The electronic structure of iron-pnictide compound superconductor Ba_2Ti_2Fe_2As_4O, which has metallic intermediate Ti_2O layers, is studied using angle-resolved photoemission spectroscopy. The Ti-related bands show ...The electronic structure of iron-pnictide compound superconductor Ba_2Ti_2Fe_2As_4O, which has metallic intermediate Ti_2O layers, is studied using angle-resolved photoemission spectroscopy. The Ti-related bands show a‘peak-dip-hump＇ line shape with two branches of dispersion associated with the polaronic states at temperatures below around 120 K. This change in the spectra occurs along with the resistivity anomaly that was not clearly understood in a previous study. Moreover, an energy gap induced by the superconducting proximity effect opens in the polaronic bands at temperatures below T_c（~21 K）. Our study provides the spectroscopic evidence that superconductivity coexists with polarons in the same bands near the Fermi level, which provides a suitable platform to study interactions between charge, lattice and spin freedoms in a correlated system.展开更多
We report the growth process of FeTe1-xSex （0 〈 x 〈 1） monolayer films on SrTi03 （STO） substrates through molecular beam epitaxy and discuss the possible ways to improve the film quality. By exploring the parame...We report the growth process of FeTe1-xSex （0 〈 x 〈 1） monolayer films on SrTi03 （STO） substrates through molecular beam epitaxy and discuss the possible ways to improve the film quality. By exploring the parameters of substrate treatment, growth control and post growth annealing, we successfully obtain a series of FeTe1-xSex monolayer films. In the whole growth process, we find the significance of the temperature control through surface roughness monitored by the reflection high-energy electron diffraction and scanning tunneling microscopy. We obtain the best quality of FeSe monolayer films with the STO substrate treated at T = 900 950℃ before growth, the FeSe deposited at T = 310℃ during growth and annealed at T = 380℃ after growth. For FeTe1-xSex （x-1）, both the growth temperature and annealing temperature decrease to T=260℃. According to the angle- resolved photoemission spectroscopy measurements, the superconductivity of the FeTe1-xSex film is robust and insensitive to Se concentration. All the above are instructive for further investigations of the superconductivity in FeTe1-xSex films.展开更多
Coupling of a phase transition to electron and phonon transports provides extra degree of freedom to improve the thermoelectric performance, while the pertinent experimental and theoretical studies are still rare. Par...Coupling of a phase transition to electron and phonon transports provides extra degree of freedom to improve the thermoelectric performance, while the pertinent experimental and theoretical studies are still rare. Particularly,the impaction of chemical compositions and phase transition characters on the abnormal thermoelectric properties across phase transitions are largely unclear. Herein, by varying the Cu content x from 1.75 to 2.10, we systemically investigate the crystal structural evolution, phase transition features, and especially the thermoelectric properties during the phase transition for Cu_(x)Se. It is found that the addition of over-stoichiometry Cu in Cu_(x)Se could alter the phase transition characters and suppress the formation of Cu vacancies. The critical scatterings of phonons and electrons during phase transitions strongly enhance the Seebeck coefficient and diminish the thermal conductivity, leading to an ultrahigh dimensionless thermoelectric figure of merit of ~1.38 at 397 K in Cu_(2.10)Se.With the decreasing Cu content, the critical electron and phonon scattering behaviors are mitigated, and the corresponding thermoelectric performances are reduced. This work offers inspirations for understanding and tuning the thermoelectric transport properties during phase transitions.展开更多
Mitochondrial toxicity induced by therapeutic drugs is a major contributor for cardiotoxicity,posing a serious threat to pharmaceutical industries and patients’lives.However,mitochondrial toxicity testing is not inco...Mitochondrial toxicity induced by therapeutic drugs is a major contributor for cardiotoxicity,posing a serious threat to pharmaceutical industries and patients’lives.However,mitochondrial toxicity testing is not incorporated into routine cardiac safety screening procedures.To accurately model native human cardiomyocytes,we comprehensively evaluated mitochondrial responses of adult human primary cardiomyocytes(h PCMs)to a nucleoside analog,remdesivir(RDV).Comparison of their response to human pluripotent stem cell-derived cardiomyocytes revealed that the latter utilized a mitophagy-based mitochondrial recovery response that was absent in h PCMs.Accordingly,action potential duration was elongated in h PCMs,reflecting clinical incidences of RDV-induced QT prolongation.In a screen for mitochondrial protectants,we identified mitochondrial ROS as a primary mediator of RDV-induced cardiotoxicity.Our study demonstrates the utility of h PCMs in the detection of clinically relevant cardiac toxicities,and offers a framework for h PCM-based high-throughput screening of cardioprotective agents.展开更多
As a new type of inorganic ductile semiconductor,silver sulfide(α-Ag_(2)S)has garnered a plethora of interests in recent years due to its promising applications in flexible electronics.However,the lack of detailed de...As a new type of inorganic ductile semiconductor,silver sulfide(α-Ag_(2)S)has garnered a plethora of interests in recent years due to its promising applications in flexible electronics.However,the lack of detailed defect calculations and chemical intuition has largely hindered the optimization of material's performance.In this study,we systematically investigate the defect chemistry of extrinsic doping inα-Ag_(2)S using first-principles calculations.We computationally examine a broad suite of 17 dopants and find that all aliovalent elements have extremely low doping limits(<0.002%)in α-Ag_(2)S,rendering them ineffective in tuning the electron concentrations.In contrast,the isovalent elements Se and Te have relatively high doping limits,being consistent with the experimental observations.While the dopant Se or Te itself does not provide additional electrons,its introduction has a significant impact on the band gap,the band-edge position,and especially the formation energy of Ag interstitials,which effectively improve the electron concentrations by 2–3 orders of magnitudes.The size effects of Se and Te doping are responsible for the more favorable Ag interstitials in Ag_(2)S_(0.875)Se_(0.125) and Ag_(2)S_(0.875)Te_(0.125) with respect to pristine Ag2S.This work serves as a theoretical foundation for the rational design of Ag_(2)S-based functional materials.展开更多
Exploring new prototypes for a given chemical composition is of great importance and interest to several disciplines.As a famous semiconducting binary compound,InSe usually exhibits a two-dimensional layered structure...Exploring new prototypes for a given chemical composition is of great importance and interest to several disciplines.As a famous semiconducting binary compound,InSe usually exhibits a two-dimensional layered structure with decent physical and mechanical properties.However,it is less noticed that InSe can also adopt a monoclinic structure,denoted as mcl-InSe.The synthesis of such a phase usually re-quires high-pressure conditions,and the knowledge is quite scarce on its chemical bonding,lattice dynamics,and thermal transport.Here in this work,by developing a facile method combining me-chanical alloying and spark plasma sintering,we successfully synthesize mcl-InSe bulks with well-crystallized nanograins.The chemical bonding of mcl-InSe is understood as compared with layered InSe via charge analysis.Low cut-off frequencies of acoustic phonons and several low-lying optical modes are demonstrated.Noticeably,mcl-InSe exhibits a low room-temperature thermal conductivity of 0.6 W·m^(-1)·K^(-1),which is smaller than that of other materials in the IneSe system and many other selenides.Low-temperature thermal analyses corroborate the role of nanograin boundaries and low-frequency optical phonons in scattering acoustic phonons.This work provides new insights into the non-common prototype of the InSe binary compound with potential applications in thermoelectrics or thermal insulation.展开更多
