Exploration of exotic phenomena in magnetic topological systems is at the frontier of condensed matter physics,holding a significant promise for applications in topological spintronics.However,complex magnetic structu...Exploration of exotic phenomena in magnetic topological systems is at the frontier of condensed matter physics,holding a significant promise for applications in topological spintronics.However,complex magnetic structures carrying nontrivial topological properties hinder its progresses.Here,we investigate the pressure effect on the novel topological kagome magnets GdV_(6)Sn_(6) and TbV_(6)Sn_(6) to dig out the interplay between magnetic Gd/Tb layers and nonmagnetic V-based kagome sublattice.The pressure-tuned magnetic transition temperature Tm in both the compounds exhibit a turning point at the critical pressure P_(c),accompanied with a sign reversal in anomalous Hall effect(AHE).The separation of intrinsic and extrinsic contributions using the Tian-Ye-Jin scaling model suggests that the intrinsic mechanism originating from the electronic Berry curvature holds the priority in the competition with extrinsic mechanism in AHE.The above-mentioned findings can be attributed to the combined effect of pressure-tuned band topology and magnetic interaction in segregated layers.Our results provide a practical route to design and manipulate the intrinsic AHE in magnetic topological materials.展开更多
Recently, giant intrinsic anomalous Hall effect(AHE) has been observed in the materials with kagome lattice.Here, we systematically investigate the influence of high pressure on the AHE in the ferromagnet LiMn_(6)Sn_(...Recently, giant intrinsic anomalous Hall effect(AHE) has been observed in the materials with kagome lattice.Here, we systematically investigate the influence of high pressure on the AHE in the ferromagnet LiMn_(6)Sn_(6) with clean Mn kagome lattice. Our in situ high-pressure Raman spectroscopy indicates that the crystal structure of LiMn_(6)Sn_(6) maintains a hexagonal phase under high pressures up to 8.51 GPa. The anomalous Hall conductivity(AHC) σ_(xy)^(A) remains around 150 Ω^(-1)·cm^(-1), dominated by the intrinsic mechanism. Combined with theoretical calculations, our results indicate that the stable AHE under pressure in Li Mn_(6)Sn_(6) originates from the robust electronic and magnetic structure.展开更多
The use of carbonized wood in various functional devices is attracting considerable attention due to its low cost,vertical channels,and high electrical conduction.However,the conventional carbonization method requires...The use of carbonized wood in various functional devices is attracting considerable attention due to its low cost,vertical channels,and high electrical conduction.However,the conventional carbonization method requires a long processing time and an inert atmosphere.Here,a microwave-assisted ultrafast carbonization technique was developed that carbonizes natural wood in seconds without the need for an inert atmosphere,and the obtained aligned-porous carbonized wood provided an excellent electrochemical performance as an anode material for lithium-ion batteries.This ultrafast carbonization technique simultaneously produced ZnO nanoparticles during the carbonization process that were uniformly distributed on the alignedporous carbon.The hierarchical structure of carbonized wood functionalized with ZnO nanoparticles was used as a host for achieving high-performance lithium-sulfur batteries:the highly conductive carbonized wood framework with vertical channels provided good electron transport pathways,and the homogeneously dispersed ZnO nanoparticles effectively adsorbed lithium polysulfide and catalyzed its conversion reactions.In summary,a new method was developed to realize the ultrafast carbonization of biomass materials with decorated metal oxide nanoparticles.展开更多
Magnetic CeTe_(2)achieving superconductivity under external pressure has received considerable attention.The intermingling of 4f and 5d electrons from Ce raised the speculation of an unconventional pairing mechanism a...Magnetic CeTe_(2)achieving superconductivity under external pressure has received considerable attention.The intermingling of 4f and 5d electrons from Ce raised the speculation of an unconventional pairing mechanism arising from magnetic fluctuations.Here,we address this speculation using a nonmagnetic 4f-electron-free LaTe_(2)as an example.No structural phase transition can be observed up to 35 GPa in the in situ synchrotron diffraction patterns.Subsequent high-pressure electrical measurements show that LaTe_(2)exhibits superconductivity at20 Gpa with its T_(c)(4.5 K)being two times higher than its Ce-counterpart.Detailed theoretical calculations reveal that charge transfer from the 4p orbitals of the planar square Te-Te network to the 5d orbitals of La is responsible for the emergence of superconductivity in LaTe_(2),as confirmed by Hall experiments.Furthermore,we study the modulation of q_(CDW)by Sb substitution and find a record high T_(c)^(onset)~6.5 K in LaTe_(1.6)Sb_(0.4).Our work provides an informative clue to comprehend the role of 5d-4p hybridization in the relationship between charge density wave(CDW)and superconductivity in these RETe_(2)(RE=rare-earth elements)compounds.展开更多
