrently thinner under magnetic influence.An anisotropic influence of the magnetic field relative to the single-crystal orientation and the cutting direction was also observed.An analytical model was derived to determine an orientation factor M that successfully describes the anisotropy while considering the single-crystal dislocation behaviour,material fracture toughness,and the orientation of the magnetic field.Previously suggested theoretical mechanism of magneto-plasticity via formation of non-singlet electronic states in defected configurations was confirmed with density functional theory calculations.The successful findings on the influence of a weak magnetic field on plasticity present an opportunity for the adoption of magnetic-assisted micro-cutting of non-magnetic materials.展开更多
Following publication of the original article[1],the authors reported that the author Hun-Gi Jung should be affiliated as 3,4 and 5 instead of 4 and 5.The author’s name“A.-Yeon Kim”needed to be updated to“A-Yeon ...Following publication of the original article[1],the authors reported that the author Hun-Gi Jung should be affiliated as 3,4 and 5 instead of 4 and 5.The author’s name“A.-Yeon Kim”needed to be updated to“A-Yeon Kim”,removing the period.The correct author’s name and affiliation have been provided in this Correction.The original article[1]has been corrected.展开更多
What factors fundamentally determine the value of superconducting transition temperature Tc in high temperature superconductors has been the subject of intense debate.Following the establishment of an empirical law kn...What factors fundamentally determine the value of superconducting transition temperature Tc in high temperature superconductors has been the subject of intense debate.Following the establishment of an empirical law known as Homes'law,there is a growing consensus in the community that the Tc value of the cuprate superconductors is closely linked to the superfluid density(ρ_(s))of its ground state and the conductivity(σ)of its normal state.However,all the data supporting this empirical law(ρ_(s)=AσT_(c))have been obtained from the ambientpressure superconductors.In this study,we present the first high-pressure results about the connection of the quantities of ρ_(s) and σ with T_(c),through the studies on the Bi_(1.74)Pb_(0.38)Sr_(1.88)CuO_(6+δ)and Bi_(2)Sr_(2)CaCu_(2)O_(8+δ),in which the value of their high-pressure resistivity(ρ=1/σ)is achieved by adopting our newly established method,while the quantity ofρs is extracted using Homes'law.We highlight that the Tc values are strongly linked to the joint response factors of magnetic field and electric field,i.e.,ρ_(s) and σ,respectively,implying that the physics determining T_(c) is governed by the intrinsic electromagnetic fields of the system.展开更多
Supercapacitors(SCs)are considered promising energy storge systems because of their outstanding power density,fast charge and discharge rate and long-term cycling stability.The exploitation of cheap and efficient elec...Supercapacitors(SCs)are considered promising energy storge systems because of their outstanding power density,fast charge and discharge rate and long-term cycling stability.The exploitation of cheap and efficient electrode materials is the key to improve the performance of supercapacitors.As the battery-type materials,transition metal phosphides(TMPs)possess high theoretical specific capacity,good electrical conductivity and superior structural stability,which have been extensively studied to be electrode materials for supercapacitors.In this review,we summarize the up-to-date progress on TMPs materials from diversified synthetic methods,diverse nanostructures and several prominent TMPs and their composites in application of supercapacitors.In the end,we also propose the remaining challenges toward the rational discovery and synthesis of high-performance TMP electrodes materials for energy storage.展开更多
In recent years,low-dimensional transition metal chalcogenide(TMC)materials have garnered growing research attention due to their superior electronic,optical,and catalytic properties compared to their bulk counterpart...In recent years,low-dimensional transition metal chalcogenide(TMC)materials have garnered growing research attention due to their superior electronic,optical,and catalytic properties compared to their bulk counterparts.The controllable synthesis and manipulation of these materials are crucial for tailoring their properties and unlocking their full potential in various applications.In this context,the atomic substitution method has emerged as a favorable approach.It involves the replacement of specific atoms within TMC structures with other elements and possesses the capability to regulate the compositions finely,crystal structures,and inherent properties of the resulting materials.In this review,we present a comprehensive overview on various strategies of atomic substitution employed in the synthesis of zero-dimensional,one-dimensional and two-dimensional TMC materials.The effects of substituting elements,substitution ratios,and substitution positions on the structures and morphologies of resulting material are discussed.The enhanced electrocatalytic performance and photovoltaic properties of the obtained materials are also provided,emphasizing the role of atomic substitution in achieving these advancements.Finally,challenges and future prospects in the field of atomic substitution for fabricating low-dimensional TMC materials are summarized.展开更多
