Comprehensive understanding of the direct transformation pathway from graphite to diamond under high temperature and high pressure has long been one of the fundamental goals in materials science.Despite considerable e...Comprehensive understanding of the direct transformation pathway from graphite to diamond under high temperature and high pressure has long been one of the fundamental goals in materials science.Despite considerable experimental and theoretical progress,current experimental studies have mainly focused on the local microstructural characterizations of recovered samples,which has certain limitations for hightemperature and high-pressure products,which often exhibit diversity.Here,we report on the pressure-induced phase transition behavior of natural single-crystal graphite under three distinct pressure-transmitting media from a macroscopic perspective using in situ two-dimensional Raman spectroscopy,scanning electron microscopy,and atomic force microscopy.The surface evolution process of graphite before and after the phase transition is captured,revealing that pressure-induced surface textures can impede the continuity of the phase transition process across the entire single crystal.Our results provide a fresh perspective for studying the phase transition behavior of graphite and greatly deepen our understanding of this behavior,which will be helpful in guiding further high-temperature and high-pressure syntheses of carbon allotropes.展开更多
Dynamic adsorption processes of reaction intermediates for alkaline hydrogen evolution(HER)catalysts are still confusing to understand.Here,we report a series of A-site ordered quadruple perovskite ruthenium-based ele...Dynamic adsorption processes of reaction intermediates for alkaline hydrogen evolution(HER)catalysts are still confusing to understand.Here,we report a series of A-site ordered quadruple perovskite ruthenium-based electrocatalysts ACu_(3)Ru_(4)O_(12)(A=Na,Ca,Nd,and La),with the target sample SrCu_(3)Ru_(4)O_(12)exhibiting a very low overpotential(46 mV@10 mA·cm^(-2))and excellent catalytic stability with little decays after 48-h durability test.Precise tuning A-site cations can change the average valence state of Cu and Ru,thus the plot of HER activity versus the average Ru valence number shows a volcano-type relationship.Density functional theory indicates that the Ru 4d orbitals of SrCu3Ru4O12possesses the most suitable d-band center position among the five samples,which might be the key parameter to determine the catalytic performance.Our work provides further insight into the discovering advanced,efficient hydrogen evolution catalysts through designing precise descriptor.展开更多
New results presented in the 2023 MRE HP Special Volume clearly demonstrate the cross-disciplinary synergistic progress in high-pressure physics and chemistry.The prevalence of pressure-induced crystal chemistry of cl...New results presented in the 2023 MRE HP Special Volume clearly demonstrate the cross-disciplinary synergistic progress in high-pressure physics and chemistry.The prevalence of pressure-induced crystal chemistry of clathrate-like host-guest cages in borides,^(1,2)nitrides,^(3)and hydrides^(4)has led to exotic compositions and physical properties.展开更多
The presence of interstitial electrons in electrides endows them with interesting attributes,such as low work function,high carrier concentration,and unique magnetic properties.Thorough knowledge and understanding of ...The presence of interstitial electrons in electrides endows them with interesting attributes,such as low work function,high carrier concentration,and unique magnetic properties.Thorough knowledge and understanding of electrides are thus of both scientific and technological significance.Here,we employ first-principles calculations to investigate Mott-insulating Ae_(5)X_(3)(Ae=Ca,Sr,and Ba;X=As and Sb)electrides with Mn_(5)Si_(3)-type structure,in which half-filled interstitial electrons serve as ions and are spin-polarized.The Mott-insulating property is induced by strong electron correlation between the nearest interstitial electrons,resulting in spin splitting and a separation between occupied and unoccupied states.The half-filled antiferromagnetic configuration and localization of the interstitial electrons are critical for the Mott-insulating properties of these materials.Compared with that in intermetallic electrides,the orbital hybridization between the half-filled interstitial electrons and the surrounding atoms is weak,leading to highly localized magnetic centers and pronounced correlation effects.Therefore,the Mott-insulating electrides Ae_(5)X_(3)have very large indirect bandgaps(0.30 eV).In addition,high pressure is found to strengthen the strong correlation effects and enlarge the bandgap.The present results provide a deeper understanding of the formation mechanism of Mott-insulating electrides and provide guidance for the search for new strongly correlated electrides.展开更多
