Polymerization of fullerenes is an interesting topic that has been studied for almost three decades.A rich polymeric phase diagram of C60 has been drawn under a variety of pressure P and temperature T conditions.Knowl...Polymerization of fullerenes is an interesting topic that has been studied for almost three decades.A rich polymeric phase diagram of C60 has been drawn under a variety of pressure P and temperature T conditions.Knowledge of the targeted preparation and structural control of fullerene polymers has become increasingly important because of their utility in producing novel fullerenebased architectures with unusual properties and potential applications.This paper focuses on the polymeric phases of fullerenes and their derivatives under high P and/or high T.First,the polymerization behavior and the various polymeric phases of C60 and C70 under such conditions are briefly reviewed.A summary of the polymerization process of intercalated fullerenes is then presented,and a synthetic strategy for novel structural and functional fullerene polymers is proposed.Finally,on the basis of the results of recent research,a proposal is made for further studies of endohedral fullerenes at high P.展开更多
The lower mantle makes up more than a half of our planet’s volume. Mineralogical and petrological experiments on realistic bulk compositions under high pressure–temperature (P–T) conditions are essential for unders...The lower mantle makes up more than a half of our planet’s volume. Mineralogical and petrological experiments on realistic bulk compositions under high pressure–temperature (P–T) conditions are essential for understanding deep mantle processes. Such high P–T experiments are commonly conducted in a laser-heated diamond anvil cell, producing a multiphase assemblage consisting of 100 nm to submicron crystallite grains. The structures of these lower mantle phases often cannot be preserved upon pressure quenching;thus, in situ characterization is needed. The X-ray diffraction (XRD) pattern of such a multiphase assemblage usually displays a mixture of diffraction spots and rings as a result of the coarse grain size relative to the small X-ray beam size (3–5 lm) available at the synchrotron facilities. Severe peak overlapping from multiple phases renders the powder XRD method inadequate for indexing new phases and minor phases. Consequently, structure determination of new phases in a high P–T multiphase assemblage has been extremely difficult using conventional XRD techniques. Our recent development of multigrain XRD in high-pressure research has enabled the indexation of hundreds of individual crystallite grains simultaneously through the determination of crystallographic orientations for these individual grains. Once indexation is achieved, each grain can be treated as a single crystal. The combined crystallographic information from individual grains can be used to determine the crystal structures of new phases and minor phases simultaneously in a multiphase system. With this new development, we have opened up a new area of crystallography under the high P–T conditions of the deep lower mantle. This paper explains key challenges in studying multiphase systems and demonstrates the unique capabilities of high-pressure multigrain XRD through successful examples of its applications.展开更多
Although nitrogen in the Earth’s interior has attracted significant attention recently,it remains the most enigmatic of the light elements in the Earth’s core.In this work,synchrotron X-ray diffraction(XRD)and elect...Although nitrogen in the Earth’s interior has attracted significant attention recently,it remains the most enigmatic of the light elements in the Earth’s core.In this work,synchrotron X-ray diffraction(XRD)and electrical conductivity experiments were conducted on iron nitrides(Fe_(2)N and Fe_(4)N)in diamond anvil cells(DACs)up to about 70 GPa at ambient temperature.These results show that iron nitrides are stable up to at least 70 GPa.From the equation of state(EOS)parameters,iron nitrides are more compressible than iron carbides.Moreover,using the van der Pauw method and Wiedemann-Franz law,the electrical and thermal conductivity of samples were determined to be much lower than that of iron carbides.The conductivities of Fe_(2)N and Fe_(4)N were similar at 20–70 GPa,suggesting no evident effects by varying the N stoichiometries in iron nitrides.Iron nitrides are less dense and conductive but more compressible than carbides at 0–70 GPa.This study indicates that less nitrogen than carbon can explain geophysical phenomena in the deep Earth,such as the density deficit.展开更多
Brucite Mg(OH)_(2) is an archetypal hydrous mineral and it has attracted a great deal of attention.However,little is known about the evolution of hydroxyl groups in brucite with respect to subduction fluids.We carried...Brucite Mg(OH)_(2) is an archetypal hydrous mineral and it has attracted a great deal of attention.However,little is known about the evolution of hydroxyl groups in brucite with respect to subduction fluids.We carried out Raman measurements up to 15.4 GPa and 874 K via an externally heated diamond anvil cell,investigating the stability of brucite under the conditions relevant to subducting slabs.The hydroxyl vibration mode A_(1g)(I) of brucite is weakened under simultaneous high pressure-temperature conditions.Meanwhile,the presence of carbonated solution can destabilize the hydroxyl groups of brucite at low pressure.Our results suggest that brucite releases water when reacting with hydrogen carbonate ion to form magnesite MgCO_(3) in subduction zones.This implies that the global water cycle is largely coupled with the deep carbon cycle in Earth’s interior.展开更多