The laminated transition metal disulfides(TMDs),which are well known as typical two-dimensional(2D)semiconductive materials,possess a unique layered structure,leading to their wide-spread applications in various field...The laminated transition metal disulfides(TMDs),which are well known as typical two-dimensional(2D)semiconductive materials,possess a unique layered structure,leading to their wide-spread applications in various fields,such as catalysis,energy storage,sensing,etc.In recent years,a lot of research work on TMDs based functional materials in the fields of electromagnetic wave absorption(EMA)has been carried out.Therefore,it is of great significance to elaborate the influence of TMDs on EMA in time to speed up the application.In this review,recent advances in the development of electromagnetic wave(EMW)absorbers based on TMDs,ranging from the VIB group to the VB group are summarized.Their compositions,microstructures,electronic properties,and synthesis methods are presented in detail.Particularly,the modulation of structure engineering from the aspects of heterostructures,defects,morphologies and phases are systematically summarized,focusing on optimizing impedance matching and increasing dielectric and magnetic losses in the EMA materials with tunable EMW absorption performance.Milestones as well as the challenges are also identified to guide the design of new TMDs based dielectric EMA materials with high performance.展开更多
The pursuit of improved quality of life standards has significantly influenced the contemporary mining model in the 21st century.This era is witnessing an unprecedented transformation driven by pressing concerns relat...The pursuit of improved quality of life standards has significantly influenced the contemporary mining model in the 21st century.This era is witnessing an unprecedented transformation driven by pressing concerns related to sustainability,climate change,the just energy transition,dynamic operating environments,and complex social challenges.Such transitions present both opportunities and obstacles.The aim of this study is to provide an extensive literature review on energy transition to identify the challenges and strategies associated with navigating transformations in energy systems.Understanding these transformations is particularly critical in the face of the severe consequences of global warming,where an accelerated energy transition is viewed as a universal remedy.Adopting a socio-technological systems perspective,specifically through the application of Actor Network Theory(ANT),this research provides a theoretical foundation while categorising challenges into five distinct domains and outlining strategies across these different dimensions.These insights are specifically tailored for emerging market countries to effectively navigate energy transition while fostering the development of resilient societies.Furthermore,our findings highlight that energy transition encompasses more than a mere technological shift;it entails fundamental changes in various systemic socio-economic imperatives.Through focusing on the role of social structures in transitions,this study makes a significant and innovative contribution to ANT,which has historically been criticised for its limited acknowledgement of social structures.Consequently,we propose an emerging market energy transition framework,which not only addresses technological aspects,but also integrates social considerations.This framework paves the way for future research and exploration of energy transition dynamics.The outcomes of this study offer valuable insights to policymakers,researchers,and practitioners engaged in the mining industry,enabling them to comprehend the multifaceted challenges involved and providing practical strategies for effective resolution.Through incorporating the social dimension into the analysis,we enhance the understanding of the complex nature of energy system transformations,facilitating a more holistic approach towards achieving sustainable and resilient energy transitions in emerging markets and beyond.展开更多
The recognition,repetition and prediction of the post-failure motion process of long-runout landslides are key scientific problems in the prevention and mitigation of geological disasters.In this study,a new numerical...The recognition,repetition and prediction of the post-failure motion process of long-runout landslides are key scientific problems in the prevention and mitigation of geological disasters.In this study,a new numerical method involving LPF3D based on a multialgorithm and multiconstitutive model was proposed to simulate long-runout landslides with high precision and efficiency.The following results were obtained:(a)The motion process of landslides showed a steric effect with mobility,including gradual disintegration and spreading.The sliding mass can be divided into three states(dense,dilute and ultradilute)in the motion process,which can be solved by three dynamic regimes(friction,collision,and inertial);(b)Coupling simulation between the solid grain and liquid phases was achieved,focusing on drag force influences;(c)Different algorithms and constitutive models were employed in phase-state simulations.The volume fraction is an important indicator to distinguish different state types and solid‒liquid ratios.The flume experimental results were favorably validated against long-runout landslide case data;and(d)In this method,matched dynamic numerical modeling was developed to better capture the realistic motion process of long-runout landslides,and the advantages of continuum media and discrete media were combined to improve the computational accuracy and efficiency.This new method can reflect the realistic physical and mechanical processes in long-runout landslide motion and provide a suitable method for risk assessment and pre-failure prediction.展开更多
