We study the effect of particle size polydispersity(δ) on the melting transition(T*), local ordering, solid–liquid coexistence phase and dynamics of two-dimensional Lennard–Jones fluids up to moderate polydispersit...We study the effect of particle size polydispersity(δ) on the melting transition(T*), local ordering, solid–liquid coexistence phase and dynamics of two-dimensional Lennard–Jones fluids up to moderate polydispersity by means of computer simulations. The particle sizes are drawn at random from the Gaussian(G) and uniform(U) distribution functions.For these systems, we further consider two different kinds of particles, viz., particles having the same mass irrespective of size, and in the other case the mass of the particle scales with its size. It is observed that with increasing polydispersity,the value of T*initially increases due to improved packing efficiency(φ) followed by a decrease and terminates at δ ≈8%(U-system) and 14%(G-system) with no significant difference for both mass types. The interesting observation is that the particular value at which φ drops suddenly coincides with the peak of the heat capacity(CP) curve, indicating a transition. The quantification of local particle ordering through the hexatic order parameter(Q_6), Voronoi construction and pair correlation function reveals that the ordering decreases with increasing δ and T. Furthermore, the solid–liquid coexistence region for the G-system is shown to be comparatively wider in the T –δ plane phase diagram than that for the U system. Finally, the study of dynamics reveals that polydisperse systems relax faster compared to monodisperse systems;however, no significant qualitative differences, depending on the distribution type and mass polydispersity, are observed.展开更多
Understanding the structural origin of the competition between oxygen 2p and transition-metal 3d orbitals in oxygen-redox(OR)layered oxides is eminently desirable for exploring reversible and high-energy-density Li/Na...Understanding the structural origin of the competition between oxygen 2p and transition-metal 3d orbitals in oxygen-redox(OR)layered oxides is eminently desirable for exploring reversible and high-energy-density Li/Na-ion cathodes.Here,we reveal the correlation between cationic ordering transition and OR degradation in ribbon-ordered P3-Na_(0.6)Li_(0.2)Mn_(0.8)O_(2) via in situ structural analysis.Comparing two different voltage windows,the OR capacity can be improved approximately twofold when suppressing the in-plane cationic ordering transition.We find that the intralayer cationic migration is promoted by electrochemical reduction from Mn^(4+)to Jahn–Teller Mn^(3+)and the concomitant NaO_(6) stacking transformation from triangular prisms to octahedra,resulting in the loss of ribbon ordering and electrochemical decay.First-principles calculations reveal that Mn^(4+)/Mn^(3+)charge ordering and alignment of the degenerate eg orbital induce lattice-level collective Jahn–Teller distortion,which favors intralayer Mn-ion migration and thereby accelerates OR degradation.These findings unravel the relationship between in-plane cationic ordering and OR reversibility and highlight the importance of superstructure protection for the rational design of reversible OR-active layered oxide cathodes.展开更多
Collective cell migration is a coordinated movement of multi-cell systems essential for various processes throughout life.The collective motions often occur under spatial restrictions,hallmarked by the collective rota...Collective cell migration is a coordinated movement of multi-cell systems essential for various processes throughout life.The collective motions often occur under spatial restrictions,hallmarked by the collective rotation of epithelial cells confined in circular substrates.Here,we aim to explore how geometric shapes of confinement regulate this collective cell movement.We develop quantitative methods for cell velocity orientation analysis,and find that boundary cells exhibit stronger tangential ordering migration than inner cells in circular pattern.Furthermore,decreased tangential ordering movement capability of collective cells in triangular and square patterns are observed,due to the disturbance of cell motion at unsmooth corners of these patterns.On the other hand,the collective cell rotation is slightly affected by a convex defect of the circular pattern,while almost hindered with a concave defect,also resulting from different smoothness features of their boundaries.Numerical simulations employing cell Potts model well reproduce and extend experimental observations.Together,our results highlight the importance of boundary smoothness in the regulation of collective cell tangential ordering migration.展开更多
In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy,the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of ab-initio molecular...In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy,the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of ab-initio molecular dynamics simulation.In liquid Mg-rich Mg-Y alloys,the strong Mg-Y interaction is determined,which promotes the formation of fivefold symmetric local structure.For Mg-Zn alloys,the weak Mg-Zn interaction results in the fivefold symmetry weakening in the liquid structure.Due to the coexistence of Y and Zn,the strong attractive interaction is introduced in liquid Mg-Y-Zn ternary alloy,and contributes to the clustering of Mg,Y,Zn launched from Zn.What is more,the distribution of local structures becomes closer to that in pure Mg compared with that in binary Mg-Y and Mg-Zn alloys.These results should relate to the origins of the Y/Zn segregation zone and close-packed stacking mode in LPSO structure,which provides a new insight into the formation mechanism of LPSO structure at atomic level.展开更多
Short-range ordering(SRO)is one of the most important structural features of high entropy alloys(HEAs).However,the chemical and structural analyses of SROs are very difficult due to their small size,complexed composit...Short-range ordering(SRO)is one of the most important structural features of high entropy alloys(HEAs).However,the chemical and structural analyses of SROs are very difficult due to their small size,complexed compositions,and varied locations.Transmission electron microscopy(TEM)as well as its aberration correction techniques are powerful for characterizing SROs in these compositionally complex alloys.In this short communication,we summarized recent progresses regarding characterization of SROs using TEM in the field of HEAs.By using advanced TEM techniques,not only the existence of SROs was confirmed,but also the effect of SROs on the deformation mechanism was clarified.Moreover,the perspective related to application of TEM techniques in HEAs are also discussed.展开更多
