Pure magnesium is a very promising material in the fields of biomedical and engineering.Obtaining pure magnesium with superior mechanical properties has consistently been a significant challenge in the area of materia...Pure magnesium is a very promising material in the fields of biomedical and engineering.Obtaining pure magnesium with superior mechanical properties has consistently been a significant challenge in the area of materials science.This study focuses on investigating the processing method and strengthening mechanism of pure magnesium by ultra-precision cutting.The research results show that the pure magnesium grains were significantly refined after ultra-precision cutting.The average grain size reduced from∼24μm to nanometers,and the average nano-hardness increased from 1.02 GPa to 2.82 GPa.Amorphous pure magnesium structure and body-centered cubic(BCC)lattice pure magnesium were reported.Molecular dynamics(MD)simulation confirmed that the high shear strain and hydrostatic pressure during ultra-precision cutting was the origin of amorphization and lattice transformation.The amorphous phase and a significant number of long-period stacking-ordered(LPSO)phases inside the pure magnesium were responsible for the high hardness after ultra-precision cutting.展开更多
Amorphous two-dimensional transition metal oxide/(oxy)hydroxide(2D TMO/TMHO)nanomaterials(NMs)have the properties of both 2D and amorphous materials,displaying outstanding physicochemical qualities.Therefore,they demo...Amorphous two-dimensional transition metal oxide/(oxy)hydroxide(2D TMO/TMHO)nanomaterials(NMs)have the properties of both 2D and amorphous materials,displaying outstanding physicochemical qualities.Therefore,they demonstrate considerable promise for use in electrocatalytic water splitting applications.Here,the primary amorphization strategies for achieving the 2D TMO/TMHO NMs are comprehensively reviewed,including low-temperature reaction,rapid reaction,exchange/doping effect,ligand modulation,and interfacial energy confinement.By integrating these strategies with various physicochemical synthesis methods,it is feasible to control the amorphization of TMO/TMHO NMs while maintaining the distinctive benefits of their 2D structures.Furthermore,it delves into the structural advantages of amorphous 2D TMO/TMHO NMs in electrocatalytic water splitting,particularly emphasizing recent advancements in enhancing their electrocatalytic performance through interface engineering.The challenges and potential future directions for the precise synthesis and practical application of amorphous 2D TMO/TMHO NMs are also provided.This review aims to establish a theoretical foundation and offer experimental instructions for developing effective and enduring electrocatalysts for water splitting.展开更多
Pressure-induced amorphous transition of Li_(2)Ge_(7)O_(15)(LGO)crystal has been investigated by using in situ high pressure energy dispersive x-ray diffraction with synchrotron radiation at the pressure up to 21.6 GP...Pressure-induced amorphous transition of Li_(2)Ge_(7)O_(15)(LGO)crystal has been investigated by using in situ high pressure energy dispersive x-ray diffraction with synchrotron radiation at the pressure up to 21.6 GPa.Diamond anvils were used to generate high pressure.Pressure was measured in terms of the diffraction of Pt as an internal pressure standard.The crystal structure of LGO is an orthorhombic lattice at atmospheric pressure.According to the high pressure x-ray diffraction results,new diffraction lines begin to appear and LGO undergoes an intermediate phase transition at the pressure of 12.9 GPa.But,the diffraction lines disappear wholly and LGO becomes an amorphous phase at the pressure of above 14.8 GPa.This amorphous transition is irreversible.展开更多
High‐entropy amorphous catalysts(HEACs)integrate multielement synergy with structural disorder,making them promising candidates for water splitting.Their distinctive features—including flexible coordination environm...High‐entropy amorphous catalysts(HEACs)integrate multielement synergy with structural disorder,making them promising candidates for water splitting.Their distinctive features—including flexible coordination environments,tunable electronic structures,abundant unsaturated active sites,and dynamic structural reassembly—collectively enhance electrochemical activity and durability under operating conditions.This review summarizes recent advances in HEACs for hydrogen evolution,oxygen evolution,and overall water splitting,highlighting their disorder-driven advantages over crystalline counterparts.Catalytic performance benchmarks are presented,and mechanistic insights are discussed,focusing on how multimetallic synergy,amorphization effect,and in‐situ reconstruction cooperatively regulate reaction pathways.These insights provide guidance for the rational design of next‐generation amorphous high‐entropy electrocatalysts with improved efficiency and durability.展开更多
The introduction of two-dimensional(2D)perovskite layers on top of three-dimensional(3D)perovskite films enhances the performance and stability of perovskite solar cells(PSCs).However,the electronic effect of the spac...The introduction of two-dimensional(2D)perovskite layers on top of three-dimensional(3D)perovskite films enhances the performance and stability of perovskite solar cells(PSCs).However,the electronic effect of the spacer cation and the quality of the 2D capping layer are critical factors in achieving the required results.In this study,we compared two fluorinated salts:4-(trifluoromethyl)benzamidine hydrochloride(4TF-BA·HCl)and 4-fluorobenzamidine hydrochloride(4F-BA·HCl)to engineer the 3D/2D perovskite films.Surprisingly,4F-BA formed a high-performance 3D/2D heterojunction,while4TF-BA produced an amorphous layer on the perovskite films.Our findings indicate that the balanced intramolecular charge polarization,which leads to effective hydrogen bonding,is more favorable in 4F-BA than in 4TF-BA,promoting the formation of a crystalline 2D perovskite.Nevertheless,4TF-BA managed to improve efficiency to 24%,surpassing the control device,primarily due to the natural passivation capabilities of benzamidine.Interestingly,the devices based on 4F-BA demonstrated an efficiency exceeding 25%with greater longevity under various storage conditions compared to 4TF-BA-based and the control devices.展开更多
