Silicon dioxide(SiO)is regarded as a promising anode candidate for high-energy-density lithium-ion batteries(LIBs)owing to its superior theoretical specific capacity.However,SiO anodes encounter substantial challenges...Silicon dioxide(SiO)is regarded as a promising anode candidate for high-energy-density lithium-ion batteries(LIBs)owing to its superior theoretical specific capacity.However,SiO anodes encounter substantial challenges,including substantial volume expansion and persistent growth of a thick solid electrolyte interphase(SEI).In this work,a composite conductive network with dual pinning and piezoelectric effects is proposed,which is cleverly designed to improve the electrochemical reaction kinetics of the electrode.Within the proposed network architecture,single-walled carbon nanotubes(CNTs)serve as fast electronic conductors and structural protective layers,forming a three-dimensional(3D)coating network on the surface of SiO particles.Barium titanate(BTO)nanoparticles are anchored at the nodes of the CNT network through the formation of rigid anchor points,dispersing stress throughout the network.Concurrently,mechanical stress induced by electrochemical reactions prompts BTO to generate a local electric field,facilitating Li+transport.Consequently,the developed anode(SiO@PCB)demonstrates remarkable electrochemical performance in LIBs,exhibiting a capacity retention rate of 94%even after 500 cycles at 1 A g-1.Furthermore,a capacity retention of 71.6%is demonstrated by SiO@PCB anode after 1000 cycles at 5 C in sulfide-based all-solid-state LIBs using an NCM83 cathode.This composite conductive network structure provides an effective guidance plan for achieving interface stability and long-term lithium storage of Si-based anodes.展开更多
TFlux dynamics,which describes the behavior of magnetic vortices in type-Ⅱsuperconductors,governs macroscopic electromagnetic properties of superconducting materials.Recently,cutting-edge approaches utilizing artific...TFlux dynamics,which describes the behavior of magnetic vortices in type-Ⅱsuperconductors,governs macroscopic electromagnetic properties of superconducting materials.Recently,cutting-edge approaches utilizing artificial periodic nanostructures for active control of the pinning centers help to deepen the understanding of relevant mechanisms of flux dynamics.This study demonstrates the controlled introduction of large-scale,periodic artificial pinning centers(APCs)in MgB2 superconducting thin films to manipulate flux dynamics.Using focused helium ion beam(He-FIB)irradiation,we fabricated a square array of nanoscale columnar artificial pinning centers with a period of 100 nm on a 30 nm MgB2 superconducting thin film.Magnetoresistance measurements near the critical temperature(Tc)reveal a pronounced vortex matching effect,evidenced by sharp resistance minima(dips)at specific integer and fractional magnetic matching fields.This effect is shown to be highly dependent on external parameters such as temperature,driving current,and the angle of the magnetic field.Furthermore,the large-area irradiation systematically suppresses Tcand broadens the superconducting transition of the film.This work establishes He-FIB as a potent tool for advanced flux pinning engineering and provides a comprehensive understanding of flux dynamics in superconductors with periodic pinning landscapes.展开更多
Plant growth depends on tightly coordinated auxin signaling and directional auxin transport,yet the molecular feedback mechanism that directly links these processes during root gravitropism has remained mechanisticall...Plant growth depends on tightly coordinated auxin signaling and directional auxin transport,yet the molecular feedback mechanism that directly links these processes during root gravitropism has remained mechanistically unresolved.The recent study by Rodriguez et al.(Cell,2025)reveals a novel cell-surface auxin signaling pathway.It is shown that gravity perception-induced initial auxin asymmetry activates transmembrane kinase 1(TMK1)in the lower side cells of the root.The activated TMK1 then interacts with pin-formed 2(PIN2)and phosphorylates its hydrophilic loop,thereby stabilizing the PIN2 protein.This asymmetric distribution of PIN2 further enhances the auxin flow on the lower side,thus forming a self-reinforcing positive feedback loop that drives force for root tip gravitropic bending.This study provides an updated perspective on the auxin signal and transport feedback,signifying a new advancement in our comprehension of the mechanisms underlying plant adaptive growth.展开更多
Although introducing second phase particles as additional pinning centers is an effective method to improve the current carrying capacity of MgB2,the thermal strain caused by second phase particles in MgB2 and t...Although introducing second phase particles as additional pinning centers is an effective method to improve the current carrying capacity of MgB2,the thermal strain caused by second phase particles in MgB2 and their impact on flux pinning have not received much attention.In this paper,flux pinning behavior of the thermal strain induced by the second phase particles in the MgB2 bulk materials was studied by doping ZrW2O8 particles which have negative thermal expansion(NTE)characteristics.Due to the significant difference in thermal expansion characters between ZrW2O8 and MgB2,drastic thermal strain was induced in the lattice of MgB2 by doping the NTE-ZrW2O8 particles.These strains work as additional flux pinning centers and significantly enhance the irreversibility field,Hirr,and critical current density,Jc,of the MgB2.Taking Jc as an example,at 4.2 K and 5 T,its Jc value reaches 4.1×104 A/cm2,which is a 105% performance improvement compared to the 2.0×104 A/cm2 of the pure MgB2 sample W-0;at 20 K and 2 T,its Jc also reaches 1.3×105 A/cm2,which is 1.78 times of the 7.3×104 A/cm2 for the pure MgB2 sample under the same conditions.It is interesting that doping ZrW2O8 does not significantly change the scaling behavior of the pinning force,indicating that the lattice strain work like surficial pinning center,while the point defect pinning center initiated by ZrW2O8 particles themselves may only contribute to the high field region,causing the peak in the pinning force scaling curve to shift towards higher fields.展开更多