The formation and evolution of Gd-rich precipitates companying with the matrix structure ordering in a Mg_(97)Gd_(2)Cd_(1)(at.%)solid-solution alloy aged at 200℃have been systemically investigated using high-angle an...The formation and evolution of Gd-rich precipitates companying with the matrix structure ordering in a Mg_(97)Gd_(2)Cd_(1)(at.%)solid-solution alloy aged at 200℃have been systemically investigated using high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM).The results show that Gd-rich precipitation dynamics during the aging treatment are noticeably affected by a continuous ordering transformation in the matrix.The ordering transformation process involving mainly re-distribution of Cd atoms was revealed to occur in the following way:random super-saturated solid solution(S.S.S.S.)→B19-type ordered domains→D019-type ordered domains.Four Gd(Cd)-rich precipitates,G.P.Ⅰ zone,G.P.Ⅱ zone,β′andβ_(1)phases,have been observed to be formed in sequence to coexist with the various ordered domains.Based on the HAADF-STEM characterization on the aging microstructures at different aging stages,it can be concluded that the Cd-addition and related matrix structure ordering can play significant roles in modifying the early-stage G.P.zone structure,altering the morphology ofβ′precipitates and promoting the forming ability of theβ_(1)precipitate.展开更多
The development of quantum optics theory based on the method of integration within an ordered product of operators(IWOP)has greatly stimulated the study of quantum states in the light field,especially non-Gaussian sta...The development of quantum optics theory based on the method of integration within an ordered product of operators(IWOP)has greatly stimulated the study of quantum states in the light field,especially non-Gaussian states with various non-classical properties.In this paper,the two-mode squeezing operator is derived with integral theory within the Weyl ordering product of operators using a combinatorial field in which one mode is a chaotic field and the other mode is a vacuum field.The density operator of the new light field,its entanglement property and photon number distribution are analyzed.We also note that tracing a three-mode pure state can yield this new light field.These methods represent a theoretical approach to investigating new density operators of light fields.展开更多
Materials with strongly coupled magnetic and electronic degrees of freedom provide new possibilities for practical applications.In this paper,we have investigated the structure,magnetic property,and magnetodielectric(...Materials with strongly coupled magnetic and electronic degrees of freedom provide new possibilities for practical applications.In this paper,we have investigated the structure,magnetic property,and magnetodielectric(MD) effect in Ho_(2)Cu_(2)O_(5) and Yb_(2)Cu_(2)O_(5) poly crystalline samples,which possess a non-centrosymmetric polar structure with space group Pna2_(1).In Ho_(2)Cu_(2)O_(5),Ho^(3+) and Cu^(2+) sublattices order simultaneously,exhibiting a typical paramagnetic to antiferromagnetic transition at 13.1 K.While for Yb_(2)Cu_(2)O_(5),two magnetic transitions which originate from the orderings of Yb^(3+)(7.8 K) and Cu^(2+)(13.5 K) sublattices are observed.A magnetic field induced metamagnetic transition is obtained in these two cuprates below Neel temperature(T_(N)).By means of dielectric measurement,distinct MD effect is demonstrated by the dielectric anomaly at T_(N.)Meanwhile,the MD effect is found to be directly related to the metamagnetic transition.Due to the specific spin configuration and different spin evolution in the magnetic field,a positive MD effect is formed in Ho_(2)Cu_(2)O_(5),and a negative one is observed in Yb_(2)Cu_(2)O_(5).The spontaneous dielectric anomaly at T_(N) is regarded as arising from the shifts in optical phonon frequencies,and the magnetoelectric coupling is used to interpret the magnetic field induced MD effect.Moreover,an H-T phase diagram is constructed for Ho_(2)Cu_(2)O_(5) and Yb_(2)Cu_(2)O_(5) based on the results of isothermal magnetic and dielectric hysteresis loops.展开更多
Taking experimental path on disordering AuCuI(AAuCu8A4)composed of A Au8 and ACu4 stem alloy genes as an example, three discoveries and a method were presented. The ability of Au Cu I(AAu Cu8 A4)to keep structure ...Taking experimental path on disordering AuCuI(AAuCu8A4)composed of A Au8 and ACu4 stem alloy genes as an example, three discoveries and a method were presented. The ability of Au Cu I(AAu Cu8 A4)to keep structure stabilization against changing temperature is attributed to the fact that the AAu8 and ACu4 potential well depths greatly surpass their vibration energies, which leads to the subequilibrium of experimental path. A new atom movement mechanism of AuCuI(AAuACu84)to change structure for suiting variation in temperature is the resonance activating-synchro alternating of alloy genes, which leads to heterogeneous and successive subequilibrium transitions. There exists jumping order degree, which leads to the existence of jumping Tj-temperature and an unexpected so-called "retro-effect" about jumping temperature retrograde shift to lower temperatures upon the increasing heating rate. A set of subequilibrium holographic network path charts were obtained by the experimental mixed enthalpy path method.展开更多