As a new type of quantum state of matter hosting low energy relativistic quasiparticles,Weyl semimetals(WSMs)have attracted significant attention for scientific community and potential quantum device applications.In t...As a new type of quantum state of matter hosting low energy relativistic quasiparticles,Weyl semimetals(WSMs)have attracted significant attention for scientific community and potential quantum device applications.In this study,we present a comprehensive investigation of the structural,magnetic,and transport properties of noncentrosymmetric RAl Si(R=Sm,Ce),which have been predicted to be new magnetic WSM candidates.Both samples exhibit nonsaturated magnetoresistance,with about 900%and 80%for Sm Al Si and Ce Al Si,respectively,at temperature of 1.8 K and magnetic field of 9 T.The carrier densities of Sm Al Si and Ce Al Si exhibit remarkable change around magnetic transition temperatures,signifying that the electronic states are sensitive to the magnetic ordering of rare-earth elements.At low temperatures,Sm Al Si reveals prominent Shubnikov–de Haas oscillations associated with the nontrivial Berry phase.High-pressure experiments demonstrate that the magnetic order is robust and survival under high pressure.Our results would yield valuable insights into WSM physics and potentials in applications to next-generation spintronic devices in the RAl Si(R=Sm,Ce)family.展开更多
Clathrate-like or caged compounds have attracted great interest owing to their structural flexibility,as well as their fertile physical properties.Here,we report the pressure-induced reemergence of superconductivity i...Clathrate-like or caged compounds have attracted great interest owing to their structural flexibility,as well as their fertile physical properties.Here,we report the pressure-induced reemergence of superconductivity in BaIr2Ge7 and Ba3Ir4Ge16,two new caged superconductors with two-dimensional building blocks of cage structures.After suppression of the ambient-pressure superconducting(SC-I)states,new superconducting(SC-II)states emerge unexpectedly,with Tc increased to a maximum of 4.4 and 4.0 K for BaIr2Ge7 and Ba3Ir4Ge16,respectively.Combined with high-pressure synchrotron x-ray diffraction and Raman measurements,we propose that the reemergence of superconductivity in these caged superconductors can be ascribed to a pressure-induced phonon softening linked to cage shrinkage.展开更多
Garnet-type oxide solid electrolytes are the critical materials for all-solid-state lithium ion batteries.Nanoscale spectroscopic analysis on solid electrolytes plays a key role in bridging the gap between microstruct...Garnet-type oxide solid electrolytes are the critical materials for all-solid-state lithium ion batteries.Nanoscale spectroscopic analysis on solid electrolytes plays a key role in bridging the gap between microstructure and properties.In this work,Auger electron spectroscopy(AES),which can directly detect lithium element and distinguish its valence state,was applied to characterize the garnet-type Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6O12)(LLZTO).Different spectroscopy parameters were evaluated and optimal acquisition conditions were provided.Electron induced precipitation of lithium metal from LLZTO was observed.By exploring the influence factors of precipitation and combining transmission electron microscopy(TEM)and focused ion beam(FIB)experiments,the underlying mechanism of the phenomenon was revealed and previous controversy was resolved.The analysis method was also extended to other types of solid electrolytes,and this work provides a reference for future in-depth research on the structure-property relationship of solid electrolytes using AES.展开更多
The development of efficient non-precious metal catalysts is important for the large-scale application of alkaline hydrogen evolution reaction(HER).Here,we synthesized a composite catalyst of Cu and Mo_(2)C(Cu/Mo_(2)C...The development of efficient non-precious metal catalysts is important for the large-scale application of alkaline hydrogen evolution reaction(HER).Here,we synthesized a composite catalyst of Cu and Mo_(2)C(Cu/Mo_(2)C)using Anderson-type polyoxometalates(POMs)synthesized by the facile soaking method as precursors.The electronic interaction between Cu and Mo_(2)C drives the positive charge of Cu,alleviating the strong adsorption of hydrogen at the Mo site by modulating the d-band center of Mo_(2)C.By studying the interfacial water structure using in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy(ATR-SEIRAS),we determined that the positively charged Cu crystals have the function of activating water molecules and optimizing the interfacial water structure.The interfacial water of Cu/Mo_(2)C contains a large amount of free water,which could facilitate the transport of reaction intermediates.Due to activated water molecules and optimized interfacial water structure and hydrogen adsorption energy,the overpotential of Cu/Mo_(2)C is 24 mV at a current density of 10 mA·cm^(-2) and 178 mV at a current density of 1000 mA·cm^(-2).This work improves catalyst performance in terms of interfacial water structure optimization and deepens the understanding of water-mediated catalysis.展开更多
Generating hollow structure inside titanium silicalite-1(TS-1)is a widely used method to improve its liquid-phase oxidation catalytic performance in industry.However,traditional dissolution-recrystallization method us...Generating hollow structure inside titanium silicalite-1(TS-1)is a widely used method to improve its liquid-phase oxidation catalytic performance in industry.However,traditional dissolution-recrystallization method usually required a large amount of aqueous solution of organic template,leading to unfavorable polluted waste,low production efficiency,and high manufacture cost.Here,a facile and environmental friendly strategy was proposed for the post-synthesis of hollow TS-1 zeolite with a solventfree method utilizing NH4HCO3 and tetrapropylammounium bromide as selective etching agents,which reduced the usage of organic template and avoided the liquid waste.The high crystallinity,the microporous structure,and the active Ti sites were preserved at a high product yield(>93%).The formation mechanism of hollow structure was also investigated by exploring effects of different reactants and experimental parameters.Meanwhile,the obtained hollow TS-1 showed an outstanding performance in the epoxidation of 1-hexene in comparison to the parent zeolite.展开更多