Metal halide perovskites(HPVs)have been greatly developed over the last decade,with various compositions,dimensionalities,and morphologies,leading to an emergence of high-performance photovoltaic and optoelectronic ap...Metal halide perovskites(HPVs)have been greatly developed over the last decade,with various compositions,dimensionalities,and morphologies,leading to an emergence of high-performance photovoltaic and optoelectronic applications.Despite the tremendous progress made,challenges remain,which calls for a better understanding of the fundamental mechanisms.Pressure,a thermodynamic variable,provides a powerful tool to tune materials’structures and properties.In combination with in situ characterization methods,high-pressure research could provide a better fundamental understanding.In this review,we summarize the recent studies of the dramatic,pressure-induced changes that occur in HPVs,particularly the enhanced and emergent properties induced under high pressure and their structure-property relationships.We first introduce the characteristics of HPVs and the basic knowledge of high-pressure techniques,as well as in situ characterization methods.We then discuss the effects of pressure on HPVs with different compositions,dimensionalities,and morphologies,and underline their common features and anomalous behaviors.In the last section,we highlight the main challenges and provide suggestions for possible future research on high-pressure HPVs.展开更多
Three tungsten powder samples—one coarse grained(c-W;grain size:1μm–3μm)and two nanocrystalline(n-W;average grain sizes:10nm and 50 nm)—are investigated under nonhydrostatic compression in a diamond anvil cell in...Three tungsten powder samples—one coarse grained(c-W;grain size:1μm–3μm)and two nanocrystalline(n-W;average grain sizes:10nm and 50 nm)—are investigated under nonhydrostatic compression in a diamond anvil cell in separate experiments,and their in situ X-ray diffraction patterns are recorded.The maximum microscopic deviatoric stress in each tungsten sample,a measure of the yield strength,is determined by analyzing the diffraction line width.Over the entire pressure range,the strength of tungsten increases noticeably as the grain size is decreased from 1μm–3μmto 10 nm.The results show that the yield strength of tungsten with an average crystal size of 10nmis around 3.5 times that of the sample with a grain size of 1μm–3μm.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
This study presents experimental evidence of the dependence of non-radiative recombination processes on the electron-phonon coupling of perovskite in perovskite solar cells(PSCs).Via A-site cation engineering,a weaker...This study presents experimental evidence of the dependence of non-radiative recombination processes on the electron-phonon coupling of perovskite in perovskite solar cells(PSCs).Via A-site cation engineering,a weaker electron-phonon coupling in perovskite has been achieved by introducing the structurally soft cyclohexane methylamine(CMA^(+))cation,which could serve as a damper to alleviate the mechanical stress caused by lattice oscillations,compared to the rigid phenethyl methylamine(PEA^(+))analog.It demonstrates a significantly lower non-radiative recombination rate,even though the two types of bulky cations have similar chemical passivation effects on perovskite,which might be explained by the suppressed carrier capture process and improved lattice geometry relaxation.The resulting PSCs achieve an exceptional power conversion efficiency(PCE)of 25.5%with a record-high opencircuit voltage(V_(OC))of 1.20 V for narrow bandgap perovskite(FAPbI_(3)).The established correlations between electron-phonon coupling and non-radiative decay provide design and screening criteria for more effective passivators for highly efficient PSCs approaching the Shockley-Queisser limit.展开更多
Carbon, hydrogen, oxygen, nitrogen, sulfur, and their compounds are volatile components that dominate the thin and fragile atmosphere, hydrosphere, and biosphere on Earth’s habitable surface. However, the vast majori...Carbon, hydrogen, oxygen, nitrogen, sulfur, and their compounds are volatile components that dominate the thin and fragile atmosphere, hydrosphere, and biosphere on Earth’s habitable surface. However, the vast majority of these volatiles are hidden in the deep interior, where the high pressure–temperature conditions drastically and categorically alter the physics and chemistry of the volatiles. Like the bloodstream of an organism, the circulations and interactions of volatiles in the deep Earth modulate climate, resources, energy, natural hazards, and other factors that define the Earth as a unique living and changing planet.展开更多
Two kinds of glassy sulfurs are synthesized by thrapid compression method from liquid sulfur at temperatures below and above the X-transition point. The glassy sulfur has different colors and transparencies, depending...Two kinds of glassy sulfurs are synthesized by thrapid compression method from liquid sulfur at temperatures below and above the X-transition point. The glassy sulfur has different colors and transparencies, depending on temperature, which may inherit some structural information from the transition. Raman spectrum studies of these samples show that a large fraction of polymeric chains exist in the glassy sulfur, even in the one solidified from T 〈 Tλ. We find that a higher compression rate instead of a higher temperature of the parent liquid captures more polymeric chains. Pressure-induced glassy sulfur presents high thermal stability compared with temperature quenched glassy sulfur and could transform into liquid sulfur directly without crystallization through an abnormal exothermic melting course. High energy x-ray diffraction is utilized to study the local order of the pressure-induced glassy sulfur.展开更多