In this study,we systematically investigated the effect of proton concentration on the kinetics of the oxygen reduction reaction(ORR)on Pt(111)in acidic solutions.Experimental results demonstrate a rectangular hyperbo...In this study,we systematically investigated the effect of proton concentration on the kinetics of the oxygen reduction reaction(ORR)on Pt(111)in acidic solutions.Experimental results demonstrate a rectangular hyperbolic relationship,i.e.,the ORR current excluding the effect of other variables increases with proton concentration and then tends to a constant value.We consider that this is caused by the limitation of ORR kinetics by the trace oxygen concentration in the solution,which determines the upper limit of ORR kinetics.A model of effective concentration is further proposed for rectangular hyperbolic relationships:when the reactant concentration is high enough to reach a critical saturation concentration,the effective reactant concentration will become a constant value.This could be due to the limited concentration of a certain reactant for reactions involving more than one reactant or the limited number of active sites available on the catalyst.Our study provides new insights into the kinetics of electrocatalytic reactions,and it is important for the proper evaluation of catalyst activity and the study of structureperformance relationships.展开更多
With plenty of popular and effective ternary organic solar cells(OSCs)construction strategies proposed and applied,its power conversion efficiencies(PCEs)have come to a new level of over 19%in single-junction devices....With plenty of popular and effective ternary organic solar cells(OSCs)construction strategies proposed and applied,its power conversion efficiencies(PCEs)have come to a new level of over 19%in single-junction devices.However,previous studies are heavily based in chloroform(CF)leaving behind substantial knowledge deficiencies in understanding the influence of solvent choice when introducing a third component.Herein,we present a case where a newly designed asymmetric small molecular acceptor using fluoro-methoxylated end-group modification strategy,named BTP-BO-3FO with enlarged bandgap,brings different morphological evolution and performance improvement effect on host system PM6:BTP-eC9,processed by CF and ortho-xylene(o-XY).With detailed analyses supported by a series of experiments,the best PCE of 19.24%for green solvent-processed OSCs is found to be a fruit of finely tuned crystalline ordering and general aggregation motif,which furthermore nourishes a favorable charge generation and recombination behavior.Likewise,over 19%PCE can be achieved by replacing spin-coating with blade coating for active layer deposition.This work focuses on understanding the commonly met yet frequently ignored issues when building ternary blends to demonstrate cutting-edge device performance,hence,will be instructive to other ternary OSC works in the future.展开更多
We theoretically investigate the Ruderman–Kittel–Kasuya–Yosida(RKKY) interaction in helical higher-order topological insulators(HOTIs), revealing distinct behaviors mediated by hinge and Dirac-type bulk carriers. O...We theoretically investigate the Ruderman–Kittel–Kasuya–Yosida(RKKY) interaction in helical higher-order topological insulators(HOTIs), revealing distinct behaviors mediated by hinge and Dirac-type bulk carriers. Our findings show that hinge-mediated interactions consist of Heisenberg, Ising, and Dzyaloshinskii–Moriya(DM) terms, exhibiting a decay with impurity spacing z and oscillations with Fermi energy εF. These interactions demonstrate ferromagnetic behaviors for the Heisenberg and Ising terms and alternating behavior for the DM term. In contrast, bulk-mediated interactions include Heisenberg, twisted Ising, and DM terms, with a conventional cubic oscillating decay. This study highlights the nuanced interplay between hinge and bulk RKKY interactions in HOTIs, offering insights into designs of next-generation quantum devices based on HOTIs.展开更多
The long-period-stacking-ordered(LPSO)structure affects the mechanical,corrosion and hydrolysis properties of Mg alloys.The current work employs high angle annular dark field-scanning transmission electron microscopy(...The long-period-stacking-ordered(LPSO)structure affects the mechanical,corrosion and hydrolysis properties of Mg alloys.The current work employs high angle annular dark field-scanning transmission electron microscopy(HAADF-STEM)and atom probe tomography(APT)to investigate the structural and local chemical information of LPSO phases formed in Mg-Ni-Y/Sm ternary alloys after extended isothermal annealing.Depending on the alloying elements and their concentrations,Mg-Ni-Y/Sm develops a two-phase LPSO+α-Mg structure in which the LPSO phase contains defects,hybrid LPSO structure,and Mg insertions.HAADF-STEM and APT indicate non-stoichiometric LPSO with incomplete Ni_(6)(Y/Sm)_(8) clusters.In addition,the APT quantitatively determines the local composition of LPSO and confirms the presence of Ni within the Mg bonding layers.These results provide insight into a better understanding of the structure and hydrolysis properties of LPSO-Mg alloys.展开更多
Metal-to-insulator transitions (MITs),which are achieved in 3d-band correlated transitional metal oxides,trigger abrupt variations in electrical,optical,and/or magnetic properties beyond those of conventional semicond...Metal-to-insulator transitions (MITs),which are achieved in 3d-band correlated transitional metal oxides,trigger abrupt variations in electrical,optical,and/or magnetic properties beyond those of conventional semiconductors.Among such material families,iron(Fe:3d^(6)4s^(2))-containing oxides pique interest owing to their widely tunable MIT properties,which are associated with the various valence states of Fe.Their potential electronic applications also show promise,given the large abundance of Fe on Earth.Representative MIT properties triggered by critical temperature (TMIT) were reported for ReFe_(2)O_(4)(Fe^(2.5+)),ReBaFe_(2)O_(5)(Fe^(2.5+)),Fe_(3)O_(4)(Fe^(2.67+)),Re_(1/3)Sr_(2/3)FeO_(3)(Fe^(3.67+)),Re Cu_(3)Fe_(4)O_(12)(Fe^(3.75+)),and Ca_(1-x)Sr_(x)FeO_(3)(Fe^(4+))(where Re represents rare-earth elements).The common feature of MITs of these Fe-containing oxides is that they are usually accompanied by charge ordering transitions or disproportionation associated with the valence states of Fe.Herein,we review the material family of Fe-containing MIT oxides,their MIT functionalities,and their respective mechanisms.From the perspective of potentially correlated electronic applications,the tunability of the TMITand its resultant resistive change in Fe-containing oxides are summarized and further compared with those of other materials exhibiting MIT functionality.In particular,we highlight the abrupt MIT and wide tunability of TMITof Fe-containing quadruple perovskites,such as Re Cu3Fe4O12.However,their effective material synthesis still needs to be further explored to cater to potential applications.展开更多