δ-(Al,Fe)OOH is considered to be one of the most important hydrous phases on Earth,remaining stable under the extreme conditions throughout the mantle.The behavior ofδ-(Al,Fe)OOH at high pressure is essential to und...δ-(Al,Fe)OOH is considered to be one of the most important hydrous phases on Earth,remaining stable under the extreme conditions throughout the mantle.The behavior ofδ-(Al,Fe)OOH at high pressure is essential to understanding the deep water cycle.δ-(Al_(0.956)Fe_(0.044))OOH crystals synthesized at 21 GPa and 1473 K were investigated by high-pressure Brillouin light scattering spectroscopy and synchrotron X-ray diffraction up to 135.4 GPa in diamond anvil cells.The incorporation of 5 mol%FeOOH increases the unit-cell volume ofδ-AlOOH by~1%and decreases the shear-wave velocity(VS)by~5%at 20–135 GPa.In particular,the compressional(V_(P))and shear(VS)wave velocities ofδ-(Al_(0.956)Fe_(0.044))OOH are 7%–16%and 10%–24%greater than all the major minerals in the mantle transition zone including wadsleyite,ringwoodite,and majorite.The distinctly high sound velocities ofδ-(Al_(0.956)Fe_(0.044))OOH at 20–25 GPa may contribute to the seismic anomalies observed at~560–680 km depths in the cold and stagnant slab beneath Izu-Bonin and/or Korea.Furthermore,the VS ofδ-(Al_(0.956)Fe_(0.044))OOH is about 10%and 4%–12%lower than iron-bearing bridgmanite Mg_(0.96)Fe_(0.05)Si_(0.99O3)and ferropericlase(Mg_(0.92)Fe_(0.08))O,respectively,under the lowermost mantle conditions,which might partially contribute to the large low-shear-velocity provinces and ultralow velocity zones at the bottom of the lower mantle.展开更多
Recently,natural van der Waals heterostructures of(MnBi2 Te4)m(Bi2 Te3)n have been theoretically predicted and experimentally shown to host tunable magnetic properties and topologically nontrivial surface states.We sy...Recently,natural van der Waals heterostructures of(MnBi2 Te4)m(Bi2 Te3)n have been theoretically predicted and experimentally shown to host tunable magnetic properties and topologically nontrivial surface states.We systematically investigate both the structural and electronic responses of MnBi2 Te4 and MnBi4 Te7 to external pressure.In addition to the suppression of antiferromagnetic order,MnBi2 Te4 is found to undergo a metalsemiconductor-metal transition upon compression.The resistivity of MnBi4 Te7 changes dramatically under high pressure and a non-monotonic evolution of p(T)is observed.The nontrivial topology is proved to persist before the structural phase transition observed in the high-pressure regime.We find that the bulk and surface states respond differently to pressure,which is consistent with the non-monotonic change of the resistivity.Interestingly,a pressure-induced amorphous state is observed in MnBi2 Te4,while two high-pressure phase transitions are revealed in MnBi4 Te7.Our combined theoretical and experimental research establishes MnBi2 Te4 and MnBi4 Te7 as highly tunable magnetic topological insulators,in which phase transitions and new ground states emerge upon compression.展开更多
High pressure science and technology is a vast area of inter-disciplinary research that encompasses the fields of physics,chem-istry,geoscience,and materials science and in which the science of ordinary matter is only...High pressure science and technology is a vast area of inter-disciplinary research that encompasses the fields of physics,chem-istry,geoscience,and materials science and in which the science of ordinary matter is only a special case under ambient condi-tions.Pressure,the physical variable of force exerted on the chem-ical bonding of a material,directly controls the material’s phys-ical and chemical properties.展开更多
Materials transform abruptly under compression,with their properties varying as strong functions of pressure.Advances in highpressure and probe technology have enabled experimental characterizations up to several hund...Materials transform abruptly under compression,with their properties varying as strong functions of pressure.Advances in highpressure and probe technology have enabled experimental characterizations up to several hundred gigapascal(GPa).Studies in the physical sciences are now expanding to include a vast previously uncharted pressure region in which transformative ideas and discoveries are becoming commonplace.Matter and Radiation under Extremes(MRE)is taking advantage of this opportunity to provide a forum for publishing the finest peer-reviewed research in highpressure science and technology on the basis of its interdisciplinary interest,importance,timeliness,and surprising conclusions.This MRE HP Special Volume gathers together a set of contemporary perspectives,highlights,reviews,and research articles in multiple disciplines of high-pressure physics,chemistry,materials,and geoscience that illustrate both current and forthcoming trends in this exciting research area.展开更多
Electrides are unique ionic compounds that electrons serve as the anions. Many electrides with fascinating physical and chemical properties have been discovered at ambient condition. Under pressure, electrides are als...Electrides are unique ionic compounds that electrons serve as the anions. Many electrides with fascinating physical and chemical properties have been discovered at ambient condition. Under pressure, electrides are also revealed to be ubiquitous crystal morphology, enriching the geometrical topologies and electronic properties of electrides. In this Review,we overview the formation mechanism of high-pressure electrides(HPEs) and outline a scheme for exploring new HPEs from pre-design, CALYPSO assisted structural searches, indicators for electrides, to experimental synthesis. Moreover, the evolution of electronic dimensionality under compression is also discussed to better understand the dimensional distribution of anionic electrons in HPEs.展开更多