Ductile Ag_(2)(Te,S)pseudobinary compounds have attracted great attention in thermoelectric community since they can be fabricated into high-performance flexible and hetero-shaped thermoelectric devices.However,in spi...Ductile Ag_(2)(Te,S)pseudobinary compounds have attracted great attention in thermoelectric community since they can be fabricated into high-performance flexible and hetero-shaped thermoelectric devices.However,in spite of the numerous studies,the‘brittleeductile’transition boundary in Ag_(2)(Te,S)is still unclear.In this work,a series of Te-rich Ag_(2)(Te,S)pseudobinary compounds have been prepared.The structure characterizations confirm they belong to the new-concept of meta-phase.The systematically investigation on the mechanical properties demonstrate that the‘brittl-eductile’transition boundary appears around x=0.1.Unexpected good ductility is observed in the Te-rich Ag_(2)Te_(1-x)S_(x)crystalizing in the Ag_(2)Te room-temperature monoclinic structure and high-temperature cubic structure,which are thought to be brittle before.Likewise,Ag content is found to be a very critical parameter determining the ductility of Te-rich Ag_(2)Te_(1-x)S_(x).Very slight Ag-deficiency can greatly deteriorate the ductility.The ther-moelectric properties of these ductile Te-rich Ag_(2)Te_(1-x)S_(x)pseudobinary compounds are investigated.A maximum thermoelectric figure-of-merit of 0.6 is obtained for Ag_(2)Te_(0.9)S_(0.1)at 600 K.This work sheds light on the future investigation of Ag_(2)(Te,S)pseudobinary compounds.展开更多
Thermoelectric(TE)materials can directly convert the industrial waste heat into useful electricity based on the Seebeck effect,providing a promising way to tackle the environmental pollution and global energy crisis[1...Thermoelectric(TE)materials can directly convert the industrial waste heat into useful electricity based on the Seebeck effect,providing a promising way to tackle the environmental pollution and global energy crisis[1].In the past several decades,many new high-performance TE materials have been discovered to enrich the TE family.Among them,Cu_(2)−δSe-based TE materials,which are in line with the“phonon-liquid electron-crystal”concept,have sparked widespread interest due to the high TE figure-of-merit(ZT)and the combination of elements that are nontoxic and earth-abundant[2].In 2012,Liu et al.[3]reported a ZT of 1.5 at 1000 K in the stoichiometric Cu_(2)Se.By alloying S at the Se-site,the ZT was enhanced to around 2.0 at 1000 K[4].Via incorporating carbon nanotubes,the ZT was further enhanced to 2.4 at 1000 K[5].Moreover,Yang et al.[6]and Zhou et al.[7]reported that the ZT of Cu_(2)Se/BiCuSeO composites can reach 2.7–2.8 around 1000 K.展开更多
Indium selenide(InSe)crystals are reported to show exceptional plasticity,a new property to twodimensional van der Waals(2D vdW)semiconductors.However,the correlation between plasticity and specific prototypes is uncl...Indium selenide(InSe)crystals are reported to show exceptional plasticity,a new property to twodimensional van der Waals(2D vdW)semiconductors.However,the correlation between plasticity and specific prototypes is unclear,and the understanding of detailed plastic deformation mechanisms is inadequate.Here three prototypes of InSe are predicted to be plastically deformable by calculation,and the plasticity of polymorphic crystals is verified by experiment.Moreover,distinct nanoindentation behaviors are seen on the cleavage and cross-section surfaces.The modulus and hardness of InSe are the lowest ones among a large variety of materials.The plastic deformation is further perceived from chemical interactions during the slip process.Particularly for the cross-layer slip,the initial In-Se bonds break while new In-In and Se-Se bonds are newly formed,maintaining a decent interaction strength.The remarkable plasticity and softness alongside the novel physical properties,endow InSe great promise for application in deformable and flexible electronics.展开更多
Bi2Te3-based alloys are the most mature commercial thermoelectric(TE)materials for the cooling application near room temperature.However,the poor mechanical properties of the commercial zone melting(ZM)ingot severely ...Bi2Te3-based alloys are the most mature commercial thermoelectric(TE)materials for the cooling application near room temperature.However,the poor mechanical properties of the commercial zone melting(ZM)ingot severely limits the further application.Meanwhile,due to the donor-like effect,the robust polycrystalline n-type bulks usually have low TE performance near room temperature.Herein,based on the commercial ZM ingots,a high figure of merit(zT)of 1.0 at 320 K and good mechanical properties are achieved via the hot extrusion.The dynamic recrystallization in the hot-extrusion process can suppress the donor-like effect and refine the large ZM grains into fine-equiaxed grains.Moreover,the obtained polycrystalline Bi2Te2.79Se0.21 has good preferential orientation and high carrier mobility(m).The high m and the weaken donor-like effect maintain the high power factor(PF)of 43.1 mW cm^(-1)K^(-2)in the hot-extruded ZM sample.Due to the enhanced phonon scattering,the total thermal conductivity ktot decreased to 1.35 W·m^(-1)·K^(-1).To demonstrate the good mechanical properties of the extruded ZM sample,micro TE dices with the cross sections of 300μm×300 mm and 200μm×200 mm are successfully cut from the extrusion sample.This study provided a fast and low-cost extrusion technique to improve the TE and mechanical properties of the commercial ZM ingot at room temperature.展开更多
We report detections of scintillation arcs for pulsars in globular clusters M5,M13 and M15 for the first time using the Fivehundred-meter Aperture Spherical radio Telescope(FAST).From observations of these arcs at mul...We report detections of scintillation arcs for pulsars in globular clusters M5,M13 and M15 for the first time using the Fivehundred-meter Aperture Spherical radio Telescope(FAST).From observations of these arcs at multiple epochs,we infer that screen-like scattering medium exists at distances 4.1_(-0.3)^(+0.2),6.7_(-0.2)^(+0.2)and 1.3_(-1.0)^(+0.7) kpc from Earth in the directions of M5,M13 and M15,respectively.This means M5's and M13's scattering screens are located at 3.0_(-0.2)^(+0.1) and 4.4_(-0.1)^(+0.1) kpc above the galactic plane,whereas,M15's is at 0.6_(-0.5)^(+0.3) kpc below the plane.We estimate the scintillation timescale and decorrelation bandwidth for each pulsar at each epoch using the one-dimensional auto-correlation in frequency and time of the dynamic spectra.We found that the boundary of the Local Bubble may have caused the scattering of M15,and detected the most distant off-plane scattering screens to date through pulsar scintillation,which provides evidence for understanding the medium circulation in the Milky Way.展开更多
