What factors fundamentally determine the value of superconducting transition temperature Tc in high temperature superconductors has been the subject of intense debate.Following the establishment of an empirical law kn...What factors fundamentally determine the value of superconducting transition temperature Tc in high temperature superconductors has been the subject of intense debate.Following the establishment of an empirical law known as Homes'law,there is a growing consensus in the community that the Tc value of the cuprate superconductors is closely linked to the superfluid density(ρ_(s))of its ground state and the conductivity(σ)of its normal state.However,all the data supporting this empirical law(ρ_(s)=AσT_(c))have been obtained from the ambientpressure superconductors.In this study,we present the first high-pressure results about the connection of the quantities of ρ_(s) and σ with T_(c),through the studies on the Bi_(1.74)Pb_(0.38)Sr_(1.88)CuO_(6+δ)and Bi_(2)Sr_(2)CaCu_(2)O_(8+δ),in which the value of their high-pressure resistivity(ρ=1/σ)is achieved by adopting our newly established method,while the quantity ofρs is extracted using Homes'law.We highlight that the Tc values are strongly linked to the joint response factors of magnetic field and electric field,i.e.,ρ_(s) and σ,respectively,implying that the physics determining T_(c) is governed by the intrinsic electromagnetic fields of the system.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-vip cages in borides,^(1,2)nitrides,^(3)and hydrides^(4)has led to exotic compositions and physical properties.展开更多
The measurement of resistivity in a compressed material within a diamond anvil cell presents significant challenges.The high-pressure exper-imental setup makes it difficult to directly measure the size changes induced...The measurement of resistivity in a compressed material within a diamond anvil cell presents significant challenges.The high-pressure exper-imental setup makes it difficult to directly measure the size changes induced by pressure in the three crystallographic directions of the sample.In this study,we introduce a novel and effective method that addresses these technical challenges.This method is anticipated to offer a valuable foundation for high-pressure investigations on quantum materials,particularly those with anisotropic layered structures.展开更多
Following the recent report by Dasenbrock-Gammon et al.[Nature 615,244–250(2023)]of near-ambient superconductivity in nitrogendoped lutetium trihydride(LuH_(3-δ)N_(ε)),significant debate has emerged surrounding the...Following the recent report by Dasenbrock-Gammon et al.[Nature 615,244–250(2023)]of near-ambient superconductivity in nitrogendoped lutetium trihydride(LuH_(3-δ)N_(ε)),significant debate has emerged surrounding the composition and interpretation of the observed sharp resistance drop.Here,we meticulously revisit these claims through comprehensive characterization and investigations.We definitively identify the reported material as lutetium dihydride(LuH_(2)),resolving the ambiguity surrounding its composition.Under similar conditions(270–295 K and 1–2 GPa),we replicate the reported sharp decrease in electrical resistance with a 30%success rate,aligning with the observations by Dasenbrock-Gammon et al.However,our extensive investigations reveal this phenomenon to be a novel pressure-induced metal-to-metal transition intrinsic to LuH_(2),distinct from superconductivity.Intriguingly,nitrogen doping exerts minimal impact on this transition.Our work not only elucidates the fundamental properties of LuH_(2)andLuH_(3),but also critically challenges the notion of superconductivity in these lutetium hydride systems.These findings pave the way for future research on lutetium hydride systems,while emphasizing the crucial importance of rigorous verification in claims of ambient-temperature superconductivity.展开更多
Compelling evidence indicates that the solid Earth consists of two physicochemically distinct zones separated radially in the middle of the lower mantle at∼1800 km depth.The inner zone is governed by pressure-induced...Compelling evidence indicates that the solid Earth consists of two physicochemically distinct zones separated radially in the middle of the lower mantle at∼1800 km depth.The inner zone is governed by pressure-induced physics and chemistry dramatically different from the conventional behavior in the outer zone.These differences generate large physical and chemical potentials between the two zones that provide fundamental driving forces for triggering major events in Earth’s history.One of the main chemical carriers between the two zones isH_(2)Oin hydrous minerals that subducts into the inner zone,releases hydrogen,and leaves oxygen to create superoxides and form oxygen-rich piles at the core–mantle boundary,resulting in localized net oxygen gain in the inner zone.Accumulation of oxygen-rich piles at the base of the mantle could eventually reach a supercritical level that triggers eruptions,injecting materials that cause chemical mantle convection,superplumes,large igneous provinces,extreme climate changes,atmospheric oxygen fluctuations,and mass extinctions.Interdisciplinary research will be the key for advancing a unified theory of the four-dimensional Earth system.展开更多