As a promising anode material for magnesium ion rechargeable batteries,magnesium metavanadate(MgV_(2)O_(6))has attracted considerable research interest in recent years.A MgV_(2)O_(6)sample was synthesized via a facile...As a promising anode material for magnesium ion rechargeable batteries,magnesium metavanadate(MgV_(2)O_(6))has attracted considerable research interest in recent years.A MgV_(2)O_(6)sample was synthesized via a facile solid-state reaction by multistep-firing stoichiometric mixtures of MgO and V2O5 powder under an air atmosphere.The solid-state phase transition fromα-MgV_(2)O_(6)toβ-MgV_(2)O_(6)occurred at 841 K and the enthalpy change was 4.37±0.04 kJ/mol.The endothermic effect at 1014 K and the enthalpy change was 26.54±0.26 kJ/mol,which is related to the incongruent melting ofβ-MgV_(2)O_(6).In situ XRD was performed to investigate phase transition of the as-prepared MgV_(2)O_(6)at high temperatures.The cell parameters obtained by Rietveld refinement indicated that it crystallizes in a monoclinic system with the C2/m space group,and the lattice parameters of a=9.280 A°,b=3.501 A°,c=6.731 A°,β=111.76°.The solid-state phase transition fromα-MgV_(2)O_(6)toβ-MgV_(2)O_(6)was further studied by thermal kinetics,indicating that this process is controlled first by a fibril-like mechanism and then by a spherulitic-type mechanism with an increasing heating rate.Additionally,the enthalpy change of MgV_(2)O_(6)at high temperatures was measured utilizing the drop calorimetry,heat capacity was calculated and given as:Cp=208.3+0.03583T-4809000T^(−2)(298-923 K)(J mol^(−1)K^(−1)),the high-temperature heat capacity can be used to calculate Gibbs free energy of MgV_(2)O_(6)at high temperatures.展开更多
Aqueous sodium-ion batteries(ASIBs)and aqueous potassium-ion batteries(APIBs)present significant potential for large-scale energy storage due to their cost-effectiveness,safety,and environmental compatibility.Nonethel...Aqueous sodium-ion batteries(ASIBs)and aqueous potassium-ion batteries(APIBs)present significant potential for large-scale energy storage due to their cost-effectiveness,safety,and environmental compatibility.Nonetheless,the intricate energy storage mechanisms in aqueous electrolytes place stringent require-ments on the host materials.Prussian blue analogs(PBAs),with their open three-dimensional framework and facile synthesis,stand out as leading candidates for aqueous energy storage.However,PBAs possess a swift capacity fade and limited cycle longevity,for their structural integrity is compromised by the pronounced dis-solution of transition metal(TM)ions in the aqueous milieu.This manuscript provides an exhaustive review of the recent advancements concerning PBAs in ASIBs and APIBs.The dissolution mechanisms of TM ions in PBAs,informed by their structural attributes and redox processes,are thoroughly examined.Moreover,this study delves into innovative design tactics to alleviate the dissolution issue of TM ions.In conclusion,the paper consolidates various strategies for suppressing the dissolution of TM ions in PBAs and posits avenues for prospective exploration of high-safety aqueous sodium-/potassium-ion batteries.展开更多
The stress response of amorphous polymers in the glass transition region shows apparent temperature and rate dependence.With increasing loading rate,amorphous polymers also exhibit a clear ductile-brittle transition o...The stress response of amorphous polymers in the glass transition region shows apparent temperature and rate dependence.With increasing loading rate,amorphous polymers also exhibit a clear ductile-brittle transition of tensile failure.The rate-dependent behaviors originate from intrinsic relaxations,ranging from perturbation of molecular bonds between polymer segments to reptation of polymer chains.In this work,we develop a constitutive model that incorporates segmental and chain dynamics into the deformation of bond and polymer networks,respectively.The dynamic scission of polymer chains is also incorporated into the theoretical framework to describe the damage evolution and ultimate failure of polymers.A comparison between theoretical predictions and experiments shows that the present model is able to simultaneously capture the observed rate-dependent features,including the transition from glassy state to rubbery state,strain hardening,and failure threshold.展开更多
It is an important way to realize rural revitalization and sustainable development to guide rural settlement transition(RST)in an appropriate way.This paper uses actor network theory(ANT)to construct a theoretical fra...It is an important way to realize rural revitalization and sustainable development to guide rural settlement transition(RST)in an appropriate way.This paper uses actor network theory(ANT)to construct a theoretical framework for the study of RST.Taking two typical villages with different transition paths in rural areas of North China Plain as examples,this paper reveals the mechanism of RST and makes a comparative analysis.The results show that:1)after identifying problems and obligatory passage point,key actors recruit heterogeneous actors into the actor network by entrusting them with common interests,and realize RST under the system operation.2)Rural settlements under different transition paths have similarities in the problems to be solved,collective actions and policy factors,but there are differences in the transition process,mechanism and effect.The actor network and mechanism of RST through the path of new rural community construction are more complex and the transition effect is more thorough.In contrast,the degree of RST of retention development path is limited if there is no resource and location advantage.3)Based on the applicable conditions of different paths,this paper designs a logical framework of‘Situation-Structure-Behavior-Result’to scientifically guide the identification of RST paths under the background of rural revitalization.展开更多
