Two-dimensional(2D)materials have emerged as a significant class of materials promising for photocatalysis,and defect engineering offers an effective route for enhancing their photocatalytic performance.In this mini-r...Two-dimensional(2D)materials have emerged as a significant class of materials promising for photocatalysis,and defect engineering offers an effective route for enhancing their photocatalytic performance.In this mini-review,a first-principles design perspective on defect engineering in 2D materials for photocatalysis is provided.Various types of defects in 2D materials,spanning point,line,and planar defects are explored,and their influence on the intrinsic properties and photocatalytic efficacy of these materials is highlighted.Additionally,the use of theoretical descriptors to characterize the stability,electronic,optical,and catalytic properties of 2D defective systems is summarized.Central to the discussion is the understanding of electronic structure,optical properties,and reaction mechanisms to inform the rational design of photocatalysts based on 2D materials for enhanced photocatalytic performance.This mini-review aims to provide insights into the computational design of 2D defect systems tailored for efficient photocatalytic applications.展开更多
Gold-platinum(Au-Pt)alloy has aroused considerable attention due to its ultra-low magnetic susceptibility(MS)in testing mass(TM)on spacecraft.However,the effect of Au content on the properties of the alloy has not yet...Gold-platinum(Au-Pt)alloy has aroused considerable attention due to its ultra-low magnetic susceptibility(MS)in testing mass(TM)on spacecraft.However,the effect of Au content on the properties of the alloy has not yet been understood.In this study,the composition design of Au-Pt alloy with ultra-low MS was achieved through density functional theory(DFT)and experimental methods.The elastic,thermal properties and electronic structure were systematically investigated,the composition range was further optimized and Au75Pt25 was determined to be the most suitable alloy for TM material.The phase composition of this alloy after cold rolling and solid solution was characterized,indicating a single-phase FCC structure.In addition,there is a good validation between the experimental Vickers hardness and the DFT results.This work provides new insights into the compositional optimization of Au-Pt alloys and lays the foundation for alloy development.展开更多
To obtain the aluminum alloy with high thermal and mechanical properties,the effects of alloying elements and the second phases on the thermal conductivity of Al alloys were investigated by CALPHAD and first-principle...To obtain the aluminum alloy with high thermal and mechanical properties,the effects of alloying elements and the second phases on the thermal conductivity of Al alloys were investigated by CALPHAD and first-principles calculation,respectively.The properties of the second phases,including Young's modulus,Poisson's ratio and minimum thermal conductivity,were systematically studied.Results show that the ranking order of the effects of the alloying elements on the thermal conductivity is Mg>Cu>Fe>Si,and for Al-12Si alloys,the mathematical model of the relationship between the alloying elements and the thermal conductivity can be expressed as λ=ax^(2)-bx+c when the second phase precipitates in the matrix.All kinds of ternary phases of Al-Fe-Si have higher deformation resistance,rigidity,theoretical hardness,Debye temperature and thermal conductivity than the other phases which possibly exist in the Al-12Si alloys.Based on the guidance of CALPHAD and first-principles calculation,the optimized chemical composition of Al alloy with high conductivity is Al-11.5Si-0.4Fe-0.2Mg(wt.%)with a thermal conductivity of 137.50 W·m^(-1)·K^(-1)and a hardness of 81.3 HBW.展开更多
The mechanical and thermodynamic properties of W-Ti alloys(including W_(15)Ti_(1),W_(14)Ti_(2),W_(12)Ti_(4) and W_(8)Ti_(8) alloys)were investigated by the first-principles approach based on density functional theory....The mechanical and thermodynamic properties of W-Ti alloys(including W_(15)Ti_(1),W_(14)Ti_(2),W_(12)Ti_(4) and W_(8)Ti_(8) alloys)were investigated by the first-principles approach based on density functional theory.The results indicate that W-Ti alloys except W_(8)Ti_(8) are thermodynamically stable.The modulus and hardness of W-Ti alloys are smaller than those of pure tungsten and gradually decrease with increasing Ti concentration.However,their B/G ratios and Poisson's ratios exceed those of pure tungsten,suggesting that the introduction of Ti decreases the mechanical strength while enhancing the ductility of W-Ti alloys.The thermal expansion coefficients for W-Ti alloys all surpass those of pure tungsten,indicating that the introduction of titanium exacerbates the thermal expansion behavior of W-Ti alloys.Nevertheless,elevated pressure has the capacity to suppress the thermal expansion tendencies in titanium-doped tungsten alloys.This study offers theoretical insights for the design of nuclear materials by exploring the mechanical and thermodynamic properties of W-Ti alloys.展开更多