Recently we are witnessing the boom of high-pressure science and technology from a small niche field to becoming a major dimension in physical sciences.One of the most important technological advances is the integrati...Recently we are witnessing the boom of high-pressure science and technology from a small niche field to becoming a major dimension in physical sciences.One of the most important technological advances is the integration of synchrotron nanotechnology with the minute samples at ultrahigh pressures.Applications of high pressure have greatly enhanced our understanding of the electronic,phonon,and doping effects on the newly emerged graphene and related 2D layered materials.High pressure has created exotic stoichiometry even in common Group 17,15,and 14 compounds and drastically altered the basic σ and π bonding of organic compounds.Differential pressure measurements enable us to study the rheology and flow of mantle minerals in solid state,thus quantitatively constraining the geodynamics.They also introduce a new approach to understand defect and plastic deformations of nano particles.These examples open new frontiers of high-pressure research.展开更多
The hydrogen molecule is made from the first and lightest element in the periodic table.When hydrogen gas is either compressed or cooled,it forms the simplest molecular solid.This solid exhibits many interesting and f...The hydrogen molecule is made from the first and lightest element in the periodic table.When hydrogen gas is either compressed or cooled,it forms the simplest molecular solid.This solid exhibits many interesting and fundamental physical phenomena.It is believed that if the density of the solid is increased by compressing it to very high pressures,hydrogen will transform into the lightest known metal with very unusual and fascinating properties,such as room temperature superconductivity and/or superfluidity.In this article,we provide a critical look at the numerous claims of hydrogen metallization and the current experimental state of affairs.展开更多
The recent report of superconductivity in nitrogen-doped lutetium hydride(Lu-H-N)at 294 K and 1 GPa brought hope for long-sought-after ambient-condition superconductors.However,the failure of scientists worldwide to i...The recent report of superconductivity in nitrogen-doped lutetium hydride(Lu-H-N)at 294 K and 1 GPa brought hope for long-sought-after ambient-condition superconductors.However,the failure of scientists worldwide to independently reproduce these results has cast intense skepticism on this exciting claim.In this work,using a reliable experimental protocol,we synthesized Lu-H-N while minimizing extrinsic influences and reproduced the sudden change in resistance near room temperature.With quantitative comparison of the temperaturedependent resistance between Lu-H-N and the pure lutetium before reaction,we were able to clarify that the drastic resistance change is most likely caused by a metal-to-poor-conductor transition rather than by superconductivity.Herein,we also briefly discuss other issues recently raised in relation to the Lu-H-N system.展开更多
A material described as lutetium–hydrogen–nitrogen(Lu-H-N in short)was recently claimed to have“near-ambient superconductivity”[Dasenbrock-Gammon et al.,Nature 615,244–250(2023)].If this result could be reproduce...A material described as lutetium–hydrogen–nitrogen(Lu-H-N in short)was recently claimed to have“near-ambient superconductivity”[Dasenbrock-Gammon et al.,Nature 615,244–250(2023)].If this result could be reproduced by other teams,it would be a major scientific breakthrough.Here,we report our results of transport and structure measurements on a material prepared using the same method as reported by Dasenbrock-Gammon et al.Our x-ray diffraction measurements indicate that the obtained sample contains three substances:the facecentered-cubic(FCC)-1 phase(Fm-3m)with lattice parameter a=5.03Å,the FCC-2 phase(Fm-3m)with a lattice parameter a=4.755Å,and Lu metal.The two FCC phases are identical to the those reported in the so-called near-ambient superconductor.However,we find from our resistance measurements in the temperature range from 300 K down to 4 K and the pressure range 0.9–3.4 GPa and our magnetic susceptibility measurements in the pressure range 0.8–3.3 GPa and the temperature range down to 100 K that the samples show no evidence of superconductivity.We also use a laser heating technique to heat a sample to 1800 XC and find no superconductivity in the produced dark blue material below 6.5 GPa.In addition,both samples remain dark blue in color in the pressure range investigated.展开更多
Hydrogen(H)is the most abundant element in the known universe,and on the Earth’s surface it bonds with oxygen to form water,which is a distinguishing feature of this planet.In the Earth’s deep mantle,His stored hydr...Hydrogen(H)is the most abundant element in the known universe,and on the Earth’s surface it bonds with oxygen to form water,which is a distinguishing feature of this planet.In the Earth’s deep mantle,His stored hydroxyl(OH−)in hydrous or nominally anhydrous minerals.Despite its ubiquity on the surface,the abundance ofHin the Earth’s deep interior is uncertain.Estimates of the totalHbudget in the Earth’s interior have ranged from less than one hydrosphere,which assumes an H-depleted interior,to hundreds of hydrospheres,which assumes thatHis siderophile(iron-loving)in the core.This discrepancy raises the questions of how H is stored and transported in the Earth’s deep interior,the answers to which will constrain its behavior in the deep lower mantle,which is defined as the layer between 1700 km depth and the core–mantle boundary.展开更多