The ultrasonic, magnetic and transport properties of Nd0.5Ca0.5Mn1-xAlxO3 (x=0, 0.03) were studied from 15 to 300 K. The temperature dependencies of resistivity and magnetization show that Nd0.5Ca0.5MnO3 undergoes a...The ultrasonic, magnetic and transport properties of Nd0.5Ca0.5Mn1-xAlxO3 (x=0, 0.03) were studied from 15 to 300 K. The temperature dependencies of resistivity and magnetization show that Nd0.5Ca0.5MnO3 undergoes a charge ordering transition at TCO-257 K. An obvious softening of the longitudinal sound velocity above TCO and a dramatic stiffening below Too accompanied by an attenuation peak were observed. These features imply a strong electron phonom interaction via the Jahn-Teller effect iu the sample, Another broad attenuation peak was observed at around Tp-80 K. This anomaly is attributed to the phase separtion between the antiferromagnetic (AFM) and paramagnetic (PM) phases and gives a direct evidence for spin-phonon coupling in the compound. For the x=0.03 sample, both the minimum of sound velocity and attenuation peaks shift to a lower temperature. The results indicate that the charge ordering and CE-type AFM state in Nd0.5Ca0.5MnO3 are both partially suppressed by replacing Mn with A1.展开更多
In recent years,fractional-order chaotic maps have been paid more attention in publications because of the memory effect.This paper presents a novel variable-order fractional sine map(VFSM)based on the discrete fracti...In recent years,fractional-order chaotic maps have been paid more attention in publications because of the memory effect.This paper presents a novel variable-order fractional sine map(VFSM)based on the discrete fractional calculus.Specially,the order is defined as an iterative function that incorporates the current state of the system.By analyzing phase diagrams,time sequences,bifurcations,Lyapunov exponents and fuzzy entropy complexity,the dynamics of the proposed map are investigated comparing with the constant-order fractional sine map.The results reveal that the variable order has a good effect on improving the chaotic performance,and it enlarges the range of available parameter values as well as reduces non-chaotic windows.Multiple coexisting attractors also enrich the dynamics of VFSM and prove its sensitivity to initial values.Moreover,the sequence generated by the proposed map passes the statistical test for pseudorandom number and shows strong robustness to parameter estimation,which proves the potential applications in the field of information security.展开更多
Understanding the drivers of variations in fine root lifespan is key to informing nutrient cycling and productivity in terrestrial ecosystems.However,the general patterns and determinants of forest fine root lifespan ...Understanding the drivers of variations in fine root lifespan is key to informing nutrient cycling and productivity in terrestrial ecosystems.However,the general patterns and determinants of forest fine root lifespan at the global scale are still limited.We compiled a dataset of 421 fine root lifespan observations from 76 tree species globally to assess phylogenetic signals among species,explored relationships between fine root lifespan and biotic and abiotic factors,and quantified the relative importance of phylogeny,root system structure and functions,climatic and edaphic factors in driving global fine root lifespan variations.Overall,fine root lifespan showed a clear phylogenetic signal,with gymnosperms having a longer fine root lifespan than angiosperms.Fine root lifespan was longer for evergreens than deciduous trees.Ectomycorrhizal(ECM)plants had an extended fine root lifespan than arbuscular mycorrhizal(AM)plants.Among different climatic zones,fine root lifespan was the longest in the boreal zone,while it did not vary between the temperate and tropical zone.Fine root lifespan increased with soil depth and root order.Furthermore,the analysis of relative importance indicated that phylogeny was the strongest driver influencing the variation in forest fine root lifespan,followed by soil clay content,root order,mean annual temperature,and soil depth,while other environmental factors and root traits exerted weaker effects.Our results suggest that the global pattern of fine root lifespan in forests is shaped by the interplay of phylogeny,root traits and environmental factors.These findings necessitate accurate representations of tree evolutionary history in earth system models to predict fine root longevity and its responses to global changes.展开更多
文摘We study the effect of particle size polydispersity(δ) on the melting transition(T*), local ordering, solid–liquid coexistence phase and dynamics of two-dimensional Lennard–Jones fluids up to moderate polydispersity by means of computer simulations. The particle sizes are drawn at random from the Gaussian(G) and uniform(U) distribution functions.For these systems, we further consider two different kinds of particles, viz., particles having the same mass irrespective of size, and in the other case the mass of the particle scales with its size. It is observed that with increasing polydispersity,the value of T*initially increases due to improved packing efficiency(φ) followed by a decrease and terminates at δ ≈8%(U-system) and 14%(G-system) with no significant difference for both mass types. The interesting observation is that the particular value at which φ drops suddenly coincides with the peak of the heat capacity(CP) curve, indicating a transition. The quantification of local particle ordering through the hexatic order parameter(Q_6), Voronoi construction and pair correlation function reveals that the ordering decreases with increasing δ and T. Furthermore, the solid–liquid coexistence region for the G-system is shown to be comparatively wider in the T –δ plane phase diagram than that for the U system. Finally, the study of dynamics reveals that polydisperse systems relax faster compared to monodisperse systems;however, no significant qualitative differences, depending on the distribution type and mass polydispersity, are observed.