Regulation of perovskite growth plays a critical role in the development of high-performance optoelectronic devices.However,judicious control of the grain growth for perovskite light emitting diodes is elusive due to ...Regulation of perovskite growth plays a critical role in the development of high-performance optoelectronic devices.However,judicious control of the grain growth for perovskite light emitting diodes is elusive due to its multiple requirements in terms of morphology,composition,and defect.Herein,we demonstrate a supramolecular dynamic coordination strategy to regulate perovskite crystallization.The combined use of crown ether and sodium trifluoroacetate can coordinate with A site and B site cations in ABX_(3) perovskite,respectively.The formation of supramolecular structure retard perovskite nucleation,while the transformation of supramolecular intermediate structure enables the release of components for slow perovskite growth.This judicious control enables a segmented growth,inducing the growth of insular nanocrystal consist of low-dimensional structure.Light emitting diode based on this perovskite film eventually brings a peak external quantum efficiency up to 23.9%,ranking among the highest efficiency achieved.The homogeneous nano-island structure also enables high-efficiency large area(1 cm^(2))device up to 21.6%,and a record high value of 13.6%for highly semi-transparent ones.展开更多
Armchair graphene nanoribbons(AGNRs)with sub-nanometer width are potential materials for the fabrication of novel nanodevices thanks to their moderate direct band gaps.AGNRs are usually synthesized by polymerizing pre...Armchair graphene nanoribbons(AGNRs)with sub-nanometer width are potential materials for the fabrication of novel nanodevices thanks to their moderate direct band gaps.AGNRs are usually synthesized by polymerizing precursor molecules on substrate surface.However,it is time-consuming and not suitable for large-scale production.AGNRs can also be grown by transforming precursor molecules inside single-walled carbon nanotubes(SWCNTs)via furnace annealing,but the obtained AGNRs are normally twisted.In this work,microwave heating is applied for transforming precursor molecules into AGNRs.The fast heating process allows synthesizing the AGNRs in seconds.Several different molecules were successfully transformed into AGNRs,suggesting that it is a universal method.More importantly,as demonstrated by Raman spectroscopy,aberrationcorrected high-resolution transmission electron microscopy and theoretical calculations,less twisted AGNRs are synthesized by the microwave heating than the furnace annealing.Our results reveal a route for rapid production of AGNRs in large scale,which would benefit future applications in novel AGNRs-based semiconductor devices.展开更多
The intricate correlation between charge degrees of freedom and physical properties is a fascinating area of research in solid state chemistry and condensed matter physics.Herein,we report on the pressureinduced succe...The intricate correlation between charge degrees of freedom and physical properties is a fascinating area of research in solid state chemistry and condensed matter physics.Herein,we report on the pressureinduced successive charge transfer and accompanied resistive evolution in honeycomb layered ruthenate AgRuO_(3).Structural revisiting and spectroscopic analyses affirm the ilmenite type R-3 structure with mixed valence cations as Ag^(+1/+2)Ru^(+4/+5)O_(3) at ambient pressure.In-situ pressure-and temperature-dependent resistance variation reveals a successive insulatormetal-insulator transition upon pressing,accompanied by unprecedented charge transfer between Ag and Ru under applied pressure,and a further structural phase transition in the insulator region at higher pressure.These phenomena are also corroborated by in-situ pressure-dependent Raman spectra,synchrotron X-ray diffraction,bond valence sums,and electronic structure calculations,emphasizing the dominated rare Ag2+,and near zero thermal expansion in the ab-plane in the metallic zone mostly due to the Jahn-Teller effect of d9-Ag2+.The multiple electronic instabilities in AgRuO_(3) may offer new possibilities toward novel and unconventionally physical and chemical behaviors in strongly correlated honeycomb lattices.展开更多
Enantiomorphic identification of chiral molecules is essential in organic chemistry and the pharmaceutical industry,as two enantiomorphic structures can show distinctively different properties.Here,we illustrate the a...Enantiomorphic identification of chiral molecules is essential in organic chemistry and the pharmaceutical industry,as two enantiomorphic structures can show distinctively different properties.Here,we illustrate the absolute structural determination of organic nanocrystals using zone-axis electron diffraction by taking advantage of electron multiple scattering.Two enantiomorphs are distinguished by comparing the reflection intensities of Friedel pairs in the zone-axis electron diffraction pattern,after confirming the absolute indices of reflections by locating relative positions of diffraction spots from two patterns that deviate from a certain angle.We demonstrate the protocol with successful applications in two chiral drug nanocrystals.展开更多