Recent reports of the superconductivity in hydrides of two different families(covalent lattice,as in SH3 and clathrate-type H-cages containing La and Y atoms,as in LaH10 and YH6)have revealed new families of high-Tc m...Recent reports of the superconductivity in hydrides of two different families(covalent lattice,as in SH3 and clathrate-type H-cages containing La and Y atoms,as in LaH10 and YH6)have revealed new families of high-Tc materials with Tc’s near room temperature values.These findings confirm earlier expectations that hydrides may have very high Tc’s due to the fact that light H atoms have very high vibrational frequencies,leading to high Tc values within the conventional Bardeen–Cooper–Schrieffer phonon mechanism of superconductivity.However,as is pointed out by Ashcroft,it is important to have the metallic hydrogen“alloyed”with the elements added to it.This concept of a metallic alloy containing a high concentration of metal-like hydrogen atoms has been instrumental in finding new high-Tc superhydrides.These new superhydride“roomtemperature”superconductors are stabilized only at very high pressures above 100 GPa,making the experimental search for their superconducting properties very difficult.We will review the current experimental and theoretical results for LaH10−x and YH6−x superhydrides.展开更多
Diamond anvil cell techniques have been improved to allow access to the multimegabar ultrahigh-pressure region for exploring novel phenomena in condensedmatter.However,the onlyway to determine crystal structures of ma...Diamond anvil cell techniques have been improved to allow access to the multimegabar ultrahigh-pressure region for exploring novel phenomena in condensedmatter.However,the onlyway to determine crystal structures of materials above 100 GPa,namely,X-ray diffraction(XRD),especially for lowZ materials,remains nontrivial in the ultrahigh-pressure region,even with the availability of brilliant synchrotron X-ray sources.In thiswork,we performa systematic study,choosing hydrogen(the lowest X-ray scatterer)as the subject,to understand how to better perform XRD measurements of low Z materials at multimegabar pressures.The techniques that we have developed have been proved to be effective in measuring the crystal structure of solid hydrogen up to 254GPa at room temperature[C.Ji et al.,Nature 573,558–562(2019)].Wepresent our discoveries and experienceswith regard to several aspects of thiswork,namely,diamond anvil selection,sample configuration for ultrahigh-pressure XRDstudies,XRDdiagnostics for low Z materials,and related issues in data interpretation and pressure calibration.Webelieve that these methods can be readily extended to other low Z materials and can pave the way for studying the crystal structure of hydrogen at higher pressures,eventually testing structural models of metallic hydrogen.展开更多
Alkanes are an important part of petroleum,the stability of alkanes under extreme conditions is of great significance to explore the origin of petroleum and the carbon cycle in the deep Earth.Here,we performed Raman a...Alkanes are an important part of petroleum,the stability of alkanes under extreme conditions is of great significance to explore the origin of petroleum and the carbon cycle in the deep Earth.Here,we performed Raman and infrared(IR)spectroscopy studies of n-hexane and cyclohexane under high pressure up to~42 GPa at room temperature(RT)and high temperature(HT).n-Hexane and cyclohexane undergo several phase transitions at RT around 1.8,8.5,18 GPa and 1.1,2.1,4.6,13,30 GPa,respectively,without any chemical reaction.By using resistive heating combined with diamond anvil cell at pressure up to 20 GPa and temperature up to 1000 K,both n-hexane and cyclohexane decompose to hydrogenated graphitic carbon and n-hexane exhibits higher stability than cyclohexane.Our results indicate that hydrocarbons tend to dehydrogenate in the upper mantle,and the extension of carbon chains may lead to the formation of some unsaturated compounds and eventually transfer into graphitic products.展开更多
The structural stability of methane hydrate under pressure at room temperature was examined by both in-situ single-crystal and powder X-ray diffraction techniques on samples with structure types I, II, and H in diamon...The structural stability of methane hydrate under pressure at room temperature was examined by both in-situ single-crystal and powder X-ray diffraction techniques on samples with structure types I, II, and H in diamond-anvil ceils. The diffraction data for types II （slI） and H （sH） were refined to the known structures with space groups Fd3m and P63/mmc, respectively. Upon compression, sl methane hydrate transforms to the sll phase at 120 MPa, and then to the sH phase at 600 MPa. The slI methane hydrate was found to coexist locally with sI phase up to 500 MPa and with sH phase up to 600 MPa. The pure sH structure was found to be stable between 600 and 900 MPa. Methane hydrate decomposes at pressures above 3 GPa to form methane with the orientationally disordered Fm3m structure and ice VII （Pn3m）. The results highlight the role of vip （CH4）-host （H2O） interactions in the stabilization of the hydrate structures under pressure.展开更多