TaSe_(3)has garnered significant research interests due to its unique quasi-one-dimensional crystal structure,which gives rise to distinctive properties.Using crystal structure search and first-principles calculations...TaSe_(3)has garnered significant research interests due to its unique quasi-one-dimensional crystal structure,which gives rise to distinctive properties.Using crystal structure search and first-principles calculations,we systematically investigated the pressure-induced structural and electronic phase transitions of quasi-one-dimensional TaSe_(3)up to 100 GPa.In addition to the ambient pressure phase(P2_(1)/m-I),we identified three high-pressure phases:P2_(1)/m-II,Pnma,and Pmma.For the P2_(1)/m-I phase,the inclusion of spin-orbit coupling(SOC)results in significant SOC splitting and changes in the band inversion characteristics.Furthermore,band structure calculations for the three high-pressure phases indicate metallic natures,and the electron localization function suggests ionic bonding between Ta and Se atoms.Our electron-phonon coupling calculations reveal a superconducting critical temperature of approximately 6.4 K for the Pmma phase at 100 GPa.This study provides valuable insights into the high-pressure electronic behavior of quasi-one-dimensional TaSe_(3).展开更多
Controlling collective electronic states hold great promise for development of innovative devices. Here, we experimentally detect the modification of the charge density wave(CDW) phase transition within a 1T-TaS_(2) l...Controlling collective electronic states hold great promise for development of innovative devices. Here, we experimentally detect the modification of the charge density wave(CDW) phase transition within a 1T-TaS_(2) layer in a WS_(2)/1T-TaS_(2) heterostructure using time-resolved ultrafast spectroscopy. Laser-induced charge transfer doping strongly suppresses the commensurate CDW phase, which results in a significant decrease in both the phase transition temperature(T_(c)) and phase transition stiffness. We interpret the phenomenon that photoinduced hole doping, when surpassing a critical threshold value of ~ 10^(18)cm^(-3), sharply decreases the phase transition energy barrier. Our results provide new insights into controlling the CDW phase transition, paving the way for optical-controlled novel devices based on CDW materials.展开更多
In October 2023,the International Energy Agency(IEA)released a report identifying inadequate grid infrastructure as a key threat to meeting the climate goals laid out by the Paris Agreement[1],the landmark 2015 intern...In October 2023,the International Energy Agency(IEA)released a report identifying inadequate grid infrastructure as a key threat to meeting the climate goals laid out by the Paris Agreement[1],the landmark 2015 international treaty in which 196 parties agreed to limit global warming to well below 2℃ above preindustrial levels[2].Importantly,funding for the treaty’s calledfor transition from fossil fuels to clean energy has accelerated[3],with recently legislated massive governmental subsidies and other incentives(e.g.,the Inflation Reduction Act[4])aimed specifically at promoting renewable energy.However,a commensurate surge in investment in electrical grids has not materialized;instead,it has stagnated for the past decade at around 300 billion USD per year worldwide[1].展开更多
基金Project(2008FJ1003)supported by the Hunan Province Science and Technology,China
文摘Effect of quenching process on the microstrucmre and mechanical properties of a kind of seamless tubes of steel 28CrMnMoV was investigated. Then, an investigation on the influence of two different quenching processes on the ductile-brittle transition behavior of this steel was undertaken. The ductile-brittle transition temperatures of the steel by two different quenching processes were also determined. The results show that a good combination of mechanical properties can be obtained through austenitizing experimental steel at 800 ℃ or 890 ℃ followed by tempering at 630 ℃. Ductile-to-brittle transition temperature of 28CrMnMoV steel austenitized at 800 ℃ followed by tempering at 640 ℃ is about -73 ℃, which is much lower than the value -37 ℃ when the steel was austenitized at 890℃ and then tempered at 650 ℃. This indicates that subcritical quenching process could decrease largely the ductile-to-brittle transition temperature of 28CrMnMoV steel.
文摘Based on the crack tip structure a new model of ductile -brittle transition was proposed. Using this new model we calculated the dependence of the transition temperature-strain rate over a wide range of strain rate. Finally the significance of this new model is discussed in detail.
基金financially supported by the National Key Research and Development Program of China (No. 2016YFB0700500)the National Natural Science Foundation of China (No. 51574027)
文摘Brittleness is a dominant issue that restricts potential applications of Mg_2Si intermetallic compounds(IMC). In this paper, guided by first-principles calculations, we found that Al doping will enhance the ductility of Mg_2Si. The underlying mechanism is that Al doping could reduce the electronic exchange effect between Mg and Si atoms, and increase the volume module/shear modulus ratio, both of which are beneficial to the deformation capability of Mg_2Si. Experimental investigations were then carried out to verify the calculation results with Al doping contents ranging from Al-free to 10 wt%. Results showed that the obtained ductile-brittle transition temperature of the Mg_2Si–Al alloy decreased and the corresponding ductility increased. Specifically, the ductile-brittle transition temperature could be reduced by about 100℃. When the content of Al reached 6 wt%, α-Al phase started to precipitate, and the ductile-brittle transition temperature of the alloy no longer decreased.
文摘The dynamic fracture toughness of a mild steel has been studied at different loading rates and temperatures.The material exhibits a transition from tough to brittle fracture with the chang- ing loading rate alone.Analysis of the fracture process by the theory of thermal activation suggests that the fracture activation energy approximates to the bond energy of the{100}of a unit cell.The toughness can be resolved into two parts,J-(fd)=J_a+J_l,where J_a is the athermal part,being independent on temperature and loading rate,while J_l=(K/K_o)^(1/n)exp(Q_f/nkT),which controls the fracture process is temperature and load- ing rate dependent.The transition of fracture mechanism caused by both temperature and loading rate is associated with the thermal movement of atoms.