Metal hydrides with high hydrogen density provide promising hydrogen storage paths for hydrogen transportation.However,the requirement of highly pure H_(2)for re-hydrogenation limits its wide application.Here,amorphou...Metal hydrides with high hydrogen density provide promising hydrogen storage paths for hydrogen transportation.However,the requirement of highly pure H_(2)for re-hydrogenation limits its wide application.Here,amorphous Al_(2)O_(3)shells(10 nm)were deposited on the surface of highly active hydrogen storage material particles(MgH_(2)-ZrTi)by atomic layer deposition to obtain MgH_(2)-ZrTi@Al_(2)O_(3),which have been demonstrated to be air stable with selective adsorption of H_(2)under a hydrogen atmosphere with different impurities(CH_(4),O_(2),N_(2),and CO_(2)).About 4.79 wt%H_(2)was adsorbed by MgH_(2)-ZrTi@10nmAl_(2)O_(3)at 75℃under 10%CH_(4)+90%H_(2)atmosphere within 3 h with no kinetic or density decay after 5 cycles(~100%capacity retention).Furthermore,about 4 wt%of H_(2)was absorbed by MgH_(2)-ZrTi@10nmAl_(2)O_(3)under 0.1%O_(2)+0.4%N_(2)+99.5%H_(2)and 0.1%CO_(2)+0.4%N_(2)+99.5%H_(2)atmospheres at 100℃within 0.5 h,respectively,demonstrating the selective hydrogen absorption of MgH_(2)-ZrTi@10nmAl_(2)O_(3)in both oxygen-containing and carbon dioxide-containing atmospheres hydrogen atmosphere.The absorption and desorption curves of MgH_(2)-ZrTi@10nmAl_(2)O_(3)with and without absorption in pure hydrogen and then in 21%O_(2)+79%N_(2)for 1 h were found to overlap,further confirming the successful shielding effect of Al_(2)O_(3)shells against O_(2)and N_(2).The MgH_(2)-ZrTi@10nmAl_(2)O_(3)has been demonstrated to be air stable and have excellent selective hydrogen absorption performance under the atmosphere with CH_(4),O_(2),N_(2),and CO_(2).展开更多
Due to the safety,high energy density,and rapid charging feature,aqueous zinc-ion batteries(AZIBs)have attracted great attention in large-scale energy storage systems.Although excellent electrochemical performances ha...Due to the safety,high energy density,and rapid charging feature,aqueous zinc-ion batteries(AZIBs)have attracted great attention in large-scale energy storage systems.Although excellent electrochemical performances have been achieved,the cycling stabilities of AZIBs are still unsatisfactory,especially at low current densities,because the cathode materials are prone to being dissolved into electrolytes.Here we develop a unique zincophilic and hydrophobic amorphous additive of ZnSnO_(3)(ZSO),which effectively prevents the irreversible dissolution and deamination of NH_(4)V_(4)O_(10)(NVO)cathode.Benefiting from the ingenious design,NVO@ZSO cathode delivers the best cycling stability at a low current density(0.1 A·g^(-1)),with an ultrahigh capacity retention of 98.8% after 300 cycles.Besides,at a high current density of 5 A·g^(-1),the NVO@ZSO cathode still possesses excellent cycling performance,and a reversible capacity of 284.6 mAh·g^(-1)is achieved even after 7000 cycles.The mechanism is clarified with the aid of density function theory calculations and molecular dynamics simulations.These findings provide a new paradigm for designing stable cathodes by introducing amorphous additive,which should promote further application exploration of AZIBs at low current densities.展开更多
The effects of the Cr3C2 content and wheel speed on the amorphization behavior of the melt-spun SmCo7-x（Cr3C2）x （x=0.10-0.25） alloys were studied systematically by X-ray diffraction analysis （XRD）, differential ...The effects of the Cr3C2 content and wheel speed on the amorphization behavior of the melt-spun SmCo7-x（Cr3C2）x （x=0.10-0.25） alloys were studied systematically by X-ray diffraction analysis （XRD）, differential scanning calorimetry （DSC） and magnetic measurements. The ribbon melt-spun at lower wheel speed （20 m/s） has composite structure composed of mostly SmCo7 and a small amount of Sm2Co17R. The grain size of SmCo7 phase decreases with the increase of Cr3C2 content. With the increase of wheel speed, the XRD peaks become lower and accompanied with a broad increase in backgrounds, indicating a considerable decrease in the grain size of the SmCo7 phase. When the wheel speed increases to 40 m/s, SmCo7-x（Cr3C2）x alloys can be obtained in the amorphous state for 0.15≤x≤0.25 with intrinsic coercive Hci of 0.004-0.007 T. The DSC analysis reveals that SmCo7 phase firstly precipitates from the amorphous matrix at 650 °C, followed by the crystallization of Sm2Co17 phase at 770 °C.展开更多
Electron irradiation effects on phase stability of the E （Al18Cr2Mg3） phase have been investigated by high- angle annular dark-field scanning transmission electron microscopy and high-resolution transmission electro...Electron irradiation effects on phase stability of the E （Al18Cr2Mg3） phase have been investigated by high- angle annular dark-field scanning transmission electron microscopy and high-resolution transmission electron microscopy （HRTEM）. The in situ HRTEM observations show that the Ala8Cr2Mg3 particles with different thickness undergo amorphization and dissolution under 300 keV electron irradiation at 25 ℃. The results indicate that the intermetallic compound Al18Cr2Mg3 is unstable under electron irradiation, and structural changes mainly depend on the thickness of particles. Amorphization in the thick particles is caused by a combination of chemical disordering and an increase in point defect concentration. Dissolution after amorphization in the thin particles is attributed to the diffusion of point defect towards the Al matrix.展开更多
Effects of pressure on lattice parameters, electronic, thermodynamic and mechanical properties of the fully ordered Ti_(2)AlNb orthorhombic phase were studied using first-principles calculations based on density funct...Effects of pressure on lattice parameters, electronic, thermodynamic and mechanical properties of the fully ordered Ti_(2)AlNb orthorhombic phase were studied using first-principles calculations based on density functional theory(DFT). The bonding nature for ordering orthorhombic Ti_(2)AlNb was revealed quantitatively through the electronic structure analyzing. The external pressures play limited roles in the elastic anisotropy of the alloy due to the outstanding dynamical and mechanical stabilities under pressure. However, the shear modulus of O phase manifests anisotropic, where {010} shear planes are the easiest planes to cleave among the principal planes under all pressures.The heat capacities, volume expansions and thermal expansion coefficients were calculated using the quasi-harmonic approximation model based on the phonon dispersion curves. Meanwhile, the bulk modulus, Young’s modulus,shear modulus and the hardness are promptly enhanced under pressure. The predicted results give hints to design Ti_(2)AlNb-based alloy as high-pressure applications.展开更多
Polycrystalline pyrochlore Lu2Ti2O7 pellets are irradiated with 600-keV Kr^3＋ions up to a fluence of 1.45 ×10^16Kr^3＋/cm^2. Irradiation induced structural modifications are examined by using grazing incidence x...Polycrystalline pyrochlore Lu2Ti2O7 pellets are irradiated with 600-keV Kr^3＋ions up to a fluence of 1.45 ×10^16Kr^3＋/cm^2. Irradiation induced structural modifications are examined by using grazing incidence x-ray diffraction（GIXRD） and cross-sectional transmission electron microscopy（TEM）. The GIXRD reveals that amorphous fraction increases with the increase of fluences up to 2 × 10^15Kr^3＋/cm^2, and the results are explained with a direct-impact model.However, when the irradiation fluence is higher than 2 × 10^15Kr^3＋/cm^2, the amorphous fraction reaches a saturation of-80%. Further TEM observations imply that nano-crystal is formed with a diameter of -10 nm within the irradiation layer at a fluence of 4 × 10^15Kr^3＋/cm^2. No full amorphization is achieved even at the highest fluence of 1.45 × 10^16Kr^3＋/cm^2（-36 displacement per atom）. The high irradiation resistance of pyrochlore Lu2Ti2O7 at higher fluence is explained on the basis of enhanced radiation tolerance of nano-crystal structure.展开更多