A biosensor device, built from graphene nanoribbons （GNRs） with nanopores, was designed and studied by first- principles quantum transport simulation. We have demonstrated the intrinsic transport properties of the d...A biosensor device, built from graphene nanoribbons （GNRs） with nanopores, was designed and studied by first- principles quantum transport simulation. We have demonstrated the intrinsic transport properties of the device and the effect of different nucleobases on device properties when they are located in the nanopores of GNRs. It was found that the device＇s current changes remarkably with the species of nucleobases, which originates from their different chemical compositions and coupling strengths with GNRs. In addition, our first-principles results clearly reveal that the distinguished ability of a device＇s current depends on the position of the pore to some extent. These results may present a new way to read off the nucleobases sequence of a single-stranded DNA （ssDNA） molecule by such GNRs-based device with designed nanopores展开更多
Based on first-principles calculation framework,the surface model,anodic dissolution,cathodic oxygen absorption reaction,and other related electrochemical corrosion models of Fe-Ce system were constructed,and the infl...Based on first-principles calculation framework,the surface model,anodic dissolution,cathodic oxygen absorption reaction,and other related electrochemical corrosion models of Fe-Ce system were constructed,and the influencing mechanism Ce doping on the corrosion resistance of Fe-Ce system in the Cl medium environment was analyzed.The results show that Ce doping on the first surface and subsurface inhibits the ionization of Fe atoms and greatly promotes the repassivation process of Fe matrix.Ce doping on the first layer is conducive to preventing the detachment of surface Fe atoms from Fe matrix and delaying the occurrence of corrosion.Ce atoms in the subsurface effectively increase the difficulty of Fe atoms detaching from the matrix at high Cl concentrations.When O diffusion is the controlling link of oxygen absorption reaction,Ce doping has no effects on the reaction rate of cathodic oxygen absorption.Ce doping enhances the electrochemical stability of Fe(100)1and reduces the anodic dissolution rate of Fe matrix,thereby improving its corrosion resistance.展开更多
The adsorption properties of a magnesium porphyrin(MgP)molecule on Au(111)surface covered with up to three lay-ers of sodium chloride(NaCl)were investigated by means of first-principles calculations.The most stable ad...The adsorption properties of a magnesium porphyrin(MgP)molecule on Au(111)surface covered with up to three lay-ers of sodium chloride(NaCl)were investigated by means of first-principles calculations.The most stable adsorption configuration of MgP on the NaCl/Au(111)heterosurfaces was found to be at the Cl-top site with a 20°angle between the[110]lattice direction of NaCl and the Mg–N bond of the molecule.Compared with MgP molecule adsorbed on bare Au(111),the inclusion of NaCl lay-ers can lead to a significant decrease in the adsorption energy of the MgP molecule.The exis-tence of NaCl layers also reduced the charge transfer between the molecule and the surface.For heterosurfaces with two or three monolayers of NaCl,the charge transfer was almost com-pletely suppressed.The obtained partial density of states(PDOS)showed that hybridization between the electronic structures of the adsorbed MgP molecule and the metal surface can be significantly suppressed when NaCl layers were added.For the heterosurface with three lay-ers of NaCl,the PDOS around the Fermi level was almost identical with that of the free molecule,suggesting the electronic structure of the MgP molecule was nicely preserved.Influ-ence of the NaCl layers on the electronic structure of the MgP molecule was mainly found for molecular orbitals(MOs)away from the Fermi level as a result of the large band gap of the NaCl layers.展开更多