基金funding supports from the National Key R&D Program of China(Grant Nos.2022YFB2404400 and 2019YFA0308500)Beijing Natural Science Foundation(Z190010)National Natural Science Foundation of China(Grant Nos.51991344,52025025,52072400,and 52002394)。
文摘Understanding the structural origin of the competition between oxygen 2p and transition-metal 3d orbitals in oxygen-redox(OR)layered oxides is eminently desirable for exploring reversible and high-energy-density Li/Na-ion cathodes.Here,we reveal the correlation between cationic ordering transition and OR degradation in ribbon-ordered P3-Na_(0.6)Li_(0.2)Mn_(0.8)O_(2) via in situ structural analysis.Comparing two different voltage windows,the OR capacity can be improved approximately twofold when suppressing the in-plane cationic ordering transition.We find that the intralayer cationic migration is promoted by electrochemical reduction from Mn^(4+)to Jahn–Teller Mn^(3+)and the concomitant NaO_(6) stacking transformation from triangular prisms to octahedra,resulting in the loss of ribbon ordering and electrochemical decay.First-principles calculations reveal that Mn^(4+)/Mn^(3+)charge ordering and alignment of the degenerate eg orbital induce lattice-level collective Jahn–Teller distortion,which favors intralayer Mn-ion migration and thereby accelerates OR degradation.These findings unravel the relationship between in-plane cationic ordering and OR reversibility and highlight the importance of superstructure protection for the rational design of reversible OR-active layered oxide cathodes.
基金supported by the National Natural Science Foundation of China(Nos.12174208 and 32227802)National Key Research and Development Program of China(No.2022YFC3400600)+2 种基金Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030009)Fundamental Research Funds for the Central Universities(Nos.2122021337 and 2122021405)the 111 Project(No.B23045).
文摘Collective cell migration is a coordinated movement of multi-cell systems essential for various processes throughout life.The collective motions often occur under spatial restrictions,hallmarked by the collective rotation of epithelial cells confined in circular substrates.Here,we aim to explore how geometric shapes of confinement regulate this collective cell movement.We develop quantitative methods for cell velocity orientation analysis,and find that boundary cells exhibit stronger tangential ordering migration than inner cells in circular pattern.Furthermore,decreased tangential ordering movement capability of collective cells in triangular and square patterns are observed,due to the disturbance of cell motion at unsmooth corners of these patterns.On the other hand,the collective cell rotation is slightly affected by a convex defect of the circular pattern,while almost hindered with a concave defect,also resulting from different smoothness features of their boundaries.Numerical simulations employing cell Potts model well reproduce and extend experimental observations.Together,our results highlight the importance of boundary smoothness in the regulation of collective cell tangential ordering migration.
基金supported by National Natural Science Foundation of China,China(No.51901117,51801116)Youth Innovation and Technology Support Program of Shandong Provincial Colleges and Universities,China(No.2020KJA002)+2 种基金Youth Fund of Shandong Academy of Sciences,China(2020QN0021)Innovation Pilot Project for Fusion of Science,Education and Industry(International Cooperation)from Qilu University of Technology(Shandong Academy of Sciences),China(No.2020KJC-GH03)Several Policies on Promoting Collaborative Innovation and Industrialization of Achievements in Universities and Research Institutes,China(No.2019GXRC030)。
文摘In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy,the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of ab-initio molecular dynamics simulation.In liquid Mg-rich Mg-Y alloys,the strong Mg-Y interaction is determined,which promotes the formation of fivefold symmetric local structure.For Mg-Zn alloys,the weak Mg-Zn interaction results in the fivefold symmetry weakening in the liquid structure.Due to the coexistence of Y and Zn,the strong attractive interaction is introduced in liquid Mg-Y-Zn ternary alloy,and contributes to the clustering of Mg,Y,Zn launched from Zn.What is more,the distribution of local structures becomes closer to that in pure Mg compared with that in binary Mg-Y and Mg-Zn alloys.These results should relate to the origins of the Y/Zn segregation zone and close-packed stacking mode in LPSO structure,which provides a new insight into the formation mechanism of LPSO structure at atomic level.
基金financially supported by the National Natural Science Foundation of China(Nos.51971017,52271003,52071024,52001184,and 52101188)the National Science Fund for distinguished Young Scholars,China(No.52225103)+3 种基金the Funds for Creative Research Groups of China(No.51921001)the National Key Research and Development Program of China(No.2022YFB4602101)the Projects of International Cooperation and Exchanges NSFC(No.52061135207)the Fundamental Research Funds for the Central Universities,China(No.FRF-TP-22-130A1)。
文摘Short-range ordering(SRO)is one of the most important structural features of high entropy alloys(HEAs).However,the chemical and structural analyses of SROs are very difficult due to their small size,complexed compositions,and varied locations.Transmission electron microscopy(TEM)as well as its aberration correction techniques are powerful for characterizing SROs in these compositionally complex alloys.In this short communication,we summarized recent progresses regarding characterization of SROs using TEM in the field of HEAs.By using advanced TEM techniques,not only the existence of SROs was confirmed,but also the effect of SROs on the deformation mechanism was clarified.Moreover,the perspective related to application of TEM techniques in HEAs are also discussed.