Garnet-type oxide is one of the most promising solid-state electrolytes(SSEs)for solid-state lithium-metal batteries(SSLMBs).However,the Li dendrite formation in garnet oxides obstructs the further development of the ...Garnet-type oxide is one of the most promising solid-state electrolytes(SSEs)for solid-state lithium-metal batteries(SSLMBs).However,the Li dendrite formation in garnet oxides obstructs the further development of the SSLMBs seriously.Here,we report a high-performance garnet oxide by using AlN as a sintering additive and Li as an anode interface layer.AlN with high thermal conductivity can promote the sintering activity of the garnet oxides,resulting in larger particle size and higher relative density.Moreover,Li3N with high ionic conductivity formed at grain boundaries and interface can also improve Li-ion transport kinetics.As a result,the garnet oxide electrolytes with AlN show enhanced thermal conductivity,improved ionic conductivity,reduced electronic conductivity,and increased critical current density(CCD),compared with the counterpart using Al_(2)O_(3) sintering aid.In addition,Li symmetric cells and Li|LiFePO_(4)(Li|LFP)half cells using the garnet electrolyte with the AlN additive exhibit good electrochemical performances.This work provides a simple and effective strategy for high-performance SSEs.展开更多
Combustion of fossil fuels in industrial settings,such as coalfired power plants,steel-smelting furnaces,and cement kilns accounts for more than 70%of CO_(2) emission.Although liquid amine scrubbing processes that are...Combustion of fossil fuels in industrial settings,such as coalfired power plants,steel-smelting furnaces,and cement kilns accounts for more than 70%of CO_(2) emission.Although liquid amine scrubbing processes that are based on 30 wt%monoethanolamine aqueous solutions are feasible in capturing CO_(2)on a large scale,significant drawbacks remain concerning the energy penalty for regeneration and environmental pollution upon their disposal after degradation[1].展开更多
The recent discovery of superconductivity up to 32 K in the pressurized MoBreignites the interest in exploring high-Tc superconductors in transition-metal diborides. Inspired by that work, we turn our attention to the...The recent discovery of superconductivity up to 32 K in the pressurized MoBreignites the interest in exploring high-Tc superconductors in transition-metal diborides. Inspired by that work, we turn our attention to the 5 d transition-metal diborides.Here we systematically investigate the responses of both structural and physical properties of WBand ReBto external pressure,which possess different types of boron layers. Similar to MoB, the pressure-induced superconductivity was also observed in WBabove 60 GPa with a maximum Tcof 15 K at 100 GPa, while no superconductivity was detected in ReBin this pressure range. Interestingly, the structures at ambient pressure for both WBand ReBpersist to high pressure without structural phase transitions. Theoretical calculations suggest that the ratio of flat boron layers in this class of transition-metal diborides may be crucial for the appearance of high Tc. The combined theoretical and experimental results highlight the effect of the geometry of boron layers on superconductivity and shed light on the exploration of novel high-Tcsuperconductors in borides.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1402203)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)+5 种基金supported by the National Key R&D Program of China(Grants No.2023YFA1406100)the Double First-Class Initiative Fund of ShanghaiTech Universitysupported by the National Natural Science Foundation of China(Grant No.52272265)supported by the National Science Basic Research Plan in the Shaanxi Province of China(Grant No.2024JC-YBQN-0390)supported by the open project from State Key Laboratory of Surface Physics and Department of Physics,Fudan University(Grant No.KF2022-13)supported by the National Natural Science Foundation of China(Grant No.52302010)。
文摘Exploration of exotic phenomena in magnetic topological systems is at the frontier of condensed matter physics,holding a significant promise for applications in topological spintronics.However,complex magnetic structures carrying nontrivial topological properties hinder its progresses.Here,we investigate the pressure effect on the novel topological kagome magnets GdV_(6)Sn_(6) and TbV_(6)Sn_(6) to dig out the interplay between magnetic Gd/Tb layers and nonmagnetic V-based kagome sublattice.The pressure-tuned magnetic transition temperature Tm in both the compounds exhibit a turning point at the critical pressure P_(c),accompanied with a sign reversal in anomalous Hall effect(AHE).The separation of intrinsic and extrinsic contributions using the Tian-Ye-Jin scaling model suggests that the intrinsic mechanism originating from the electronic Berry curvature holds the priority in the competition with extrinsic mechanism in AHE.The above-mentioned findings can be attributed to the combined effect of pressure-tuned band topology and magnetic interaction in segregated layers.Our results provide a practical route to design and manipulate the intrinsic AHE in magnetic topological materials.
基金supported by the National Natural Science Foundation of China (Grant No. 52272265)the National Key R&D Program of China (Grant Nos. 2023YFA1607400 and 2018YFA0704300)+4 种基金the support from the National Natural Science Foundation of China (Grant Nos. 52271016 and 52188101)the support from Analytical Instrumentation Center (# SPST-AIC10112914), SPST, Shanghai Tech Universitythe European Research Council (ERC Advanced Grant No. 742068 ‘TOPMAT’)the DFG through SFB 1143 (Project ID 247310070)the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter ct.qmat (EXC2147,Project ID 390858490)。
文摘Recently, giant intrinsic anomalous Hall effect(AHE) has been observed in the materials with kagome lattice.Here, we systematically investigate the influence of high pressure on the AHE in the ferromagnet LiMn_(6)Sn_(6) with clean Mn kagome lattice. Our in situ high-pressure Raman spectroscopy indicates that the crystal structure of LiMn_(6)Sn_(6) maintains a hexagonal phase under high pressures up to 8.51 GPa. The anomalous Hall conductivity(AHC) σ_(xy)^(A) remains around 150 Ω^(-1)·cm^(-1), dominated by the intrinsic mechanism. Combined with theoretical calculations, our results indicate that the stable AHE under pressure in Li Mn_(6)Sn_(6) originates from the robust electronic and magnetic structure.