We report on a systematic investigation of the effects of columnar defects induced by heavy ion irradiation in YBa2Cu3O7-δthin films.The study encompasses their structural characterization by transmission el...We report on a systematic investigation of the effects of columnar defects induced by heavy ion irradiation in YBa2Cu3O7-δthin films.The study encompasses their structural characterization by transmission electron microscopy imaging(HAADF-STEM)and their impact on the vortex-pinning parameters,determined in the microwave frequency range by a coplanar waveguide resonator(CPWR)technique.The films were irradiated with 1.15-GeV Pb ions,and the resulting columnar defects revealed a core-shell structure with an amorphous core surrounded by a strained crystalline shell.Statistical analysis(considering any cluster as an individual defect)yield a mean column radius of r=6nm,which is in remarkable agreement with the radius of the confinement region obtained from fitting the irreversibility line within the Bose-glass model,r0=5.8nm,providing strong experimental validation of the functional characterization through direct structural imaging.The core of the analysis lies in the determination of the main superconducting parameters(such as the penetration depth)and the vortex dynamics and pinning parameters-including the pinning constant,viscosity,depinning and crossover frequencies,creep factor,and pinning energy-through the CPWR microwave technique.These parameters are analyzed and discussed within the theoretical frameworks proposed by Gittleman-Rosenblum,Coffey-Clem,and Blatter et al.Overall,columnar defects were found to enhance the pinning efficiency and,consequently,the critical current density jc and its ratio to the depairing current density,jc/j0.To determine their absolute values,a comparative analysis was carried out by combining results from the different experimental techniques with a theoretical treatment of jc/j0as a function of the STEM-measured column radius.All results converge into a consistent framework,yielding jc(5K,1T)=8.8·1011Am-2and jc/j0=0.34 for the YBCO films with irradiation-induced columnar defects.展开更多
Intrinsic properties of Fe(Se,Te),such as the high value of the upper critical field as well as the weaker dependence of the critical current density(Jc)on the grain misalignment than in cuprate superconductors,mak...Intrinsic properties of Fe(Se,Te),such as the high value of the upper critical field as well as the weaker dependence of the critical current density(Jc)on the grain misalignment than in cuprate superconductors,make this compound a promising candidate for the fabrication of high-field superconducting magnets.On the other hand,irradiation was demonstrated to be a powerful tool for tuning the pinning properties in superconducting materials.In this paper,we investigate the effect of 230 MeV Au-ion irradiation on Jc and pinning force(Fp)of biaxially-oriented Fe(Se,Te)films grown on YSZ substrate buffered with a thin Zr-doped CeO2 epitaxial layer.This structure is interesting as it can be considered a precursor template for Fe(Se,Te)coated conductors.The irradiation produces correlated defects,which-on transmission electron microscope analysis-appear as slightly meandering tracks composed of dislocation chains placed parallel to the c-axis of the crystal lattice.The Jc measurements as a function of the applied magnetic field evidence an improvement at low temperatures,with a maximum modulated in both position and height by the irradiation fluence.In the same range of temperature,the development of the irradiation tracks strongly reduces the anisotropy of the critical current density by varying the applied field orientation.Likewise,the Fp analysis highlights that irradiation defects behave as twodimensional extended defects,which strengthen the point-pinning landscape active before irradiation.Conversely,approaching the transition temperature,the effectiveness of the irradiation-induced defects decreases and a widespread Jc and Fp worsening occurs.展开更多
摘要Silicon dioxide(SiO)is regarded as a promising anode candidate for high-energy-density lithium-ion batteries(LIBs)owing to its superior theoretical specific capacity.However,SiO anodes encounter substantial challenges,including substantial volume expansion and persistent growth of a thick solid electrolyte interphase(SEI).In this work,a composite conductive network with dual pinning and piezoelectric effects is proposed,which is cleverly designed to improve the electrochemical reaction kinetics of the electrode.Within the proposed network architecture,single-walled carbon nanotubes(CNTs)serve as fast electronic conductors and structural protective layers,forming a three-dimensional(3D)coating network on the surface of SiO particles.Barium titanate(BTO)nanoparticles are anchored at the nodes of the CNT network through the formation of rigid anchor points,dispersing stress throughout the network.Concurrently,mechanical stress induced by electrochemical reactions prompts BTO to generate a local electric field,facilitating Li+transport.Consequently,the developed anode(SiO@PCB)demonstrates remarkable electrochemical performance in LIBs,exhibiting a capacity retention rate of 94%even after 500 cycles at 1 A g-1.Furthermore,a capacity retention of 71.6%is demonstrated by SiO@PCB anode after 1000 cycles at 5 C in sulfide-based all-solid-state LIBs using an NCM83 cathode.This composite conductive network structure provides an effective guidance plan for achieving interface stability and long-term lithium storage of Si-based anodes.