We successfully grow a new superconductor GaBa2Ca3Cu4O11+δ(Ga-1234) with a transition temperature of 113 K, using the Walker-type high-pressure synthesis apparatus. X-ray diffraction measurements on the powderized sa...We successfully grow a new superconductor GaBa2Ca3Cu4O11+δ(Ga-1234) with a transition temperature of 113 K, using the Walker-type high-pressure synthesis apparatus. X-ray diffraction measurements on the powderized samples show a mixture of the Ga-1234 phase and the Ca0.85CuO2phase, and the former is dominant. Under the scanning electron microscope, plate-like crystals of the Ga-based 1234 phase with shiny surfaces can be seen.The obtained local chemical compositions revealed by energy dispersion x-ray spectroscopy are very close to the stoichiometric values. On some sub-millimeter crystal-like samples of the 1234 phase, we obtain a full Meissner shielding volume. From the temperature-dependent magnetizations, we determine the irreversibility fields and find that the system exhibits a highly anisotropic behavior.展开更多
We observed superconductivity in a cubic La_(3)Al single crystal that exhibits metallic behavior in the normal state without an observable structural transition and enters the superconducting state below T_(c)~6.32 K....We observed superconductivity in a cubic La_(3)Al single crystal that exhibits metallic behavior in the normal state without an observable structural transition and enters the superconducting state below T_(c)~6.32 K.Detailed characterization and analysis indicate that cubic La_(3)Al is a bulk type-Ⅱ BCS superconductor.Moreover,theoretical calculations show that it can host interstitial anionic electrons located at the body center of the cubic unit cell,which confirms electron-phonon coupling as the superconducting mechanism.Therefore,cubic La_(3)Al can be considered as a novel electride superconductor.展开更多
Strain engineering can serve as a powerful technique for modulating the exotic properties arising from the atomic structure of materials.Examples have been demonstrated that one-dimensional(1D)structure can serve as a...Strain engineering can serve as a powerful technique for modulating the exotic properties arising from the atomic structure of materials.Examples have been demonstrated that one-dimensional(1D)structure can serve as a great platform for modulating electronic band structure and phonon dispersion via strain control.Particularly,in a van der Waals material silicon diphosphide(SiP_(2)),quasi-1D zigzag phosphorus–phosphorus(P–P)chains are embedded inside the crystal structure,and can show unique phonon vibration modes and realize quasi-1D excitons.Manipulating those optical properties by the atom displacements via strain engineering is of great interest in understanding underlying mechanism of such P–P chains,however,which remains elusive.Herein,we demonstrate the strain engineering of Raman and photoluminescence(PL)spectra in quasi-1D P–P chains and resulting in anisotropic manipulation in SiP_(2).We find that the phonon frequencies of SiP_(2)in Raman spectra linearly evolve with a uniaxial strain along/perpendicular to the quasi-1D P–P chain directions.Interestingly,by applying tensile strain along the P–P chains,the band gap energy of strained SiP_(2)can significantly decrease with a tunable value of~55 meV.Based on arsenic(As)element doping into SiP_(2),the strain-induced redshifts of phonon frequencies decrease,indicating the stiffening of the phonon vibration with the increased arsenic doping level.Such results provide an opportunity for strain engineering of the light–matter interactions in the quasi-1D P–P chains of SiP_(2)crystal for potential optical applications.展开更多
Advanced materials with superior comprehensive mechanical properties are strongly desired,but it has long been a challenge to achieve high ductility in high-strength materials.Here,we proposed a new V 0.5 Cr 0.5 CoNi ...Advanced materials with superior comprehensive mechanical properties are strongly desired,but it has long been a challenge to achieve high ductility in high-strength materials.Here,we proposed a new V 0.5 Cr 0.5 CoNi medium-entropy alloy(MEA)with a face-centered cubic/hexagonal close-packed(FCC/HCP)dual-phase ultrafine-grained(UFG)architecture containing stacking faults(SFs)and local chemical order(LCO)in HCP solid solution,to obtain an ultrahigh yield strength of 1476 MPa and uniform elongation of 13.2%at ambient temperature.The ultrahigh yield strength originates mainly from fine grain strength-ening of the UFG FCC matrix and HCP second-phase strengthening assisted by the SFs and LCO inside,whereas the large ductility correlates to the superior ability of the UFG FCC matrix to storage disloca-tions and the function of deformation-induced SFs in the vicinity of the FCC/HCP boundary to eliminate the stress concentration.This work provides new guidance by engineering novel composition and stable UFG structure for upgrading the mechanical properties of metallic materials.展开更多