The comprehension of the composition and physical state of the deep interiors of large planets,as well as the impact events pertinent to planetary formation and evolution,necessitates an understanding of the propertie...The comprehension of the composition and physical state of the deep interiors of large planets,as well as the impact events pertinent to planetary formation and evolution,necessitates an understanding of the properties of planetary materials under extreme conditions.Forsterite(Mg2SiO4),a significant geological mineral,has not been fully characterized in terms of its behavior under shock compression due to a lack of consensus among previous experiments and simulations aimed at determining its Hugoniot,as well as the absence of knowledge of sound velocity at high pressures,a critical parameter indicative of phase transformation and melting.In this study,we delineated the Hugoniot curve of the mineral forsterite up to immense pressures of 1200 GPa.For the first time,we successfully constrained its sound velocity along the Hugoniot curve up to 760 GPa by combining laser-driven shock experiments with first-principles molecular dynamics simulations.The measured Hugoniot data for forsterite corroborated previous findings and suggested the occurrence of incongruent melting during shock compression.Remarkably,along their respective Hugoniot curves,the sound velocity of forsterite was observed to fall between that of the minerals bridgmanite and periclase.The remarkable agreement between the experimental results and simulation data provides reliable sound velocity measurements on the forsterite Hugoniot,which is critical for comprehensively understanding the phase transition and melting behavior of forsterite under ultra-high pressures.This knowledge sheds invaluable light on the behavior of this significant geological mineral under extreme conditions akin to those found in the interiors of planets.展开更多
Zero-dimensional(0D)hybrid metal halides are under intensive investigation owing to their unique physical properties,such as the broadband emission from highly localized excitons that is promising for white-emitting l...Zero-dimensional(0D)hybrid metal halides are under intensive investigation owing to their unique physical properties,such as the broadband emission from highly localized excitons that is promising for white-emitting lighting.However,fundamental understanding of emission variations and structure–property relationships is still limited.Here,by using pressure processing,we obtain robust exciton emission in 0D(C_(9)NH_(20))_(6)Pb_(3)Br_(12) at room temperature that can survive to 80 GPa,the recorded highest value among all the hybrid metal halides.In situ experimental characterization and first-principles calculations reveal that the pressure-induced emission is mainly caused by the largely suppressed phonon-assisted nonradiative pathway.Lattice compression leads to phonon hardening,which considerably weakens the exciton–phonon interaction and thus enhances the emission.The robust emission is attributed to the unique structure of separated spring-like[Pb_(3)Br_(12)]^(6−)trimers,which leads to the outstanding stability of the optically active inorganic units.Our findings not only reveal abnormally robust emission in a 0D metal halide,but also provide new insight into the design and optimization of local structures of trimers and oligomers in lowdimensional hybrid materials.展开更多
The geologic production of abiotic organic compounds has been the subject of increasing scientific attention due to their use in the global carbon flux balance,by chemosynthetic biological communities,and for energy r...The geologic production of abiotic organic compounds has been the subject of increasing scientific attention due to their use in the global carbon flux balance,by chemosynthetic biological communities,and for energy resources.Extensive analysis of methane(CH_(4))and other organics in diverse geologic settings,combined with thermodynamic modelings and laboratory simulations,have yielded insights into the distribution of specific abiotic organic molecules on Earth and the favorable conditions and pathways under which they form.This updated and comprehensive review summarizes published results of petrological,thermodynamic,and experimental investigations of possible pathways for the formation of particular species of abiotic simple hydrocarbon molecules such as CH_(4),and of complex hydrocarbon systems,e.g.,long-chain hydrocarbons and even solid carbonaceous matters,in various geologic processes,distinguished into three classes:(1)pre-to early planetary processes;(2)mantle and magmatic processes;and(3)the gas/water-rock reaction processes in low-pressure ultramafic rock and high-pressure subduction zone systems.We not only emphasize how organics are abiotically synthesized but also explore the role or changes of organics in evolutionary geological environments after synthesis,such as phase transitions or organic-mineral interactions.Correspondingly,there is an urgent need to explore the diversity of abiotic organic compounds prevailing on Earth.展开更多
Pressure evolution of local structure and vibrational dynamics of the perovskite-type relaxor ferroelectric single crystal of 0.935(Na0.5Bi0.5)TiO3-0.065BaTiO3(NBT-6.5BT)is systematically investigated via in situ Rama...Pressure evolution of local structure and vibrational dynamics of the perovskite-type relaxor ferroelectric single crystal of 0.935(Na0.5Bi0.5)TiO3-0.065BaTiO3(NBT-6.5BT)is systematically investigated via in situ Raman spectroscopy.The pressure dependence of phonon modes up to 30GPa reveals two characteristic pressures:one is at around 4.6GPa which corresponds to the rhombohedral-to-tetragonal phase transition,showing that the pressure strongly suppresses the coupling between the off-centered A-and B-site cations;the other structural transition involving the oxygen octahedral tilt and vibration occurs at pressure∼13–15GPa with certain degree of order-disorder transition,evidenced by the abnormal changes of intensity and FWHM in Raman spectrum.展开更多
