Garnet lithium lanthanum zirconium oxide(Li_(7)La_(3)Zr_(2)O_(12),LLZO)is a benchmark solid-state electrolyte(SSE)material receiving considerable attention owing to its high conductivity and chemical stability against...Garnet lithium lanthanum zirconium oxide(Li_(7)La_(3)Zr_(2)O_(12),LLZO)is a benchmark solid-state electrolyte(SSE)material receiving considerable attention owing to its high conductivity and chemical stability against Li metal.Although its electro-chemo-mechanical failure mechanisms have been much investigated,the equivocal roles of grain boundary strength and grain size of LLZO remain under-explored,hindering further performance improvements.Here we decoupled the effects of grain size and grain boundary strength of polycrystalline LLZO via the combination of electrochemical kinetics and the cohesive zone model.We discovered that the disintegration of LLZO is initiated by the accumulation of local displacements,which strongly relates to the changes in both grain size and grain boundary strength.However,variations in grain boundary strength affect the diffusion and propagation pathways of damage,while the failure of LLZO is determined by the grain size.Large LLZO grains facilitate transgranular damage under low grain boundary strength,which can alter local chemo-mechanics within the bulk of LLZO,leading to more extensive damage propagation.The results showcase the structure optimization pathways by preferentially controlling the growth of lithium dendrites at grain boundaries and their penetration in garnet-type SSE.展开更多
Grain boundary plays a key role in electromigration process of polycrystal interconnection. We take a free volume to represent a ＇vacancy-ion complex＇ as a function of grain boundary specific resistivity, and develo...Grain boundary plays a key role in electromigration process of polycrystal interconnection. We take a free volume to represent a ＇vacancy-ion complex＇ as a function of grain boundary specific resistivity, and develop a new characterisation model for grain boundary noise. This model reveals the internal relation between the boundary scattering section and electromigration noise. Comparing the simulation result with our experimental result, we find the source as well as the form of noise change in the electromigration process. In order to describe the noise enhancement at grain boundary quantitatively, we propose a new parameter--grain boundary noise enhancement factor, which reflects that the grain boundary noise can characterise the electromigration damage sensitively.展开更多
Ferritic/martensitic(F/M)steel is widely used as a structural material in thermal and nuclear power plants.However,it is susceptible to intergranular damage,which is a critical issue,under service conditions.In this s...Ferritic/martensitic(F/M)steel is widely used as a structural material in thermal and nuclear power plants.However,it is susceptible to intergranular damage,which is a critical issue,under service conditions.In this study,to improve the resistance to intergranular damage of F/M steel,a thermomechanical process(TMP)was employed to achieve a grain boundary engineering(GBE)microstructure in F/M steel P92.The TMP,including cold-rolling thickness reduction of 6%,9%,and 12%,followed by austenitization at 1323 K for 40 min and tempering at 1053 K for 45 min,was applied to the as-received(AR)P92 steel.The prior austenite grain(PAG)size,prior austenite grain boundary character distribution(GBCD),and connectivity of prior austenite grain boundaries(PAGBs)were investigated.Compared to the AR specimen,the PAG size did not change significantly.The fraction of coincident site lattice boundaries(CSLBs,3≤Σ≤29)and Σ3^(n) boundaries along PAGBs decreased with increasing reduction ratio because the recrystallization fraction increased with increasing reduction ratio.The PAGB connectivity of the 6%deformed specimen slightly deteriorated compared with that of the AR specimen.Moreover,potentiodynamic polarization studies revealed that the intergranular damage resistance of the studied steel could be improved by increasing the fraction of CSLBs along the PAGBs,indicating that the TMP,which involves low deformation,could enhance the intergranular damage resistance.展开更多
Quantitative relationship between nanosecond pulsed laser parameters and the characteristics of laser-generated ultrasonic waves in polycrystalline materials was evaluated.The high energy of the pulsed laser with a la...Quantitative relationship between nanosecond pulsed laser parameters and the characteristics of laser-generated ultrasonic waves in polycrystalline materials was evaluated.The high energy of the pulsed laser with a large irradiation spot simultaneously generated ultrasonic longitudinal and shear waves at the epicenter under the slight ablation regime.An optimized denoising technique based on wavelet thresholding and variational mode decomposition was applied to reduce noise in shear waves with a low signal-to-noise ratio.An approach for characterizing grain size was proposed using spectral central frequency ratio(SCFR)based on time-frequency analysis.The results demonstrate that the generation regime of ultrasonic waves is not solely determined by the laser power density;even at high power densities,a high energy with a large spot can generate an ultrasonic waveform dominated by the thermoelastic effect.This is ascribed to the intensification of the thermoelastic effect with the proportional increase in laser irradiation spot area for a given laser power density.Furthermore,both longitudinal and shear wave SCFRs are linearly related to grain size in polycrystalline materials;however,the shear wave SCFR is more sensitive to finer-grained materials.This study holds great significance for evaluating metal material properties using laser ultrasound.展开更多