Fluoride ferrous(FeF_(2))is viewed as a promising conversion cathode material for next-generation lithiumion batteries(LIBs)due to its high theoretical specific capacity and low cost.Unfortunately,issues such as poor ...Fluoride ferrous(FeF_(2))is viewed as a promising conversion cathode material for next-generation lithiumion batteries(LIBs)due to its high theoretical specific capacity and low cost.Unfortunately,issues such as poor intrinsic conductivity,iron dissolution,and phase separation hinder the application of FeF_(2)in highenergy cathodes.Here,a pressure-induced morphology control method is designed to prepare coralloidlike FeF_(2)nanocrystals with nitrogen-rich carbon coating(c-FeF_(2)@NC).The coralloid-like interconnected crystal structure of c-FeF_(2)@NC contributes to reducing interfacial resistance and enhancing the topotactic transformation during the conversion reaction,and the nitrogen-rich carbon(NC)coating can enhance interfacial stability and kinetic performance.When used as a conversion cathode for LIBs,c-FeF_(2)@NC exhibits a high initial reversible capacity of 503.57 mA h g^(-1)and excellent cycling stability of497.61 m A h g^(-1)with a low capacity decay of 1.19%over 50 cycles at 0.1 A/g.Even at 1 A/g,a stable capacity of 263.78 mA h g^(-1)can still be retained after 200 cycles.The capability of c-FeF_(2)@NC as a conversion cathode for sodium-ion batteries(SIBs)was also evaluated to expand its field of application.Furthermore,two kinds of full batteries have been assembled by employing c-FeF_(2)@NC as cathodes and quantitative limited-Li(LLi)and pre-lithiated reduced graphene oxide(PGO)as anodes,respectively,to envisage the feasibility of practical applications of conversion materials.展开更多
Starting from elemental powders, complete MoSi2 powder forms abruptly between 3.5and 4 h during mechanical alloying (MA) of the Mo-66 at.% Si powders. Continuous milling of this MoSi2 Phase leads to a nanocrystalline ...Starting from elemental powders, complete MoSi2 powder forms abruptly between 3.5and 4 h during mechanical alloying (MA) of the Mo-66 at.% Si powders. Continuous milling of this MoSi2 Phase leads to a nanocrystalline powder and amorphizationtransformation takes place after 100 h milling. Howeven MA of the Mo-37.5 at.%Si powders does not result in the formation of the Mo5Si3 crystalline phase, but the formation of a Mo(Si) supersaturated solid solution (SSS) and a completely amorphots phase after 5 h and 70 h milling, respectively. The free energy of the Mo-Sisystem has been calculated and it has been found that there is no driving force for the amorphization reaction under normal conditions. The amorphization by MA of the Mo-Si system is attributed to a solid-state amorphization reaction in which defects and a very fine grain size induced during milling process may raise the free energy of the crystalline intermetallic phase (for MoSi2) or the Mo(Si) supersaturated solid solution (for Mo5Si3) above that of the amorphous phase.展开更多
The amorphization of alloys is of both broad scientific interests and engineering significance.Despite considered as an efficient strategy to regulate and even achieve record-breaking properties of metallic materials,...The amorphization of alloys is of both broad scientific interests and engineering significance.Despite considered as an efficient strategy to regulate and even achieve record-breaking properties of metallic materials,a facile and rapid method to trigger solid-state amorphization is still being pursued.Here we report such a method to utilize ultrasonic vibration to trigger amorphization of intermetallic compound.The ultrasonic vibrations can cause tunable amorphization at room temperature and low stress(2 MPa)conveniently.Remarkably,the ultrasonic-induced amorphization could be achieved in 60 s,which is 360 times faster than the ball milling(2.16×10^(4) s)with the similar proportion of amorphization.The elements redistribute uniformly and rapidly via the activated short-circuit diffusion.Both experimental evidences and simulations show that the amorphous phase initiates and expands at nanograin boundaries,owing to the induction of lattice instability.This work provides a groundbreaking strategy for developing novel materials with tunable structures and properties.展开更多
Step-scheme(S-scheme)heterojunctions in photocatalysts can provide novel and practical insight on promoting photogenerated carrier separation.The latter is critical in controlling the overall efficiency in one-step ph...Step-scheme(S-scheme)heterojunctions in photocatalysts can provide novel and practical insight on promoting photogenerated carrier separation.The latter is critical in controlling the overall efficiency in one-step photoexcitation systems.In this study,a nanosized BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4 )solid solution was prepared by a coprecipitation method following with hydrothermal or calcination processes.The S-scheme heterojunction was fabricated by in-situ pressure-induced transformations of bismuth vanadate from the tetragonal zircon phase to the monoclinic scheelite phase,which led to the formation of BiVO4 nanoparticles with a diameter of approximately 5 nm on the surface of BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4)/Bi_(0.6)Y_(0.4)VO_(4)with S-scheme heterojunctions showed significantly enhanced photocatalytic overall water splitting activity compared with using bare BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4).Characterization of the carrier dynamics demonstrated that a superior carrier separation through S-type heterojunctions might have caused the enhanced overall water splitting(OWS)activity.Surface photovoltage spectra and the results of selective photodeposition experiments indicated that the photogenerated holes mainly migrated to the BiVO4 nanoparticles in the heterojunction.This confirmed that the charge transfer route corresponds to an S-scheme rather than a type-II heterojunction mechanism under light illumination.This study presents a facile and efficient strategy to construct S-scheme heterojunctions through a pressure-induced phase transition.The results demonstrated that S-scheme junctions composed of different crystalline phases can boost the carrier separation capacity and eventually improve the photocatalytic OWS activity.展开更多