基金supported by the National Natural Science Foundation of China(Grant No.12104016)the Natural Science Foundation of Beijing,China(Grant No.2244106)+1 种基金the National Key Research and Development Program of China(Grant Nos.2020YFF01014706 and 2021YFB3800201)the Peking University Funding on“Instrument Innovation and Key Technology R&D”(Grant No.2024)。
摘要TFlux dynamics,which describes the behavior of magnetic vortices in type-Ⅱsuperconductors,governs macroscopic electromagnetic properties of superconducting materials.Recently,cutting-edge approaches utilizing artificial periodic nanostructures for active control of the pinning centers help to deepen the understanding of relevant mechanisms of flux dynamics.This study demonstrates the controlled introduction of large-scale,periodic artificial pinning centers(APCs)in MgB2 superconducting thin films to manipulate flux dynamics.Using focused helium ion beam(He-FIB)irradiation,we fabricated a square array of nanoscale columnar artificial pinning centers with a period of 100 nm on a 30 nm MgB2 superconducting thin film.Magnetoresistance measurements near the critical temperature(Tc)reveal a pronounced vortex matching effect,evidenced by sharp resistance minima(dips)at specific integer and fractional magnetic matching fields.This effect is shown to be highly dependent on external parameters such as temperature,driving current,and the angle of the magnetic field.Furthermore,the large-area irradiation systematically suppresses Tcand broadens the superconducting transition of the film.This work establishes He-FIB as a potent tool for advanced flux pinning engineering and provides a comprehensive understanding of flux dynamics in superconductors with periodic pinning landscapes.
基金supported by the National Natural Science Foundation of China(32372599)the Agricultural Science and Technology Innovation Program(No.CAAS-BRC-GLCA-2025-01).
摘要Plant growth depends on tightly coordinated auxin signaling and directional auxin transport,yet the molecular feedback mechanism that directly links these processes during root gravitropism has remained mechanistically unresolved.The recent study by Rodriguez et al.(Cell,2025)reveals a novel cell-surface auxin signaling pathway.It is shown that gravity perception-induced initial auxin asymmetry activates transmembrane kinase 1(TMK1)in the lower side cells of the root.The activated TMK1 then interacts with pin-formed 2(PIN2)and phosphorylates its hydrophilic loop,thereby stabilizing the PIN2 protein.This asymmetric distribution of PIN2 further enhances the auxin flow on the lower side,thus forming a self-reinforcing positive feedback loop that drives force for root tip gravitropic bending.This study provides an updated perspective on the auxin signal and transport feedback,signifying a new advancement in our comprehension of the mechanisms underlying plant adaptive growth.
基金financial support of the National Natural Science Foundation of China(Grant No 52277023)the National Key Research and Development Plan of China(2017YFE0301401)the Fujian Normal University for the financial support of the talent project.
摘要Although introducing second phase particles as additional pinning centers is an effective method to improve the current carrying capacity of MgB2,the thermal strain caused by second phase particles in MgB2 and their impact on flux pinning have not received much attention.In this paper,flux pinning behavior of the thermal strain induced by the second phase particles in the MgB2 bulk materials was studied by doping ZrW2O8 particles which have negative thermal expansion(NTE)characteristics.Due to the significant difference in thermal expansion characters between ZrW2O8 and MgB2,drastic thermal strain was induced in the lattice of MgB2 by doping the NTE-ZrW2O8 particles.These strains work as additional flux pinning centers and significantly enhance the irreversibility field,Hirr,and critical current density,Jc,of the MgB2.Taking Jc as an example,at 4.2 K and 5 T,its Jc value reaches 4.1×104 A/cm2,which is a 105% performance improvement compared to the 2.0×104 A/cm2 of the pure MgB2 sample W-0;at 20 K and 2 T,its Jc also reaches 1.3×105 A/cm2,which is 1.78 times of the 7.3×104 A/cm2 for the pure MgB2 sample under the same conditions.It is interesting that doping ZrW2O8 does not significantly change the scaling behavior of the pinning force,indicating that the lattice strain work like surficial pinning center,while the point defect pinning center initiated by ZrW2O8 particles themselves may only contribute to the high field region,causing the peak in the pinning force scaling curve to shift towards higher fields.