Developing and understanding electron-rich electrides offers a promising opportunity for a variety of electronic and catalytic applications.Using a geometrical identification strategy,here we identify a new class of e...Developing and understanding electron-rich electrides offers a promising opportunity for a variety of electronic and catalytic applications.Using a geometrical identification strategy,here we identify a new class of electride material,yttrium/scandium chlorides Y(Sc)_(x)Cl_(y)(yx<2).Anionic electrons are found in the metal octahedral framework topology.The diverse electronic dimensionality of these electrides is quantified explicitly by quasi-two-dimensional(2D)electrides for[YCl]^(+)∙e−and[ScCl]^(+∙)e−and one-dimensional(1D)electrides for[Y_(2)Cl_(3)]^(+)∙e−,[Sc_(7)Cl_(10)]^(+)∙e−,and[Sc5Cl8]2+∙2e−with divalent metal elements(Sc^(2+):3d^(1) and Y^(2+):4d^(1)).The localized anionic electrons were confined within the inner-layer spaces,rather than inter-layer spaces that are observed in A_(2)B-type 2D electrides,e.g.Ca_(2)N.Moreover,when hydrogen atoms are introduced into the host structures to form YClH and Y2Cl3H,the generated phases transform to conventional ionic compounds but exhibited a surprising reduction of work function,arising from the increased Fermi level energy,contrary to the conventional electrides reported so far.Y_(2C)l_(3) was experimentally confirmed to be a semiconductor with a band gap of 1.14 eV.These results may help to promote the rational design and discovery of new electride materials for further technological applications.展开更多
Light-matter interactions in low-dimensional quantum-confined structures can dominate the optical properties of the materials and lead to optoelectronic applications.In anisotropic layered silicon diphosphide(SiP2)cry...Light-matter interactions in low-dimensional quantum-confined structures can dominate the optical properties of the materials and lead to optoelectronic applications.In anisotropic layered silicon diphosphide(SiP2)crystal,the embedded quasi-onedimensional(1D)phosphorus–phosphorus(P–P)chains directly result in an unconventional quasi-1D excitonic state,and a special phonon mode vibrating along the P–P chains,establishing a unique 1D quantum-confined system.Alloying SiP2 with the homologous element serves as an effective way to study the properties of these excitons and phonons associated with the quasi-1D P–P chains,as well as the strong interaction between these quasiparticles.However,the experimental observation and the related optical spectral understanding of SiP2 with isoelectronic dopants remain elusive.Herein,with the photoluminescence and Raman spectroscopy measurements,we demonstrate the redshift of the confined excitonic peak and the stiffening of the phonon vibration mode■of a series of Si(P1−xAsx)2 alloys with increasing arsenic(As)compositions.This anomalous stiffening of■is attributed to the selective substitution of As atoms for P atoms within the P–P chains,which is confirmed via our scanning transmission electron microscopy investigation.Such optical spectra evolutions with selective substitution pave a new way to understand the 1D quantum confinement in semiconductors,offering opportunities to explore quasi-1D characteristics in SiP2 and the resulting photonic device application.展开更多
Pressure produces closely packed,high-density materials,thereby providing a promising strategy to obtain high-energy-density materials.However,new phases or structures of energetic materials at high pressure are often...Pressure produces closely packed,high-density materials,thereby providing a promising strategy to obtain high-energy-density materials.However,new phases or structures of energetic materials at high pressure are often not quenchable under ambient conditions.In this work,high-pressure topochemical methodology is first introduced for the preparation of stable energetic materials under ambient conditions.A pressure-induced polymerizable energetic material named PIP-1 is designed and prepared.The experimental measurements demonstrate that the polymerization of PIP-1 is caused by the breakage of C≡C bonds and the generation of C=C bonds.In accord with the experimental results,density functional theory calculations further revealed that the monomer PIP-1 is polymerized to generate 1D PIP-1 tape,and the density of polymerized PIP-1 is increased by 4.9%upon decompression.The successful realization of high-energy-density structure using high pressure showcases a new design strategy for advanced polymerizable energetic materials.展开更多
基金support from the National Science Fund for Distinguished Young Scholars(Grant No.T2225027)the NSAF(Grant No.U1930401)+1 种基金the National Key R&D Program of China(MOST)(Grant No.2023YFA1406500)the National Natural Science Foundation of China(NSFC)(Grant No.61674045).
文摘Comprehensive understanding of the direct transformation pathway from graphite to diamond under high temperature and high pressure has long been one of the fundamental goals in materials science.Despite considerable experimental and theoretical progress,current experimental studies have mainly focused on the local microstructural characterizations of recovered samples,which has certain limitations for hightemperature and high-pressure products,which often exhibit diversity.Here,we report on the pressure-induced phase transition behavior of natural single-crystal graphite under three distinct pressure-transmitting media from a macroscopic perspective using in situ two-dimensional Raman spectroscopy,scanning electron microscopy,and atomic force microscopy.The surface evolution process of graphite before and after the phase transition is captured,revealing that pressure-induced surface textures can impede the continuity of the phase transition process across the entire single crystal.Our results provide a fresh perspective for studying the phase transition behavior of graphite and greatly deepen our understanding of this behavior,which will be helpful in guiding further high-temperature and high-pressure syntheses of carbon allotropes.