Topochemical reactions are a promising method to obtain crystalline polymeric materials with distance-determined regio-or stereoselectivity.It has been concluded on an empirical basis that the closest intermolecular C...Topochemical reactions are a promising method to obtain crystalline polymeric materials with distance-determined regio-or stereoselectivity.It has been concluded on an empirical basis that the closest intermolecular C⋅⋅⋅C distance in crystals of alkynes,d(C⋅⋅⋅C)min,should reach a threshold of∼3Åfor bonding to occur at room temperature.To understand this empirical threshold,we study here the polymerization of acetylene in the crystalline state under high pressure by calculating the structural geometry,vibrational modes,and reaction profile.We find d(C⋅⋅⋅C)min to be the sum of an intrinsic threshold of 2.3Åand a thermal displacement of 0.8Å(at room temperature).Molecules at the empirical threshold move via several phonon modes to reach the intrinsic threshold,at which the intermolecular electronic interaction is sharply enhanced and bonding commences.A distance–vibration-based reaction picture is thus demonstrated,which provides a basis for the prediction and design of topochemical reactions,as well as an enhanced understanding of the bonding process in solids.展开更多
An impact structure 1400 m in diameter,formed by a bolide impact,has been discovered on Baijifeng Mountain in Tonghua City in Northeast China’s Jilin province.The impact structure takes the form of a cirque-shaped de...An impact structure 1400 m in diameter,formed by a bolide impact,has been discovered on Baijifeng Mountain in Tonghua City in Northeast China’s Jilin province.The impact structure takes the form of a cirque-shaped depression on the top of the mountain and is located in a basement mainly composed of Proterozoic sandstone and Jurassic granite.A large number of rock fragments composed mainly of sandstone,with a small amount of granite,are distributed on the top of Baijifeng Mountain.Planar deformation features(PDFs)have been found in quartz in the rock and mineral clasts collected from the surface inside the depression.The forms of the PDFs indexed in the quartz include among others,{1013},{1012},and{1011}.The presence of these PDFs provides diagnostic evidence for shock metamorphism and the impact origin of the structure.The impact event took place after the Jurassic Period and probably much later.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
High pressures induce changes of properties and structures that could greatly impact materials science if such changes were preserved for ambient applications.Mimicking the geological process of diamond formation that...High pressures induce changes of properties and structures that could greatly impact materials science if such changes were preserved for ambient applications.Mimicking the geological process of diamond formation that the pressures and high-pressure phases in diamond inclusions can be preserved by the strong diamond envelope,we discuss the perspectives that such process revolutionizes high-pressure science and technology and opens a great potential for creation of functional materials with extremely favorable 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
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
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFA1401800 and 2022YFA1403900)the National Natural Science Foundation of China(Grant Nos.U2032214,12122414,12104487,and 12004419)+1 种基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB25000000)supported by the US Department of Energy,Office of Basic Energy Sciences(Grant No.DOE-sc0012704)。
文摘What factors fundamentally determine the value of superconducting transition temperature Tc in high temperature superconductors has been the subject of intense debate.Following the establishment of an empirical law known as Homes'law,there is a growing consensus in the community that the Tc value of the cuprate superconductors is closely linked to the superfluid density(ρ_(s))of its ground state and the conductivity(σ)of its normal state.However,all the data supporting this empirical law(ρ_(s)=AσT_(c))have been obtained from the ambientpressure superconductors.In this study,we present the first high-pressure results about the connection of the quantities of ρ_(s) and σ with T_(c),through the studies on the Bi_(1.74)Pb_(0.38)Sr_(1.88)CuO_(6+δ)and Bi_(2)Sr_(2)CaCu_(2)O_(8+δ),in which the value of their high-pressure resistivity(ρ=1/σ)is achieved by adopting our newly established method,while the quantity ofρs is extracted using Homes'law.We highlight that the Tc values are strongly linked to the joint response factors of magnetic field and electric field,i.e.,ρ_(s) and σ,respectively,implying that the physics determining T_(c) is governed by the intrinsic electromagnetic fields of the system.