During the last two decades,we have witnessed great progress in research on thermoelectrics.There are two primary focuses.One is the fundamental understanding of electrical and thermal transport,enabled by the interpl...During the last two decades,we have witnessed great progress in research on thermoelectrics.There are two primary focuses.One is the fundamental understanding of electrical and thermal transport,enabled by the interplay of theory and experiment;the other is the substantial enhancement of the performance of various thermoelectric materials,through synergistic optimisation of those intercorrelated transport parameters.Here we review some of the successful strategies for tuning electrical and thermal transport.For electrical transport,we start from the classical but still very active strategy of tuning band degeneracy(or band convergence),then discuss the engineering of carrier scattering,and finally address the concept of conduction channels and conductive networks that emerge in complex thermoelectric materials.For thermal transport,we summarise the approaches for studying thermal transport based on phonon–phonon interactions valid for conventional solids,as well as some quantitative efforts for nanostructures.We also discuss the thermal transport in complex materials with chemical-bond hierarchy,in which a portion of the atoms(or subunits)are weakly bonded to the rest of the structure,leading to an intrinsic manifestation of part-crystalline part-liquid state at elevated temperatures.In this review,we provide a summary of achievements made in recent studies of thermoelectric transport properties,and demonstrate how they have led to improvements in thermoelectric performance by the integration of modern theory and experiment,and point out some challenges and possible directions.展开更多
We performed angle-resolved photoemission spectroscopy studies on a series of FeTe_(1-x)Se_x monolayer films grown on Sr TiO_3.The superconductivity of the films is robust and rather insensitive to the variations of t...We performed angle-resolved photoemission spectroscopy studies on a series of FeTe_(1-x)Se_x monolayer films grown on Sr TiO_3.The superconductivity of the films is robust and rather insensitive to the variations of the band position and effective mass caused by the substitution of Se by Te.However,the band gap between the electron-and hole-like bands at the Brillouin zone center decreases towards band inversion and parity exchange,which drive the system to a nontrivial topological state predicted by theoretical calculations.Our results provide a clear experimental indication that the FeTe_(1-x)Se_x monolayer materials are high-temperature connate topological superconductors in which band topology and superconductivity are integrated intrinsically.展开更多
Copper sulfide Cu2S is a p-type semiconducting compound that has attracted great attentions in the thermoelectric （TE） community most recently. Considering the intrinsic ultralow lattice thermal conductivity, the en...Copper sulfide Cu2S is a p-type semiconducting compound that has attracted great attentions in the thermoelectric （TE） community most recently. Considering the intrinsic ultralow lattice thermal conductivity, the enhancement of TE performance in CuzS should be achieved through improving its electrical transport properties. To achieve this goal, lithium element was doped into CuzS in this study. A series of Cu2_xLixS samples with different Li contents （x = 0, 0.005, 0.010, 0.050, and 0.100） was synthesized by the melting-annealing method. When x 〈 0.05, the Cuz_xLixS samples are stable and pure phases, having the same monoclinic structure with the pristine Cu2S at room temperature. The electrical conductivities in the Cu2_xLixS samples are greatly improved with the Li-doping content increasing due to the enhanced carrier concentrations. Meanwhile, doping Li into CuzS increases the ionic activation energy and lessens the influence of mobile Cu ions on the heat-carrying phonons. Thus, the thermal conductivities of the Li-doped Cu2S samples increase. A maximal figure of merit （zT） of 0.84 at 900 K is obtained in Cul.99Lio.018, about 133% improvement as compared with that in Cu2S matrix.展开更多
By virtue of the excellent plasticity and tunable transport properties,Ag_(2)S-based materials demonstrate an intriguing prospect for flexible or hetero-shaped thermoelectric applications.Among them,Ag_(2)S_(1-x)Te_(x...By virtue of the excellent plasticity and tunable transport properties,Ag_(2)S-based materials demonstrate an intriguing prospect for flexible or hetero-shaped thermoelectric applications.Among them,Ag_(2)S_(1-x)Te_(x)exhibits rich and interesting variations in crystal structure,mechanical and thermoelectric transport properties.However,Te alloying obviously introduces extremely large order-disorder distributions of cations and anions,leading to quite complicated crystal structures and thermoelectric properties.Detailed composition-structure-performance correlation of Ag_(2)S_(1-x)Te_(x)still remains to be established.In this work,we designed and prepared a series of Ag_(2)S_(1-x)Te_(x)(x=0-0.3)materials with low Te content.We discovered that the monoclinic-to-cubic phase transition occurs around x=0.16 at room temperature.Te alloying plays a similar role as heating in facilitating this monoclinic-to-cubic phase transition,which is analyzed based on the thermodynamic principles.Compared with the monoclinic counterparts,the cubic-structured phases are more ductile and softer in mechanical properties.In addition,the cubic phases show a degenerately semiconducting behavior with higher thermoelectric performance.A maximum zT=0.8 at 600 K and bending strain larger than 20% at room temperature were obtained in Ag_(2)S_(0.7)Te_(0.3).This work provides a useful guidance for designing Ag_(2)S-based alloys with enhanced plasticity and high thermoelectric performance.展开更多
Cu-based chalcogenides have received increasing attention as promising thermoelectric materials due to their high efficiency,tunable transport properties,high elemental abundance and low toxicity.In this review,we sum...Cu-based chalcogenides have received increasing attention as promising thermoelectric materials due to their high efficiency,tunable transport properties,high elemental abundance and low toxicity.In this review,we summarize the recent research progress on this large family compounds covering diamond-like chalcogenides and liquid-like Cu2X (X=S,Se,Te)binary compounds as well as their multinary derivatives.These materials have the general features of two sublattices to decouple electron and phonon transport properties.On the one hand,the complex crystal structure and the disordered or even liquid-like sublattice bring about an intrinsically low lattice thermal conductivity.On the other hand, the rigid sublattice constitutes the charge-transport network, maintaining a decent electrical performance.For specific material systems,we demonstrate their unique structural features and outline the structure-performance correlation. Various design strategies including doping,alloying,band engineering and nanostructure architecture,covering nearly all the material scale,are also presented.Finally,the potential of the application of Cu-based chalcogenides as high-performance thermoelectric materials is briefly discussed from material design to device development.展开更多