基金The authors would like to acknowledge the financial supports from the National Natural Science Foundation of China[grant number 11274027]Beijing Municipal Natural Science Foundation[grant number 2092005].
文摘The formation and evolution of Gd-rich precipitates companying with the matrix structure ordering in a Mg_(97)Gd_(2)Cd_(1)(at.%)solid-solution alloy aged at 200℃have been systemically investigated using high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM).The results show that Gd-rich precipitation dynamics during the aging treatment are noticeably affected by a continuous ordering transformation in the matrix.The ordering transformation process involving mainly re-distribution of Cd atoms was revealed to occur in the following way:random super-saturated solid solution(S.S.S.S.)→B19-type ordered domains→D019-type ordered domains.Four Gd(Cd)-rich precipitates,G.P.Ⅰ zone,G.P.Ⅱ zone,β′andβ_(1)phases,have been observed to be formed in sequence to coexist with the various ordered domains.Based on the HAADF-STEM characterization on the aging microstructures at different aging stages,it can be concluded that the Cd-addition and related matrix structure ordering can play significant roles in modifying the early-stage G.P.zone structure,altering the morphology ofβ′precipitates and promoting the forming ability of theβ_(1)precipitate.
基金Project supported by the National Natural Science Foundation of China(Grant No.11775208)the Foundation for Young Talents in College of Anhui Province,China(Grant Nos.gxyq2021210 and gxyq2019077)the Natural Science Foundation of the Anhui Higher Education Institutions of China(Grant Nos.KJ2020A0638 and 2022AH051586)。
文摘The development of quantum optics theory based on the method of integration within an ordered product of operators(IWOP)has greatly stimulated the study of quantum states in the light field,especially non-Gaussian states with various non-classical properties.In this paper,the two-mode squeezing operator is derived with integral theory within the Weyl ordering product of operators using a combinatorial field in which one mode is a chaotic field and the other mode is a vacuum field.The density operator of the new light field,its entanglement property and photon number distribution are analyzed.We also note that tracing a three-mode pure state can yield this new light field.These methods represent a theoretical approach to investigating new density operators of light fields.
基金Project supported by the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.11704091)the Open Project of Guangxi Key Laboratory of Nuclear Physics and Nuclear Technology(Grant No.NLK2021-10)the Open Project of Key Laboratory of Novel Materials for Sensor of Zhejiang Province,China(Grant No.ZJKLNMS2021010)。
文摘Materials with strongly coupled magnetic and electronic degrees of freedom provide new possibilities for practical applications.In this paper,we have investigated the structure,magnetic property,and magnetodielectric(MD) effect in Ho_(2)Cu_(2)O_(5) and Yb_(2)Cu_(2)O_(5) poly crystalline samples,which possess a non-centrosymmetric polar structure with space group Pna2_(1).In Ho_(2)Cu_(2)O_(5),Ho^(3+) and Cu^(2+) sublattices order simultaneously,exhibiting a typical paramagnetic to antiferromagnetic transition at 13.1 K.While for Yb_(2)Cu_(2)O_(5),two magnetic transitions which originate from the orderings of Yb^(3+)(7.8 K) and Cu^(2+)(13.5 K) sublattices are observed.A magnetic field induced metamagnetic transition is obtained in these two cuprates below Neel temperature(T_(N)).By means of dielectric measurement,distinct MD effect is demonstrated by the dielectric anomaly at T_(N.)Meanwhile,the MD effect is found to be directly related to the metamagnetic transition.Due to the specific spin configuration and different spin evolution in the magnetic field,a positive MD effect is formed in Ho_(2)Cu_(2)O_(5),and a negative one is observed in Yb_(2)Cu_(2)O_(5).The spontaneous dielectric anomaly at T_(N) is regarded as arising from the shifts in optical phonon frequencies,and the magnetoelectric coupling is used to interpret the magnetic field induced MD effect.Moreover,an H-T phase diagram is constructed for Ho_(2)Cu_(2)O_(5) and Yb_(2)Cu_(2)O_(5) based on the results of isothermal magnetic and dielectric hysteresis loops.
基金Project(51071181)supported by the National Natural Science Foundation of ChinaProject(2013FJ4043)supported by the Natural Science Foundation of Hunan Province,China
文摘Taking experimental path on disordering AuCuI(AAuCu8A4)composed of A Au8 and ACu4 stem alloy genes as an example, three discoveries and a method were presented. The ability of Au Cu I(AAu Cu8 A4)to keep structure stabilization against changing temperature is attributed to the fact that the AAu8 and ACu4 potential well depths greatly surpass their vibration energies, which leads to the subequilibrium of experimental path. A new atom movement mechanism of AuCuI(AAuACu84)to change structure for suiting variation in temperature is the resonance activating-synchro alternating of alloy genes, which leads to heterogeneous and successive subequilibrium transitions. There exists jumping order degree, which leads to the existence of jumping Tj-temperature and an unexpected so-called "retro-effect" about jumping temperature retrograde shift to lower temperatures upon the increasing heating rate. A set of subequilibrium holographic network path charts were obtained by the experimental mixed enthalpy path method.