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-vip cages in borides,^(1,2)nitrides,^(3)and hydrides^(4)has led to exotic compositions and physical properties.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1403900 and 2021YFA1401800)the NSF of China(Grant Nos.U2032214 and 12104487).
文摘The measurement of resistivity in a compressed material within a diamond anvil cell presents significant challenges.The high-pressure exper-imental setup makes it difficult to directly measure the size changes induced by pressure in the three crystallographic directions of the sample.In this study,we introduce a novel and effective method that addresses these technical challenges.This method is anticipated to offer a valuable foundation for high-pressure investigations on quantum materials,particularly those with anisotropic layered structures.
基金the National Key Research and Development Program of China(Grant Nos.2022YFA1402301 and 2018YFA0305703)the National Natural Science Foundation of China(Grant No.U2230401)+2 种基金the National Key R&D Program of China(Grant No.2021YFA1400200),the National Natural Science Foundation of China(Grant Nos.12025408 and 11921004)the Strategic Priority Research Program of CAS(Grant No.XDB33000000).
文摘Following the recent report by Dasenbrock-Gammon et al.[Nature 615,244–250(2023)]of near-ambient superconductivity in nitrogendoped lutetium trihydride(LuH_(3-δ)N_(ε)),significant debate has emerged surrounding the composition and interpretation of the observed sharp resistance drop.Here,we meticulously revisit these claims through comprehensive characterization and investigations.We definitively identify the reported material as lutetium dihydride(LuH_(2)),resolving the ambiguity surrounding its composition.Under similar conditions(270–295 K and 1–2 GPa),we replicate the reported sharp decrease in electrical resistance with a 30%success rate,aligning with the observations by Dasenbrock-Gammon et al.However,our extensive investigations reveal this phenomenon to be a novel pressure-induced metal-to-metal transition intrinsic to LuH_(2),distinct from superconductivity.Intriguingly,nitrogen doping exerts minimal impact on this transition.Our work not only elucidates the fundamental properties of LuH_(2)andLuH_(3),but also critically challenges the notion of superconductivity in these lutetium hydride systems.These findings pave the way for future research on lutetium hydride systems,while emphasizing the crucial importance of rigorous verification in claims of ambient-temperature superconductivity.
基金We thank Yu He,Qingyang Hu,Jin Liu,Duckyoung Kim,and Li Zhang for sharing preliminary information.W.L.Mao acknowledges support from NSF Geophysics Grant No.EAR 1446969H.-k.Mao acknowledges supports from NSF Geochemistry Grant No.EAR-1447438+1 种基金NSF Geophysics Grant No.EAR-1722515This work was also partially supported by the National Natural Science Foundation of China Grant No.U1530402 and U1930401.
文摘Compelling evidence indicates that the solid Earth consists of two physicochemically distinct zones separated radially in the middle of the lower mantle at∼1800 km depth.The inner zone is governed by pressure-induced physics and chemistry dramatically different from the conventional behavior in the outer zone.These differences generate large physical and chemical potentials between the two zones that provide fundamental driving forces for triggering major events in Earth’s history.One of the main chemical carriers between the two zones isH_(2)Oin hydrous minerals that subducts into the inner zone,releases hydrogen,and leaves oxygen to create superoxides and form oxygen-rich piles at the core–mantle boundary,resulting in localized net oxygen gain in the inner zone.Accumulation of oxygen-rich piles at the base of the mantle could eventually reach a supercritical level that triggers eruptions,injecting materials that cause chemical mantle convection,superplumes,large igneous provinces,extreme climate changes,atmospheric oxygen fluctuations,and mass extinctions.Interdisciplinary research will be the key for advancing a unified theory of the four-dimensional Earth system.