Self-powered wearable electronics require thermoelectric materials simultaneously with a high dimensionless figure of merit(zT)and good flexibility to convert the heat discharged by the human body into electricity.Ag_...Self-powered wearable electronics require thermoelectric materials simultaneously with a high dimensionless figure of merit(zT)and good flexibility to convert the heat discharged by the human body into electricity.Ag_(2)(S,Se)-based semiconducting materials can well satisfy these requirements,and thus,they are attracting great attention in thermoelectric society recently.Ag_(2)(S,Se)crystalizes in an orthorhombic structure or monoclinic structure,depending on the detailed S/Se atomic ratio,but the relationship between its crystalline structure and mechanical/thermoelectric performance is still unclear to date.In this study,a series of Ag_(2)Se_(1-x)S_(x)(x=0,0.1,0.2,0.3,0.4,and 0.45)samples were prepared and their mechanical and thermoelectric performance dependence on the crystalline structure was systematically investigated.x=0:3 in the Ag_(2)Se_(1-x)S_(x)system was found to be the transition boundary between orthorhombic and monoclinic structures.Mechanical property measurement shows that the orthorhombic Ag_(2)Se_(1-x)S_(x)samples are brittle while the monoclinic Ag_(2)Se_(1-x)S_(x)samples are ductile and flexible.In addition,the orthorhombic Ag_(2)Se_(1-x)S_(x)samples show better electrical transport performance and higher zT than the monoclinic samples under a comparable carrier concentration,most likely due to their weaker electron-phonon interactions.This study sheds light on the further development of flexible inorganic TE materials.展开更多
Flexible electronics ushers in a revolution to the electronics industry in the 21st century.Ideally,all components of a flexible electronic device including the functional component shall comply with the deformation t...Flexible electronics ushers in a revolution to the electronics industry in the 21st century.Ideally,all components of a flexible electronic device including the functional component shall comply with the deformation to ensure the structural and functional integrity,imposing a pressing need for developing roomtemperature strain-tolerant semiconductors.To this end,there is a long-standing material dilemma:inorganic semiconductors are typically brittle at room temperature except for size-induced flexibility;by contrast,organic semiconductors are intrinsically soft and flexible but the electrical performance is poor.This is why the discovery of bulk plasticity in Ag2S at room temperature and ZnS in darkness is groundbreaking in solving this long-standing material dilemma between the mechanical deformability and the electrical performance.The present review summarizes the background knowledge and latest advances in the emerging field of plastic inorganic semiconductors.At the outset,we argue that the plasticity of inorganic semiconductors is vital to strain tolerance of electronic devices,which has not been adequately emphasized.The mechanisms of plasticity are illustrated from the perspective of chemical bonding and dislocations.Plastic inorganic materials,for example,ionic crystals(insulators),ZnS in darkness,and Ag2S,are discussed in detail in terms of their prominent mechanical properties and potential applications.We conclude the article with several key scientific and technological questions to address in the future study.展开更多
Cardiovascular diseases are the most common cause of death globally.Accurately modeling cardiac homeostasis,dysfunction,and drug response lies at the heart of cardiac research.Adult human primary cardiomyocytes(hPCMs)...Cardiovascular diseases are the most common cause of death globally.Accurately modeling cardiac homeostasis,dysfunction,and drug response lies at the heart of cardiac research.Adult human primary cardiomyocytes(hPCMs)are a promising cellular model,but unstable isolation efficiency and quality,rapid cell death in culture,and unknown response to cryopreservation prevent them from becoming a reliable and flexible in vitro cardiac model.Combing the use of a reversible inhibitor of myosinⅡATPase,(-)-blebbistatin(Bleb),and multiple optimization steps of the isolation procedure,we achieved a 2.74-fold increase in cell viability over traditional methods,accompanied by better cellular morphology,minimally perturbed gene expression,intact electrophysiology,and normal neurohormonal signaling.Further optimization of culture conditions established a method that was capable of maintaining optimal cell viability,morphology,and mitochondrial respiration for at least 7 days.Most importantly,we successfully cryopreserved hPCMs,which were structurally,molecularly,and functionally intact after undergoing the freeze-thaw cycle.hPCMs demonstrated greater sensitivity towards a set of cardiotoxic drugs,compared to human-induced pluripotent stem cell-derived cardiomyocytes(hiPSC-CMs).Further dissection of cardiomyocyte drug response at both the population and single-cell transcriptomic level revealed that hPCM responses were more pronouncedly enriched in cardiac function,whereas hiPSC-CMs responses reflected cardiac development.Together,we established a full set of methodologies for the efficient isolation and prolonged maintenance of functional primary adult human cardiomyocytes in vitro,unlocking their potential as a cellular model for cardiovascular research,drug discovery,and safety pharmacology.展开更多
AgSbTe_(2)-based ternary chalcogenides show excellent thermoelectric performance at low-and middletemperature ranges,yet their practical applications are greatly limited by their intrinsic poor thermodynamic stability...AgSbTe_(2)-based ternary chalcogenides show excellent thermoelectric performance at low-and middletemperature ranges,yet their practical applications are greatly limited by their intrinsic poor thermodynamic stability.In this work,we demonstrate that AgSbTe_(2)-based ternary chalcogenides can be stabilized for service below their decomposition threshold.A series of AgxSb_(2-x)Te_(3-x)(x=1.0,0.9,0.8 and 0.7)samples have been prepared by the melt-quenching method.Among them,phase pure Ag0.9Sb1.1Te2.1 is verified by comprehensive structural characterizations from macroscale by X-ray diffraction to microscale by energy-dispersive spectroscopy and then to sub-nanometer scale by atom probe tomography.This composition is further chosen for the stability investigation.The decomposition threshold of Ag_(0.9)Sb_(1.1)Te_(2.1)appears around 473 K.Below this temperature,the chemical compositions and thermoelectric properties are barely changed even after 720 h annealing at 473 K.The figure-of-merit(zT)value of Ag_(0.9)Sb_(1.1)Te_(2.1)below the decomposition threshold is very competitive for real applications even compared with Bi_(2)Te_(3-)based alloys.The average zT of Ag_(0.9)Sb_(1.1)Te_(2.1)at 300e473 K reaches 0.84,which is higher than most other thermoelectric materials in a similar temperature range,promising applications in miniaturized refrigeration and power generation near room temperature.展开更多
基金Supported by the National Basic Research Program of China under Grant Nos 2013CB921700,2015CB921300 and2015CB921301the National Natural Science Foundation of China under Grant Nos 11234014,11622435,11274362,11674371 and11474340+1 种基金the National Key Research and Development Program of China under Grant Nos 2016YFA0300300,2016YFA0300600,2016YFA0401000 and 2016YFA0400902the Open Large Infrastructure Research of Chinese Academy of Sciences,and the Pioneer Hundred Talents Program(Type C)of Chinese Academy of Sciences
文摘The electronic structure of iron-pnictide compound superconductor Ba_2Ti_2Fe_2As_4O, which has metallic intermediate Ti_2O layers, is studied using angle-resolved photoemission spectroscopy. The Ti-related bands show a‘peak-dip-hump＇ line shape with two branches of dispersion associated with the polaronic states at temperatures below around 120 K. This change in the spectra occurs along with the resistivity anomaly that was not clearly understood in a previous study. Moreover, an energy gap induced by the superconducting proximity effect opens in the polaronic bands at temperatures below T_c（~21 K）. Our study provides the spectroscopic evidence that superconductivity coexists with polarons in the same bands near the Fermi level, which provides a suitable platform to study interactions between charge, lattice and spin freedoms in a correlated system.