Introducing high-valence Ta element is an essential strategy for addressing the structu ral deterioration of the Ni-rich LiNi_(1-x-y)Co_(x)Mn_(y)O_(2)(NCM)cathode,but the enlarged Li/Ni cation mixing leads to the infe...Introducing high-valence Ta element is an essential strategy for addressing the structu ral deterioration of the Ni-rich LiNi_(1-x-y)Co_(x)Mn_(y)O_(2)(NCM)cathode,but the enlarged Li/Ni cation mixing leads to the inferior rate capability originating from the hindered Li~+migration.Note that the non-magnetic Ti~(4+)ion can suppress Li/Ni disorder by removing the magnetic frustration in the transition metal layer.However,it is still challenging to directionally design expected Ta/Ti dual-modification,resulting from the complexity of the elemental distribution and the uncertainty of in-situ formed coating compounds by introducing foreign elements.Herein,a LiTaO_3 grain boundary(GB)coating and bulk Ti-doping have been successfully achieved in LiNi_(0.834)Co_(0.11)Mn_(0.056)O_(2) cathode by thermodynamic guidance,in which the structural formation energy and interfacial binding energy are employed to predict the elemental diffusion discrepancy and thermodynamically stable coating compounds.Thanks to the coupling effect of strengthened structural/interfacial stability and improved Li~+diffusion kinetics by simultaneous bulk/GB engineering,the Ta/Ti-NCM cathode exhibits outstanding capacity retention,reaching 91.1%after 400 cycles at 1 C.This elaborate work contributes valuable insights into rational dual-modification engineering from a thermodynamic perspective for maximizing the electrochemical performances of NCM cathodes.展开更多
Grain boundaries(GBs)play a crucial role on the structural stability and mechanical properties of Cu and its alloys.In this work,molecular dynamics(MD)simulations are employed to study the effects of Fe solutes on the...Grain boundaries(GBs)play a crucial role on the structural stability and mechanical properties of Cu and its alloys.In this work,molecular dynamics(MD)simulations are employed to study the effects of Fe solutes on the formation energy,excess volume,dislocations and melting behaviors of GBs in CuFe alloys.It is illustrated that Fe solute affects the structural stability of Cu GBs substantially,the formation energy of GBs is reduced,but the thickness and melting point of GBs are increased,that is,the structural stability of Cu GBs is significantly improved owing to the Fe solutes.A strong scaling law exists between the formation energy,excess volume,thickness and melting point of GBs.Therefore,Fe solid solute plays an important role in the characteristics of GBs in bi-crystal Cu.展开更多
The helium bubbles induced by 14 MeV neutron irradiation can cause intergranular fractures in reduced activation ferritic martensitic steel,which is a candidate structural material for fusion reactors.In order to eluc...The helium bubbles induced by 14 MeV neutron irradiation can cause intergranular fractures in reduced activation ferritic martensitic steel,which is a candidate structural material for fusion reactors.In order to elucidate the susceptibility of different grain boundaries(GBs)to helium-induced embrittlement,the tensile fracture processes of 10 types of GBs with and without helium bubbles in body-centered cubic(bcc)iron at the relevant service temperature of 600 K were investigated via molecular dynamics methods.The results indicate that in the absence of helium bubbles,the GBs studied here can be classified into two distinct categories:brittle GBs and ductile GBs.The atomic scale analysis shows that the plastic deformation of ductile GB at high temperatures originates from complex plastic deformation mechanisms,including the Bain/Burgers path phase transition and deformation twinning,in which the Bain path phase transition is the most dominant plastic deformation mechanism.However,the presence of helium bubbles severely inhibits the plastic deformation channels of the GBs,resulting in a significant decrease in elongation at fractures.For bubble-decorated GBs,the ultimate tensile strength increases with the increase in the misorientation angle.Interestingly,the coherent twin boundary∑3{112}was found to maintain relatively high fracture strength and maximum failure strain under the influence of helium bubbles.展开更多
Numerous irradiation-induced gas bubbles are created in the nuclear fuel during irradiation, leading to the change of microstructure and the degradation of mechanical and thermal properties. The grain size of fuel is ...Numerous irradiation-induced gas bubbles are created in the nuclear fuel during irradiation, leading to the change of microstructure and the degradation of mechanical and thermal properties. The grain size of fuel is one of the important factors affecting bubble evolution. In current study, we first predict the thermodynamic behaviors of point defects as well as the interplay between vacancy and gas atom in both UO_(2) and U_(3)Si_(2) according to ab initio approach. Then, we establish the irradiation-induced bubble phase-field model to investigate the formation and evolution of intra-and inter-granular gas bubbles. The effects of fission rate and temperature on the evolutions of bubble morphologies in UO_(2) and U_(3)Si_(2) have been revealed. Especially, a comparison of porosities under different grain sizes is examined and analyzed. To understand the thermal conductivity as functions of grain size and porosity, the heat transfer capability of U_(3)Si_(2) is evaluated.展开更多
Bismuth-based catalysts are highly promising for the electrochemical carbon dioxide reduction reaction(eCO_(2)RR)to formate product.However,achieving high activity and selectivity towards formate and ensuring long-ter...Bismuth-based catalysts are highly promising for the electrochemical carbon dioxide reduction reaction(eCO_(2)RR)to formate product.However,achieving high activity and selectivity towards formate and ensuring long-term stability remains challenging.This work reports the oxygen plasma inducing strategy to construct the abundant grain boundaries of Bi/BiO_x on ultrathin two-dimensional Bi nanosheets.The oxygen plasma-treated Bi nanosheet(OP-Bi)exhibits over 90%Faradaic efficiency(FE)for formate at a wide potential range from-0.5 to-1.1 V,and maintains a great stability catalytic performance without significant decay over 30 h in flow cell.Moreover,membrane electrode assembly(MEA)device with OPBi as catalyst sustains the robust current density of 100 mA cm^(-2)over 50 h,maintaining a formate FE above 90%.In addition,rechargeable Zn-CO_(2)battery presents the peak power density of1.22 mW cm^(-2)with OP-Bi as bifunctional catalyst.The mechanism experiments demonstrate that the high-density grain boundaries of OP-Bi provide more exposed active sites,faster electron transfer capacity,and the stronger intrinsic activity of Bi atoms.In situ spectroscopy and theo retical calculations further elucidate that the unsaturated Bi coordination atoms between the grain boundaries can effectively activate CO_(2)molecules through elongating the C-O bond,and reducing the formation energy barrier of the key intermediate(^(*)OCOH),thereby enhancing the catalytic performance of eCO_(2)RR to formate product.展开更多