基金supported by the National Natural Science Foundation of China (No.52222311)the Shanghai RisingStar Program (20QA1406600)+2 种基金ChEM,SPST of Shanghai Tech University (#EM02161943)Shanghai Science and Technology Plan (21DZ2260400)Double First-Class Initiative Fund of Shanghai Tech University for supporting
文摘The use of carbonized wood in various functional devices is attracting considerable attention due to its low cost,vertical channels,and high electrical conduction.However,the conventional carbonization method requires a long processing time and an inert atmosphere.Here,a microwave-assisted ultrafast carbonization technique was developed that carbonizes natural wood in seconds without the need for an inert atmosphere,and the obtained aligned-porous carbonized wood provided an excellent electrochemical performance as an anode material for lithium-ion batteries.This ultrafast carbonization technique simultaneously produced ZnO nanoparticles during the carbonization process that were uniformly distributed on the alignedporous carbon.The hierarchical structure of carbonized wood functionalized with ZnO nanoparticles was used as a host for achieving high-performance lithium-sulfur batteries:the highly conductive carbonized wood framework with vertical channels provided good electron transport pathways,and the homogeneously dispersed ZnO nanoparticles effectively adsorbed lithium polysulfide and catalyzed its conversion reactions.In summary,a new method was developed to realize the ultrafast carbonization of biomass materials with decorated metal oxide nanoparticles.
基金financially supported by the National Key Research and Development Program of China(Grant Nos.2018YFE0202600,2021YFA1401800,2017YFA0304700)the National Natural Science Foundation of China(Grant Nos.51922105,11804184,11974208,11774424,12174443,U1932217,and11974246)+1 种基金Beijing Natural Science Foundation(Grant No.Z200005)supported by the Synergetic Extreme Condition User Facility(SECUF)。
文摘Magnetic CeTe_(2)achieving superconductivity under external pressure has received considerable attention.The intermingling of 4f and 5d electrons from Ce raised the speculation of an unconventional pairing mechanism arising from magnetic fluctuations.Here,we address this speculation using a nonmagnetic 4f-electron-free LaTe_(2)as an example.No structural phase transition can be observed up to 35 GPa in the in situ synchrotron diffraction patterns.Subsequent high-pressure electrical measurements show that LaTe_(2)exhibits superconductivity at20 Gpa with its T_(c)(4.5 K)being two times higher than its Ce-counterpart.Detailed theoretical calculations reveal that charge transfer from the 4p orbitals of the planar square Te-Te network to the 5d orbitals of La is responsible for the emergence of superconductivity in LaTe_(2),as confirmed by Hall experiments.Furthermore,we study the modulation of q_(CDW)by Sb substitution and find a record high T_(c)^(onset)~6.5 K in LaTe_(1.6)Sb_(0.4).Our work provides an informative clue to comprehend the role of 5d-4p hybridization in the relationship between charge density wave(CDW)and superconductivity in these RETe_(2)(RE=rare-earth elements)compounds.
基金supported by the National Key R&D Program of China(Grant Nos.2018YFA0704300 and 2017YFB0503302)the National Natural Science Foundation of China(Grant Nos.U1932217,11974246,12004252,61771234,and 12004251)+6 种基金the Natural Science Foundation of Shanghai(Grant Nos.19ZR1477300 and 20ZR1436100)the Science and Technology Commission of Shanghai Municipality(Grant Nos.19JC1413900 and YDZX20203100001438)the Shanghai Science and Technology Plan(Grant No.21DZ2260400),the Shanghai Sailing Program(Grant No.21YF1429200)the Interdisciplinary Program of Wuhan National High Magnetic Field Center(Grant No.WHMFC202124)the Beijing National Laboratory for Condensed Matter Physicsthe support from Analytical Instrumentation Center(Grant No.SPST-AIC10112914)Centre for High-resolution Electron Microscopy(ChEM)(Grant No.EM02161943),SPST,Shanghai Tech University。
文摘As a new type of quantum state of matter hosting low energy relativistic quasiparticles,Weyl semimetals(WSMs)have attracted significant attention for scientific community and potential quantum device applications.In this study,we present a comprehensive investigation of the structural,magnetic,and transport properties of noncentrosymmetric RAl Si(R=Sm,Ce),which have been predicted to be new magnetic WSM candidates.Both samples exhibit nonsaturated magnetoresistance,with about 900%and 80%for Sm Al Si and Ce Al Si,respectively,at temperature of 1.8 K and magnetic field of 9 T.The carrier densities of Sm Al Si and Ce Al Si exhibit remarkable change around magnetic transition temperatures,signifying that the electronic states are sensitive to the magnetic ordering of rare-earth elements.At low temperatures,Sm Al Si reveals prominent Shubnikov–de Haas oscillations associated with the nontrivial Berry phase.High-pressure experiments demonstrate that the magnetic order is robust and survival under high pressure.Our results would yield valuable insights into WSM physics and potentials in applications to next-generation spintronic devices in the RAl Si(R=Sm,Ce)family.