Ion beam assisted deposition technique (IBAD) was utilized to systematically study amorphization in binary metal systems of Nb-magnetic element, i.e., Nb-M (M=Fe, Co or Ni). The glass forming range termed as Nb fracti...Ion beam assisted deposition technique (IBAD) was utilized to systematically study amorphization in binary metal systems of Nb-magnetic element, i.e., Nb-M (M=Fe, Co or Ni). The glass forming range termed as Nb fraction of Nb-Fe system was about 34at.% to 56at.%, that of Nb-Co system was about 32at.% to 72at.% and that of Nb-Ni about 20at. % to 80at. %. Similar percolation patterns were found in amorphous alloy films. The fractal dimensions of the percolation patterns approach to 2, which indicates 2-D layer growth for amorphous phases. It is regarded that the assisted Ar+ ion beam during the deposition process plays important role for the 2-D layer growth. Some metastable crystalline phases were obtained in these three systems by IBAD, e.g., bcc supersaturated solid solutions in Nb-Fe and Nb-Co systems, fcc and hcp phases in Nb-Co and Nb-Ni systems. The formation and competing between the amorphous and the metastable crystalline phases were determined by both the phases' thermodynamic states in binary metal systems and kinetics during IBAD process.展开更多
Designing active,robust and cost-effective catalysts for the nitrogen reduction reaction(NRR) is of paramount significance for sustainable electrochemical NH3 synthesis.Transition-metal diborides(TMB_2)have been recen...Designing active,robust and cost-effective catalysts for the nitrogen reduction reaction(NRR) is of paramount significance for sustainable electrochemical NH3 synthesis.Transition-metal diborides(TMB_2)have been recently theoretically predicted to be a new class of potential NRR catalysts,but direct experimental evidence is still lacking.Herein,we present the first experimental demonstration that amorphous FeB_2 porous nanosheets(a-FeB_2 PNSs) could be a highly efficient NRR catalyst,which exhibited an NH3 yield of 39.8 μg h^(-1) mg^(-1)(-0.3 V) and a Faradaic efficiency of 16.7%(-0.2 V),significantly outperforming their crystalline counterpart and most of existing NRR catalysts.First-principle calculations unveiled that the amorphization could induce the upraised d-band center of a-FeB_2 to boost d-2π~* coupling between the active Fe site and ~*N_2 H intermediate,resulting in enhanced ~*N_2 H stabilization and reduced reaction barrier.Out study may facilitate the development and understanding of earth-abundant TMB_2-based catalysts for electrocatalytic N_2 fixation.展开更多
Nuclear engineering materials are required to possess outstanding extreme environmental tolerance and irradiation resistance.A promising novel pyrochlore-type of(Sm_(0.2)Eu_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2))2 Hf_(2)O_(7)h...Nuclear engineering materials are required to possess outstanding extreme environmental tolerance and irradiation resistance.A promising novel pyrochlore-type of(Sm_(0.2)Eu_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2))2 Hf_(2)O_(7)high-entropy ceramic(HE-RE2 Hf_(2)O_(7))for control rod was prepared by solid-state reaction method.The ion irradiation of HE-RE_(2) Hf_(2)O_(7)with 400 keV Kr+at 400℃was investigated using a 400 kV ion implanter and compared with single-component pyrochlore Gd2 Hf_(2)O_(7)to evaluate the irradiation resistance.For HE-RE2 Hf_(2)O_(7),the phase transition from pyrochlore to defective fluorite is revealed after irradiation at 60 dpa.After irradiation at 120 dpa,it maintained crystalline,which is comparable to Gd2 Hf_(2)O_(7)but superior to the titanate pyrochlores previously studied.Moreover,the lattice expansion of HE-RE2 Hf_(2)O_(7)(_(0.2)2%)is much lower than that of Gd2 Hf_(2)O_(7)(0.62%),indicating excellent irradiation damage resistance.Nanoindentation tests displayed an irradiation-induced increase in hardness and a decrease in elastic modulus by about 2.6%.Irradiation-induced segregation of elements is observed on the surface of irradiated samples.In addition,HE-RE2 Hf_(2)O_(7)demonstrates a more sluggish grain growth rate than Gd2 Hf_(2)O_(7)at 1200℃,suggesting better high-temperature stability.The linear thermal expansion coefficient of HE-RE2 Hf_(2)O_(7)is 10.7×10-6 K-1 at 298–1273 K.In general,it provides a new strategy for the design of the next advanced nuclear engineering materials.展开更多
Anatase TiO_(2) is a promising anode material for sodium-ion batteries,yet the low electronic and ionic conductivities are the main obstacles for its practical application.Even though the amorphization of TiO_(2) upon...Anatase TiO_(2) is a promising anode material for sodium-ion batteries,yet the low electronic and ionic conductivities are the main obstacles for its practical application.Even though the amorphization of TiO_(2) upon sodiation has already been observed,its underneath mechanisms are not fully elucidated.Herein,a low-cost nitrogen-containing carbon source of polyacrylonitrile is adopted to modify commercial anatase TiO_(2) by a convenient and nontoxic ball-milling technique combined with subsequent annealing treatment.In particular,the employment of a nitrogen-doping approach accompanied by nitrogendoped carbon coating,results in a greatly improved conductivity,overall leading to a high reversible capacity of about 260 m A h g^(-1)at 25 m A g^(-1),superior rate capabilities,and an ultra-stable capacity of about 186 m A h g^(-1)after 1600 cycles at 500 m A g^(-1).Detailed characterizations denote that the improved conductivity as well as the small size of the synthesized TiO_(2) grains play a key role in the TiO_(2) amorphization upon sodiation,with the TiO_(2)/C nanocomposite undergoing a complete amorphization in just few cycles.Finally,the irreversible amorphization of TiO_(2) is confirmed to be a crucial ingredient facilitating the Na+diffusion kinetics and pseudocapacitive behavior,thus boosting the sodium storage performance.展开更多
The mechanical response of a single crystal titanium sample against(0001)α surface impact was investigated using molecular dynamics simulation.Remarkably,non-uniform plastic deformation was observed in the sample.At ...The mechanical response of a single crystal titanium sample against(0001)α surface impact was investigated using molecular dynamics simulation.Remarkably,non-uniform plastic deformation was observed in the sample.At high strain rates,amorphization occurred near the edge of the contact region where severe shear strain induced a large number of stacking faults(SFs)and dislocations.In contrast,the central part of the contact region underwent less deformation with significantly fewer dislocations.Moreover,instead of amorphization by consuming SFs and dislocations,there was a gradual increase in the density of dislocations and SFs during the process of amorphization.These local amorphous regions eventually grew into shear bands.展开更多
基金the National Natural Science Foundation of China(Nos.52175430 and 52105478)for their support of this work.