Generally,layered Ni-rich cathode materials exhibit the morphology of polycrystalline secondary sphere composed of numerous primary particles.While the arrangement of primary particles plays a very important role in t...Generally,layered Ni-rich cathode materials exhibit the morphology of polycrystalline secondary sphere composed of numerous primary particles.While the arrangement of primary particles plays a very important role in the properties of Ni-rich cathodes.The disordered particle arrangement is harmful to the cyclic performance and structural stability,yet the fundamental understanding of disordered structure on the structural degradation behavior is unclarified.Herein,we have designed three kinds of LiNi_(0.83)Co_(0.06)Mn_(0.11)O_(2) cathode materials with different primary particle orientations by regulating the precursor coprecipitation process.Combining finite element simulation and in-situ characterization,the Li^(+)transport and structure evolution behaviors of different materials are unraveled.Specifically,the smooth Li^(+)diffusion minimizes the reaction heterogeneity,homogenizes the phase transition within grains,and mitigates the anisotropic microstructural change,thereby modulating the crack evolution behavior.Meanwhile,the optimized structure evolution ensures radial tight junctions of the primary particles,enabling enhanced Li^(+)diffusion during dynamic processes.Closed-loop bidirectional enhancement mechanism becomes critical for grain orientation regulation to stabilize the cyclic performance.This precursor engineering with particle orientation regulation provides the useful guidance for the structural design and feature enhancement of Ni-rich layered cathodes.展开更多
Based on 2D and 3D seismic data and well logging data,this paper studies the distribution of well-seismic stratigraphic filling and shoal controlled reservoirs of Upper Cambrian Xixiangchi Formation in the south slope...Based on 2D and 3D seismic data and well logging data,this paper studies the distribution of well-seismic stratigraphic filling and shoal controlled reservoirs of Upper Cambrian Xixiangchi Formation in the south slope of Leshan-Longnüsi paleouplift in the Sichuan Basin,to reveal the genetic relationship between stratigraphic filling,paleogeomorphology and large-scale grain shoal.(1)The Xixiangchi Formation in the study area is overlapped and filled gradually to the Leshan-Longnüsi paleouplift,but gets thin sharply due to truncation only near the denudation pinch-out line of the paleouplift.Two overlap slope break belts and one erosion slope break belt are identified,and the Xixiangchi Formation is divided into 4 members from bottom to top.(2)The filling pattern of the overlapping at the base and erosion at the top indicates that the thickness of Xixiangchi Formation can reflect the pre-depositional paleogeomorphology,and reveals that the studied area has a monoclinal geomorphic feature of plunging to southeast and being controlled by multistage slope break belts.(3)The large-scale grain shoals and shoal controlled reservoirs are developed longitudinally in the third and fourth members of the Xixiangchi Formation,and laterally in the vicinity of the multistage overlap slope break belts.(4)Overlap slope break belts are closely related to northwest trending reverse faults.The western margin of the South China Plate converging with the Qiangtang-Himalaya massif in the middle-late Cambrian resulted in the rapid uplift of the northwestern margin of the Yangtze Plate and expanding toward southeast,leaving gradually plunging multistage slope breaks and large-scale northeast grain shoal reservoir belts.Considering oil and gas test results,it is predicted that the favorable exploration zone of the grain shoal controlled reservoirs covers an area of 3340 km^(2).展开更多
Experimental study has been conducted for an interstitial free(IF) sheet steel on its surface roughness evolution and formability with respect to grain size and sheet thickness effect. The surface roughness of IF she...Experimental study has been conducted for an interstitial free(IF) sheet steel on its surface roughness evolution and formability with respect to grain size and sheet thickness effect. The surface roughness of IF sheet steel is proportional to effective strain, grain size and inversely proportional to sheet thickness; the larger grain reduces the formability by accelerating the surface roughening rate and enhance formability by raising the workhardening rate, while the latter effect plays the dominate role. The grain size effect on surface roughening and formability is more obvious when the sheets are thinner.展开更多
Describes a new computer program (Regress-3D) to simulate the regression of complex 3D grain cavity and calculate the burning surface area. It has a large region of applicability in solid rocket motor design and has...Describes a new computer program (Regress-3D) to simulate the regression of complex 3D grain cavity and calculate the burning surface area. It has a large region of applicability in solid rocket motor design and has made new improvements compared with other available codes. User can easily and rapidly build his initial grain shapes and then obtain geometric information of his design. Considering with the calclulting results, redesigning can be performed as desire until reaching at the satisfied result. Advantages and disadvantages of this method are also discussed.展开更多