Control of hyperfine interaction strength of shallow donors in Si is one of the central issues in realizing Kane quantum computers.First-principles calculations on the hyperfine Stark shift of shallow donors are chall...Control of hyperfine interaction strength of shallow donors in Si is one of the central issues in realizing Kane quantum computers.First-principles calculations on the hyperfine Stark shift of shallow donors are challenging since large supercells are needed to accommodate the delocalized donor wave functions.In this work,we investigated the hyperfine Stark shift and its strain tunability for shallow donors P and As in Si using the potential patching method based on first-principles density functional theory calculations.The good agreement between our calculations and experimental results confirms that the potential patching method is a feasible and accurate first-principles approach for studying wave-function-related properties of shallow impurities,such as the Stark shift parameter.It is further shown that the application of strain expands the range of hyperfine Stark shift and helps improve the response of shallow donor based qubit gates.The results could be useful for developing quantum computing architectures based on shallow donors in Si.展开更多
Thermal expansion is crucial for various industrial processes and is increasingly the focus of research endeavors aimed at improving material performance.However,it is the continuous advancements in first-principles c...Thermal expansion is crucial for various industrial processes and is increasingly the focus of research endeavors aimed at improving material performance.However,it is the continuous advancements in first-principles calculations that have enabled researchers to understand the microscopic origins of thermal expansion.In this study,we propose a coefficient of thermal expansion(CTE)calculation scheme based on self-consistent phonon theory,incorporating the fourth-order anharmonicity.We selected four structures(Si,CaZrF_(6),SrTiO_(3),NaBr)to investigate high-order anharmonicity’s impact on their CTEs,based on bonding types.The results indicate that our method goes beyond the second-order quasi-harmonic approximation and the third-order perturbation theory,aligning closely with experimental data.Furthermore,we observed that an increase in the ionicity of the structures leads to a more pronounced influence of high-order anharmonicity on CTE,with this effect primarily manifesting in variations of the Grüneisen parameter.Our research provides a theoretical foundation for accurately predicting and regulating the thermal expansion behavior of materials.展开更多
In this study,6061 aluminum alloy and galvanized steel fusion-brazed lap joints were obtained using a laser-arc hybrid heat source,and the effects of laser power variation on the microstructure,mechanical properties,a...In this study,6061 aluminum alloy and galvanized steel fusion-brazed lap joints were obtained using a laser-arc hybrid heat source,and the effects of laser power variation on the microstructure,mechanical properties,and fracture mechanism of the joints were ana-lyzed.The results showed that the tensile shear load initially increased with rising laser power,followed by a decrease.At a laser power of 240 W,the maximum tensile shear load was 2479.8 N/cm and the weak section of joint was in the Al-Fe reaction layer con-sisting of Fe(Al,Si)_(3),Fe_(2)(Al,Si)_(5),and Fe(Al,Si)intermetallic compounds(IMCs).Computational results showed that the inherently high brittleness and hardness of Fe(Al,Si)_(3) and the high mismatch rates of Fe(Al,Si)_(3)/Al interfaces were the key factor leading to the failure of the joints at lower heat input.展开更多
MgO is one of the most abundant minerals in the Earth’s interior,and its structure and properties at high temperature and pressure are important for us to understand the composition and behavior in the deep Earth.In ...MgO is one of the most abundant minerals in the Earth’s interior,and its structure and properties at high temperature and pressure are important for us to understand the composition and behavior in the deep Earth.In the present work,firstprinciples molecular dynamics calculations were performed to investigate the pressure-induced structural evolution of the MgO melts at 4000 K and 5000 K.The results predicted the liquid-solid phase boundaries,and the calculated viscosities of the melts may help us to understand the transport behavior under the corresponding Earth conditions.展开更多