基金the support from the CIPHER Project(IIID 2018-008)funded by the Commission on Higher Education-Philippine California Advanced Research Institutes(CHED-PCARI)。
文摘Transition metal phosphides(TMPs)have been regarded as alternative hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts owing to their comparable activity to those of noble metal-based catalysts.TMPs have been produced in various morphologies,including hollow and porous nanostructures,which are features deemed desirable for electrocatalytic materials.Templated synthesis routes are often responsible for such morphologies.This paper reviews the latest advances and existing challenges in the synthesis of TMP-based OER and HER catalysts through templated methods.A comprehensive review of the structure-property-performance of TMP-based HER and OER catalysts prepared using different templates is presented.The discussion proceeds according to application,first by HER and further divided among the types of templates used-from hard templates,sacrificial templates,and soft templates to the emerging dynamic hydrogen bubble template.OER catalysts are then reviewed and grouped according to their morphology.Finally,prospective research directions for the synthesis of hollow and porous TMP-based catalysts,such as improvements on both activity and stability of TMPs,design of environmentally benign templates and processes,and analysis of the reaction mechanism through advanced material characterization techniques and theoretical calculations,are suggested.
基金supported by the Ministry of Education,Singapore,under its Academic Research Funds(Grant Nos.:MOE-T2EP50120-0010,MOE-T2EP50220-0010)the funding from the Ministère des Relations Internationales et de la Francophonie du Québec,Coopération Québec-Singapour,with which this work was partially supported。
文摘Magneto-plasticity occurs when a weak magnetic field alters material plasticity and offers a viable solution to enhance ductile-mode cutting of brittle materials.This study demonstrates the susceptibility of non-magnetic single-crystal calcium fluoride(CaF_(2))to the magneto-plastic effect.The influence of magneto-plasticity on CaF_(2) was confirmed in micro-deformation tests under a weak magnetic field of 20 mT.The surface pile-up effect was weakened by 10-15 nm along with an enlarged plastic zone and suppressed crack propagation under the influence of the magnetic field.Micro-cutting tests along different crystal orientations on the(111)plane of CaF_(2) revealed an increase in the ductile-brittle transition of the machined surface with the aid of magneto-plasticity where the largest increase in ductile-brittle transition occurred along the[112]orientation from 512 nm to a range of 664-806 nm.Meanwhile,the subsurface damage layer was concurrently thinner under magnetic influence.An anisotropic influence of the magnetic field relative to the single-crystal orientation and the cutting direction was also observed.An analytical model was derived to determine an orientation factor M that successfully describes the anisotropy while considering the single-crystal dislocation behaviour,material fracture toughness,and the orientation of the magnetic field.Previously suggested theoretical mechanism of magneto-plasticity via formation of non-singlet electronic states in defected configurations was confirmed with density functional theory calculations.The successful findings on the influence of a weak magnetic field on plasticity present an opportunity for the adoption of magnetic-assisted micro-cutting of non-magnetic materials.
文摘Following publication of the original article[1],the authors reported that the author Hun-Gi Jung should be affiliated as 3,4 and 5 instead of 4 and 5.The author’s name“A.-Yeon Kim”needed to be updated to“A-Yeon Kim”,removing the period.The correct author’s name and affiliation have been provided in this Correction.The original article[1]has been corrected.
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFA1401800 and 2022YFA1403900)the National Natural Science Foundation of China(Grant Nos.U2032214,12122414,12104487,and 12004419)+1 种基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB25000000)supported by the US Department of Energy,Office of Basic Energy Sciences(Grant No.DOE-sc0012704)。
文摘What factors fundamentally determine the value of superconducting transition temperature Tc in high temperature superconductors has been the subject of intense debate.Following the establishment of an empirical law known as Homes'law,there is a growing consensus in the community that the Tc value of the cuprate superconductors is closely linked to the superfluid density(ρ_(s))of its ground state and the conductivity(σ)of its normal state.However,all the data supporting this empirical law(ρ_(s)=AσT_(c))have been obtained from the ambientpressure superconductors.In this study,we present the first high-pressure results about the connection of the quantities of ρ_(s) and σ with T_(c),through the studies on the Bi_(1.74)Pb_(0.38)Sr_(1.88)CuO_(6+δ)and Bi_(2)Sr_(2)CaCu_(2)O_(8+δ),in which the value of their high-pressure resistivity(ρ=1/σ)is achieved by adopting our newly established method,while the quantity ofρs is extracted using Homes'law.We highlight that the Tc values are strongly linked to the joint response factors of magnetic field and electric field,i.e.,ρ_(s) and σ,respectively,implying that the physics determining T_(c) is governed by the intrinsic electromagnetic fields of the system.
基金supported by National Undergraduate Training Programs for Innovations[grant number 202210225259]the Outstanding Youth Project of Natural Science Foundation in Heilongjiang Province(YQ2022E040)+3 种基金the Shandong Provincial Natural Science Foundation(ZR2022ME166)the Postdoctoral Scientific Research Developmental Fund of Heilongjiang Province(LBH-Q20023)the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(UNPYSCT-2020197)the 111 Project(B20088).