Volatile elements—such as carbon, hydrogen, sulfur, nitrogen, and halogens—are minor constituents of Earth’s deep interior. Despite their low abundances, deep volatiles mediate major Earth processes, including magm...Volatile elements—such as carbon, hydrogen, sulfur, nitrogen, and halogens—are minor constituents of Earth’s deep interior. Despite their low abundances, deep volatiles mediate major Earth processes, including magma generation, volcanism, mantle convection, and plate tectonics, which control the exchange of volatiles between Earth’s deep interior and its surface. Over geological time, deep volatiles play critical, primary roles in governing energy resources, natural hazards, atmospheric composition, climate, and planetary habitability. Human activities after the industrial revolution have played an impactful, secondary role, and the resulting risk of add-on effects that could lead to irreversible runaway catastrophes has greatly increased.展开更多
Iron oxides are widely found as ores in Earth's crust and are also important constituents of its interiors.Their polymorphism,composition changes,and electronic structures play essential roles in controlling the s...Iron oxides are widely found as ores in Earth's crust and are also important constituents of its interiors.Their polymorphism,composition changes,and electronic structures play essential roles in controlling the structure and geodynamic properties of the solid Earth.While all-natural occurring iron oxides are semiconductors or insulators at ambient pressure,they start to metalize under pressure.Here in this work,we review the electronic conductivity and metallization of iron oxides under high-pressure conditions found in Earth's lower mantle.We summarize that the metallization of iron oxides is generally controlled by the pressure-induced bandgap closure near the Fermi level.After metallization,they possess much higher electrical and thermal conductivity,which will facilitate the thermal convection,support a more stable and thicker D′′layer,and formulate Earth's magnetic field,all of which will constrain the large-scale dynamos of the mantle and core.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
Basalt is an igneous rock originating from the cooling and solidification of magma and covers approximately 70% of Earth’s surface.Basaltic glass melting in the deep Earth is a fundamental subject of research for und...Basalt is an igneous rock originating from the cooling and solidification of magma and covers approximately 70% of Earth’s surface.Basaltic glass melting in the deep Earth is a fundamental subject of research for understanding geophysics,geochemistry,and geodynamic processes.In this study,we design a laser flash heating system using two-dimensional,four-color multi-wavelength imaging radiometry to measure the basaltic glass melting temperature under high pressure conditions in diamond anvil cells.Our experiment not only determines the temperature at the center of heating but also constructs a temperature distribution map for the surface heating area,and enables us to assess the temperature gradient.Through precise temperature measurements,we observe that the basaltic glass melting temperature is higher than those in previous reports,which is near the normal upper-mantle isotherm,approaching the hot geotherm.This suggests that basalt should not melt in most of the normal upper mantle and the basaltic melts could exist in some hot regions.展开更多
A broad tunability of the thermoelectric and mechanical properties of CoSb_(3) has been demonstrated by adjusting the composition with the addition of an increasing number of elements.However,such a strategy may negat...A broad tunability of the thermoelectric and mechanical properties of CoSb_(3) has been demonstrated by adjusting the composition with the addition of an increasing number of elements.However,such a strategy may negatively impact processing repeatability and composition control.In this work,singleelement-filled skutterudite is engineered to have high thermoelectric and mechanical performances.Increased Yb filling fraction is found to increase phonon scattering,whereas cryogenic grinding contributes additional microstructural scattering.A peak zT of 1.55 and an average zT of about 1.09,which is comparable to the reported results of multiple-filled SKDs,are realized by the combination of simple composition and microstructure engineering.Furthermore,the mechanical properties of Yb single-filled CoSb_(3) skutterudite are improved by manipulation of the microstructure through cryogenic grinding.These findings highlight the realistic prospect of producing high-performance thermoelectric materials with reduced compositional complexity.展开更多
Two-dimensional materials are widely considered to be highly promising for the development of photodetectors.To improve the performance of these devices,researchers often employ techniques such as defect engineering.H...Two-dimensional materials are widely considered to be highly promising for the development of photodetectors.To improve the performance of these devices,researchers often employ techniques such as defect engineering.Herein,pressure is employed as a clean and novel means to manipulate the structural and physical properties of EuSbTe_(3),an emerging two-dimensional semiconductor.The experimental results demonstrate that the structural phase transformation of EuSbTe_(3)occurs under pressure,with an increase in infrared reflectivity,a band gap closure,and a metallization at pressures.Combined with X-ray diffraction(XRD)and Raman characterizations,it is evident that the pressure-driven transition from semiconductor Pmmn phase to metallic Cmcm phase causes the disappearance of the charge density wave.Furthermore,at a mild pressure,approximately 2 GPa,the maximum photocurrent of EuSbTe_(3)is three times higher than that at ambient condition,suggesting an untapped potential for various practical applications.展开更多
基金This work was mainly supported by National Science Associated Funding(NSAF,Grant No.U1530402)the Natural Science Foundation of China(Grant No.11874076)+1 种基金the Science Challenging Program(Grant No.JCKY2016212A501)the Postdoctoral Science Foundation(2015M572499).