文摘Pure magnesium is a very promising material in the fields of biomedical and engineering.Obtaining pure magnesium with superior mechanical properties has consistently been a significant challenge in the area of materials science.This study focuses on investigating the processing method and strengthening mechanism of pure magnesium by ultra-precision cutting.The research results show that the pure magnesium grains were significantly refined after ultra-precision cutting.The average grain size reduced from∼24μm to nanometers,and the average nano-hardness increased from 1.02 GPa to 2.82 GPa.Amorphous pure magnesium structure and body-centered cubic(BCC)lattice pure magnesium were reported.Molecular dynamics(MD)simulation confirmed that the high shear strain and hydrostatic pressure during ultra-precision cutting was the origin of amorphization and lattice transformation.The amorphous phase and a significant number of long-period stacking-ordered(LPSO)phases inside the pure magnesium were responsible for the high hardness after ultra-precision cutting.
基金supported by the National Key Research and Development Program of China(No.2018YFA0703700)the National Natural Science Foundation of China(No.12034002)the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities,No.FRF-IDRY-23-033)。
文摘Amorphous two-dimensional transition metal oxide/(oxy)hydroxide(2D TMO/TMHO)nanomaterials(NMs)have the properties of both 2D and amorphous materials,displaying outstanding physicochemical qualities.Therefore,they demonstrate considerable promise for use in electrocatalytic water splitting applications.Here,the primary amorphization strategies for achieving the 2D TMO/TMHO NMs are comprehensively reviewed,including low-temperature reaction,rapid reaction,exchange/doping effect,ligand modulation,and interfacial energy confinement.By integrating these strategies with various physicochemical synthesis methods,it is feasible to control the amorphization of TMO/TMHO NMs while maintaining the distinctive benefits of their 2D structures.Furthermore,it delves into the structural advantages of amorphous 2D TMO/TMHO NMs in electrocatalytic water splitting,particularly emphasizing recent advancements in enhancing their electrocatalytic performance through interface engineering.The challenges and potential future directions for the precise synthesis and practical application of amorphous 2D TMO/TMHO NMs are also provided.This review aims to establish a theoretical foundation and offer experimental instructions for developing effective and enduring electrocatalysts for water splitting.
基金Supported by the National Natural Science Foundation of China.
文摘Pressure-induced amorphous transition of Li_(2)Ge_(7)O_(15)(LGO)crystal has been investigated by using in situ high pressure energy dispersive x-ray diffraction with synchrotron radiation at the pressure up to 21.6 GPa.Diamond anvils were used to generate high pressure.Pressure was measured in terms of the diffraction of Pt as an internal pressure standard.The crystal structure of LGO is an orthorhombic lattice at atmospheric pressure.According to the high pressure x-ray diffraction results,new diffraction lines begin to appear and LGO undergoes an intermediate phase transition at the pressure of 12.9 GPa.But,the diffraction lines disappear wholly and LGO becomes an amorphous phase at the pressure of above 14.8 GPa.This amorphous transition is irreversible.
基金supported by the Australian Research Council(ARC)Projects(DP220101139,DP220101142,and LP240100542).
文摘High‐entropy amorphous catalysts(HEACs)integrate multielement synergy with structural disorder,making them promising candidates for water splitting.Their distinctive features—including flexible coordination environments,tunable electronic structures,abundant unsaturated active sites,and dynamic structural reassembly—collectively enhance electrochemical activity and durability under operating conditions.This review summarizes recent advances in HEACs for hydrogen evolution,oxygen evolution,and overall water splitting,highlighting their disorder-driven advantages over crystalline counterparts.Catalytic performance benchmarks are presented,and mechanistic insights are discussed,focusing on how multimetallic synergy,amorphization effect,and in‐situ reconstruction cooperatively regulate reaction pathways.These insights provide guidance for the rational design of next‐generation amorphous high‐entropy electrocatalysts with improved efficiency and durability.
基金supported by the National Key Research and Development Programs-Intergovernmental International Cooperation in Science and Technology Innovation Project(Grant No.2022YFE0118400)the Natural Science Foundation of Hunan Province(2023JJ50132)+1 种基金Shenzhen Science and Technology Innovation Committee(Grants Nos.JCYJ20220818100211025,and KCXST20221021111616039)Shenzhen Science and Technology Program(No.20231128110928003)。
文摘The introduction of two-dimensional(2D)perovskite layers on top of three-dimensional(3D)perovskite films enhances the performance and stability of perovskite solar cells(PSCs).However,the electronic effect of the spacer cation and the quality of the 2D capping layer are critical factors in achieving the required results.In this study,we compared two fluorinated salts:4-(trifluoromethyl)benzamidine hydrochloride(4TF-BA·HCl)and 4-fluorobenzamidine hydrochloride(4F-BA·HCl)to engineer the 3D/2D perovskite films.Surprisingly,4F-BA formed a high-performance 3D/2D heterojunction,while4TF-BA produced an amorphous layer on the perovskite films.Our findings indicate that the balanced intramolecular charge polarization,which leads to effective hydrogen bonding,is more favorable in 4F-BA than in 4TF-BA,promoting the formation of a crystalline 2D perovskite.Nevertheless,4TF-BA managed to improve efficiency to 24%,surpassing the control device,primarily due to the natural passivation capabilities of benzamidine.Interestingly,the devices based on 4F-BA demonstrated an efficiency exceeding 25%with greater longevity under various storage conditions compared to 4TF-BA-based and the control devices.
基金supported by the National Natural Science Foundation of China(22175136)the State Key Laboratory of Electrical Insulation and Power Equipment(EIPE23127)the Fundamental Research Funds for the Central Universities(xtr052024009).
文摘Metal hydrides with high hydrogen density provide promising hydrogen storage paths for hydrogen transportation.However,the requirement of highly pure H_(2)for re-hydrogenation limits its wide application.Here,amorphous Al_(2)O_(3)shells(10 nm)were deposited on the surface of highly active hydrogen storage material particles(MgH_(2)-ZrTi)by atomic layer deposition to obtain MgH_(2)-ZrTi@Al_(2)O_(3),which have been demonstrated to be air stable with selective adsorption of H_(2)under a hydrogen atmosphere with different impurities(CH_(4),O_(2),N_(2),and CO_(2)).About 4.79 wt%H_(2)was adsorbed by MgH_(2)-ZrTi@10nmAl_(2)O_(3)at 75℃under 10%CH_(4)+90%H_(2)atmosphere within 3 h with no kinetic or density decay after 5 cycles(~100%capacity retention).Furthermore,about 4 wt%of H_(2)was absorbed by MgH_(2)-ZrTi@10nmAl_(2)O_(3)under 0.1%O_(2)+0.4%N_(2)+99.5%H_(2)and 0.1%CO_(2)+0.4%N_(2)+99.5%H_(2)atmospheres at 100℃within 0.5 h,respectively,demonstrating the selective hydrogen absorption of MgH_(2)-ZrTi@10nmAl_(2)O_(3)in both oxygen-containing and carbon dioxide-containing atmospheres hydrogen atmosphere.The absorption and desorption curves of MgH_(2)-ZrTi@10nmAl_(2)O_(3)with and without absorption in pure hydrogen and then in 21%O_(2)+79%N_(2)for 1 h were found to overlap,further confirming the successful shielding effect of Al_(2)O_(3)shells against O_(2)and N_(2).The MgH_(2)-ZrTi@10nmAl_(2)O_(3)has been demonstrated to be air stable and have excellent selective hydrogen absorption performance under the atmosphere with CH_(4),O_(2),N_(2),and CO_(2).