基金Project supported financially by the National Key Research and Development Program of China(Grant No.2023YFA1406000)the National Natural Science Foundation of China(Grant Nos.22171283 and 12474002)+3 种基金the Fundamental Research Funds for the Central Universities(Grant Nos.2023ZCJH03 and 2021XD-A041)the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications,China)the Teaching Reform Projects at BUPT(Grant No.2022CXCYB03)the BUPT Excellent Ph.D.Students Foundation(Grant No.CX2023108)。
文摘Dynamic adsorption processes of reaction intermediates for alkaline hydrogen evolution(HER)catalysts are still confusing to understand.Here,we report a series of A-site ordered quadruple perovskite ruthenium-based electrocatalysts ACu_(3)Ru_(4)O_(12)(A=Na,Ca,Nd,and La),with the target sample SrCu_(3)Ru_(4)O_(12)exhibiting a very low overpotential(46 mV@10 mA·cm^(-2))and excellent catalytic stability with little decays after 48-h durability test.Precise tuning A-site cations can change the average valence state of Cu and Ru,thus the plot of HER activity versus the average Ru valence number shows a volcano-type relationship.Density functional theory indicates that the Ru 4d orbitals of SrCu3Ru4O12possesses the most suitable d-band center position among the five samples,which might be the key parameter to determine the catalytic performance.Our work provides further insight into the discovering advanced,efficient hydrogen evolution catalysts through designing precise descriptor.
基金financial support from the Shanghai Key Laboratory of MFree,China(Grant No.22dz2260800)the Shanghai Science and Technology Committee,China(Grant No.22JC1410300)。
文摘New results presented in the 2023 MRE HP Special Volume clearly demonstrate the cross-disciplinary synergistic progress in high-pressure physics and chemistry.The prevalence of pressure-induced crystal chemistry of clathrate-like host-guest cages in borides,^(1,2)nitrides,^(3)and hydrides^(4)has led to exotic compositions and physical properties.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.12204419 and 12074013)。
文摘The presence of interstitial electrons in electrides endows them with interesting attributes,such as low work function,high carrier concentration,and unique magnetic properties.Thorough knowledge and understanding of electrides are thus of both scientific and technological significance.Here,we employ first-principles calculations to investigate Mott-insulating Ae_(5)X_(3)(Ae=Ca,Sr,and Ba;X=As and Sb)electrides with Mn_(5)Si_(3)-type structure,in which half-filled interstitial electrons serve as ions and are spin-polarized.The Mott-insulating property is induced by strong electron correlation between the nearest interstitial electrons,resulting in spin splitting and a separation between occupied and unoccupied states.The half-filled antiferromagnetic configuration and localization of the interstitial electrons are critical for the Mott-insulating properties of these materials.Compared with that in intermetallic electrides,the orbital hybridization between the half-filled interstitial electrons and the surrounding atoms is weak,leading to highly localized magnetic centers and pronounced correlation effects.Therefore,the Mott-insulating electrides Ae_(5)X_(3)have very large indirect bandgaps(0.30 eV).In addition,high pressure is found to strengthen the strong correlation effects and enlarge the bandgap.The present results provide a deeper understanding of the formation mechanism of Mott-insulating electrides and provide guidance for the search for new strongly correlated electrides.
基金the National Key Research and Development Program of China(2019YFA0708502)the National Natural Science Foundation of China(Grant No.U1930401)+3 种基金BL14U1 of the Shanghai Synchrotron Radiation Facility for beamtime access based on proposal 2019-SSRF-PT-011035 and Geo-SoilEnviroCARS(Sector 13-BMC and 13-BMD)at the Advanced Photon Source,Argonne National Laboratory,USAthe National Science Foundation Earth Sciences(Grant No.EAR1128799)the Department of Energy-GeoSciences(Grant No.DEFG02-94ER14466)The Advanced Photon Source is a U.S.Department of Energy(DOE)Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No.DE-AC02-06CH11357.