文摘Polymerization of fullerenes is an interesting topic that has been studied for almost three decades.A rich polymeric phase diagram of C60 has been drawn under a variety of pressure P and temperature T conditions.Knowledge of the targeted preparation and structural control of fullerene polymers has become increasingly important because of their utility in producing novel fullerenebased architectures with unusual properties and potential applications.This paper focuses on the polymeric phases of fullerenes and their derivatives under high P and/or high T.First,the polymerization behavior and the various polymeric phases of C60 and C70 under such conditions are briefly reviewed.A summary of the polymerization process of intercalated fullerenes is then presented,and a synthetic strategy for novel structural and functional fullerene polymers is proposed.Finally,on the basis of the results of recent research,a proposal is made for further studies of endohedral fullerenes at high P.
基金the National Natural Science Foundation of China (41574080 and U1530402).
文摘The lower mantle makes up more than a half of our planet’s volume. Mineralogical and petrological experiments on realistic bulk compositions under high pressure–temperature (P–T) conditions are essential for understanding deep mantle processes. Such high P–T experiments are commonly conducted in a laser-heated diamond anvil cell, producing a multiphase assemblage consisting of 100 nm to submicron crystallite grains. The structures of these lower mantle phases often cannot be preserved upon pressure quenching;thus, in situ characterization is needed. The X-ray diffraction (XRD) pattern of such a multiphase assemblage usually displays a mixture of diffraction spots and rings as a result of the coarse grain size relative to the small X-ray beam size (3–5 lm) available at the synchrotron facilities. Severe peak overlapping from multiple phases renders the powder XRD method inadequate for indexing new phases and minor phases. Consequently, structure determination of new phases in a high P–T multiphase assemblage has been extremely difficult using conventional XRD techniques. Our recent development of multigrain XRD in high-pressure research has enabled the indexation of hundreds of individual crystallite grains simultaneously through the determination of crystallographic orientations for these individual grains. Once indexation is achieved, each grain can be treated as a single crystal. The combined crystallographic information from individual grains can be used to determine the crystal structures of new phases and minor phases simultaneously in a multiphase system. With this new development, we have opened up a new area of crystallography under the high P–T conditions of the deep lower mantle. This paper explains key challenges in studying multiphase systems and demonstrates the unique capabilities of high-pressure multigrain XRD through successful examples of its applications.
基金the China Postdoctoral Science Foundation(18NZ021-0213-216308)GeoSoilEnviroCARS is supported by the National Science Foundation-Earth Sciences(EAR-1634415)+2 种基金the Department of Energy-GeoSciences(DE-FG02-94ER14466)13BM-C is partially supported by COMPRES under NSF Cooperative Agreement EAR-1606856the Advanced Photon Source,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Although nitrogen in the Earth’s interior has attracted significant attention recently,it remains the most enigmatic of the light elements in the Earth’s core.In this work,synchrotron X-ray diffraction(XRD)and electrical conductivity experiments were conducted on iron nitrides(Fe_(2)N and Fe_(4)N)in diamond anvil cells(DACs)up to about 70 GPa at ambient temperature.These results show that iron nitrides are stable up to at least 70 GPa.From the equation of state(EOS)parameters,iron nitrides are more compressible than iron carbides.Moreover,using the van der Pauw method and Wiedemann-Franz law,the electrical and thermal conductivity of samples were determined to be much lower than that of iron carbides.The conductivities of Fe_(2)N and Fe_(4)N were similar at 20–70 GPa,suggesting no evident effects by varying the N stoichiometries in iron nitrides.Iron nitrides are less dense and conductive but more compressible than carbides at 0–70 GPa.This study indicates that less nitrogen than carbon can explain geophysical phenomena in the deep Earth,such as the density deficit.
基金Supported by the National Key Research and Development Program of China(Grant No.2019YFA0708502)。
文摘Brucite Mg(OH)_(2) is an archetypal hydrous mineral and it has attracted a great deal of attention.However,little is known about the evolution of hydroxyl groups in brucite with respect to subduction fluids.We carried out Raman measurements up to 15.4 GPa and 874 K via an externally heated diamond anvil cell,investigating the stability of brucite under the conditions relevant to subducting slabs.The hydroxyl vibration mode A_(1g)(I) of brucite is weakened under simultaneous high pressure-temperature conditions.Meanwhile,the presence of carbonated solution can destabilize the hydroxyl groups of brucite at low pressure.Our results suggest that brucite releases water when reacting with hydrogen carbonate ion to form magnesite MgCO_(3) in subduction zones.This implies that the global water cycle is largely coupled with the deep carbon cycle in Earth’s interior.
文摘Metal halide perovskites(HPVs)have been greatly developed over the last decade,with various compositions,dimensionalities,and morphologies,leading to an emergence of high-performance photovoltaic and optoelectronic applications.Despite the tremendous progress made,challenges remain,which calls for a better understanding of the fundamental mechanisms.Pressure,a thermodynamic variable,provides a powerful tool to tune materials’structures and properties.In combination with in situ characterization methods,high-pressure research could provide a better fundamental understanding.In this review,we summarize the recent studies of the dramatic,pressure-induced changes that occur in HPVs,particularly the enhanced and emergent properties induced under high pressure and their structure-property relationships.We first introduce the characteristics of HPVs and the basic knowledge of high-pressure techniques,as well as in situ characterization methods.We then discuss the effects of pressure on HPVs with different compositions,dimensionalities,and morphologies,and underline their common features and anomalous behaviors.In the last section,we highlight the main challenges and provide suggestions for possible future research on high-pressure HPVs.