基金the National Natural Science Foundation of China(Grant Nos.U1932217,11974246,and 12004252)the National Key R&D Program of China(Grant No.2018YFA0704300)+3 种基金the Natural Science Foundation of Shanghai(Grant No.19ZR1477300)the Science and Technology Commission of Shanghai Municipality(Grant No.19JC1413900)the Shanghai Science and Technology Plan(Grant No.21DZ2260400)the Analytical Instrumentation Center(Grant No.SPST-AIC10112914),SPST,ShanghaiTech University.
文摘Clathrate-like or caged compounds have attracted great interest owing to their structural flexibility,as well as their fertile physical properties.Here,we report the pressure-induced reemergence of superconductivity in BaIr2Ge7 and Ba3Ir4Ge16,two new caged superconductors with two-dimensional building blocks of cage structures.After suppression of the ambient-pressure superconducting(SC-I)states,new superconducting(SC-II)states emerge unexpectedly,with Tc increased to a maximum of 4.4 and 4.0 K for BaIr2Ge7 and Ba3Ir4Ge16,respectively.Combined with high-pressure synchrotron x-ray diffraction and Raman measurements,we propose that the reemergence of superconductivity in these caged superconductors can be ascribed to a pressure-induced phonon softening linked to cage shrinkage.
基金supported by the Shanghai Science and Technology Plan(No.21DZ2260400)the startup funding from ShanghaiTech University.The electron microscopy characterization was supported by the Center for High-resolution Electron Microscopy(CћEM)at ShanghaiTech University。
文摘Garnet-type oxide solid electrolytes are the critical materials for all-solid-state lithium ion batteries.Nanoscale spectroscopic analysis on solid electrolytes plays a key role in bridging the gap between microstructure and properties.In this work,Auger electron spectroscopy(AES),which can directly detect lithium element and distinguish its valence state,was applied to characterize the garnet-type Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6O12)(LLZTO).Different spectroscopy parameters were evaluated and optimal acquisition conditions were provided.Electron induced precipitation of lithium metal from LLZTO was observed.By exploring the influence factors of precipitation and combining transmission electron microscopy(TEM)and focused ion beam(FIB)experiments,the underlying mechanism of the phenomenon was revealed and previous controversy was resolved.The analysis method was also extended to other types of solid electrolytes,and this work provides a reference for future in-depth research on the structure-property relationship of solid electrolytes using AES.
基金supported by National Natural Science Foundation of China(Nos.52376060 and 51976081).
文摘The development of efficient non-precious metal catalysts is important for the large-scale application of alkaline hydrogen evolution reaction(HER).Here,we synthesized a composite catalyst of Cu and Mo_(2)C(Cu/Mo_(2)C)using Anderson-type polyoxometalates(POMs)synthesized by the facile soaking method as precursors.The electronic interaction between Cu and Mo_(2)C drives the positive charge of Cu,alleviating the strong adsorption of hydrogen at the Mo site by modulating the d-band center of Mo_(2)C.By studying the interfacial water structure using in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy(ATR-SEIRAS),we determined that the positively charged Cu crystals have the function of activating water molecules and optimizing the interfacial water structure.The interfacial water of Cu/Mo_(2)C contains a large amount of free water,which could facilitate the transport of reaction intermediates.Due to activated water molecules and optimized interfacial water structure and hydrogen adsorption energy,the overpotential of Cu/Mo_(2)C is 24 mV at a current density of 10 mA·cm^(-2) and 178 mV at a current density of 1000 mA·cm^(-2).This work improves catalyst performance in terms of interfacial water structure optimization and deepens the understanding of water-mediated catalysis.
基金This work was supported by the National Natural Science Foundation of China(Nos.21875140,21835002,21522105,and 51861145313)the Shanghai Science and Technology Plan(No.21DZ2260400)+4 种基金the China Ministry of Science and Technology(No.2021YFA1501401)The authors thank the support from Analytical Instrumentation Center(No.SPSTAIC10112914)SPST,ShanghaiTech UniversityThe authors also thank Prof.Osamu Terasaki and CħEM SPST,ShanghaiTech University(No.EM02161943)for scientific and characterization support.Y.F.thanks Junyan Li(Jilin University)for his assistance in 3D tomographic data collection.
文摘Generating hollow structure inside titanium silicalite-1(TS-1)is a widely used method to improve its liquid-phase oxidation catalytic performance in industry.However,traditional dissolution-recrystallization method usually required a large amount of aqueous solution of organic template,leading to unfavorable polluted waste,low production efficiency,and high manufacture cost.Here,a facile and environmental friendly strategy was proposed for the post-synthesis of hollow TS-1 zeolite with a solventfree method utilizing NH4HCO3 and tetrapropylammounium bromide as selective etching agents,which reduced the usage of organic template and avoided the liquid waste.The high crystallinity,the microporous structure,and the active Ti sites were preserved at a high product yield(>93%).The formation mechanism of hollow structure was also investigated by exploring effects of different reactants and experimental parameters.Meanwhile,the obtained hollow TS-1 showed an outstanding performance in the epoxidation of 1-hexene in comparison to the parent zeolite.