基金supported by the National Natural Science Foundation of China(21972131)。
文摘In this study,we systematically investigated the effect of proton concentration on the kinetics of the oxygen reduction reaction(ORR)on Pt(111)in acidic solutions.Experimental results demonstrate a rectangular hyperbolic relationship,i.e.,the ORR current excluding the effect of other variables increases with proton concentration and then tends to a constant value.We consider that this is caused by the limitation of ORR kinetics by the trace oxygen concentration in the solution,which determines the upper limit of ORR kinetics.A model of effective concentration is further proposed for rectangular hyperbolic relationships:when the reactant concentration is high enough to reach a critical saturation concentration,the effective reactant concentration will become a constant value.This could be due to the limited concentration of a certain reactant for reactions involving more than one reactant or the limited number of active sites available on the catalyst.Our study provides new insights into the kinetics of electrocatalytic reactions,and it is important for the proper evaluation of catalyst activity and the study of structureperformance relationships.
基金R.Ma thanks the support from PolyU Distinguished Postdoc Fellowship(1-YW4C)Z.Luo thanks the National Natural Science Foundation of China(NSFC,No.22309119)+7 种基金J.Wu thanks the Guangdong government and the Guangzhou government for funding(2021QN02C110)the Guangzhou Municipal Science and Technology Project(No.2023A03J0097 and 2023A03J0003)H.Yan appreciates the support from the National Key Research and Development Program of China(No.2019YFA0705900)funded by MOST,the Basic and Applied Research Major Program of Guangdong Province(No.2019B030302007)the Shen Zhen Technology and Innovation Commission through(Shenzhen Fundamental Research Program,JCYJ20200109140801751)the Hong Kong Research Grants Council(research fellow scheme RFS2021-6S05,RIF project R6021-18,CRF project C6023‐19G,GRF project 16310019,16310020,16309221,and 16309822)Hong Kong Innovation and Technology Commission(ITC‐CNERC14SC01)Foshan‐HKUST(Project NO.FSUST19‐CAT0202)Zhongshan Municipal Bureau of Science and Technology(NO.ZSST20SC02)and Tencent Xplorer Prize。
文摘With plenty of popular and effective ternary organic solar cells(OSCs)construction strategies proposed and applied,its power conversion efficiencies(PCEs)have come to a new level of over 19%in single-junction devices.However,previous studies are heavily based in chloroform(CF)leaving behind substantial knowledge deficiencies in understanding the influence of solvent choice when introducing a third component.Herein,we present a case where a newly designed asymmetric small molecular acceptor using fluoro-methoxylated end-group modification strategy,named BTP-BO-3FO with enlarged bandgap,brings different morphological evolution and performance improvement effect on host system PM6:BTP-eC9,processed by CF and ortho-xylene(o-XY).With detailed analyses supported by a series of experiments,the best PCE of 19.24%for green solvent-processed OSCs is found to be a fruit of finely tuned crystalline ordering and general aggregation motif,which furthermore nourishes a favorable charge generation and recombination behavior.Likewise,over 19%PCE can be achieved by replacing spin-coating with blade coating for active layer deposition.This work focuses on understanding the commonly met yet frequently ignored issues when building ternary blends to demonstrate cutting-edge device performance,hence,will be instructive to other ternary OSC works in the future.
基金supported by the research foundation of Institute for Advanced Sciences of CQUPT(Grant No.E011A2022328)。
文摘We theoretically investigate the Ruderman–Kittel–Kasuya–Yosida(RKKY) interaction in helical higher-order topological insulators(HOTIs), revealing distinct behaviors mediated by hinge and Dirac-type bulk carriers. Our findings show that hinge-mediated interactions consist of Heisenberg, Ising, and Dzyaloshinskii–Moriya(DM) terms, exhibiting a decay with impurity spacing z and oscillations with Fermi energy εF. These interactions demonstrate ferromagnetic behaviors for the Heisenberg and Ising terms and alternating behavior for the DM term. In contrast, bulk-mediated interactions include Heisenberg, twisted Ising, and DM terms, with a conventional cubic oscillating decay. This study highlights the nuanced interplay between hinge and bulk RKKY interactions in HOTIs, offering insights into designs of next-generation quantum devices based on HOTIs.
基金the financial support provided by ANR(Project ANR-22-PEHY-0007)DGA(French Direction Générale des Armées,2018600045)Région Nouvelle Aquitaine(agreement 2018–1R10126).
文摘The long-period-stacking-ordered(LPSO)structure affects the mechanical,corrosion and hydrolysis properties of Mg alloys.The current work employs high angle annular dark field-scanning transmission electron microscopy(HAADF-STEM)and atom probe tomography(APT)to investigate the structural and local chemical information of LPSO phases formed in Mg-Ni-Y/Sm ternary alloys after extended isothermal annealing.Depending on the alloying elements and their concentrations,Mg-Ni-Y/Sm develops a two-phase LPSO+α-Mg structure in which the LPSO phase contains defects,hybrid LPSO structure,and Mg insertions.HAADF-STEM and APT indicate non-stoichiometric LPSO with incomplete Ni_(6)(Y/Sm)_(8) clusters.In addition,the APT quantitatively determines the local composition of LPSO and confirms the presence of Ni within the Mg bonding layers.These results provide insight into a better understanding of the structure and hydrolysis properties of LPSO-Mg alloys.