文摘δ-(Al,Fe)OOH is considered to be one of the most important hydrous phases on Earth,remaining stable under the extreme conditions throughout the mantle.The behavior ofδ-(Al,Fe)OOH at high pressure is essential to understanding the deep water cycle.δ-(Al_(0.956)Fe_(0.044))OOH crystals synthesized at 21 GPa and 1473 K were investigated by high-pressure Brillouin light scattering spectroscopy and synchrotron X-ray diffraction up to 135.4 GPa in diamond anvil cells.The incorporation of 5 mol%FeOOH increases the unit-cell volume ofδ-AlOOH by~1%and decreases the shear-wave velocity(VS)by~5%at 20–135 GPa.In particular,the compressional(V_(P))and shear(VS)wave velocities ofδ-(Al_(0.956)Fe_(0.044))OOH are 7%–16%and 10%–24%greater than all the major minerals in the mantle transition zone including wadsleyite,ringwoodite,and majorite.The distinctly high sound velocities ofδ-(Al_(0.956)Fe_(0.044))OOH at 20–25 GPa may contribute to the seismic anomalies observed at~560–680 km depths in the cold and stagnant slab beneath Izu-Bonin and/or Korea.Furthermore,the VS ofδ-(Al_(0.956)Fe_(0.044))OOH is about 10%and 4%–12%lower than iron-bearing bridgmanite Mg_(0.96)Fe_(0.05)Si_(0.99O3)and ferropericlase(Mg_(0.92)Fe_(0.08))O,respectively,under the lowermost mantle conditions,which might partially contribute to the large low-shear-velocity provinces and ultralow velocity zones at the bottom of the lower mantle.
基金Supported by the National Key Research and Development Program of China under Grant Nos.2018YFA0704300 and2017YFE0131300the National Natural Science Foundation of China under Grant Nos.U1932217,11974246,11874263 and10225417+1 种基金the Natural Science Foundation of Shanghai under Grant No.19ZR1477300the support from Analytical Instrumentation Center(SPST-AIC10112914),SPST,ShanghaiTech Universitysupported by Collaborative Research Project of Materials and Structures Laboratory,Tokyo Institute of Technology,Japan,Part of this research is supported by COMPRES(NSF Cooperative Agreement EAR-1661511)。
文摘Recently,natural van der Waals heterostructures of(MnBi2 Te4)m(Bi2 Te3)n have been theoretically predicted and experimentally shown to host tunable magnetic properties and topologically nontrivial surface states.We systematically investigate both the structural and electronic responses of MnBi2 Te4 and MnBi4 Te7 to external pressure.In addition to the suppression of antiferromagnetic order,MnBi2 Te4 is found to undergo a metalsemiconductor-metal transition upon compression.The resistivity of MnBi4 Te7 changes dramatically under high pressure and a non-monotonic evolution of p(T)is observed.The nontrivial topology is proved to persist before the structural phase transition observed in the high-pressure regime.We find that the bulk and surface states respond differently to pressure,which is consistent with the non-monotonic change of the resistivity.Interestingly,a pressure-induced amorphous state is observed in MnBi2 Te4,while two high-pressure phase transitions are revealed in MnBi4 Te7.Our combined theoretical and experimental research establishes MnBi2 Te4 and MnBi4 Te7 as highly tunable magnetic topological insulators,in which phase transitions and new ground states emerge upon compression.
基金H.K.Mao is supported by the National Natural Science Foundation of China under Grant No.U1930401.
文摘High pressure science and technology is a vast area of inter-disciplinary research that encompasses the fields of physics,chem-istry,geoscience,and materials science and in which the science of ordinary matter is only a special case under ambient condi-tions.Pressure,the physical variable of force exerted on the chem-ical bonding of a material,directly controls the material’s phys-ical and chemical properties.
文摘Materials transform abruptly under compression,with their properties varying as strong functions of pressure.Advances in highpressure and probe technology have enabled experimental characterizations up to several hundred gigapascal(GPa).Studies in the physical sciences are now expanding to include a vast previously uncharted pressure region in which transformative ideas and discoveries are becoming commonplace.Matter and Radiation under Extremes(MRE)is taking advantage of this opportunity to provide a forum for publishing the finest peer-reviewed research in highpressure science and technology on the basis of its interdisciplinary interest,importance,timeliness,and surprising conclusions.This MRE HP Special Volume gathers together a set of contemporary perspectives,highlights,reviews,and research articles in multiple disciplines of high-pressure physics,chemistry,materials,and geoscience that illustrate both current and forthcoming trends in this exciting research area.
文摘Electrides are unique ionic compounds that electrons serve as the anions. Many electrides with fascinating physical and chemical properties have been discovered at ambient condition. Under pressure, electrides are also revealed to be ubiquitous crystal morphology, enriching the geometrical topologies and electronic properties of electrides. In this Review,we overview the formation mechanism of high-pressure electrides(HPEs) and outline a scheme for exploring new HPEs from pre-design, CALYPSO assisted structural searches, indicators for electrides, to experimental synthesis. Moreover, the evolution of electronic dimensionality under compression is also discussed to better understand the dimensional distribution of anionic electrons in HPEs.