基金support from INFN-CSN5 under the SAMARA and SuperMAD experimentsprovided by the Italian Infrastruc-ture Beyond-Nano UPGRADE-Materials and processes Beyond the Nanoscale。
摘要We report on a systematic investigation of the effects of columnar defects induced by heavy ion irradiation in YBa2Cu3O7-δthin films.The study encompasses their structural characterization by transmission electron microscopy imaging(HAADF-STEM)and their impact on the vortex-pinning parameters,determined in the microwave frequency range by a coplanar waveguide resonator(CPWR)technique.The films were irradiated with 1.15-GeV Pb ions,and the resulting columnar defects revealed a core-shell structure with an amorphous core surrounded by a strained crystalline shell.Statistical analysis(considering any cluster as an individual defect)yield a mean column radius of r=6nm,which is in remarkable agreement with the radius of the confinement region obtained from fitting the irreversibility line within the Bose-glass model,r0=5.8nm,providing strong experimental validation of the functional characterization through direct structural imaging.The core of the analysis lies in the determination of the main superconducting parameters(such as the penetration depth)and the vortex dynamics and pinning parameters-including the pinning constant,viscosity,depinning and crossover frequencies,creep factor,and pinning energy-through the CPWR microwave technique.These parameters are analyzed and discussed within the theoretical frameworks proposed by Gittleman-Rosenblum,Coffey-Clem,and Blatter et al.Overall,columnar defects were found to enhance the pinning efficiency and,consequently,the critical current density jc and its ratio to the depairing current density,jc/j0.To determine their absolute values,a comparative analysis was carried out by combining results from the different experimental techniques with a theoretical treatment of jc/j0as a function of the STEM-measured column radius.All results converge into a consistent framework,yielding jc(5K,1T)=8.8·1011Am-2and jc/j0=0.34 for the YBCO films with irradiation-induced columnar defects.
基金support from MUR funded PRIN project HIBiSCUS 201785KWLE,from the Joint Research Agreement Eni-CNR,from INFN-CSN5 under the experiment SuperMAD,from the project Space It Up funded by the Italian Space Agency,ASI,and the Ministry of University and Research,MUR,under Contract No.2024-5-E.0-CUP n.I53D24000060005from the project NODES,which has received funding from the MUR-M4C21.5 of PNRR funded by the European Union-NextGenerationEU(Grant agreement no.ECS00000036)provided by the Italian Infrastructure Beyond-Nano UPGRADE-Materials and processes Beyond the Nano-scale(CUP:DFM.AD006.173..funded by CNR-Dipartimento Scienze Fisiche e Tecnologie della Materia。
摘要Intrinsic properties of Fe(Se,Te),such as the high value of the upper critical field as well as the weaker dependence of the critical current density(Jc)on the grain misalignment than in cuprate superconductors,make this compound a promising candidate for the fabrication of high-field superconducting magnets.On the other hand,irradiation was demonstrated to be a powerful tool for tuning the pinning properties in superconducting materials.In this paper,we investigate the effect of 230 MeV Au-ion irradiation on Jc and pinning force(Fp)of biaxially-oriented Fe(Se,Te)films grown on YSZ substrate buffered with a thin Zr-doped CeO2 epitaxial layer.This structure is interesting as it can be considered a precursor template for Fe(Se,Te)coated conductors.The irradiation produces correlated defects,which-on transmission electron microscope analysis-appear as slightly meandering tracks composed of dislocation chains placed parallel to the c-axis of the crystal lattice.The Jc measurements as a function of the applied magnetic field evidence an improvement at low temperatures,with a maximum modulated in both position and height by the irradiation fluence.In the same range of temperature,the development of the irradiation tracks strongly reduces the anisotropy of the critical current density by varying the applied field orientation.Likewise,the Fp analysis highlights that irradiation defects behave as twodimensional extended defects,which strengthen the point-pinning landscape active before irradiation.Conversely,approaching the transition temperature,the effectiveness of the irradiation-induced defects decreases and a widespread Jc and Fp worsening occurs.