基金Supported by the Ministry of Science and Technology of China under Grant Nos 2015CB921000,2016YFA0401000,2015CB921301 and 2016YFA0300300the National Natural Science Foundation of China under Grant Nos 11274381,11574371,11274362,1190020,11334012 and 11674371
文摘We report the growth process of FeTe1-xSex （0 〈 x 〈 1） monolayer films on SrTi03 （STO） substrates through molecular beam epitaxy and discuss the possible ways to improve the film quality. By exploring the parameters of substrate treatment, growth control and post growth annealing, we successfully obtain a series of FeTe1-xSex monolayer films. In the whole growth process, we find the significance of the temperature control through surface roughness monitored by the reflection high-energy electron diffraction and scanning tunneling microscopy. We obtain the best quality of FeSe monolayer films with the STO substrate treated at T = 900 950℃ before growth, the FeSe deposited at T = 310℃ during growth and annealed at T = 380℃ after growth. For FeTe1-xSex （x-1）, both the growth temperature and annealing temperature decrease to T=260℃. According to the angle- resolved photoemission spectroscopy measurements, the superconductivity of the FeTe1-xSex film is robust and insensitive to Se concentration. All the above are instructive for further investigations of the superconductivity in FeTe1-xSex films.
基金Supported by the National Key Research and Development Program of China (Grant No. 2018YFB0703600)the National Natural Science Foundation of China (Grant Nos. 91963208, 51625205, 51961135106, and 51902199)+2 种基金Shanghai Government (Grant No. 20JC1415100)the CAS-DOE Program of Chinese Academy of Sciences (Grant No. 121631KYSB20180060)the Shanghai Sailing Program (Grant No. 19YF1422800)。
文摘Coupling of a phase transition to electron and phonon transports provides extra degree of freedom to improve the thermoelectric performance, while the pertinent experimental and theoretical studies are still rare. Particularly,the impaction of chemical compositions and phase transition characters on the abnormal thermoelectric properties across phase transitions are largely unclear. Herein, by varying the Cu content x from 1.75 to 2.10, we systemically investigate the crystal structural evolution, phase transition features, and especially the thermoelectric properties during the phase transition for Cu_(x)Se. It is found that the addition of over-stoichiometry Cu in Cu_(x)Se could alter the phase transition characters and suppress the formation of Cu vacancies. The critical scatterings of phonons and electrons during phase transitions strongly enhance the Seebeck coefficient and diminish the thermal conductivity, leading to an ultrahigh dimensionless thermoelectric figure of merit of ~1.38 at 397 K in Cu_(2.10)Se.With the decreasing Cu content, the critical electron and phonon scattering behaviors are mitigated, and the corresponding thermoelectric performances are reduced. This work offers inspirations for understanding and tuning the thermoelectric transport properties during phase transitions.
基金supported by the CAMS Innovation Fund for Medical Sciences(CIFMS)(2021-1-I2M-006,2023-I2M-1-003,2022-I2M-2-001,2021-1-I2M-019)the National Natural Science Foundation of China(82070287,82088101 and 82025004)the National Key Research and Development Program of China(2022YFA1104500)。
文摘Mitochondrial toxicity induced by therapeutic drugs is a major contributor for cardiotoxicity,posing a serious threat to pharmaceutical industries and patients’lives.However,mitochondrial toxicity testing is not incorporated into routine cardiac safety screening procedures.To accurately model native human cardiomyocytes,we comprehensively evaluated mitochondrial responses of adult human primary cardiomyocytes(h PCMs)to a nucleoside analog,remdesivir(RDV).Comparison of their response to human pluripotent stem cell-derived cardiomyocytes revealed that the latter utilized a mitophagy-based mitochondrial recovery response that was absent in h PCMs.Accordingly,action potential duration was elongated in h PCMs,reflecting clinical incidences of RDV-induced QT prolongation.In a screen for mitochondrial protectants,we identified mitochondrial ROS as a primary mediator of RDV-induced cardiotoxicity.Our study demonstrates the utility of h PCMs in the detection of clinically relevant cardiac toxicities,and offers a framework for h PCM-based high-throughput screening of cardioprotective agents.
基金This work was supported by the National Natural Science Foundation of China(No.52372209 and 52232010)the Shanghai Pilot Program for Basic Research-Chinese Academy of Science,Shanghai Branch(JCYJ-SHFY-2022-002)。
文摘As a new type of inorganic ductile semiconductor,silver sulfide(α-Ag_(2)S)has garnered a plethora of interests in recent years due to its promising applications in flexible electronics.However,the lack of detailed defect calculations and chemical intuition has largely hindered the optimization of material's performance.In this study,we systematically investigate the defect chemistry of extrinsic doping inα-Ag_(2)S using first-principles calculations.We computationally examine a broad suite of 17 dopants and find that all aliovalent elements have extremely low doping limits(<0.002%)in α-Ag_(2)S,rendering them ineffective in tuning the electron concentrations.In contrast,the isovalent elements Se and Te have relatively high doping limits,being consistent with the experimental observations.While the dopant Se or Te itself does not provide additional electrons,its introduction has a significant impact on the band gap,the band-edge position,and especially the formation energy of Ag interstitials,which effectively improve the electron concentrations by 2–3 orders of magnitudes.The size effects of Se and Te doping are responsible for the more favorable Ag interstitials in Ag_(2)S_(0.875)Se_(0.125) and Ag_(2)S_(0.875)Te_(0.125) with respect to pristine Ag2S.This work serves as a theoretical foundation for the rational design of Ag_(2)S-based functional materials.
基金supported by the National Natural Science Foundation of China(T2122013,52232010)the Basic Research Project of the Shanghai Science and Technology Committee(20JC1415100).
文摘Exploring new prototypes for a given chemical composition is of great importance and interest to several disciplines.As a famous semiconducting binary compound,InSe usually exhibits a two-dimensional layered structure with decent physical and mechanical properties.However,it is less noticed that InSe can also adopt a monoclinic structure,denoted as mcl-InSe.The synthesis of such a phase usually re-quires high-pressure conditions,and the knowledge is quite scarce on its chemical bonding,lattice dynamics,and thermal transport.Here in this work,by developing a facile method combining me-chanical alloying and spark plasma sintering,we successfully synthesize mcl-InSe bulks with well-crystallized nanograins.The chemical bonding of mcl-InSe is understood as compared with layered InSe via charge analysis.Low cut-off frequencies of acoustic phonons and several low-lying optical modes are demonstrated.Noticeably,mcl-InSe exhibits a low room-temperature thermal conductivity of 0.6 W·m^(-1)·K^(-1),which is smaller than that of other materials in the IneSe system and many other selenides.Low-temperature thermal analyses corroborate the role of nanograin boundaries and low-frequency optical phonons in scattering acoustic phonons.This work provides new insights into the non-common prototype of the InSe binary compound with potential applications in thermoelectrics or thermal insulation.
基金supported by the National Natural Science Foundation of China(grants 52122213,52232010,91963208)the Shanghai Pilot Program for Basic Research-Chinese Academy of Science,Shanghai Branch(JCYJ-SHFY-2022-002)Shanghai Government(20JC1415100).