文摘Supercapacitors(SCs)are considered promising energy storge systems because of their outstanding power density,fast charge and discharge rate and long-term cycling stability.The exploitation of cheap and efficient electrode materials is the key to improve the performance of supercapacitors.As the battery-type materials,transition metal phosphides(TMPs)possess high theoretical specific capacity,good electrical conductivity and superior structural stability,which have been extensively studied to be electrode materials for supercapacitors.In this review,we summarize the up-to-date progress on TMPs materials from diversified synthetic methods,diverse nanostructures and several prominent TMPs and their composites in application of supercapacitors.In the end,we also propose the remaining challenges toward the rational discovery and synthesis of high-performance TMP electrodes materials for energy storage.
基金supported by the Teli Fellowship from Beijing Institute of Technology,the National Natural Science Foundation of China(Nos.52303366,22173109).
文摘In recent years,low-dimensional transition metal chalcogenide(TMC)materials have garnered growing research attention due to their superior electronic,optical,and catalytic properties compared to their bulk counterparts.The controllable synthesis and manipulation of these materials are crucial for tailoring their properties and unlocking their full potential in various applications.In this context,the atomic substitution method has emerged as a favorable approach.It involves the replacement of specific atoms within TMC structures with other elements and possesses the capability to regulate the compositions finely,crystal structures,and inherent properties of the resulting materials.In this review,we present a comprehensive overview on various strategies of atomic substitution employed in the synthesis of zero-dimensional,one-dimensional and two-dimensional TMC materials.The effects of substituting elements,substitution ratios,and substitution positions on the structures and morphologies of resulting material are discussed.The enhanced electrocatalytic performance and photovoltaic properties of the obtained materials are also provided,emphasizing the role of atomic substitution in achieving these advancements.Finally,challenges and future prospects in the field of atomic substitution for fabricating low-dimensional TMC materials are summarized.
基金This work was supported by the National Natural Science Foundation of China(52372289,52102368,52072192 and 51977009)Regional Joint Fund for Basic Research and Applied Basic Research of Guangdong Province(No.2020SA001515110905).
文摘The laminated transition metal disulfides(TMDs),which are well known as typical two-dimensional(2D)semiconductive materials,possess a unique layered structure,leading to their wide-spread applications in various fields,such as catalysis,energy storage,sensing,etc.In recent years,a lot of research work on TMDs based functional materials in the fields of electromagnetic wave absorption(EMA)has been carried out.Therefore,it is of great significance to elaborate the influence of TMDs on EMA in time to speed up the application.In this review,recent advances in the development of electromagnetic wave(EMW)absorbers based on TMDs,ranging from the VIB group to the VB group are summarized.Their compositions,microstructures,electronic properties,and synthesis methods are presented in detail.Particularly,the modulation of structure engineering from the aspects of heterostructures,defects,morphologies and phases are systematically summarized,focusing on optimizing impedance matching and increasing dielectric and magnetic losses in the EMA materials with tunable EMW absorption performance.Milestones as well as the challenges are also identified to guide the design of new TMDs based dielectric EMA materials with high performance.
基金University of the Witwatersrand Additional funding is from the DSI-National Research Foundation(NRF)Thuthuka Grant(Grant UID:121973)and DSI-NRF CIMERA.
文摘The pursuit of improved quality of life standards has significantly influenced the contemporary mining model in the 21st century.This era is witnessing an unprecedented transformation driven by pressing concerns related to sustainability,climate change,the just energy transition,dynamic operating environments,and complex social challenges.Such transitions present both opportunities and obstacles.The aim of this study is to provide an extensive literature review on energy transition to identify the challenges and strategies associated with navigating transformations in energy systems.Understanding these transformations is particularly critical in the face of the severe consequences of global warming,where an accelerated energy transition is viewed as a universal remedy.Adopting a socio-technological systems perspective,specifically through the application of Actor Network Theory(ANT),this research provides a theoretical foundation while categorising challenges into five distinct domains and outlining strategies across these different dimensions.These insights are specifically tailored for emerging market countries to effectively navigate energy transition while fostering the development of resilient societies.Furthermore,our findings highlight that energy transition encompasses more than a mere technological shift;it entails fundamental changes in various systemic socio-economic imperatives.Through focusing on the role of social structures in transitions,this study makes a significant and innovative contribution to ANT,which has historically been criticised for its limited acknowledgement of social structures.Consequently,we propose an emerging market energy transition framework,which not only addresses technological aspects,but also integrates social considerations.This framework paves the way for future research and exploration of energy transition dynamics.The outcomes of this study offer valuable insights to policymakers,researchers,and practitioners engaged in the mining industry,enabling them to comprehend the multifaceted challenges involved and providing practical strategies for effective resolution.Through incorporating the social dimension into the analysis,we enhance the understanding of the complex nature of energy system transformations,facilitating a more holistic approach towards achieving sustainable and resilient energy transitions in emerging markets and beyond.