基金supported by the National Natural Science Foundation of China(Grant Nos.11927809,13001241,and E0209/52072170)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB25000000)。
文摘We successfully grow a new superconductor GaBa2Ca3Cu4O11+δ(Ga-1234) with a transition temperature of 113 K, using the Walker-type high-pressure synthesis apparatus. X-ray diffraction measurements on the powderized samples show a mixture of the Ga-1234 phase and the Ca0.85CuO2phase, and the former is dominant. Under the scanning electron microscope, plate-like crystals of the Ga-based 1234 phase with shiny surfaces can be seen.The obtained local chemical compositions revealed by energy dispersion x-ray spectroscopy are very close to the stoichiometric values. On some sub-millimeter crystal-like samples of the 1234 phase, we obtain a full Meissner shielding volume. From the temperature-dependent magnetizations, we determine the irreversibility fields and find that the system exhibits a highly anisotropic behavior.
基金supported by the National Key R&D Program of China(Grant Nos.2022YFA1403800,2023YFA1406500,and 2022YFA1403103)the National Natural Science Foundation of China(Grant Nos.12274459,12174443,12074013,and 12404266)the Science Research Project of Hebei Education Department(Grant No.BJ2025060)。
文摘We observed superconductivity in a cubic La_(3)Al single crystal that exhibits metallic behavior in the normal state without an observable structural transition and enters the superconducting state below T_(c)~6.32 K.Detailed characterization and analysis indicate that cubic La_(3)Al is a bulk type-Ⅱ BCS superconductor.Moreover,theoretical calculations show that it can host interstitial anionic electrons located at the body center of the cubic unit cell,which confirms electron-phonon coupling as the superconducting mechanism.Therefore,cubic La_(3)Al can be considered as a novel electride superconductor.
基金the National Natural Science Foundation of China(Nos.51861145201,52072168,21733001,and 91750101)the National Key Basic Research Program of the Ministry of Science and Technology of China(Nos.2018YFA0306200 and 2021YFA1202901)Jiangsu Key Laboratory of Artificial Functional Materials.L.Y.F.acknowledges financial support from the start-up fund of Chongqing University(No.02110011044171).
文摘Strain engineering can serve as a powerful technique for modulating the exotic properties arising from the atomic structure of materials.Examples have been demonstrated that one-dimensional(1D)structure can serve as a great platform for modulating electronic band structure and phonon dispersion via strain control.Particularly,in a van der Waals material silicon diphosphide(SiP_(2)),quasi-1D zigzag phosphorus–phosphorus(P–P)chains are embedded inside the crystal structure,and can show unique phonon vibration modes and realize quasi-1D excitons.Manipulating those optical properties by the atom displacements via strain engineering is of great interest in understanding underlying mechanism of such P–P chains,however,which remains elusive.Herein,we demonstrate the strain engineering of Raman and photoluminescence(PL)spectra in quasi-1D P–P chains and resulting in anisotropic manipulation in SiP_(2).We find that the phonon frequencies of SiP_(2)in Raman spectra linearly evolve with a uniaxial strain along/perpendicular to the quasi-1D P–P chain directions.Interestingly,by applying tensile strain along the P–P chains,the band gap energy of strained SiP_(2)can significantly decrease with a tunable value of~55 meV.Based on arsenic(As)element doping into SiP_(2),the strain-induced redshifts of phonon frequencies decrease,indicating the stiffening of the phonon vibration with the increased arsenic doping level.Such results provide an opportunity for strain engineering of the light–matter interactions in the quasi-1D P–P chains of SiP_(2)crystal for potential optical applications.
基金supported by the National Natural Science Foundation of China(Nos.U1530401,52071038,51871194)the Fundamental Research Funds for the Central Universities(No.N2102008)the Innovation Research Group Project of Hebei Natural Science Foundation,China(No.E2021203011).
文摘Advanced materials with superior comprehensive mechanical properties are strongly desired,but it has long been a challenge to achieve high ductility in high-strength materials.Here,we proposed a new V 0.5 Cr 0.5 CoNi medium-entropy alloy(MEA)with a face-centered cubic/hexagonal close-packed(FCC/HCP)dual-phase ultrafine-grained(UFG)architecture containing stacking faults(SFs)and local chemical order(LCO)in HCP solid solution,to obtain an ultrahigh yield strength of 1476 MPa and uniform elongation of 13.2%at ambient temperature.The ultrahigh yield strength originates mainly from fine grain strength-ening of the UFG FCC matrix and HCP second-phase strengthening assisted by the SFs and LCO inside,whereas the large ductility correlates to the superior ability of the UFG FCC matrix to storage disloca-tions and the function of deformation-induced SFs in the vicinity of the FCC/HCP boundary to eliminate the stress concentration.This work provides new guidance by engineering novel composition and stable UFG structure for upgrading the mechanical properties of metallic materials.
基金This project was supported by the National Natural Science Foundation of China(NSFC)under Grants no.51201148 and U1530402the Thousand Youth Talents Plan.This work was also supported by MEXT Element Strategy Initiative and ACCEL of the Japan Science and Technology Agency in Japan.H.H.acknowledges MEXT KAKEHI(Grant no.17H06153)Stay of H.G.at Tokyo Tech was supported by WRHI program.Y.F.L.was supported by the JSPS fellowship for young scientists(No.18J00745).