Declaration of Conflict-of-Interest statements were incorrect for the following articles that appeared in previous issues of Grain&Oil Science and Technology.The appropriate Declaration/Conflict of Interest statem...Declaration of Conflict-of-Interest statements were incorrect for the following articles that appeared in previous issues of Grain&Oil Science and Technology.The appropriate Declaration/Conflict of Interest statements are included below.展开更多
The microstructure and magnetic properties of Fe_(40)Co_(40)Zr_(9)B_(10)Ge_(1)(Mo-free)and Fe_(40)Co_(40)Zr_(5)Mo_(4)B_(10)Ge_(1)(Mocontaining)nanocrystalline alloys,prepared using an amorphous crystallization method,...The microstructure and magnetic properties of Fe_(40)Co_(40)Zr_(9)B_(10)Ge_(1)(Mo-free)and Fe_(40)Co_(40)Zr_(5)Mo_(4)B_(10)Ge_(1)(Mocontaining)nanocrystalline alloys,prepared using an amorphous crystallization method,were investigated.Mo addition affects the crystallization of the Fe_(40)Co_(40)Zr_(9)B_(10)Ge_(1) amorphous alloy and decreases the grain size of theα-Fe(Co)phase below 650℃.For the Mo-free alloy annealed at 600℃ and the Mo-containing alloy annealed at 575℃,with a singleα-Fe(Co)crystallization phase and approximately similar crystallization volume fractions,the Mo-containing alloy showed smaller,more regularly shaped grains and a significantly narrower grain-size distribution than the Mo-free alloy.The Fe and Co contents in the nanograins of the two alloys also differed.For the Mo-free alloy,a higher concentration of Co distributed in the residual amorphous matrix.For the Mo-containing alloy,a higher concentration Co dissolved in the nanograins.The specific saturation magnetization and coercivity of the Mo-free alloy were 1.05-and 1.59-times higher than those of the Mo-containing alloy,respectively.展开更多
Solution-processed chalcopyrite solar cells are widely regarded as a promising alternative method in reducing the cost compared with vacuum-based techniques.It is noted that the absorber layer usually needs to be prep...Solution-processed chalcopyrite solar cells are widely regarded as a promising alternative method in reducing the cost compared with vacuum-based techniques.It is noted that the absorber layer usually needs to be prepared under a high insert pressure(~1.6 atm)to suppress element loss or under a mild pressure but additional surface etching is needed for fabricating high efficient solar cell.Herein,a copper gradient structured precursor is proposed to prepare CuIn(S,Se)_(2)(CISSe)film under a mild pressure(1.1 atm).The designed gradient Cu not only promotes crystal grain growth and tailors the defects,but also avoids the surface etching of the formed CISSe film for the fabrication of high efficient solar cells.Further,Cu gradient design decreases the conduction band offset of heterojunction,boosting the carriers transport across the p-n heterojunction.Accordingly,a 13,35%efficient CISSe solar cell,comparable to the high efficient CISSe solar cell prepared by this method under high pressure or with film surface etching,is fabricated.This work provides a facile pathway to fabricate high efficient solution-processed chalcopyrite solar cell,avoiding high selenization pressure and film etching,and shows huge potential for solutionprocessed copper-based solar cells.展开更多
Grain boundaries(GBs)have critical influences on the stability and properties of various materials.In this study,first-principles calculations were performed to determine the effects of four metallic impurities(Ni,Al,...Grain boundaries(GBs)have critical influences on the stability and properties of various materials.In this study,first-principles calculations were performed to determine the effects of four metallic impurities(Ni,Al,Bi,and Pb)and three nonmetallic impurities(H,O,and N)on the GBs of silicon carbide(SiC),using the ∑5(210)GBs as models.The GB energy and segregation energy(SE)were calculated to identify the effects of impurities on the GB stability.Electronic interactions considerably influenced the bonding effects of SiC.The formation of weak bonds resulted in the corrosion and embrittlement of GBs.The co-segregation of Bi,Pb,and O was also investigated in detail.展开更多
Organic cation and halide anion defects are omnipresent in the perovskite films,which will destroy perovskite electronic structure and downgrade the properties of devices.Defect passivation in halide perovskites is cr...Organic cation and halide anion defects are omnipresent in the perovskite films,which will destroy perovskite electronic structure and downgrade the properties of devices.Defect passivation in halide perovskites is crucial to the application of solar cells.Herein,tiny amounts of trivalent rhodium ion incorporation can help the nucleation of perovskite grain and passivate the defects in the grain boundaries,which can improve efficiency and stability of perovskite solar cells.Through first-principle calculations,rhodium ion incorporation into the perovskite structure can induce ordered arrangement and tune bandgap.In experiment,rhodium ion incorporation with perovskite can contribute to preparing larger crystalline and uniform film,reducing trap-state density and enlarging charge carrier lifetime.After optimizing the content of 1% rhodium,the devices achieved an efficiency up to 20.71% without obvious hysteresis,from 19.09% of that pristine perovskite.In addition,the unencapsulated solar cells maintain 92% of its initial efficiency after 500 h in dry air.This work highlights the advantages of trivalent rhodium ion incorporation in the characteristics of perovskite solar cells,which will promote the future industrial application.展开更多
基金the financial support from the National Natural Science Foundation of China(12102328,52104312,22278329)the Qin Chuangyuan Talent Project of Shaanxi Province(2021QCYRC4-43,QCYRCXM-2022-308)the Fundamental Research Funds for the Central Universities,China.