基金supported by the National Science Foundation of China(Grant No.42177172)China Geological Survey Project(Grant No.DD20230538).
文摘The recognition,repetition and prediction of the post-failure motion process of long-runout landslides are key scientific problems in the prevention and mitigation of geological disasters.In this study,a new numerical method involving LPF3D based on a multialgorithm and multiconstitutive model was proposed to simulate long-runout landslides with high precision and efficiency.The following results were obtained:(a)The motion process of landslides showed a steric effect with mobility,including gradual disintegration and spreading.The sliding mass can be divided into three states(dense,dilute and ultradilute)in the motion process,which can be solved by three dynamic regimes(friction,collision,and inertial);(b)Coupling simulation between the solid grain and liquid phases was achieved,focusing on drag force influences;(c)Different algorithms and constitutive models were employed in phase-state simulations.The volume fraction is an important indicator to distinguish different state types and solid‒liquid ratios.The flume experimental results were favorably validated against long-runout landslide case data;and(d)In this method,matched dynamic numerical modeling was developed to better capture the realistic motion process of long-runout landslides,and the advantages of continuum media and discrete media were combined to improve the computational accuracy and efficiency.This new method can reflect the realistic physical and mechanical processes in long-runout landslide motion and provide a suitable method for risk assessment and pre-failure prediction.
基金supported by the National Key R&D Program of China(2018YFC1900500)the Graduate Scientific Research and Innovation Foundation of Chongqing,China(Grant No.CYB20002).
文摘As a promising anode material for magnesium ion rechargeable batteries,magnesium metavanadate(MgV_(2)O_(6))has attracted considerable research interest in recent years.A MgV_(2)O_(6)sample was synthesized via a facile solid-state reaction by multistep-firing stoichiometric mixtures of MgO and V2O5 powder under an air atmosphere.The solid-state phase transition fromα-MgV_(2)O_(6)toβ-MgV_(2)O_(6)occurred at 841 K and the enthalpy change was 4.37±0.04 kJ/mol.The endothermic effect at 1014 K and the enthalpy change was 26.54±0.26 kJ/mol,which is related to the incongruent melting ofβ-MgV_(2)O_(6).In situ XRD was performed to investigate phase transition of the as-prepared MgV_(2)O_(6)at high temperatures.The cell parameters obtained by Rietveld refinement indicated that it crystallizes in a monoclinic system with the C2/m space group,and the lattice parameters of a=9.280 A°,b=3.501 A°,c=6.731 A°,β=111.76°.The solid-state phase transition fromα-MgV_(2)O_(6)toβ-MgV_(2)O_(6)was further studied by thermal kinetics,indicating that this process is controlled first by a fibril-like mechanism and then by a spherulitic-type mechanism with an increasing heating rate.Additionally,the enthalpy change of MgV_(2)O_(6)at high temperatures was measured utilizing the drop calorimetry,heat capacity was calculated and given as:Cp=208.3+0.03583T-4809000T^(−2)(298-923 K)(J mol^(−1)K^(−1)),the high-temperature heat capacity can be used to calculate Gibbs free energy of MgV_(2)O_(6)at high temperatures.
基金This work was supported by the National Natural Science Foundation of China(52373306,52172233,and 51832004)the Natural Science Foundation of Hubei Province(2023AFA053)the Hainan Provincial Joint Project of Sanya Yazhou Bay Science and Technology City(2021CXLH0007).
文摘Aqueous sodium-ion batteries(ASIBs)and aqueous potassium-ion batteries(APIBs)present significant potential for large-scale energy storage due to their cost-effectiveness,safety,and environmental compatibility.Nonetheless,the intricate energy storage mechanisms in aqueous electrolytes place stringent require-ments on the host materials.Prussian blue analogs(PBAs),with their open three-dimensional framework and facile synthesis,stand out as leading candidates for aqueous energy storage.However,PBAs possess a swift capacity fade and limited cycle longevity,for their structural integrity is compromised by the pronounced dis-solution of transition metal(TM)ions in the aqueous milieu.This manuscript provides an exhaustive review of the recent advancements concerning PBAs in ASIBs and APIBs.The dissolution mechanisms of TM ions in PBAs,informed by their structural attributes and redox processes,are thoroughly examined.Moreover,this study delves into innovative design tactics to alleviate the dissolution issue of TM ions.In conclusion,the paper consolidates various strategies for suppressing the dissolution of TM ions in PBAs and posits avenues for prospective exploration of high-safety aqueous sodium-/potassium-ion batteries.
基金supported by the National Natural Science Foundation of China(Grant Nos.12022204,12002302 and 12072316)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ21A020008)the Fundamental Research Funds of Zhejiang Sci-Tech University(Grant No.2021Q039).