基金This study was supported by the National Key R&D Program of China(Grant No.2018YFA0305900)
文摘Three tungsten powder samples—one coarse grained(c-W;grain size:1μm–3μm)and two nanocrystalline(n-W;average grain sizes:10nm and 50 nm)—are investigated under nonhydrostatic compression in a diamond anvil cell in separate experiments,and their in situ X-ray diffraction patterns are recorded.The maximum microscopic deviatoric stress in each tungsten sample,a measure of the yield strength,is determined by analyzing the diffraction line width.Over the entire pressure range,the strength of tungsten increases noticeably as the grain size is decreased from 1μm–3μmto 10 nm.The results show that the yield strength of tungsten with an average crystal size of 10nmis around 3.5 times that of the sample with a grain size of 1μm–3μm.
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supported by the National Natural Science Foundation of China(U21A20331,81903743,22005322,22279151,and 22275004)National Science Fund for Distinguished Young Scholars(21925506).
文摘This study presents experimental evidence of the dependence of non-radiative recombination processes on the electron-phonon coupling of perovskite in perovskite solar cells(PSCs).Via A-site cation engineering,a weaker electron-phonon coupling in perovskite has been achieved by introducing the structurally soft cyclohexane methylamine(CMA^(+))cation,which could serve as a damper to alleviate the mechanical stress caused by lattice oscillations,compared to the rigid phenethyl methylamine(PEA^(+))analog.It demonstrates a significantly lower non-radiative recombination rate,even though the two types of bulky cations have similar chemical passivation effects on perovskite,which might be explained by the suppressed carrier capture process and improved lattice geometry relaxation.The resulting PSCs achieve an exceptional power conversion efficiency(PCE)of 25.5%with a record-high opencircuit voltage(V_(OC))of 1.20 V for narrow bandgap perovskite(FAPbI_(3)).The established correlations between electron-phonon coupling and non-radiative decay provide design and screening criteria for more effective passivators for highly efficient PSCs approaching the Shockley-Queisser limit.
基金Alfred P. Sloan Foundation (G-2016-7065) to the DCO Secretariatthe National Natural Science Foundation of China (U1530402) to HPSTAR.
文摘Carbon, hydrogen, oxygen, nitrogen, sulfur, and their compounds are volatile components that dominate the thin and fragile atmosphere, hydrosphere, and biosphere on Earth’s habitable surface. However, the vast majority of these volatiles are hidden in the deep interior, where the high pressure–temperature conditions drastically and categorically alter the physics and chemistry of the volatiles. Like the bloodstream of an organism, the circulations and interactions of volatiles in the deep Earth modulate climate, resources, energy, natural hazards, and other factors that define the Earth as a unique living and changing planet.
基金supported by the Joint Funds of the National Natural Science Foundation of China(Grant No.U1530402)the National Natural Science Foundation of China(Grant No.11004163)+2 种基金the Fundamental Research Funds for the Central Universities,China(Grant No.2682014ZT31)the Department of Energy National Nuclear Security Administration(Grant No.DE-NA0001974)the Department of Energy Basic Energy Sciences(Grant Nos.DE-FG02-99ER45775and DE-AC02-06CH11357)
文摘Two kinds of glassy sulfurs are synthesized by thrapid compression method from liquid sulfur at temperatures below and above the X-transition point. The glassy sulfur has different colors and transparencies, depending on temperature, which may inherit some structural information from the transition. Raman spectrum studies of these samples show that a large fraction of polymeric chains exist in the glassy sulfur, even in the one solidified from T 〈 Tλ. We find that a higher compression rate instead of a higher temperature of the parent liquid captures more polymeric chains. Pressure-induced glassy sulfur presents high thermal stability compared with temperature quenched glassy sulfur and could transform into liquid sulfur directly without crystallization through an abnormal exothermic melting course. High energy x-ray diffraction is utilized to study the local order of the pressure-induced glassy sulfur.
基金the financial support from the Natural Science Foundation of China(41925017)Toshimori Sekine acknowledges the financial support from Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments,China(No.22dz2260800)+1 种基金Shanghai Science and Technology Committee,China(No.22JC1410300)the financial support from the Sichuan Science and Technology Program(No.2023NSFSC1910).