基金The authors gratefully acknowledge financial support from the National Natural Science Foundation of China(Nos.61935016,92056119,22175118,62288102,62274135)National Key Research and Development Program of China(under Grants No.2021YFA0715502)+2 种基金Double First-Class Initiative Fund of ShanghaiTech University,and the Science and Technology Commission of Shanghai Municipality(Nos.20XD1402500 and 20JC1415800)Bertil och Britt Svenssons Stiftelse and Swedish Energy Agency(P2022-00394)The authors appreciate the Instrument Analysis Center and Centre for High-resolution Electron Microscopy(CħEM)and the high-performance computing(HPC)Platform of ShanghaiTech University.The authors gratefully thank professor John A.McGuire for the helpful discussion.
文摘Regulation of perovskite growth plays a critical role in the development of high-performance optoelectronic devices.However,judicious control of the grain growth for perovskite light emitting diodes is elusive due to its multiple requirements in terms of morphology,composition,and defect.Herein,we demonstrate a supramolecular dynamic coordination strategy to regulate perovskite crystallization.The combined use of crown ether and sodium trifluoroacetate can coordinate with A site and B site cations in ABX_(3) perovskite,respectively.The formation of supramolecular structure retard perovskite nucleation,while the transformation of supramolecular intermediate structure enables the release of components for slow perovskite growth.This judicious control enables a segmented growth,inducing the growth of insular nanocrystal consist of low-dimensional structure.Light emitting diode based on this perovskite film eventually brings a peak external quantum efficiency up to 23.9%,ranking among the highest efficiency achieved.The homogeneous nano-island structure also enables high-efficiency large area(1 cm^(2))device up to 21.6%,and a record high value of 13.6%for highly semi-transparent ones.
基金partially supported by Shanghai Rising-Star Program(20QA1406600)the Centre for High-resolution Electron Microscopy(CℏEM)+2 种基金School of Physical Science and Technology,ShanghaiTech University(EM02161943)Shanghai Science and Technology Plan(21DZ2260400)Double-Class Initiative Fund of ShanghaiTech University for support。
基金This work was supported by Guangzhou Basic and Applied Basic Research Foundation(No.202201011790)Open Project of Guangdong Province Key Lab of Display Material and Technology(2020B1212060030)+2 种基金National Natural Science Foundation of China(No.51902353)Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.22lgqb03)State Key Laboratory of Optoelectronic Materials and Technologies(No.OEMT-2022-ZRC-01).
文摘Armchair graphene nanoribbons(AGNRs)with sub-nanometer width are potential materials for the fabrication of novel nanodevices thanks to their moderate direct band gaps.AGNRs are usually synthesized by polymerizing precursor molecules on substrate surface.However,it is time-consuming and not suitable for large-scale production.AGNRs can also be grown by transforming precursor molecules inside single-walled carbon nanotubes(SWCNTs)via furnace annealing,but the obtained AGNRs are normally twisted.In this work,microwave heating is applied for transforming precursor molecules into AGNRs.The fast heating process allows synthesizing the AGNRs in seconds.Several different molecules were successfully transformed into AGNRs,suggesting that it is a universal method.More importantly,as demonstrated by Raman spectroscopy,aberrationcorrected high-resolution transmission electron microscopy and theoretical calculations,less twisted AGNRs are synthesized by the microwave heating than the furnace annealing.Our results reveal a route for rapid production of AGNRs in large scale,which would benefit future applications in novel AGNRs-based semiconductor devices.
基金supported by the National Science Foundation of China(grant nos.NSFC-22090041,21875287,U1932217,11974246,12004252,12025408,11921004,11974432,and 92165204)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(grant no.2017ZT07C069)NKRDPC-2017YFA0206203,NKRDPC-2018YFA0306001.
文摘The intricate correlation between charge degrees of freedom and physical properties is a fascinating area of research in solid state chemistry and condensed matter physics.Herein,we report on the pressureinduced successive charge transfer and accompanied resistive evolution in honeycomb layered ruthenate AgRuO_(3).Structural revisiting and spectroscopic analyses affirm the ilmenite type R-3 structure with mixed valence cations as Ag^(+1/+2)Ru^(+4/+5)O_(3) at ambient pressure.In-situ pressure-and temperature-dependent resistance variation reveals a successive insulatormetal-insulator transition upon pressing,accompanied by unprecedented charge transfer between Ag and Ru under applied pressure,and a further structural phase transition in the insulator region at higher pressure.These phenomena are also corroborated by in-situ pressure-dependent Raman spectra,synchrotron X-ray diffraction,bond valence sums,and electronic structure calculations,emphasizing the dominated rare Ag2+,and near zero thermal expansion in the ab-plane in the metallic zone mostly due to the Jahn-Teller effect of d9-Ag2+.The multiple electronic instabilities in AgRuO_(3) may offer new possibilities toward novel and unconventionally physical and chemical behaviors in strongly correlated honeycomb lattices.