文摘The stress response of amorphous polymers in the glass transition region shows apparent temperature and rate dependence.With increasing loading rate,amorphous polymers also exhibit a clear ductile-brittle transition of tensile failure.The rate-dependent behaviors originate from intrinsic relaxations,ranging from perturbation of molecular bonds between polymer segments to reptation of polymer chains.In this work,we develop a constitutive model that incorporates segmental and chain dynamics into the deformation of bond and polymer networks,respectively.The dynamic scission of polymer chains is also incorporated into the theoretical framework to describe the damage evolution and ultimate failure of polymers.A comparison between theoretical predictions and experiments shows that the present model is able to simultaneously capture the observed rate-dependent features,including the transition from glassy state to rubbery state,strain hardening,and failure threshold.
基金Under the auspices of the Taishan Scholars Project Special FundsNational Natural Science Fundation of China(No.42077434,42001199)Youth Innovation Technology Project of Higher School in Shandong Province(No.2019RWG016)。
文摘It is an important way to realize rural revitalization and sustainable development to guide rural settlement transition(RST)in an appropriate way.This paper uses actor network theory(ANT)to construct a theoretical framework for the study of RST.Taking two typical villages with different transition paths in rural areas of North China Plain as examples,this paper reveals the mechanism of RST and makes a comparative analysis.The results show that:1)after identifying problems and obligatory passage point,key actors recruit heterogeneous actors into the actor network by entrusting them with common interests,and realize RST under the system operation.2)Rural settlements under different transition paths have similarities in the problems to be solved,collective actions and policy factors,but there are differences in the transition process,mechanism and effect.The actor network and mechanism of RST through the path of new rural community construction are more complex and the transition effect is more thorough.In contrast,the degree of RST of retention development path is limited if there is no resource and location advantage.3)Based on the applicable conditions of different paths,this paper designs a logical framework of‘Situation-Structure-Behavior-Result’to scientifically guide the identification of RST paths under the background of rural revitalization.
基金supported by the National Natural Science Foundation of China(Grant Nos.12304022 and 52361035)the Fundamental Research Funds for the Central Universities.The calculations were carried out using supercomputers at the School of Physics at Ningxia University.
文摘TaSe_(3)has garnered significant research interests due to its unique quasi-one-dimensional crystal structure,which gives rise to distinctive properties.Using crystal structure search and first-principles calculations,we systematically investigated the pressure-induced structural and electronic phase transitions of quasi-one-dimensional TaSe_(3)up to 100 GPa.In addition to the ambient pressure phase(P2_(1)/m-I),we identified three high-pressure phases:P2_(1)/m-II,Pnma,and Pmma.For the P2_(1)/m-I phase,the inclusion of spin-orbit coupling(SOC)results in significant SOC splitting and changes in the band inversion characteristics.Furthermore,band structure calculations for the three high-pressure phases indicate metallic natures,and the electron localization function suggests ionic bonding between Ta and Se atoms.Our electron-phonon coupling calculations reveal a superconducting critical temperature of approximately 6.4 K for the Pmma phase at 100 GPa.This study provides valuable insights into the high-pressure electronic behavior of quasi-one-dimensional TaSe_(3).
基金supported by the National Key Research and Development Program of China (Grant No. 2021YFA1400201)the CAS Project for Young Scientists in Basic Research (Grant No. YSBR059)+5 种基金the Beijing Natural Science Foundation (Grant No. 4191003)the National Natural Science Foundation of China (Grant No. 11774408)the Scientific Instrument Developing Project of the Chinese Academy of Sciences (Grant No. GJJSTD20200005)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant Nos. XDB36000000 and XDB30000000)the International Partnership Program of Chinese Academy of Sciences (Grant No. GJHZ1826)CAS Interdisciplinary Innovation Team。
文摘Controlling collective electronic states hold great promise for development of innovative devices. Here, we experimentally detect the modification of the charge density wave(CDW) phase transition within a 1T-TaS_(2) layer in a WS_(2)/1T-TaS_(2) heterostructure using time-resolved ultrafast spectroscopy. Laser-induced charge transfer doping strongly suppresses the commensurate CDW phase, which results in a significant decrease in both the phase transition temperature(T_(c)) and phase transition stiffness. We interpret the phenomenon that photoinduced hole doping, when surpassing a critical threshold value of ~ 10^(18)cm^(-3), sharply decreases the phase transition energy barrier. Our results provide new insights into controlling the CDW phase transition, paving the way for optical-controlled novel devices based on CDW materials.
文摘In October 2023,the International Energy Agency(IEA)released a report identifying inadequate grid infrastructure as a key threat to meeting the climate goals laid out by the Paris Agreement[1],the landmark 2015 international treaty in which 196 parties agreed to limit global warming to well below 2℃ above preindustrial levels[2].Importantly,funding for the treaty’s calledfor transition from fossil fuels to clean energy has accelerated[3],with recently legislated massive governmental subsidies and other incentives(e.g.,the Inflation Reduction Act[4])aimed specifically at promoting renewable energy.However,a commensurate surge in investment in electrical grids has not materialized;instead,it has stagnated for the past decade at around 300 billion USD per year worldwide[1].