文摘Garnet lithium lanthanum zirconium oxide(Li_(7)La_(3)Zr_(2)O_(12),LLZO)is a benchmark solid-state electrolyte(SSE)material receiving considerable attention owing to its high conductivity and chemical stability against Li metal.Although its electro-chemo-mechanical failure mechanisms have been much investigated,the equivocal roles of grain boundary strength and grain size of LLZO remain under-explored,hindering further performance improvements.Here we decoupled the effects of grain size and grain boundary strength of polycrystalline LLZO via the combination of electrochemical kinetics and the cohesive zone model.We discovered that the disintegration of LLZO is initiated by the accumulation of local displacements,which strongly relates to the changes in both grain size and grain boundary strength.However,variations in grain boundary strength affect the diffusion and propagation pathways of damage,while the failure of LLZO is determined by the grain size.Large LLZO grains facilitate transgranular damage under low grain boundary strength,which can alter local chemo-mechanics within the bulk of LLZO,leading to more extensive damage propagation.The results showcase the structure optimization pathways by preferentially controlling the growth of lithium dendrites at grain boundaries and their penetration in garnet-type SSE.
基金supported by the National Natural Science Foundation of China (Grant No.60376023)the Innovative Foundation of Xi’an Applied Materials Inc.China (Grant No.XA-AM-200603)
文摘Grain boundary plays a key role in electromigration process of polycrystal interconnection. We take a free volume to represent a ＇vacancy-ion complex＇ as a function of grain boundary specific resistivity, and develop a new characterisation model for grain boundary noise. This model reveals the internal relation between the boundary scattering section and electromigration noise. Comparing the simulation result with our experimental result, we find the source as well as the form of noise change in the electromigration process. In order to describe the noise enhancement at grain boundary quantitatively, we propose a new parameter--grain boundary noise enhancement factor, which reflects that the grain boundary noise can characterise the electromigration damage sensitively.
基金supported by the National Natural Science Foundation of China(Nos.12175231 and 11805131),Anhui Natural Science Foundation of China(No.2108085J05)Projects of International Cooperation and Exchanges NSFC(No.51111140389)the Collaborative Innovation Program of the Hefei Science Center,CAS(Nos.2021HSC-CIP020 and 2022HSCCIP009).
文摘Ferritic/martensitic(F/M)steel is widely used as a structural material in thermal and nuclear power plants.However,it is susceptible to intergranular damage,which is a critical issue,under service conditions.In this study,to improve the resistance to intergranular damage of F/M steel,a thermomechanical process(TMP)was employed to achieve a grain boundary engineering(GBE)microstructure in F/M steel P92.The TMP,including cold-rolling thickness reduction of 6%,9%,and 12%,followed by austenitization at 1323 K for 40 min and tempering at 1053 K for 45 min,was applied to the as-received(AR)P92 steel.The prior austenite grain(PAG)size,prior austenite grain boundary character distribution(GBCD),and connectivity of prior austenite grain boundaries(PAGBs)were investigated.Compared to the AR specimen,the PAG size did not change significantly.The fraction of coincident site lattice boundaries(CSLBs,3≤Σ≤29)and Σ3^(n) boundaries along PAGBs decreased with increasing reduction ratio because the recrystallization fraction increased with increasing reduction ratio.The PAGB connectivity of the 6%deformed specimen slightly deteriorated compared with that of the AR specimen.Moreover,potentiodynamic polarization studies revealed that the intergranular damage resistance of the studied steel could be improved by increasing the fraction of CSLBs along the PAGBs,indicating that the TMP,which involves low deformation,could enhance the intergranular damage resistance.
基金supported in part by the Natural Science Foundation of Shandong Province,China (Grant No.ZR2023ME073)the National Natural Science Foundation of China (Grant No.51805304)+1 种基金the Education Department of Shandong Province,China (Grant No.2022KJ130)Qilu University of Technology (Shandong Academy of Sciences),China (Grant Nos.2023PY009,2021JC02008 and 2022GH005)。
文摘Quantitative relationship between nanosecond pulsed laser parameters and the characteristics of laser-generated ultrasonic waves in polycrystalline materials was evaluated.The high energy of the pulsed laser with a large irradiation spot simultaneously generated ultrasonic longitudinal and shear waves at the epicenter under the slight ablation regime.An optimized denoising technique based on wavelet thresholding and variational mode decomposition was applied to reduce noise in shear waves with a low signal-to-noise ratio.An approach for characterizing grain size was proposed using spectral central frequency ratio(SCFR)based on time-frequency analysis.The results demonstrate that the generation regime of ultrasonic waves is not solely determined by the laser power density;even at high power densities,a high energy with a large spot can generate an ultrasonic waveform dominated by the thermoelastic effect.This is ascribed to the intensification of the thermoelastic effect with the proportional increase in laser irradiation spot area for a given laser power density.Furthermore,both longitudinal and shear wave SCFRs are linearly related to grain size in polycrystalline materials;however,the shear wave SCFR is more sensitive to finer-grained materials.This study holds great significance for evaluating metal material properties using laser ultrasound.