Second period elements(B,C,N,and O)usually appear at the grain boundary(GB)and strongly affect the mechanical performance in austenitic stainless steels.Therefore,it is significant to investigate the effect of solute ...Second period elements(B,C,N,and O)usually appear at the grain boundary(GB)and strongly affect the mechanical performance in austenitic stainless steels.Therefore,it is significant to investigate the effect of solute elements(B,C,N,and O)on the GB.The first-principles calculation based on the density function theory was applied to explore the effect of B,C,N,and O onγ-FeΣ5(210)[001]GB.The GB energy,the segregation energy,the Voronoi volume,and the theoretical tensile test were calculated to investigate the segregation behavior and the strengthening effect.The structural change and electronic evolution were also investigated by bond change,charge density distribution,and density of states.The results show that B is favored to segregate at the capped trigonal prism(CTP)position with a large void and has a strengthening effect on the GB strength,while O and N are preferred to locate at the octahedral(OCT)site and have an embrittling effect on GB cohesion.C can segregate at both the CTP site and the OCT location with little energy difference.As C segregates at the OCT site,it is beneficial for GB strength.However,it is detrimental at the CTP position.It can be seen that the influence of solutes is closely related to the element type and segregated position.展开更多
The influence mechanism of trace Nb on the corrosion resistance of surface corrosion products of high-strength anti-seismic rebar in the simulated marine environment was studied by combining first-principles calculati...The influence mechanism of trace Nb on the corrosion resistance of surface corrosion products of high-strength anti-seismic rebar in the simulated marine environment was studied by combining first-principles calculations with corrosion mass loss method,surface analysis,cross-sectional analysis,quantitative analysis,and electrochemical test.The results demonstrated that the addition of trace Nb effectively improved the compactness and stability of surface corrosion layer of rebar,and the corrosion resistance of corrosion layer increased with the increase in Nb content.The beneficial effect of Nb content on the corrosion layer summarized two important key points.Firstly,the addition of Nb was beneficial to promoting the improvement in the structural stability of α-FeOOH,and α-FeOOH structure of solid solution Nb atoms was beneficial to strengthening the fixation of Cl atoms,thus increasing α/(β+γ)ratio,total impedance value,and corrosion potential.Secondly,the formation of Nb oxides can not only repair the corrosion layer,but also play a role in the fixation Cl atoms,resulting in the improvement in corrosion resistance of corrosion layer.展开更多
Herein,a first-principles investigation was innovatively conducted to research the surface oxidation of ZnS-like sphalerite in the absence and presence of H_(2)O .The findings showed that single O_(2) was preferred to...Herein,a first-principles investigation was innovatively conducted to research the surface oxidation of ZnS-like sphalerite in the absence and presence of H_(2)O .The findings showed that single O_(2) was preferred to be dissociated adsorption on sphalerite surface by generating SAO and Zn AO bonds,and the S atom on the surface was the most energy-supported site for O_(2) adsorption,on which a≡Zn-O-S-O-Zn≡structure will be formed.However,dissociated adsorption of single H_(2)O will not happen.It was preferred to be adsorbed on the top Zn atom on sphalerite surface in molecular form through Zn-O bond.Besides,sphalerite oxidation can occur as if O_(2) was present regardless of the presence of H_(2)O ,and when H_(2)O and O_(2) coexisted,the formation of sulfur oxide(SO_(2) )needed a lower energy barrier and it was easier to form on sphalerite surface than that only O_(2) existed.In the absence of H_(2)O ,when SO_(2) was generated,further oxidation of which would form neutral zinc sulfate.In the presence of H_(2)O ,the formation of SO_(2) on sphalerite surface was easier and the rate of further oxidation to form sulfate was also greater.Consequently,the occurrence of sphalerite oxidation was accelerated.展开更多