文摘Recently we are witnessing the boom of high-pressure science and technology from a small niche field to becoming a major dimension in physical sciences.One of the most important technological advances is the integration of synchrotron nanotechnology with the minute samples at ultrahigh pressures.Applications of high pressure have greatly enhanced our understanding of the electronic,phonon,and doping effects on the newly emerged graphene and related 2D layered materials.High pressure has created exotic stoichiometry even in common Group 17,15,and 14 compounds and drastically altered the basic σ and π bonding of organic compounds.Differential pressure measurements enable us to study the rheology and flow of mantle minerals in solid state,thus quantitatively constraining the geodynamics.They also introduce a new approach to understand defect and plastic deformations of nano particles.These examples open new frontiers of high-pressure research.
文摘The hydrogen molecule is made from the first and lightest element in the periodic table.When hydrogen gas is either compressed or cooled,it forms the simplest molecular solid.This solid exhibits many interesting and fundamental physical phenomena.It is believed that if the density of the solid is increased by compressing it to very high pressures,hydrogen will transform into the lightest known metal with very unusual and fascinating properties,such as room temperature superconductivity and/or superfluidity.In this article,we provide a critical look at the numerous claims of hydrogen metallization and the current experimental state of affairs.
文摘The recent report of superconductivity in nitrogen-doped lutetium hydride(Lu-H-N)at 294 K and 1 GPa brought hope for long-sought-after ambient-condition superconductors.However,the failure of scientists worldwide to independently reproduce these results has cast intense skepticism on this exciting claim.In this work,using a reliable experimental protocol,we synthesized Lu-H-N while minimizing extrinsic influences and reproduced the sudden change in resistance near room temperature.With quantitative comparison of the temperaturedependent resistance between Lu-H-N and the pure lutetium before reaction,we were able to clarify that the drastic resistance change is most likely caused by a metal-to-poor-conductor transition rather than by superconductivity.Herein,we also briefly discuss other issues recently raised in relation to the Lu-H-N system.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1403900 and 2021YFA1401800)the NSF of China(Grant Nos.U2032214,12104487,12122414,and 12004419)+2 种基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB25000000)J.G.and S.C.are grateful for support from the Youth Innovation Promotion Association of the CAS(Grant No.2019008)the China Postdoctoral Science Foundation(Grant No.E0BK111).
文摘A material described as lutetium–hydrogen–nitrogen(Lu-H-N in short)was recently claimed to have“near-ambient superconductivity”[Dasenbrock-Gammon et al.,Nature 615,244–250(2023)].If this result could be reproduced by other teams,it would be a major scientific breakthrough.Here,we report our results of transport and structure measurements on a material prepared using the same method as reported by Dasenbrock-Gammon et al.Our x-ray diffraction measurements indicate that the obtained sample contains three substances:the facecentered-cubic(FCC)-1 phase(Fm-3m)with lattice parameter a=5.03Å,the FCC-2 phase(Fm-3m)with a lattice parameter a=4.755Å,and Lu metal.The two FCC phases are identical to the those reported in the so-called near-ambient superconductor.However,we find from our resistance measurements in the temperature range from 300 K down to 4 K and the pressure range 0.9–3.4 GPa and our magnetic susceptibility measurements in the pressure range 0.8–3.3 GPa and the temperature range down to 100 K that the samples show no evidence of superconductivity.We also use a laser heating technique to heat a sample to 1800 XC and find no superconductivity in the produced dark blue material below 6.5 GPa.In addition,both samples remain dark blue in color in the pressure range investigated.
基金We thank Yanhao Lin for helpful discussions.Q.H.is supported by a CAEP Research Project(Grant No.CX20210048)a Tencent Xplorer prize.The work is also partially supported by the National Natural Science Foundation of China(NSFC)Grant No.U1930401.
文摘Hydrogen(H)is the most abundant element in the known universe,and on the Earth’s surface it bonds with oxygen to form water,which is a distinguishing feature of this planet.In the Earth’s deep mantle,His stored hydroxyl(OH−)in hydrous or nominally anhydrous minerals.Despite its ubiquity on the surface,the abundance ofHin the Earth’s deep interior is uncertain.Estimates of the totalHbudget in the Earth’s interior have ranged from less than one hydrosphere,which assumes an H-depleted interior,to hundreds of hydrospheres,which assumes thatHis siderophile(iron-loving)in the core.This discrepancy raises the questions of how H is stored and transported in the Earth’s deep interior,the answers to which will constrain its behavior in the deep lower mantle,which is defined as the layer between 1700 km depth and the core–mantle boundary.