基金supported by the National Natural Science Foundation of China (52374299,52304320 and 52204306)the Outstanding Youth Foundation of Hunan Province (2023JJ10044)+1 种基金the Key Project of Hunan Provincial Department of Education (22A0211)the Natural Science Foundation of Hunan Province (2023JJ40014)。
文摘Introducing high-valence Ta element is an essential strategy for addressing the structu ral deterioration of the Ni-rich LiNi_(1-x-y)Co_(x)Mn_(y)O_(2)(NCM)cathode,but the enlarged Li/Ni cation mixing leads to the inferior rate capability originating from the hindered Li~+migration.Note that the non-magnetic Ti~(4+)ion can suppress Li/Ni disorder by removing the magnetic frustration in the transition metal layer.However,it is still challenging to directionally design expected Ta/Ti dual-modification,resulting from the complexity of the elemental distribution and the uncertainty of in-situ formed coating compounds by introducing foreign elements.Herein,a LiTaO_3 grain boundary(GB)coating and bulk Ti-doping have been successfully achieved in LiNi_(0.834)Co_(0.11)Mn_(0.056)O_(2) cathode by thermodynamic guidance,in which the structural formation energy and interfacial binding energy are employed to predict the elemental diffusion discrepancy and thermodynamically stable coating compounds.Thanks to the coupling effect of strengthened structural/interfacial stability and improved Li~+diffusion kinetics by simultaneous bulk/GB engineering,the Ta/Ti-NCM cathode exhibits outstanding capacity retention,reaching 91.1%after 400 cycles at 1 C.This elaborate work contributes valuable insights into rational dual-modification engineering from a thermodynamic perspective for maximizing the electrochemical performances of NCM cathodes.
基金supported by National Key Research and Development Program of China(No.2021YFB3400800)National Natural Science Foundation of China(Grant No.52271136,51901177)Natural Science Foundation of Shaanxi Province(No.2021JC-06,2019TD-020).
文摘Grain boundaries(GBs)play a crucial role on the structural stability and mechanical properties of Cu and its alloys.In this work,molecular dynamics(MD)simulations are employed to study the effects of Fe solutes on the formation energy,excess volume,dislocations and melting behaviors of GBs in CuFe alloys.It is illustrated that Fe solute affects the structural stability of Cu GBs substantially,the formation energy of GBs is reduced,but the thickness and melting point of GBs are increased,that is,the structural stability of Cu GBs is significantly improved owing to the Fe solutes.A strong scaling law exists between the formation energy,excess volume,thickness and melting point of GBs.Therefore,Fe solid solute plays an important role in the characteristics of GBs in bi-crystal Cu.
基金supported by the National Natural Science Foundation of China(Nos.12175231 and 11805131)Anhui Natural Science Foundation of China(No.2108085J05)+1 种基金the National Key Research and Development Plan of China(No.2018YFE0307101)the Collaborative Innovation Program of the Hefei Science Center,CAS(Nos.2021HSC-CIP020 and 2022HSC-CIP009)。
文摘The helium bubbles induced by 14 MeV neutron irradiation can cause intergranular fractures in reduced activation ferritic martensitic steel,which is a candidate structural material for fusion reactors.In order to elucidate the susceptibility of different grain boundaries(GBs)to helium-induced embrittlement,the tensile fracture processes of 10 types of GBs with and without helium bubbles in body-centered cubic(bcc)iron at the relevant service temperature of 600 K were investigated via molecular dynamics methods.The results indicate that in the absence of helium bubbles,the GBs studied here can be classified into two distinct categories:brittle GBs and ductile GBs.The atomic scale analysis shows that the plastic deformation of ductile GB at high temperatures originates from complex plastic deformation mechanisms,including the Bain/Burgers path phase transition and deformation twinning,in which the Bain path phase transition is the most dominant plastic deformation mechanism.However,the presence of helium bubbles severely inhibits the plastic deformation channels of the GBs,resulting in a significant decrease in elongation at fractures.For bubble-decorated GBs,the ultimate tensile strength increases with the increase in the misorientation angle.Interestingly,the coherent twin boundary∑3{112}was found to maintain relatively high fracture strength and maximum failure strain under the influence of helium bubbles.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.U2167217,12205286,and 11905025)the National MCF Energy Research and Development Program of China (Grant No.2018YFE0308105)。
文摘Numerous irradiation-induced gas bubbles are created in the nuclear fuel during irradiation, leading to the change of microstructure and the degradation of mechanical and thermal properties. The grain size of fuel is one of the important factors affecting bubble evolution. In current study, we first predict the thermodynamic behaviors of point defects as well as the interplay between vacancy and gas atom in both UO_(2) and U_(3)Si_(2) according to ab initio approach. Then, we establish the irradiation-induced bubble phase-field model to investigate the formation and evolution of intra-and inter-granular gas bubbles. The effects of fission rate and temperature on the evolutions of bubble morphologies in UO_(2) and U_(3)Si_(2) have been revealed. Especially, a comparison of porosities under different grain sizes is examined and analyzed. To understand the thermal conductivity as functions of grain size and porosity, the heat transfer capability of U_(3)Si_(2) is evaluated.