文摘Ductile Ag_(2)(Te,S)pseudobinary compounds have attracted great attention in thermoelectric community since they can be fabricated into high-performance flexible and hetero-shaped thermoelectric devices.However,in spite of the numerous studies,the‘brittleeductile’transition boundary in Ag_(2)(Te,S)is still unclear.In this work,a series of Te-rich Ag_(2)(Te,S)pseudobinary compounds have been prepared.The structure characterizations confirm they belong to the new-concept of meta-phase.The systematically investigation on the mechanical properties demonstrate that the‘brittl-eductile’transition boundary appears around x=0.1.Unexpected good ductility is observed in the Te-rich Ag_(2)Te_(1-x)S_(x)crystalizing in the Ag_(2)Te room-temperature monoclinic structure and high-temperature cubic structure,which are thought to be brittle before.Likewise,Ag content is found to be a very critical parameter determining the ductility of Te-rich Ag_(2)Te_(1-x)S_(x).Very slight Ag-deficiency can greatly deteriorate the ductility.The ther-moelectric properties of these ductile Te-rich Ag_(2)Te_(1-x)S_(x)pseudobinary compounds are investigated.A maximum thermoelectric figure-of-merit of 0.6 is obtained for Ag_(2)Te_(0.9)S_(0.1)at 600 K.This work sheds light on the future investigation of Ag_(2)(Te,S)pseudobinary compounds.
文摘Thermoelectric(TE)materials can directly convert the industrial waste heat into useful electricity based on the Seebeck effect,providing a promising way to tackle the environmental pollution and global energy crisis[1].In the past several decades,many new high-performance TE materials have been discovered to enrich the TE family.Among them,Cu_(2)−δSe-based TE materials,which are in line with the“phonon-liquid electron-crystal”concept,have sparked widespread interest due to the high TE figure-of-merit(ZT)and the combination of elements that are nontoxic and earth-abundant[2].In 2012,Liu et al.[3]reported a ZT of 1.5 at 1000 K in the stoichiometric Cu_(2)Se.By alloying S at the Se-site,the ZT was enhanced to around 2.0 at 1000 K[4].Via incorporating carbon nanotubes,the ZT was further enhanced to 2.4 at 1000 K[5].Moreover,Yang et al.[6]and Zhou et al.[7]reported that the ZT of Cu_(2)Se/BiCuSeO composites can reach 2.7–2.8 around 1000 K.
基金the National Natural Science Foundation of China(T2122013,52232010)the Basic Research Project of the Shanghai Science and Technology Committee(20JC1415100)。
文摘Indium selenide(InSe)crystals are reported to show exceptional plasticity,a new property to twodimensional van der Waals(2D vdW)semiconductors.However,the correlation between plasticity and specific prototypes is unclear,and the understanding of detailed plastic deformation mechanisms is inadequate.Here three prototypes of InSe are predicted to be plastically deformable by calculation,and the plasticity of polymorphic crystals is verified by experiment.Moreover,distinct nanoindentation behaviors are seen on the cleavage and cross-section surfaces.The modulus and hardness of InSe are the lowest ones among a large variety of materials.The plastic deformation is further perceived from chemical interactions during the slip process.Particularly for the cross-layer slip,the initial In-Se bonds break while new In-In and Se-Se bonds are newly formed,maintaining a decent interaction strength.The remarkable plasticity and softness alongside the novel physical properties,endow InSe great promise for application in deformable and flexible electronics.
基金supported by the National Nature Science Foundation of China(U1738114)the China Postdoctoral Science Foundation(2020TQ0330 and 2021M703331).
文摘Bi2Te3-based alloys are the most mature commercial thermoelectric(TE)materials for the cooling application near room temperature.However,the poor mechanical properties of the commercial zone melting(ZM)ingot severely limits the further application.Meanwhile,due to the donor-like effect,the robust polycrystalline n-type bulks usually have low TE performance near room temperature.Herein,based on the commercial ZM ingots,a high figure of merit(zT)of 1.0 at 320 K and good mechanical properties are achieved via the hot extrusion.The dynamic recrystallization in the hot-extrusion process can suppress the donor-like effect and refine the large ZM grains into fine-equiaxed grains.Moreover,the obtained polycrystalline Bi2Te2.79Se0.21 has good preferential orientation and high carrier mobility(m).The high m and the weaken donor-like effect maintain the high power factor(PF)of 43.1 mW cm^(-1)K^(-2)in the hot-extruded ZM sample.Due to the enhanced phonon scattering,the total thermal conductivity ktot decreased to 1.35 W·m^(-1)·K^(-1).To demonstrate the good mechanical properties of the extruded ZM sample,micro TE dices with the cross sections of 300μm×300 mm and 200μm×200 mm are successfully cut from the extrusion sample.This study provided a fast and low-cost extrusion technique to improve the TE and mechanical properties of the commercial ZM ingot at room temperature.
基金supported by the National SKA Program of China (Grant Nos. 2020SKA0120200, 2022SKA0130100, and 2022SKA0130104)the National Nature Science Foundation of China (Grant Nos. 12273008, 11873067, 12041303, 12041304, 61875087, U1831120, U1838106, 61803373, 11303069, 11373011, 11873080, U2031117, and 12103069)+10 种基金the Natural Science and Technology Foundation of Guizhou Province (Grant No. [2023]024)the National Key R&D Program of China (Grant No. 2017YFB0503300)the Guizhou Provincial Science and Technology Foundation (Grant Nos. ZK[2023]024, ZK[2022]304, [2017]5726-37, and [2018]5769-02)the Major Science and Technology Program of Xinjiang Uygur Autonomous Region (Grant Nos. 2022A03013-4, and 2022A030132)the Scientific Research Project of the Guizhou Provincial Education (Grant Nos. KY[2022]132, and KY[2022]137)the Guizhou Province Science and Technology Support Program (General Project) (Grant No. Qianhe Support [2023] General 333)the Foundation of Guizhou Provincial Education Department (Grant No. KY (2020) 003)the Natural Science Foundation of Xinjiiang Uygur Autonomous Region (Grant No. 2022D01D85)the Youth Innovation Promotion Association CAS (Grant No. 2021055)the CAS Project for Young Scientists in Basic Research (Grant No. YSBR-006)the Cultivation Project for FAST Scientific Payoff and Research Achievement of CAMS-CAS and ACAMAR Postdoctoral Fellowship。
文摘We report detections of scintillation arcs for pulsars in globular clusters M5,M13 and M15 for the first time using the Fivehundred-meter Aperture Spherical radio Telescope(FAST).From observations of these arcs at multiple epochs,we infer that screen-like scattering medium exists at distances 4.1_(-0.3)^(+0.2),6.7_(-0.2)^(+0.2)and 1.3_(-1.0)^(+0.7) kpc from Earth in the directions of M5,M13 and M15,respectively.This means M5's and M13's scattering screens are located at 3.0_(-0.2)^(+0.1) and 4.4_(-0.1)^(+0.1) kpc above the galactic plane,whereas,M15's is at 0.6_(-0.5)^(+0.3) kpc below the plane.We estimate the scintillation timescale and decorrelation bandwidth for each pulsar at each epoch using the one-dimensional auto-correlation in frequency and time of the dynamic spectra.We found that the boundary of the Local Bubble may have caused the scattering of M15,and detected the most distant off-plane scattering screens to date through pulsar scintillation,which provides evidence for understanding the medium circulation in the Milky Way.