基金V.S.acknowledges support fromthe Thousand Talent Program by the State Council of the People’s Republic of China.Portions of this work were performed at GeoSoilEnviroCARS(The University of Chicago,Sector 13)Advanced Photon Source(APS),Argonne National Laboratory.GeoSoilEnviroCARS is supported by the National Science Foundation-Earth Sciences(Grant No.EAR-1634415)Department of Energy-GeoSciences(Grant No.DE-FG02-94ER14466).This research used resources from the Advanced Photon Source,a U.S.Department of Energy(DOE)Office of the Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No.DEAC02-06CH11357.I.T.and A.G.acknowledge support from the Ministry of Science and Higher Education of the Russian Federation within the State assignment of the FSRC“Crystallography and Photonics”of RAS in part of the high-pressure structural experiments and from the Russian Science Foundation(Project No.19-12-00414)in part of the high-pressure studies of superconductivity.A.G.acknowledges the use of the facilities of the Center for Collective Use“AcceleratorCenter for NeutronResearch of the Structure of Substance and Nuclear Medicine”of the INR RAS.
文摘Recent reports of the superconductivity in hydrides of two different families(covalent lattice,as in SH3 and clathrate-type H-cages containing La and Y atoms,as in LaH10 and YH6)have revealed new families of high-Tc materials with Tc’s near room temperature values.These findings confirm earlier expectations that hydrides may have very high Tc’s due to the fact that light H atoms have very high vibrational frequencies,leading to high Tc values within the conventional Bardeen–Cooper–Schrieffer phonon mechanism of superconductivity.However,as is pointed out by Ashcroft,it is important to have the metallic hydrogen“alloyed”with the elements added to it.This concept of a metallic alloy containing a high concentration of metal-like hydrogen atoms has been instrumental in finding new high-Tc superhydrides.These new superhydride“roomtemperature”superconductors are stabilized only at very high pressures above 100 GPa,making the experimental search for their superconducting properties very difficult.We will review the current experimental and theoretical results for LaH10−x and YH6−x superhydrides.
基金This research was supported by the National Natural Science Foundation of China under Award No.U1930401the Department of Energy(DOE),Office of Basic Energy Science,Division of Materials Sciences and Engineering under Award No.DE-FG02-99ER45775
文摘Diamond anvil cell techniques have been improved to allow access to the multimegabar ultrahigh-pressure region for exploring novel phenomena in condensedmatter.However,the onlyway to determine crystal structures of materials above 100 GPa,namely,X-ray diffraction(XRD),especially for lowZ materials,remains nontrivial in the ultrahigh-pressure region,even with the availability of brilliant synchrotron X-ray sources.In thiswork,we performa systematic study,choosing hydrogen(the lowest X-ray scatterer)as the subject,to understand how to better perform XRD measurements of low Z materials at multimegabar pressures.The techniques that we have developed have been proved to be effective in measuring the crystal structure of solid hydrogen up to 254GPa at room temperature[C.Ji et al.,Nature 573,558–562(2019)].Wepresent our discoveries and experienceswith regard to several aspects of thiswork,namely,diamond anvil selection,sample configuration for ultrahigh-pressure XRDstudies,XRDdiagnostics for low Z materials,and related issues in data interpretation and pressure calibration.Webelieve that these methods can be readily extended to other low Z materials and can pave the way for studying the crystal structure of hydrogen at higher pressures,eventually testing structural models of metallic hydrogen.
基金the National Key Research and Development Program of China(2019YFA0708502)the support of the National Natural Science Foundation of China(NSFC)(Grant Nos.21771011 and 21875006)。
文摘Alkanes are an important part of petroleum,the stability of alkanes under extreme conditions is of great significance to explore the origin of petroleum and the carbon cycle in the deep Earth.Here,we performed Raman and infrared(IR)spectroscopy studies of n-hexane and cyclohexane under high pressure up to~42 GPa at room temperature(RT)and high temperature(HT).n-Hexane and cyclohexane undergo several phase transitions at RT around 1.8,8.5,18 GPa and 1.1,2.1,4.6,13,30 GPa,respectively,without any chemical reaction.By using resistive heating combined with diamond anvil cell at pressure up to 20 GPa and temperature up to 1000 K,both n-hexane and cyclohexane decompose to hydrogenated graphitic carbon and n-hexane exhibits higher stability than cyclohexane.Our results indicate that hydrocarbons tend to dehydrogenate in the upper mantle,and the extension of carbon chains may lead to the formation of some unsaturated compounds and eventually transfer into graphitic products.