文摘The comprehension of the composition and physical state of the deep interiors of large planets,as well as the impact events pertinent to planetary formation and evolution,necessitates an understanding of the properties of planetary materials under extreme conditions.Forsterite(Mg2SiO4),a significant geological mineral,has not been fully characterized in terms of its behavior under shock compression due to a lack of consensus among previous experiments and simulations aimed at determining its Hugoniot,as well as the absence of knowledge of sound velocity at high pressures,a critical parameter indicative of phase transformation and melting.In this study,we delineated the Hugoniot curve of the mineral forsterite up to immense pressures of 1200 GPa.For the first time,we successfully constrained its sound velocity along the Hugoniot curve up to 760 GPa by combining laser-driven shock experiments with first-principles molecular dynamics simulations.The measured Hugoniot data for forsterite corroborated previous findings and suggested the occurrence of incongruent melting during shock compression.Remarkably,along their respective Hugoniot curves,the sound velocity of forsterite was observed to fall between that of the minerals bridgmanite and periclase.The remarkable agreement between the experimental results and simulation data provides reliable sound velocity measurements on the forsterite Hugoniot,which is critical for comprehensively understanding the phase transition and melting behavior of forsterite under ultra-high pressures.This knowledge sheds invaluable light on the behavior of this significant geological mineral under extreme conditions akin to those found in the interiors of planets.
基金supported by the National Nature Science Foundation of China(NSFC)(Grant Nos.U1930401 and 51527801)support from the National Science Foundation(Grant No.DMR-1709116)+2 种基金supported by the National Science Foundation–Earth Sciences(Grant No.EAR-1634415)the Department of Energy–GeoSciences(Grant No.DE-FG02-94ER14466)partially by COMPRES under NSF Cooperative Agreement No.EAR-1606856.
文摘Zero-dimensional(0D)hybrid metal halides are under intensive investigation owing to their unique physical properties,such as the broadband emission from highly localized excitons that is promising for white-emitting lighting.However,fundamental understanding of emission variations and structure–property relationships is still limited.Here,by using pressure processing,we obtain robust exciton emission in 0D(C_(9)NH_(20))_(6)Pb_(3)Br_(12) at room temperature that can survive to 80 GPa,the recorded highest value among all the hybrid metal halides.In situ experimental characterization and first-principles calculations reveal that the pressure-induced emission is mainly caused by the largely suppressed phonon-assisted nonradiative pathway.Lattice compression leads to phonon hardening,which considerably weakens the exciton–phonon interaction and thus enhances the emission.The robust emission is attributed to the unique structure of separated spring-like[Pb_(3)Br_(12)]^(6−)trimers,which leads to the outstanding stability of the optically active inorganic units.Our findings not only reveal abnormally robust emission in a 0D metal halide,but also provide new insight into the design and optimization of local structures of trimers and oligomers in lowdimensional hybrid materials.
基金financially supported by the National Key Research and Development Program of China(Grant No.2019YFA0708501)the NSFC Major Research Plan on West-Pacific Earth System Multispheric Interactions(Grant No.92158206)。
文摘The geologic production of abiotic organic compounds has been the subject of increasing scientific attention due to their use in the global carbon flux balance,by chemosynthetic biological communities,and for energy resources.Extensive analysis of methane(CH_(4))and other organics in diverse geologic settings,combined with thermodynamic modelings and laboratory simulations,have yielded insights into the distribution of specific abiotic organic molecules on Earth and the favorable conditions and pathways under which they form.This updated and comprehensive review summarizes published results of petrological,thermodynamic,and experimental investigations of possible pathways for the formation of particular species of abiotic simple hydrocarbon molecules such as CH_(4),and of complex hydrocarbon systems,e.g.,long-chain hydrocarbons and even solid carbonaceous matters,in various geologic processes,distinguished into three classes:(1)pre-to early planetary processes;(2)mantle and magmatic processes;and(3)the gas/water-rock reaction processes in low-pressure ultramafic rock and high-pressure subduction zone systems.We not only emphasize how organics are abiotically synthesized but also explore the role or changes of organics in evolutionary geological environments after synthesis,such as phase transitions or organic-mineral interactions.Correspondingly,there is an urgent need to explore the diversity of abiotic organic compounds prevailing on Earth.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11674231,11974250,and 51772192)the Science and Technology Commission of Shanghai Municipality(Grant Nos.17070502700 and 19070502800)the Shenzhen Development and Reform Commission Foundation for Shenzhen Engineering Research Center for Frontier Materials Synthesis at High Pressures.
文摘Pressure evolution of local structure and vibrational dynamics of the perovskite-type relaxor ferroelectric single crystal of 0.935(Na0.5Bi0.5)TiO3-0.065BaTiO3(NBT-6.5BT)is systematically investigated via in situ Raman spectroscopy.The pressure dependence of phonon modes up to 30GPa reveals two characteristic pressures:one is at around 4.6GPa which corresponds to the rhombohedral-to-tetragonal phase transition,showing that the pressure strongly suppresses the coupling between the off-centered A-and B-site cations;the other structural transition involving the oxygen octahedral tilt and vibration occurs at pressure∼13–15GPa with certain degree of order-disorder transition,evidenced by the abnormal changes of intensity and FWHM in Raman spectrum.