基金support of the National Science Foundation of China[grant nos.22222108(Y.M.),12027804(Y.M.)]the Shanghai Science and Technology Plan[grant no.21DZ2260400(Y.M.)]+1 种基金gratefully acknowledge CℏEM,School of Physical Sciences and Technology,Shanghai-Tech University(grant no.EM02161943)for the support of their EM facilities and the Analytical Instrumentation Center(grant no.SPSTAIC10112914),School of Physical Sciences and Technology,ShanghaiTech University.
文摘Enantiomorphic identification of chiral molecules is essential in organic chemistry and the pharmaceutical industry,as two enantiomorphic structures can show distinctively different properties.Here,we illustrate the absolute structural determination of organic nanocrystals using zone-axis electron diffraction by taking advantage of electron multiple scattering.Two enantiomorphs are distinguished by comparing the reflection intensities of Friedel pairs in the zone-axis electron diffraction pattern,after confirming the absolute indices of reflections by locating relative positions of diffraction spots from two patterns that deviate from a certain angle.We demonstrate the protocol with successful applications in two chiral drug nanocrystals.
基金the National Key R&D Program of China(No.2019YFA0210600)the National Natural Science Foundation of China(No.21805185)+2 种基金Shanghai Science and Technology Plan(No.21DZ2260400)Shanghai Rising-Star Program(No.20QA1406600)Center for High-resolution Electron Microscopy,SPST of ShanghaiTech University(No.EM02161943)for support.
文摘Garnet-type oxide is one of the most promising solid-state electrolytes(SSEs)for solid-state lithium-metal batteries(SSLMBs).However,the Li dendrite formation in garnet oxides obstructs the further development of the SSLMBs seriously.Here,we report a high-performance garnet oxide by using AlN as a sintering additive and Li as an anode interface layer.AlN with high thermal conductivity can promote the sintering activity of the garnet oxides,resulting in larger particle size and higher relative density.Moreover,Li3N with high ionic conductivity formed at grain boundaries and interface can also improve Li-ion transport kinetics.As a result,the garnet oxide electrolytes with AlN show enhanced thermal conductivity,improved ionic conductivity,reduced electronic conductivity,and increased critical current density(CCD),compared with the counterpart using Al_(2)O_(3) sintering aid.In addition,Li symmetric cells and Li|LiFePO_(4)(Li|LFP)half cells using the garnet electrolyte with the AlN additive exhibit good electrochemical performances.This work provides a simple and effective strategy for high-performance SSEs.
基金supported by the National Natural Science Foundation of China(21522105 and 51861145313)the Science and Technology Commission of Shanghai Municipality(21XD1402300,21JC1401700,and 21DZ2260400)+1 种基金the Alliance of International Science Organization(ANSO-CR-PP-2020-06)the Research Startup Fund of Shanghai Tech University。
文摘Combustion of fossil fuels in industrial settings,such as coalfired power plants,steel-smelting furnaces,and cement kilns accounts for more than 70%of CO_(2) emission.Although liquid amine scrubbing processes that are based on 30 wt%monoethanolamine aqueous solutions are feasible in capturing CO_(2)on a large scale,significant drawbacks remain concerning the energy penalty for regeneration and environmental pollution upon their disposal after degradation[1].
基金supported by the National Key R&D Program of China(Grant Nos.2018YFA0704300,2018YFE0202600,and 2017YFA0302903)the National Natural Science Foundation of China(Grant Nos.U1932217,11974246,12004252,12174443,and 11774424)+5 种基金the Natural Science Foundation of Shanghai(Grant No.19ZR1477300)the Science and Technology Commission of Shanghai Municipality(Grant No.19JC1413900)the Shanghai Science and Technology Plan(Grant No.21DZ2260400)the Beijing Natural Science Foundation(Grant No.Z200005)the Fundamental Research Funds for the Central Universities and Research Funds of Renmin University of China(RUC)(Grant Nos.18XNLG14,19XNLG13,19XNLG17,and 22XNKJ40)support from Analytical Instrumentation Center(Grant No.SPSTAIC10112914),SPST,Shanghai Tech University。
文摘The recent discovery of superconductivity up to 32 K in the pressurized MoBreignites the interest in exploring high-Tc superconductors in transition-metal diborides. Inspired by that work, we turn our attention to the 5 d transition-metal diborides.Here we systematically investigate the responses of both structural and physical properties of WBand ReBto external pressure,which possess different types of boron layers. Similar to MoB, the pressure-induced superconductivity was also observed in WBabove 60 GPa with a maximum Tcof 15 K at 100 GPa, while no superconductivity was detected in ReBin this pressure range. Interestingly, the structures at ambient pressure for both WBand ReBpersist to high pressure without structural phase transitions. Theoretical calculations suggest that the ratio of flat boron layers in this class of transition-metal diborides may be crucial for the appearance of high Tc. The combined theoretical and experimental results highlight the effect of the geometry of boron layers on superconductivity and shed light on the exploration of novel high-Tcsuperconductors in borides.