Extensive first-principles calculations have been performed to examine the electrochemical properties of Na-ion-intercalatable heterostructures formed by transitional metal dichalcogenides(MS_(2),where M=Ti,V,Nb and M...Extensive first-principles calculations have been performed to examine the electrochemical properties of Na-ion-intercalatable heterostructures formed by transitional metal dichalcogenides(MS_(2),where M=Ti,V,Nb and Mo)and blue phosphorus(BlueP),which have been reported as potential anode materials for rechargeable sodium-ion batteries.Upon formation of heterostructures,much improved structural stabilities have observed compared with the pristine MS_(2) and BlueP.Metallic T-TiS_(2),T-MoS_(2),H(T)-VS_(2) and H(T)-NbS_(2) would retain the conductive character after formation of heterostructures with BlueP,however,HTiS_(2)/BlueP and H-MoS_(2)/BlueP would undergo a semiconductor to metallic transition accompanied by Na intercalation.Moreover,the presence of relatively low diffusion barriers ranging from 0.04 eV to 0.08 eV,coupled with the suitable average open-circuit voltage spanning from 0.12 eV to 0.89 eV,guarantee exceptional charge-discharge rates and ensure the safety of battery performance.Among these heterostructures,H(T)-NbS_(2)/BlueP and T-TiS_(2)/BlueP exhibit best Na adsorption ability of up to 4 layers,corresponding to theoretical capacities of 570.2 and 746.7 mAh/g,respectively.These encouraging properties indicate that T-TiS_(2)/BlueP and H(T)-NbS_(2)/BlueP could serve as suitable anode materials for high-performance sodiumion batteries.展开更多
The lattice thermal conductivity(κ_(latt))of mantle minerals plays a crucial role in the heat flow and temperature distribution within the Earth.MgSiO_(3)akimotoite is stable at the bottom of the mantle transition zo...The lattice thermal conductivity(κ_(latt))of mantle minerals plays a crucial role in the heat flow and temperature distribution within the Earth.MgSiO_(3)akimotoite is stable at the bottom of the mantle transition zone;it transitions to MgSiO_(3)perovskite(MgPv).Inκ_(latt)this work,we carry out a study of the of MgSiO_(3)akimotoite for pressures up to 25 GPa and temperatures up to 2500 K,based onκ_(latt)first-principles calculations combined with lattice dynamics theory.At 300 K and 25 GPa,the of MgSiO_(3)akimotoite is 37.66 W m^(-1)K^(-1),κ_(latt)larger than that of MgPv(13.46 W m^(-1)K^(-1)),which implies that the phase transition explains the reduction in.At 300 K,the pressureκ_(latt)κ_(latt)dependence of is 0.68 W m^(-1)K^(-1)GPa-1,stronger than that of MgPv(0.48 W m^(-1)K^(-1)GPa-1).The azimuthal anisotropy in of MgSiO_(3)akimotoite decreases from 45.5%at 0 GPa to 28.94%at 25 GPa,while the variation trend is opposite to that of MgPv.In MgSiO_(3)κ_(latt)akimotoite,Fe incorporating in the mineral leads to a decrease in and an increase in azimuthal anisotropy.Along the geotherm,theκ_(latt)of MgSiO_(3)akimotoite is lower than that of ringwoodite,which would suggest that MgSiO_(3)akimotoite slows down heat conduction at the bottom of mantle transition zone.These findings are useful for determining the thermal structure of,and understanding heat transfer in,the interior of the Earth.展开更多
As a new layered semiconductor material,Bi_(2)SeO_(5) has shown potential in the field of ultraviolet electronic devices in recent years because of its unique crystal structure and wide band gap.In this paper,the crys...As a new layered semiconductor material,Bi_(2)SeO_(5) has shown potential in the field of ultraviolet electronic devices in recent years because of its unique crystal structure and wide band gap.In this paper,the crystal structure,electronic structure,and thermodynamic stability of Bi_(2)SeO_(5) are studied based on first-principles calculations.The ultraviolet luminescence property of BiSe defect is predicated from defect property,which provides theoretical basis for experimental design of high-performance Bi2SeO5 photoelectric devices.展开更多
To explain the influence mechanism of MgO on the consolidation and reduction characteristics of roasted iron pellets,the properties and structure of pellets were investigated from multi-dimensions.It indicated that th...To explain the influence mechanism of MgO on the consolidation and reduction characteristics of roasted iron pellets,the properties and structure of pellets were investigated from multi-dimensions.It indicated that the MgO addition decreased the reduction swelling index(RSI)and reduction degree of pellets in both CO and H_(2)atmospheres.During the stepwise reduction process of Fe2O3→Fe3O4→FeO,the reduction behaviour of pellets in CO and H_(2)was similar,while the reduction rate of pellets in H_(2)atmosphere was almost twice as high as that in CO atmosphere.During the stepwise reduction process of FeO→Fe,the RSI of pellets showed a logarithmic increase in CO atmosphere and a linear decrease in H_(2)atmosphere.As investigated by first-principles calculations,C and Fe mainly formed chemical bonds,and the CO reduction process released energy,promoting the formation of iron whiskers.However,H and Fe produced weak physical adsorption,and the H_(2)reduction process was endothermic,inhibiting the generation of iron whiskers.With Mg2+doping in FexO,the nucleation region of iron whiskers expanded in CO reduction process,and the morphology of iron whiskers transformed from“slender”to“stocky,”reducing RSI of the pellets.展开更多