基金supported by the National Natural Science Foundation of China(Nos.U24A2055 and 92164103)the National Key R&D Program of China(No.2021YFA1200800)+2 种基金the Natural Science Foundation of Hubei Province(No.2024AFA052)Wuhan Science and Technology Bureau(Knowledge Innovation Program of Wuhan-Basic Research,No.2023010201010067)the Fundamental Research Funds for the Central Universities(No.2042023kf0187).
文摘Due to the safety,high energy density,and rapid charging feature,aqueous zinc-ion batteries(AZIBs)have attracted great attention in large-scale energy storage systems.Although excellent electrochemical performances have been achieved,the cycling stabilities of AZIBs are still unsatisfactory,especially at low current densities,because the cathode materials are prone to being dissolved into electrolytes.Here we develop a unique zincophilic and hydrophobic amorphous additive of ZnSnO_(3)(ZSO),which effectively prevents the irreversible dissolution and deamination of NH_(4)V_(4)O_(10)(NVO)cathode.Benefiting from the ingenious design,NVO@ZSO cathode delivers the best cycling stability at a low current density(0.1 A·g^(-1)),with an ultrahigh capacity retention of 98.8% after 300 cycles.Besides,at a high current density of 5 A·g^(-1),the NVO@ZSO cathode still possesses excellent cycling performance,and a reversible capacity of 284.6 mAh·g^(-1)is achieved even after 7000 cycles.The mechanism is clarified with the aid of density function theory calculations and molecular dynamics simulations.These findings provide a new paradigm for designing stable cathodes by introducing amorphous additive,which should promote further application exploration of AZIBs at low current densities.
基金Project (51104188) supported by the National Natural Science Foundation for Young Scholars of China
文摘The effects of the Cr3C2 content and wheel speed on the amorphization behavior of the melt-spun SmCo7-x（Cr3C2）x （x=0.10-0.25） alloys were studied systematically by X-ray diffraction analysis （XRD）, differential scanning calorimetry （DSC） and magnetic measurements. The ribbon melt-spun at lower wheel speed （20 m/s） has composite structure composed of mostly SmCo7 and a small amount of Sm2Co17R. The grain size of SmCo7 phase decreases with the increase of Cr3C2 content. With the increase of wheel speed, the XRD peaks become lower and accompanied with a broad increase in backgrounds, indicating a considerable decrease in the grain size of the SmCo7 phase. When the wheel speed increases to 40 m/s, SmCo7-x（Cr3C2）x alloys can be obtained in the amorphous state for 0.15≤x≤0.25 with intrinsic coercive Hci of 0.004-0.007 T. The DSC analysis reveals that SmCo7 phase firstly precipitates from the amorphous matrix at 650 °C, followed by the crystallization of Sm2Co17 phase at 770 °C.
基金financially supported by the 111 Project (No. B08040) of ChinaNational Natural Science Foundation of China (No. 51071125)
文摘Electron irradiation effects on phase stability of the E （Al18Cr2Mg3） phase have been investigated by high- angle annular dark-field scanning transmission electron microscopy and high-resolution transmission electron microscopy （HRTEM）. The in situ HRTEM observations show that the Ala8Cr2Mg3 particles with different thickness undergo amorphization and dissolution under 300 keV electron irradiation at 25 ℃. The results indicate that the intermetallic compound Al18Cr2Mg3 is unstable under electron irradiation, and structural changes mainly depend on the thickness of particles. Amorphization in the thick particles is caused by a combination of chemical disordering and an increase in point defect concentration. Dissolution after amorphization in the thin particles is attributed to the diffusion of point defect towards the Al matrix.
基金financially supported by the National Natural Science Foundation of China (Nos.50971043 and 51171046)the Research Fund for the Doctoral Program of Higher Education of China (No.20133514110006)+1 种基金the Natural Science Foundation of Fujian Province,China (No.2014J01176)the Program for New Century Excellent Talents in University of Fujian Province,China (No.JA10013)。
文摘Effects of pressure on lattice parameters, electronic, thermodynamic and mechanical properties of the fully ordered Ti_(2)AlNb orthorhombic phase were studied using first-principles calculations based on density functional theory(DFT). The bonding nature for ordering orthorhombic Ti_(2)AlNb was revealed quantitatively through the electronic structure analyzing. The external pressures play limited roles in the elastic anisotropy of the alloy due to the outstanding dynamical and mechanical stabilities under pressure. However, the shear modulus of O phase manifests anisotropic, where {010} shear planes are the easiest planes to cleave among the principal planes under all pressures.The heat capacities, volume expansions and thermal expansion coefficients were calculated using the quasi-harmonic approximation model based on the phonon dispersion curves. Meanwhile, the bulk modulus, Young’s modulus,shear modulus and the hardness are promptly enhanced under pressure. The predicted results give hints to design Ti_(2)AlNb-based alloy as high-pressure applications.
基金Project sponsored by the National Natural Science Foundation of China(Grant No.11205128)the Fundamental Research Funds for the Central UniversitiesChina(Grant No.2012121034)
文摘Polycrystalline pyrochlore Lu2Ti2O7 pellets are irradiated with 600-keV Kr^3＋ions up to a fluence of 1.45 ×10^16Kr^3＋/cm^2. Irradiation induced structural modifications are examined by using grazing incidence x-ray diffraction（GIXRD） and cross-sectional transmission electron microscopy（TEM）. The GIXRD reveals that amorphous fraction increases with the increase of fluences up to 2 × 10^15Kr^3＋/cm^2, and the results are explained with a direct-impact model.However, when the irradiation fluence is higher than 2 × 10^15Kr^3＋/cm^2, the amorphous fraction reaches a saturation of-80%. Further TEM observations imply that nano-crystal is formed with a diameter of -10 nm within the irradiation layer at a fluence of 4 × 10^15Kr^3＋/cm^2. No full amorphization is achieved even at the highest fluence of 1.45 × 10^16Kr^3＋/cm^2（-36 displacement per atom）. The high irradiation resistance of pyrochlore Lu2Ti2O7 at higher fluence is explained on the basis of enhanced radiation tolerance of nano-crystal structure.