文摘Developing and understanding electron-rich electrides offers a promising opportunity for a variety of electronic and catalytic applications.Using a geometrical identification strategy,here we identify a new class of electride material,yttrium/scandium chlorides Y(Sc)_(x)Cl_(y)(yx<2).Anionic electrons are found in the metal octahedral framework topology.The diverse electronic dimensionality of these electrides is quantified explicitly by quasi-two-dimensional(2D)electrides for[YCl]^(+)∙e−and[ScCl]^(+∙)e−and one-dimensional(1D)electrides for[Y_(2)Cl_(3)]^(+)∙e−,[Sc_(7)Cl_(10)]^(+)∙e−,and[Sc5Cl8]2+∙2e−with divalent metal elements(Sc^(2+):3d^(1) and Y^(2+):4d^(1)).The localized anionic electrons were confined within the inner-layer spaces,rather than inter-layer spaces that are observed in A_(2)B-type 2D electrides,e.g.Ca_(2)N.Moreover,when hydrogen atoms are introduced into the host structures to form YClH and Y2Cl3H,the generated phases transform to conventional ionic compounds but exhibited a surprising reduction of work function,arising from the increased Fermi level energy,contrary to the conventional electrides reported so far.Y_(2C)l_(3) was experimentally confirmed to be a semiconductor with a band gap of 1.14 eV.These results may help to promote the rational design and discovery of new electride materials for further technological applications.
基金This research was supported by the National Natural Science Foundation of China(Nos.52072168,51861145201,21733001 and 91750101)the National Key R&D Program of China(Nos.2018YFA0306200 and 2021YFA1202901)Y.F.L.acknowledges financial support by the start-up fund from Chongqing University(No.02110011044171).
文摘Light-matter interactions in low-dimensional quantum-confined structures can dominate the optical properties of the materials and lead to optoelectronic applications.In anisotropic layered silicon diphosphide(SiP2)crystal,the embedded quasi-onedimensional(1D)phosphorus–phosphorus(P–P)chains directly result in an unconventional quasi-1D excitonic state,and a special phonon mode vibrating along the P–P chains,establishing a unique 1D quantum-confined system.Alloying SiP2 with the homologous element serves as an effective way to study the properties of these excitons and phonons associated with the quasi-1D P–P chains,as well as the strong interaction between these quasiparticles.However,the experimental observation and the related optical spectral understanding of SiP2 with isoelectronic dopants remain elusive.Herein,with the photoluminescence and Raman spectroscopy measurements,we demonstrate the redshift of the confined excitonic peak and the stiffening of the phonon vibration mode■of a series of Si(P1−xAsx)2 alloys with increasing arsenic(As)compositions.This anomalous stiffening of■is attributed to the selective substitution of As atoms for P atoms within the P–P chains,which is confirmed via our scanning transmission electron microscopy investigation.Such optical spectra evolutions with selective substitution pave a new way to understand the 1D quantum confinement in semiconductors,offering opportunities to explore quasi-1D characteristics in SiP2 and the resulting photonic device application.
基金supported by the National Natural Science Foundation of China(12004252,52272265,U1932217,11974246,52072400,52025025,and 92065109)the National Key R&D Program of China(2018YFA0704300,2021YFA1401800,2018YFE0202601,2020YFA0308800,and 2022YFA1403400)+2 种基金Shanghai Science and Technology Plan(21DZ2260400)Beijing Natural Science Foundation(Z190010,Z210006,and Z190006)the support from the Analytical Instrumentation Center(#SPST-AIC10112914),School of Physical Science and Technology(SPST),ShanghaiTech University。
基金supported by the Presidential Foundation of CAEP(grant no.YZJJLX2019006)the National Science Foundation of China(grant nos.22075259 and 22175157).
文摘Pressure produces closely packed,high-density materials,thereby providing a promising strategy to obtain high-energy-density materials.However,new phases or structures of energetic materials at high pressure are often not quenchable under ambient conditions.In this work,high-pressure topochemical methodology is first introduced for the preparation of stable energetic materials under ambient conditions.A pressure-induced polymerizable energetic material named PIP-1 is designed and prepared.The experimental measurements demonstrate that the polymerization of PIP-1 is caused by the breakage of C≡C bonds and the generation of C=C bonds.In accord with the experimental results,density functional theory calculations further revealed that the monomer PIP-1 is polymerized to generate 1D PIP-1 tape,and the density of polymerized PIP-1 is increased by 4.9%upon decompression.The successful realization of high-energy-density structure using high pressure showcases a new design strategy for advanced polymerizable energetic materials.