基金supported by the Hainan Province Science and Technology Special Fund(ZDYF2024SHFZ074,ZDYF2024SHFZ072,ZDYF2022SHFZ299)the National Natural Science Foundation of China(22109035,22202053,52164028,52274297,22309037)+4 种基金the Start-up Research Foundation of Hainan University(KYQD(ZR)-20008,20083,20084,21125,23035)the collaborative Innovation Center of Marine Science and Technology,Hainan University(XTCX2022HYC04,XTCX2022HYC05)the Innovative Research Projects for Graduate Students of Hainan Province(Qhyb2022-89,Qhyb2022-87,Qhys2022-174)the Scientific Research Program Funded by Shaanxi Provincial Education Department(Program No.23JK0439)the specific research fund of The Innovation Platform for Academicians of Hainan Province(YSPTZX202315)。
文摘Bismuth-based catalysts are highly promising for the electrochemical carbon dioxide reduction reaction(eCO_(2)RR)to formate product.However,achieving high activity and selectivity towards formate and ensuring long-term stability remains challenging.This work reports the oxygen plasma inducing strategy to construct the abundant grain boundaries of Bi/BiO_x on ultrathin two-dimensional Bi nanosheets.The oxygen plasma-treated Bi nanosheet(OP-Bi)exhibits over 90%Faradaic efficiency(FE)for formate at a wide potential range from-0.5 to-1.1 V,and maintains a great stability catalytic performance without significant decay over 30 h in flow cell.Moreover,membrane electrode assembly(MEA)device with OPBi as catalyst sustains the robust current density of 100 mA cm^(-2)over 50 h,maintaining a formate FE above 90%.In addition,rechargeable Zn-CO_(2)battery presents the peak power density of1.22 mW cm^(-2)with OP-Bi as bifunctional catalyst.The mechanism experiments demonstrate that the high-density grain boundaries of OP-Bi provide more exposed active sites,faster electron transfer capacity,and the stronger intrinsic activity of Bi atoms.In situ spectroscopy and theo retical calculations further elucidate that the unsaturated Bi coordination atoms between the grain boundaries can effectively activate CO_(2)molecules through elongating the C-O bond,and reducing the formation energy barrier of the key intermediate(^(*)OCOH),thereby enhancing the catalytic performance of eCO_(2)RR to formate product.
基金supported by National Natural Science Foundation of China (52070194,52073309)Natural Science Foundation of Hunan Province (2022JJ20069)。
文摘Generally,layered Ni-rich cathode materials exhibit the morphology of polycrystalline secondary sphere composed of numerous primary particles.While the arrangement of primary particles plays a very important role in the properties of Ni-rich cathodes.The disordered particle arrangement is harmful to the cyclic performance and structural stability,yet the fundamental understanding of disordered structure on the structural degradation behavior is unclarified.Herein,we have designed three kinds of LiNi_(0.83)Co_(0.06)Mn_(0.11)O_(2) cathode materials with different primary particle orientations by regulating the precursor coprecipitation process.Combining finite element simulation and in-situ characterization,the Li^(+)transport and structure evolution behaviors of different materials are unraveled.Specifically,the smooth Li^(+)diffusion minimizes the reaction heterogeneity,homogenizes the phase transition within grains,and mitigates the anisotropic microstructural change,thereby modulating the crack evolution behavior.Meanwhile,the optimized structure evolution ensures radial tight junctions of the primary particles,enabling enhanced Li^(+)diffusion during dynamic processes.Closed-loop bidirectional enhancement mechanism becomes critical for grain orientation regulation to stabilize the cyclic performance.This precursor engineering with particle orientation regulation provides the useful guidance for the structural design and feature enhancement of Ni-rich layered cathodes.
基金Supported by the Cooperation Project of China National Natural Science Foundation and Petro China(U23B20154)Science and Technology Cooperation Project of Petro China and Southwest Petroleum University(2020CX010000)。
文摘Based on 2D and 3D seismic data and well logging data,this paper studies the distribution of well-seismic stratigraphic filling and shoal controlled reservoirs of Upper Cambrian Xixiangchi Formation in the south slope of Leshan-Longnüsi paleouplift in the Sichuan Basin,to reveal the genetic relationship between stratigraphic filling,paleogeomorphology and large-scale grain shoal.(1)The Xixiangchi Formation in the study area is overlapped and filled gradually to the Leshan-Longnüsi paleouplift,but gets thin sharply due to truncation only near the denudation pinch-out line of the paleouplift.Two overlap slope break belts and one erosion slope break belt are identified,and the Xixiangchi Formation is divided into 4 members from bottom to top.(2)The filling pattern of the overlapping at the base and erosion at the top indicates that the thickness of Xixiangchi Formation can reflect the pre-depositional paleogeomorphology,and reveals that the studied area has a monoclinal geomorphic feature of plunging to southeast and being controlled by multistage slope break belts.(3)The large-scale grain shoals and shoal controlled reservoirs are developed longitudinally in the third and fourth members of the Xixiangchi Formation,and laterally in the vicinity of the multistage overlap slope break belts.(4)Overlap slope break belts are closely related to northwest trending reverse faults.The western margin of the South China Plate converging with the Qiangtang-Himalaya massif in the middle-late Cambrian resulted in the rapid uplift of the northwestern margin of the Yangtze Plate and expanding toward southeast,leaving gradually plunging multistage slope breaks and large-scale northeast grain shoal reservoir belts.Considering oil and gas test results,it is predicted that the favorable exploration zone of the grain shoal controlled reservoirs covers an area of 3340 km^(2).
文摘Experimental study has been conducted for an interstitial free(IF) sheet steel on its surface roughness evolution and formability with respect to grain size and sheet thickness effect. The surface roughness of IF sheet steel is proportional to effective strain, grain size and inversely proportional to sheet thickness; the larger grain reduces the formability by accelerating the surface roughening rate and enhance formability by raising the workhardening rate, while the latter effect plays the dominate role. The grain size effect on surface roughening and formability is more obvious when the sheets are thinner.
文摘Describes a new computer program (Regress-3D) to simulate the regression of complex 3D grain cavity and calculate the burning surface area. It has a large region of applicability in solid rocket motor design and has made new improvements compared with other available codes. User can easily and rapidly build his initial grain shapes and then obtain geometric information of his design. Considering with the calclulting results, redesigning can be performed as desire until reaching at the satisfied result. Advantages and disadvantages of this method are also discussed.