基金supported by Foundation for the Sichuan University and Zigong City Joint research project(2021CDZG-2)the Foundation for the Sichuan University and Yibin City Strategic Cooperation Project(2020CDYB-32)the Guangxi Key Laboratory of Low Carbon Energy Material(2020GKLLCEM02)。
文摘Fluoride ferrous(FeF_(2))is viewed as a promising conversion cathode material for next-generation lithiumion batteries(LIBs)due to its high theoretical specific capacity and low cost.Unfortunately,issues such as poor intrinsic conductivity,iron dissolution,and phase separation hinder the application of FeF_(2)in highenergy cathodes.Here,a pressure-induced morphology control method is designed to prepare coralloidlike FeF_(2)nanocrystals with nitrogen-rich carbon coating(c-FeF_(2)@NC).The coralloid-like interconnected crystal structure of c-FeF_(2)@NC contributes to reducing interfacial resistance and enhancing the topotactic transformation during the conversion reaction,and the nitrogen-rich carbon(NC)coating can enhance interfacial stability and kinetic performance.When used as a conversion cathode for LIBs,c-FeF_(2)@NC exhibits a high initial reversible capacity of 503.57 mA h g^(-1)and excellent cycling stability of497.61 m A h g^(-1)with a low capacity decay of 1.19%over 50 cycles at 0.1 A/g.Even at 1 A/g,a stable capacity of 263.78 mA h g^(-1)can still be retained after 200 cycles.The capability of c-FeF_(2)@NC as a conversion cathode for sodium-ion batteries(SIBs)was also evaluated to expand its field of application.Furthermore,two kinds of full batteries have been assembled by employing c-FeF_(2)@NC as cathodes and quantitative limited-Li(LLi)and pre-lithiated reduced graphene oxide(PGO)as anodes,respectively,to envisage the feasibility of practical applications of conversion materials.
文摘Starting from elemental powders, complete MoSi2 powder forms abruptly between 3.5and 4 h during mechanical alloying (MA) of the Mo-66 at.% Si powders. Continuous milling of this MoSi2 Phase leads to a nanocrystalline powder and amorphizationtransformation takes place after 100 h milling. Howeven MA of the Mo-37.5 at.%Si powders does not result in the formation of the Mo5Si3 crystalline phase, but the formation of a Mo(Si) supersaturated solid solution (SSS) and a completely amorphots phase after 5 h and 70 h milling, respectively. The free energy of the Mo-Sisystem has been calculated and it has been found that there is no driving force for the amorphization reaction under normal conditions. The amorphization by MA of the Mo-Si system is attributed to a solid-state amorphization reaction in which defects and a very fine grain size induced during milling process may raise the free energy of the crystalline intermetallic phase (for MoSi2) or the Mo(Si) supersaturated solid solution (for Mo5Si3) above that of the amorphous phase.
基金financially supported by the Key Basic and Applied Research Program of Guangdong Province,China(No.2019B030302010)the National Natural Science Foundation of China(Nos.52122105,51971150,51871157)+3 种基金the National Key Research and Development Program of China(No.2018YFA0703605)the financial support from the National Natural Science Foundation of China(No.12072344)the Youth Innovation Promotion Association of the Chinese Academy of Sciencessupported by the Beijing Electron Positron Collider(BEPC)project(No.2020-BEPC-PT-004661).
文摘The amorphization of alloys is of both broad scientific interests and engineering significance.Despite considered as an efficient strategy to regulate and even achieve record-breaking properties of metallic materials,a facile and rapid method to trigger solid-state amorphization is still being pursued.Here we report such a method to utilize ultrasonic vibration to trigger amorphization of intermetallic compound.The ultrasonic vibrations can cause tunable amorphization at room temperature and low stress(2 MPa)conveniently.Remarkably,the ultrasonic-induced amorphization could be achieved in 60 s,which is 360 times faster than the ball milling(2.16×10^(4) s)with the similar proportion of amorphization.The elements redistribute uniformly and rapidly via the activated short-circuit diffusion.Both experimental evidences and simulations show that the amorphous phase initiates and expands at nanograin boundaries,owing to the induction of lattice instability.This work provides a groundbreaking strategy for developing novel materials with tunable structures and properties.
文摘Step-scheme(S-scheme)heterojunctions in photocatalysts can provide novel and practical insight on promoting photogenerated carrier separation.The latter is critical in controlling the overall efficiency in one-step photoexcitation systems.In this study,a nanosized BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4 )solid solution was prepared by a coprecipitation method following with hydrothermal or calcination processes.The S-scheme heterojunction was fabricated by in-situ pressure-induced transformations of bismuth vanadate from the tetragonal zircon phase to the monoclinic scheelite phase,which led to the formation of BiVO4 nanoparticles with a diameter of approximately 5 nm on the surface of BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4)/Bi_(0.6)Y_(0.4)VO_(4)with S-scheme heterojunctions showed significantly enhanced photocatalytic overall water splitting activity compared with using bare BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4).Characterization of the carrier dynamics demonstrated that a superior carrier separation through S-type heterojunctions might have caused the enhanced overall water splitting(OWS)activity.Surface photovoltage spectra and the results of selective photodeposition experiments indicated that the photogenerated holes mainly migrated to the BiVO4 nanoparticles in the heterojunction.This confirmed that the charge transfer route corresponds to an S-scheme rather than a type-II heterojunction mechanism under light illumination.This study presents a facile and efficient strategy to construct S-scheme heterojunctions through a pressure-induced phase transition.The results demonstrated that S-scheme junctions composed of different crystalline phases can boost the carrier separation capacity and eventually improve the photocatalytic OWS activity.
基金This work was supported in part by the National Natural Science Foundation of China(Grant No.19875027)the Ministry of Scienc
文摘Ion beam assisted deposition technique (IBAD) was utilized to systematically study amorphization in binary metal systems of Nb-magnetic element, i.e., Nb-M (M=Fe, Co or Ni). The glass forming range termed as Nb fraction of Nb-Fe system was about 34at.% to 56at.%, that of Nb-Co system was about 32at.% to 72at.% and that of Nb-Ni about 20at. % to 80at. %. Similar percolation patterns were found in amorphous alloy films. The fractal dimensions of the percolation patterns approach to 2, which indicates 2-D layer growth for amorphous phases. It is regarded that the assisted Ar+ ion beam during the deposition process plays important role for the 2-D layer growth. Some metastable crystalline phases were obtained in these three systems by IBAD, e.g., bcc supersaturated solid solutions in Nb-Fe and Nb-Co systems, fcc and hcp phases in Nb-Co and Nb-Ni systems. The formation and competing between the amorphous and the metastable crystalline phases were determined by both the phases' thermodynamic states in binary metal systems and kinetics during IBAD process.