基金financially supported by the National Key Research and Development Program of China (No.2021YFA0718900)the National Natural Science Foundation of China (No.62074014)the Xiaomi Scholar project。
文摘Metal-to-insulator transitions (MITs),which are achieved in 3d-band correlated transitional metal oxides,trigger abrupt variations in electrical,optical,and/or magnetic properties beyond those of conventional semiconductors.Among such material families,iron(Fe:3d^(6)4s^(2))-containing oxides pique interest owing to their widely tunable MIT properties,which are associated with the various valence states of Fe.Their potential electronic applications also show promise,given the large abundance of Fe on Earth.Representative MIT properties triggered by critical temperature (TMIT) were reported for ReFe_(2)O_(4)(Fe^(2.5+)),ReBaFe_(2)O_(5)(Fe^(2.5+)),Fe_(3)O_(4)(Fe^(2.67+)),Re_(1/3)Sr_(2/3)FeO_(3)(Fe^(3.67+)),Re Cu_(3)Fe_(4)O_(12)(Fe^(3.75+)),and Ca_(1-x)Sr_(x)FeO_(3)(Fe^(4+))(where Re represents rare-earth elements).The common feature of MITs of these Fe-containing oxides is that they are usually accompanied by charge ordering transitions or disproportionation associated with the valence states of Fe.Herein,we review the material family of Fe-containing MIT oxides,their MIT functionalities,and their respective mechanisms.From the perspective of potentially correlated electronic applications,the tunability of the TMITand its resultant resistive change in Fe-containing oxides are summarized and further compared with those of other materials exhibiting MIT functionality.In particular,we highlight the abrupt MIT and wide tunability of TMITof Fe-containing quadruple perovskites,such as Re Cu3Fe4O12.However,their effective material synthesis still needs to be further explored to cater to potential applications.
基金supported by the National Natural Science Foundation of China(No.10274075)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20030358056).
文摘The ultrasonic, magnetic and transport properties of Nd0.5Ca0.5Mn1-xAlxO3 (x=0, 0.03) were studied from 15 to 300 K. The temperature dependencies of resistivity and magnetization show that Nd0.5Ca0.5MnO3 undergoes a charge ordering transition at TCO-257 K. An obvious softening of the longitudinal sound velocity above TCO and a dramatic stiffening below Too accompanied by an attenuation peak were observed. These features imply a strong electron phonom interaction via the Jahn-Teller effect iu the sample, Another broad attenuation peak was observed at around Tp-80 K. This anomaly is attributed to the phase separtion between the antiferromagnetic (AFM) and paramagnetic (PM) phases and gives a direct evidence for spin-phonon coupling in the compound. For the x=0.03 sample, both the minimum of sound velocity and attenuation peaks shift to a lower temperature. The results indicate that the charge ordering and CE-type AFM state in Nd0.5Ca0.5MnO3 are both partially suppressed by replacing Mn with A1.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62071496,61901530,and 62061008)the Natural Science Foundation of Hunan Province of China(Grant No.2020JJ5767).
文摘In recent years,fractional-order chaotic maps have been paid more attention in publications because of the memory effect.This paper presents a novel variable-order fractional sine map(VFSM)based on the discrete fractional calculus.Specially,the order is defined as an iterative function that incorporates the current state of the system.By analyzing phase diagrams,time sequences,bifurcations,Lyapunov exponents and fuzzy entropy complexity,the dynamics of the proposed map are investigated comparing with the constant-order fractional sine map.The results reveal that the variable order has a good effect on improving the chaotic performance,and it enlarges the range of available parameter values as well as reduces non-chaotic windows.Multiple coexisting attractors also enrich the dynamics of VFSM and prove its sensitivity to initial values.Moreover,the sequence generated by the proposed map passes the statistical test for pseudorandom number and shows strong robustness to parameter estimation,which proves the potential applications in the field of information security.
基金provided by the National Key R&D Program of China(2023YFD2200904)the Scientific Research Project of Anhui Province(2022AH050873)+1 种基金the State Key Laboratory of Subtropical Silviculture(SKLSS-KF2023-08)the Anhui Provincial Science and Technology Special Project(202204c06020014)。
文摘Understanding the drivers of variations in fine root lifespan is key to informing nutrient cycling and productivity in terrestrial ecosystems.However,the general patterns and determinants of forest fine root lifespan at the global scale are still limited.We compiled a dataset of 421 fine root lifespan observations from 76 tree species globally to assess phylogenetic signals among species,explored relationships between fine root lifespan and biotic and abiotic factors,and quantified the relative importance of phylogeny,root system structure and functions,climatic and edaphic factors in driving global fine root lifespan variations.Overall,fine root lifespan showed a clear phylogenetic signal,with gymnosperms having a longer fine root lifespan than angiosperms.Fine root lifespan was longer for evergreens than deciduous trees.Ectomycorrhizal(ECM)plants had an extended fine root lifespan than arbuscular mycorrhizal(AM)plants.Among different climatic zones,fine root lifespan was the longest in the boreal zone,while it did not vary between the temperate and tropical zone.Fine root lifespan increased with soil depth and root order.Furthermore,the analysis of relative importance indicated that phylogeny was the strongest driver influencing the variation in forest fine root lifespan,followed by soil clay content,root order,mean annual temperature,and soil depth,while other environmental factors and root traits exerted weaker effects.Our results suggest that the global pattern of fine root lifespan in forests is shaped by the interplay of phylogeny,root traits and environmental factors.These findings necessitate accurate representations of tree evolutionary history in earth system models to predict fine root longevity and its responses to global changes.