文摘Volatile elements—such as carbon, hydrogen, sulfur, nitrogen, and halogens—are minor constituents of Earth’s deep interior. Despite their low abundances, deep volatiles mediate major Earth processes, including magma generation, volcanism, mantle convection, and plate tectonics, which control the exchange of volatiles between Earth’s deep interior and its surface. Over geological time, deep volatiles play critical, primary roles in governing energy resources, natural hazards, atmospheric composition, climate, and planetary habitability. Human activities after the industrial revolution have played an impactful, secondary role, and the resulting risk of add-on effects that could lead to irreversible runaway catastrophes has greatly increased.
基金supported by the National Natural Science Foundation of China(Grant Nos.42150101 and 42150102)supported by the CAEP Research Project(Grant No.CX20210048)a Tencent Xplorer Prize(Grant No.XPLORER-2020-1013)。
文摘Iron oxides are widely found as ores in Earth's crust and are also important constituents of its interiors.Their polymorphism,composition changes,and electronic structures play essential roles in controlling the structure and geodynamic properties of the solid Earth.While all-natural occurring iron oxides are semiconductors or insulators at ambient pressure,they start to metalize under pressure.Here in this work,we review the electronic conductivity and metallization of iron oxides under high-pressure conditions found in Earth's lower mantle.We summarize that the metallization of iron oxides is generally controlled by the pressure-induced bandgap closure near the Fermi level.After metallization,they possess much higher electrical and thermal conductivity,which will facilitate the thermal convection,support a more stable and thicker D′′layer,and formulate Earth's magnetic field,all of which will constrain the large-scale dynamos of the mantle and core.
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financially supported by the National Natural Science Foundation of China(Grant Nos.42150101 and U1530402)the CAEP Research Project(Grant No.CX20210048)+3 种基金supported by the China Postdoctoral Science Foundation(Grant No.18NZ021-0213-216308)supported by the Tencent Xplorer Prizethe funding support from Chinese Academy of Sciences and State Key Laboratory of Isotope Geochemistry(Grant Nos.29Y93301701 and 51Y8340107)the Strategic Priority Research Program(B)(Grant No.XDB18030604)。
文摘Basalt is an igneous rock originating from the cooling and solidification of magma and covers approximately 70% of Earth’s surface.Basaltic glass melting in the deep Earth is a fundamental subject of research for understanding geophysics,geochemistry,and geodynamic processes.In this study,we design a laser flash heating system using two-dimensional,four-color multi-wavelength imaging radiometry to measure the basaltic glass melting temperature under high pressure conditions in diamond anvil cells.Our experiment not only determines the temperature at the center of heating but also constructs a temperature distribution map for the surface heating area,and enables us to assess the temperature gradient.Through precise temperature measurements,we observe that the basaltic glass melting temperature is higher than those in previous reports,which is near the normal upper-mantle isotherm,approaching the hot geotherm.This suggests that basalt should not melt in most of the normal upper mantle and the basaltic melts could exist in some hot regions.
基金funded by Natural Science Foundation of China(Nos.51774096,51871053)Shanghai Committee of Science and Technology(Nos.16JC1401800,18JC1411200)+1 种基金supported by the NASA Science Missions Directorate under the Radioisotope Power Systems Programsupport from the National Science Foundation(DMREF-1333335 and DMREF-1729487).
文摘A broad tunability of the thermoelectric and mechanical properties of CoSb_(3) has been demonstrated by adjusting the composition with the addition of an increasing number of elements.However,such a strategy may negatively impact processing repeatability and composition control.In this work,singleelement-filled skutterudite is engineered to have high thermoelectric and mechanical performances.Increased Yb filling fraction is found to increase phonon scattering,whereas cryogenic grinding contributes additional microstructural scattering.A peak zT of 1.55 and an average zT of about 1.09,which is comparable to the reported results of multiple-filled SKDs,are realized by the combination of simple composition and microstructure engineering.Furthermore,the mechanical properties of Yb single-filled CoSb_(3) skutterudite are improved by manipulation of the microstructure through cryogenic grinding.These findings highlight the realistic prospect of producing high-performance thermoelectric materials with reduced compositional complexity.
基金financially supported by the National Natural Science Foundation of China(No.U2130116)Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments(MFree),China(No.22dz2260800)Shanghai Science and Technology Committee,China(No.22JC1410300)。
文摘Two-dimensional materials are widely considered to be highly promising for the development of photodetectors.To improve the performance of these devices,researchers often employ techniques such as defect engineering.Herein,pressure is employed as a clean and novel means to manipulate the structural and physical properties of EuSbTe_(3),an emerging two-dimensional semiconductor.The experimental results demonstrate that the structural phase transformation of EuSbTe_(3)occurs under pressure,with an increase in infrared reflectivity,a band gap closure,and a metallization at pressures.Combined with X-ray diffraction(XRD)and Raman characterizations,it is evident that the pressure-driven transition from semiconductor Pmmn phase to metallic Cmcm phase causes the disappearance of the charge density wave.Furthermore,at a mild pressure,approximately 2 GPa,the maximum photocurrent of EuSbTe_(3)is three times higher than that at ambient condition,suggesting an untapped potential for various practical applications.