基金supported by the National Natural Science Foundation of China (51761024)the CAS ‘‘Light of West China” Program, ‘‘Feitian Scholar” Program of Gansu Provincethe Foundation of A Hundred Youth Talents Training Program of Lanzhou Jiaotong University。
文摘Designing active,robust and cost-effective catalysts for the nitrogen reduction reaction(NRR) is of paramount significance for sustainable electrochemical NH3 synthesis.Transition-metal diborides(TMB_2)have been recently theoretically predicted to be a new class of potential NRR catalysts,but direct experimental evidence is still lacking.Herein,we present the first experimental demonstration that amorphous FeB_2 porous nanosheets(a-FeB_2 PNSs) could be a highly efficient NRR catalyst,which exhibited an NH3 yield of 39.8 μg h^(-1) mg^(-1)(-0.3 V) and a Faradaic efficiency of 16.7%(-0.2 V),significantly outperforming their crystalline counterpart and most of existing NRR catalysts.First-principle calculations unveiled that the amorphization could induce the upraised d-band center of a-FeB_2 to boost d-2π~* coupling between the active Fe site and ~*N_2 H intermediate,resulting in enhanced ~*N_2 H stabilization and reduced reaction barrier.Out study may facilitate the development and understanding of earth-abundant TMB_2-based catalysts for electrocatalytic N_2 fixation.
基金supported by the Lingchuang Research Project of China National Nuclear Corporation,the National Key Research and Development Program of China(No.2022YFB3504302)the key core technology research project in Beicang District,Ningbo(Grant No.2021BLG009)+4 种基金the key deployment project of the Chinese Academy of Sciences(Grant No.ZDRW-CN-2021-3)the Fujian Provincial Natural Fund Project(Grant No.2021J05101)the Young Elite Scientists Sponsorship Program by CAST(Grant No.2021QNRC001)the independent deployment project of Ganjiang Innovation Research Institute of Chinese Academy of Sciences(Grant No.E055A002)In addition,thanks for the assistance of Jinchi Huang from the School of Energy,Xiamen University for the ion irradiation experiment.
文摘Nuclear engineering materials are required to possess outstanding extreme environmental tolerance and irradiation resistance.A promising novel pyrochlore-type of(Sm_(0.2)Eu_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2))2 Hf_(2)O_(7)high-entropy ceramic(HE-RE2 Hf_(2)O_(7))for control rod was prepared by solid-state reaction method.The ion irradiation of HE-RE_(2) Hf_(2)O_(7)with 400 keV Kr+at 400℃was investigated using a 400 kV ion implanter and compared with single-component pyrochlore Gd2 Hf_(2)O_(7)to evaluate the irradiation resistance.For HE-RE2 Hf_(2)O_(7),the phase transition from pyrochlore to defective fluorite is revealed after irradiation at 60 dpa.After irradiation at 120 dpa,it maintained crystalline,which is comparable to Gd2 Hf_(2)O_(7)but superior to the titanate pyrochlores previously studied.Moreover,the lattice expansion of HE-RE2 Hf_(2)O_(7)(_(0.2)2%)is much lower than that of Gd2 Hf_(2)O_(7)(0.62%),indicating excellent irradiation damage resistance.Nanoindentation tests displayed an irradiation-induced increase in hardness and a decrease in elastic modulus by about 2.6%.Irradiation-induced segregation of elements is observed on the surface of irradiated samples.In addition,HE-RE2 Hf_(2)O_(7)demonstrates a more sluggish grain growth rate than Gd2 Hf_(2)O_(7)at 1200℃,suggesting better high-temperature stability.The linear thermal expansion coefficient of HE-RE2 Hf_(2)O_(7)is 10.7×10-6 K-1 at 298–1273 K.In general,it provides a new strategy for the design of the next advanced nuclear engineering materials.
基金financially supported by the Shandong Provincial Natural Science Foundation,China (Grant No.ZR2022QE181)。
文摘Anatase TiO_(2) is a promising anode material for sodium-ion batteries,yet the low electronic and ionic conductivities are the main obstacles for its practical application.Even though the amorphization of TiO_(2) upon sodiation has already been observed,its underneath mechanisms are not fully elucidated.Herein,a low-cost nitrogen-containing carbon source of polyacrylonitrile is adopted to modify commercial anatase TiO_(2) by a convenient and nontoxic ball-milling technique combined with subsequent annealing treatment.In particular,the employment of a nitrogen-doping approach accompanied by nitrogendoped carbon coating,results in a greatly improved conductivity,overall leading to a high reversible capacity of about 260 m A h g^(-1)at 25 m A g^(-1),superior rate capabilities,and an ultra-stable capacity of about 186 m A h g^(-1)after 1600 cycles at 500 m A g^(-1).Detailed characterizations denote that the improved conductivity as well as the small size of the synthesized TiO_(2) grains play a key role in the TiO_(2) amorphization upon sodiation,with the TiO_(2)/C nanocomposite undergoing a complete amorphization in just few cycles.Finally,the irreversible amorphization of TiO_(2) is confirmed to be a crucial ingredient facilitating the Na+diffusion kinetics and pseudocapacitive behavior,thus boosting the sodium storage performance.
基金the National Natural Science Foundation of China(U2241245,91960202 and 52271012)the National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact(6142902220301)+2 种基金the Aeronautical Science Foundation of China(2022Z053092001)the Shanghai Engineering Research Center of High-Performance Medical Device Materials(20DZ2255500)the Opening Project of National Key Laboratory of Shock Wave and Detonation Physics(2022JCJQLB05702).
文摘The mechanical response of a single crystal titanium sample against(0001)α surface impact was investigated using molecular dynamics simulation.Remarkably,non-uniform plastic deformation was observed in the sample.At high strain rates,amorphization occurred near the edge of the contact region where severe shear strain induced a large number of stacking faults(SFs)and dislocations.In contrast,the central part of the contact region underwent less deformation with significantly fewer dislocations.Moreover,instead of amorphization by consuming SFs and dislocations,there was a gradual increase in the density of dislocations and SFs during the process of amorphization.These local amorphous regions eventually grew into shear bands.