基金supported by National Basic Research Program of China(973-program)under project number 2013CB632501National Natural Science Foundation of China under contract number 11234012+7 种基金the Key Research Program of Chinese Academy of Sciences(Grant No.KGZD-EW-T06)research grants(14DZ2261200 and 15JC1400301)from Science and Technology Commission of Shanghai MunicipalityInternational S&T Cooperation Program of China(2015DFA51050)supported by the U.S.Department of Energy,Office of Basic Energy Sciences under award number DE-SC-0008574supported by the Department of Energy through the S3TEC Energy Frontier Research Center award#DE-SC0001299/DE-FG02–09ER46577supported by the U.S.Department of Energy under corporate agreement DE-FC26-04NT42278by GM,and by National Science Foundation under award number 1235535support from Shanghai Institute of Materials Genome.
文摘During the last two decades,we have witnessed great progress in research on thermoelectrics.There are two primary focuses.One is the fundamental understanding of electrical and thermal transport,enabled by the interplay of theory and experiment;the other is the substantial enhancement of the performance of various thermoelectric materials,through synergistic optimisation of those intercorrelated transport parameters.Here we review some of the successful strategies for tuning electrical and thermal transport.For electrical transport,we start from the classical but still very active strategy of tuning band degeneracy(or band convergence),then discuss the engineering of carrier scattering,and finally address the concept of conduction channels and conductive networks that emerge in complex thermoelectric materials.For thermal transport,we summarise the approaches for studying thermal transport based on phonon–phonon interactions valid for conventional solids,as well as some quantitative efforts for nanostructures.We also discuss the thermal transport in complex materials with chemical-bond hierarchy,in which a portion of the atoms(or subunits)are weakly bonded to the rest of the structure,leading to an intrinsic manifestation of part-crystalline part-liquid state at elevated temperatures.In this review,we provide a summary of achievements made in recent studies of thermoelectric transport properties,and demonstrate how they have led to improvements in thermoelectric performance by the integration of modern theory and experiment,and point out some challenges and possible directions.
基金supported by grants from the Ministry of Science and Technology of China(2015CB921000,2016YFA0401000,2015CB921301,2016YFA0300300)the National Natural Science Foundation of China(11574371,11274362,1190020,11334012,11274381,11674371)
文摘We performed angle-resolved photoemission spectroscopy studies on a series of FeTe_(1-x)Se_x monolayer films grown on Sr TiO_3.The superconductivity of the films is robust and rather insensitive to the variations of the band position and effective mass caused by the substitution of Se by Te.However,the band gap between the electron-and hole-like bands at the Brillouin zone center decreases towards band inversion and parity exchange,which drive the system to a nontrivial topological state predicted by theoretical calculations.Our results provide a clear experimental indication that the FeTe_(1-x)Se_x monolayer materials are high-temperature connate topological superconductors in which band topology and superconductivity are integrated intrinsically.
基金financially supported by the National Natural Science Foundation of China (Nos. 51472262 and 51625205)the Key Research Program of Chinese Academy of Sciences (No.KFZD-SW-421)the Shanghai Government (No. 15JC1400301)
文摘Copper sulfide Cu2S is a p-type semiconducting compound that has attracted great attentions in the thermoelectric （TE） community most recently. Considering the intrinsic ultralow lattice thermal conductivity, the enhancement of TE performance in CuzS should be achieved through improving its electrical transport properties. To achieve this goal, lithium element was doped into CuzS in this study. A series of Cu2_xLixS samples with different Li contents （x = 0, 0.005, 0.010, 0.050, and 0.100） was synthesized by the melting-annealing method. When x 〈 0.05, the Cuz_xLixS samples are stable and pure phases, having the same monoclinic structure with the pristine Cu2S at room temperature. The electrical conductivities in the Cu2_xLixS samples are greatly improved with the Li-doping content increasing due to the enhanced carrier concentrations. Meanwhile, doping Li into CuzS increases the ionic activation energy and lessens the influence of mobile Cu ions on the heat-carrying phonons. Thus, the thermal conductivities of the Li-doped Cu2S samples increase. A maximal figure of merit （zT） of 0.84 at 900 K is obtained in Cul.99Lio.018, about 133% improvement as compared with that in Cu2S matrix.
基金This work is supported by the National Key Research and Development Program of China(2018YFB0703600)National Natural Science Foundation of China(91963208,51625205,51961135106,51802333)+2 种基金the CAS-DOE Program of Chinese Academy of Sciences(121631KYSB20180060)the Shanghai Government(20JC1415100)the Swedish Research Council(VR 2018e06030).
文摘By virtue of the excellent plasticity and tunable transport properties,Ag_(2)S-based materials demonstrate an intriguing prospect for flexible or hetero-shaped thermoelectric applications.Among them,Ag_(2)S_(1-x)Te_(x)exhibits rich and interesting variations in crystal structure,mechanical and thermoelectric transport properties.However,Te alloying obviously introduces extremely large order-disorder distributions of cations and anions,leading to quite complicated crystal structures and thermoelectric properties.Detailed composition-structure-performance correlation of Ag_(2)S_(1-x)Te_(x)still remains to be established.In this work,we designed and prepared a series of Ag_(2)S_(1-x)Te_(x)(x=0-0.3)materials with low Te content.We discovered that the monoclinic-to-cubic phase transition occurs around x=0.16 at room temperature.Te alloying plays a similar role as heating in facilitating this monoclinic-to-cubic phase transition,which is analyzed based on the thermodynamic principles.Compared with the monoclinic counterparts,the cubic-structured phases are more ductile and softer in mechanical properties.In addition,the cubic phases show a degenerately semiconducting behavior with higher thermoelectric performance.A maximum zT=0.8 at 600 K and bending strain larger than 20% at room temperature were obtained in Ag_(2)S_(0.7)Te_(0.3).This work provides a useful guidance for designing Ag_(2)S-based alloys with enhanced plasticity and high thermoelectric performance.
基金supported by the National Key Research and Development Program of China (2018YFB0703600)the National Natural Science Foundation of China (51625205)+3 种基金 the Key Research Program of Chinese Academy of Sciences (KFZD-SW-421)Program of Shanghai Subject Chief Scientist (16XD1403900)Youth Innovation Promotion Association, CAS (2016232)Shanghai Sailing Program (18YF1426700).
文摘Cu-based chalcogenides have received increasing attention as promising thermoelectric materials due to their high efficiency,tunable transport properties,high elemental abundance and low toxicity.In this review,we summarize the recent research progress on this large family compounds covering diamond-like chalcogenides and liquid-like Cu2X (X=S,Se,Te)binary compounds as well as their multinary derivatives.These materials have the general features of two sublattices to decouple electron and phonon transport properties.On the one hand,the complex crystal structure and the disordered or even liquid-like sublattice bring about an intrinsically low lattice thermal conductivity.On the other hand, the rigid sublattice constitutes the charge-transport network, maintaining a decent electrical performance.For specific material systems,we demonstrate their unique structural features and outline the structure-performance correlation. Various design strategies including doping,alloying,band engineering and nanostructure architecture,covering nearly all the material scale,are also presented.Finally,the potential of the application of Cu-based chalcogenides as high-performance thermoelectric materials is briefly discussed from material design to device development.