基金HPSynC is supported as part of EFree,an EnergyFrontier Research Center funded by the U.S.Department of Energy(DOE),Office of Science, Office of Basic Energy Sciences(BES) under Award Number DE-SC0001057HPCAT is supported by CIW,CDAC,UNLV and LLNL through funding from DOE-NNSA,DOE-BES and NSFAPS is supported by DOE-BES,under Contract No.DE-AC02-06CH 11357
文摘The structural stability of methane hydrate under pressure at room temperature was examined by both in-situ single-crystal and powder X-ray diffraction techniques on samples with structure types I, II, and H in diamond-anvil ceils. The diffraction data for types II （slI） and H （sH） were refined to the known structures with space groups Fd3m and P63/mmc, respectively. Upon compression, sl methane hydrate transforms to the sll phase at 120 MPa, and then to the sH phase at 600 MPa. The slI methane hydrate was found to coexist locally with sI phase up to 500 MPa and with sH phase up to 600 MPa. The pure sH structure was found to be stable between 600 and 900 MPa. Methane hydrate decomposes at pressures above 3 GPa to form methane with the orientationally disordered Fm3m structure and ice VII （Pn3m）. The results highlight the role of vip （CH4）-host （H2O） interactions in the stabilization of the hydrate structures under pressure.
基金support of the National Natural Science Foundation of China(NSFC)(Grant Nos.22022101,21875006,11704024,and 12174200)The authors also acknowledge support from the National Key Research and Development Program of China(Grant No.2019YFA0708502)from the Nature Science Foundation of Tianjin(Grant No.20JCYBJC01530).
文摘Topochemical reactions are a promising method to obtain crystalline polymeric materials with distance-determined regio-or stereoselectivity.It has been concluded on an empirical basis that the closest intermolecular C⋅⋅⋅C distance in crystals of alkynes,d(C⋅⋅⋅C)min,should reach a threshold of∼3Åfor bonding to occur at room temperature.To understand this empirical threshold,we study here the polymerization of acetylene in the crystalline state under high pressure by calculating the structural geometry,vibrational modes,and reaction profile.We find d(C⋅⋅⋅C)min to be the sum of an intrinsic threshold of 2.3Åand a thermal displacement of 0.8Å(at room temperature).Molecules at the empirical threshold move via several phonon modes to reach the intrinsic threshold,at which the intermolecular electronic interaction is sharply enhanced and bonding commences.A distance–vibration-based reaction picture is thus demonstrated,which provides a basis for the prediction and design of topochemical reactions,as well as an enhanced understanding of the bonding process in solids.
基金supported by the National Natural Science Foundation of China(Grant No.42050203).
文摘An impact structure 1400 m in diameter,formed by a bolide impact,has been discovered on Baijifeng Mountain in Tonghua City in Northeast China’s Jilin province.The impact structure takes the form of a cirque-shaped depression on the top of the mountain and is located in a basement mainly composed of Proterozoic sandstone and Jurassic granite.A large number of rock fragments composed mainly of sandstone,with a small amount of granite,are distributed on the top of Baijifeng Mountain.Planar deformation features(PDFs)have been found in quartz in the rock and mineral clasts collected from the surface inside the depression.The forms of the PDFs indexed in the quartz include among others,{1013},{1012},and{1011}.The presence of these PDFs provides diagnostic evidence for shock metamorphism and the impact origin of the structure.The impact event took place after the Jurassic Period and probably much later.
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.
基金W.L.M.acknowledges support from NSF Geophysics Grant No.EAR 1446969H.-K.M.is supported by the National Natural Science Foundation of China Grant No.U1930401.
文摘High pressures induce changes of properties and structures that could greatly impact materials science if such changes were preserved for ambient applications.Mimicking the geological process of diamond formation that the pressures and high-pressure phases in diamond inclusions can be preserved by the strong diamond envelope,we discuss the perspectives that such process revolutionizes high-pressure science and technology and opens a great potential for creation of functional materials with extremely favorable 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.
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.