文摘Declaration of Conflict-of-Interest statements were incorrect for the following articles that appeared in previous issues of Grain&Oil Science and Technology.The appropriate Declaration/Conflict of Interest statements are included below.
基金Project supported by the Natural Science Foundation of Jilin Province,China(Grant No.YDZJ202201ZYTS319)the Fund from Sinoma Institute of Materials Research(Guangzhou)Co.,Ltd.(SIMR)for assisting with the TEM characterization。
文摘The microstructure and magnetic properties of Fe_(40)Co_(40)Zr_(9)B_(10)Ge_(1)(Mo-free)and Fe_(40)Co_(40)Zr_(5)Mo_(4)B_(10)Ge_(1)(Mocontaining)nanocrystalline alloys,prepared using an amorphous crystallization method,were investigated.Mo addition affects the crystallization of the Fe_(40)Co_(40)Zr_(9)B_(10)Ge_(1) amorphous alloy and decreases the grain size of theα-Fe(Co)phase below 650℃.For the Mo-free alloy annealed at 600℃ and the Mo-containing alloy annealed at 575℃,with a singleα-Fe(Co)crystallization phase and approximately similar crystallization volume fractions,the Mo-containing alloy showed smaller,more regularly shaped grains and a significantly narrower grain-size distribution than the Mo-free alloy.The Fe and Co contents in the nanograins of the two alloys also differed.For the Mo-free alloy,a higher concentration of Co distributed in the residual amorphous matrix.For the Mo-containing alloy,a higher concentration Co dissolved in the nanograins.The specific saturation magnetization and coercivity of the Mo-free alloy were 1.05-and 1.59-times higher than those of the Mo-containing alloy,respectively.
基金supported by the National Natural Science Foundation of China(U1902218).
文摘Solution-processed chalcopyrite solar cells are widely regarded as a promising alternative method in reducing the cost compared with vacuum-based techniques.It is noted that the absorber layer usually needs to be prepared under a high insert pressure(~1.6 atm)to suppress element loss or under a mild pressure but additional surface etching is needed for fabricating high efficient solar cell.Herein,a copper gradient structured precursor is proposed to prepare CuIn(S,Se)_(2)(CISSe)film under a mild pressure(1.1 atm).The designed gradient Cu not only promotes crystal grain growth and tailors the defects,but also avoids the surface etching of the formed CISSe film for the fabrication of high efficient solar cells.Further,Cu gradient design decreases the conduction band offset of heterojunction,boosting the carriers transport across the p-n heterojunction.Accordingly,a 13,35%efficient CISSe solar cell,comparable to the high efficient CISSe solar cell prepared by this method under high pressure or with film surface etching,is fabricated.This work provides a facile pathway to fabricate high efficient solution-processed chalcopyrite solar cell,avoiding high selenization pressure and film etching,and shows huge potential for solutionprocessed copper-based solar cells.
基金supported by the National Natural Science Foundation of China(Nos.11832019,11472313,11572355,and 11705264)the Science and Technology Plan Project of Guangdong Province(No.2020A0505020005)+2 种基金the Fundamental Research Funds for the Central Universities(No.19lgpy298)the State Key Laboratory of Powder MetallurgyCentral South University,Changsha,China。
文摘Grain boundaries(GBs)have critical influences on the stability and properties of various materials.In this study,first-principles calculations were performed to determine the effects of four metallic impurities(Ni,Al,Bi,and Pb)and three nonmetallic impurities(H,O,and N)on the GBs of silicon carbide(SiC),using the ∑5(210)GBs as models.The GB energy and segregation energy(SE)were calculated to identify the effects of impurities on the GB stability.Electronic interactions considerably influenced the bonding effects of SiC.The formation of weak bonds resulted in the corrosion and embrittlement of GBs.The co-segregation of Bi,Pb,and O was also investigated in detail.
基金supported by the Ministry of Education of China(IRT1148)the National Natural Science Foundation of China(U1732126,11804166,51602161,51372119)+3 种基金China Postdoctoral Science Foundation(2018M630587)the Priority Academic Program Development of Jiangsu Higher Education Institutions(YX03001)Guangdong Science and Technology Program(2017B030314002)Graduate Research Innovation Fund of Jiangsu Province(KYCX18_0863,KYCX18_0847,KYCX18_0869)。
文摘Organic cation and halide anion defects are omnipresent in the perovskite films,which will destroy perovskite electronic structure and downgrade the properties of devices.Defect passivation in halide perovskites is crucial to the application of solar cells.Herein,tiny amounts of trivalent rhodium ion incorporation can help the nucleation of perovskite grain and passivate the defects in the grain boundaries,which can improve efficiency and stability of perovskite solar cells.Through first-principle calculations,rhodium ion incorporation into the perovskite structure can induce ordered arrangement and tune bandgap.In experiment,rhodium ion incorporation with perovskite can contribute to preparing larger crystalline and uniform film,reducing trap-state density and enlarging charge carrier lifetime.After optimizing the content of 1% rhodium,the devices achieved an efficiency up to 20.71% without obvious hysteresis,from 19.09% of that pristine perovskite.In addition,the unencapsulated solar cells maintain 92% of its initial efficiency after 500 h in dry air.This work highlights the advantages of trivalent rhodium ion incorporation in the characteristics of perovskite solar cells,which will promote the future industrial application.