基金This work is supported by the National Key Research and Development Program of China(2018YFB0703600)the National Natural Science Foundation of China(51625205,91963208,and 5181101519)+3 种基金X.S.thanks the support by the CAS-DOE Program of Chinese Academy of Sciences under Grant No.121631KYSB20180060P.Q.thanks the support by the Youth Innovation Promotion Association of CAS under Grant No.2016232Shanghai Rising-Star Program under Grant No.19QA1410200This work is also partially supported by the Swedish Research Council(VR)via the Sweden-China collaborative project 2018-06030.
文摘Self-powered wearable electronics require thermoelectric materials simultaneously with a high dimensionless figure of merit(zT)and good flexibility to convert the heat discharged by the human body into electricity.Ag_(2)(S,Se)-based semiconducting materials can well satisfy these requirements,and thus,they are attracting great attention in thermoelectric society recently.Ag_(2)(S,Se)crystalizes in an orthorhombic structure or monoclinic structure,depending on the detailed S/Se atomic ratio,but the relationship between its crystalline structure and mechanical/thermoelectric performance is still unclear to date.In this study,a series of Ag_(2)Se_(1-x)S_(x)(x=0,0.1,0.2,0.3,0.4,and 0.45)samples were prepared and their mechanical and thermoelectric performance dependence on the crystalline structure was systematically investigated.x=0:3 in the Ag_(2)Se_(1-x)S_(x)system was found to be the transition boundary between orthorhombic and monoclinic structures.Mechanical property measurement shows that the orthorhombic Ag_(2)Se_(1-x)S_(x)samples are brittle while the monoclinic Ag_(2)Se_(1-x)S_(x)samples are ductile and flexible.In addition,the orthorhombic Ag_(2)Se_(1-x)S_(x)samples show better electrical transport performance and higher zT than the monoclinic samples under a comparable carrier concentration,most likely due to their weaker electron-phonon interactions.This study sheds light on the further development of flexible inorganic TE materials.
基金National Key Research and Development Program of China,Grant/Award Number:2018YFB0703600National Natural Science Foundation of China,Grant/Award Numbers:51625205,51961135106,91963208Shanghai Sailing Program,Grant/Award Number:18YF1426700。
文摘Flexible electronics ushers in a revolution to the electronics industry in the 21st century.Ideally,all components of a flexible electronic device including the functional component shall comply with the deformation to ensure the structural and functional integrity,imposing a pressing need for developing roomtemperature strain-tolerant semiconductors.To this end,there is a long-standing material dilemma:inorganic semiconductors are typically brittle at room temperature except for size-induced flexibility;by contrast,organic semiconductors are intrinsically soft and flexible but the electrical performance is poor.This is why the discovery of bulk plasticity in Ag2S at room temperature and ZnS in darkness is groundbreaking in solving this long-standing material dilemma between the mechanical deformability and the electrical performance.The present review summarizes the background knowledge and latest advances in the emerging field of plastic inorganic semiconductors.At the outset,we argue that the plasticity of inorganic semiconductors is vital to strain tolerance of electronic devices,which has not been adequately emphasized.The mechanisms of plasticity are illustrated from the perspective of chemical bonding and dislocations.Plastic inorganic materials,for example,ionic crystals(insulators),ZnS in darkness,and Ag2S,are discussed in detail in terms of their prominent mechanical properties and potential applications.We conclude the article with several key scientific and technological questions to address in the future study.
基金supported by the CAMS Initiative for Innovative Medicine Program(grants 2021-1-I2M-006 and 2017-I2M-1-003)the National Natural Science Foundation of China(grants 82070287 and 81700337).
文摘Cardiovascular diseases are the most common cause of death globally.Accurately modeling cardiac homeostasis,dysfunction,and drug response lies at the heart of cardiac research.Adult human primary cardiomyocytes(hPCMs)are a promising cellular model,but unstable isolation efficiency and quality,rapid cell death in culture,and unknown response to cryopreservation prevent them from becoming a reliable and flexible in vitro cardiac model.Combing the use of a reversible inhibitor of myosinⅡATPase,(-)-blebbistatin(Bleb),and multiple optimization steps of the isolation procedure,we achieved a 2.74-fold increase in cell viability over traditional methods,accompanied by better cellular morphology,minimally perturbed gene expression,intact electrophysiology,and normal neurohormonal signaling.Further optimization of culture conditions established a method that was capable of maintaining optimal cell viability,morphology,and mitochondrial respiration for at least 7 days.Most importantly,we successfully cryopreserved hPCMs,which were structurally,molecularly,and functionally intact after undergoing the freeze-thaw cycle.hPCMs demonstrated greater sensitivity towards a set of cardiotoxic drugs,compared to human-induced pluripotent stem cell-derived cardiomyocytes(hiPSC-CMs).Further dissection of cardiomyocyte drug response at both the population and single-cell transcriptomic level revealed that hPCM responses were more pronouncedly enriched in cardiac function,whereas hiPSC-CMs responses reflected cardiac development.Together,we established a full set of methodologies for the efficient isolation and prolonged maintenance of functional primary adult human cardiomyocytes in vitro,unlocking their potential as a cellular model for cardiovascular research,drug discovery,and safety pharmacology.
基金supported by the National Natural Science Foundation of China(91963208 and 52122213)Shanghai Government(20JC1415100)+3 种基金Shanghai Pilot Program for Basic Research-Chinese Academy of Science,Shanghai Branch(JCYJ-SHFY-2022-002)the CAS-DOE Program of Chinese Academy of Sciences(121631KYSB20180060)the financial support from DFG SFB 917 projectthe financial support under the Excellence Strategy of the Federal Government and the Lander within the ERS RWTH Start-Up grant(Grant No.StUpPD_392e21).
文摘AgSbTe_(2)-based ternary chalcogenides show excellent thermoelectric performance at low-and middletemperature ranges,yet their practical applications are greatly limited by their intrinsic poor thermodynamic stability.In this work,we demonstrate that AgSbTe_(2)-based ternary chalcogenides can be stabilized for service below their decomposition threshold.A series of AgxSb_(2-x)Te_(3-x)(x=1.0,0.9,0.8 and 0.7)samples have been prepared by the melt-quenching method.Among them,phase pure Ag0.9Sb1.1Te2.1 is verified by comprehensive structural characterizations from macroscale by X-ray diffraction to microscale by energy-dispersive spectroscopy and then to sub-nanometer scale by atom probe tomography.This composition is further chosen for the stability investigation.The decomposition threshold of Ag_(0.9)Sb_(1.1)Te_(2.1)appears around 473 K.Below this temperature,the chemical compositions and thermoelectric properties are barely changed even after 720 h annealing at 473 K.The figure-of-merit(zT)value of Ag_(0.9)Sb_(1.1)Te_(2.1)below the decomposition threshold is very competitive for real applications even compared with Bi_(2)Te_(3-)based alloys.The average zT of Ag_(0.9)Sb_(1.1)Te_(2.1)at 300e473 K reaches 0.84,which is higher than most other thermoelectric materials in a similar temperature range,promising applications in miniaturized refrigeration and power generation near room temperature.