Currently,the development of high-efficiency two-dimensional(2D)transistors is still hindered by the limited availability of suitable semiconductors and the contact resistance between the metal contact and the 2D semi...Currently,the development of high-efficiency two-dimensional(2D)transistors is still hindered by the limited availability of suitable semiconductors and the contact resistance between the metal contact and the 2D semiconductors.Endeavors to address these challenges are highly desired.In this study,we conducted a comprehensive exploration of the potential 2D transition metal dinitrides(TMN_(2)s,TM=all the 3d,4d and 5d transition metals)with hexagonal(h-)and trigonal(t-)phases through systematic first-principles calculations.Among all h-TMN_(2)s and t-TMN_(2)s structures,we identified 8 TMN_(2)s that exhibit dynamical and thermal stability at room temperature.Of these,the h-TiN_(2),h-ZrN_(2)and h-HfN_(2)arefound to be semiconductors,and their direct bang gap,calculated at the HSE06 level,are 1.48,1.96 and 2.64 eV,respectively.The electron and hole mobility(μ_(e)andμ_(h))of these three structures exceed 1×10^(4)and1×10^(3)cm^(2)·V^(-1)·s^(-1),respectively.Especially,theμeof h-TiN_(2)amounts to 2.5×10^(4)cm^(2)·V^(-1)·s^(-1),and theμhof h-ZrN_(2)reaches to 7.7×10^(3)cm^(2)·V^(-1)·s^(-1).Importantly,unlike the MoS_(2)system,h-TMN_(2)forms Ohm contacts with both transition metals(e.g.,Cu)and 2D metals(e.g.,graphene),with tunneling possibilities exceeding 50%in the Cu system.These outstanding intrinsic semiconductor properties and contact characteristics exhibited by h-TMN_(2)highlight the immense potential of transition metal dinitrides in driving the advancement of next-generation information devices.Our findings significantly broaden the range of 2D materials and provide valuable insights for the development of high-eficiency 2D information devices.展开更多
Ag/Al_(2)O_(3) powders are highly effective catalytic materials utilized in the epoxidation of ethylene to produce ethylene oxide.One of the critical challenges in this catalytic process is the stability of nano-sized...Ag/Al_(2)O_(3) powders are highly effective catalytic materials utilized in the epoxidation of ethylene to produce ethylene oxide.One of the critical challenges in this catalytic process is the stability of nano-sized Ag particles,especially during high-temperature catalysis.However,this issue can be effectively addressed through in-situ reaction synthesis.To gain a deeper understanding of the underlying mechanisms,the phase transformation process and the thermodynamic mechanism of the oxidation reaction in the Ag/Al_(2)O_(3) system have been investigated using firstprinciples thermodynamic calculations in conjunction with traditional thermodynamic data.These calculations,whose accuracy has been verified,provide valuable insights into the behavior of Ag and Al under different conditions.The results indicate that,during AgAl solid-solution oxidation,Ag-containing Al preferentially forms the stable intermediate phase Ag2Al instead of undergoing direct oxidation;this pathway becomes thermodynamically more favorable at higher Ag concentrations.With increasing temperature,Ag2Al is further oxidized to yield Ag and Al_(2)O_(3).It is also found that above 237℃,Ag2O and AgAlO2 become unstable.The overall reaction pathway is solid solution→Ag2Al→Ag+Al_(2)O_(3).This comprehensive study provides a robust theoretical calculation basis for the development and optimization of in-situ reaction-synthesized Ag/Al_(2)O_(3) powder composite materials,which have significant potential for practical applications in catalysis.展开更多
文摘Two-dimensional(2D)materials have emerged as a significant class of materials promising for photocatalysis,and defect engineering offers an effective route for enhancing their photocatalytic performance.In this mini-review,a first-principles design perspective on defect engineering in 2D materials for photocatalysis is provided.Various types of defects in 2D materials,spanning point,line,and planar defects are explored,and their influence on the intrinsic properties and photocatalytic efficacy of these materials is highlighted.Additionally,the use of theoretical descriptors to characterize the stability,electronic,optical,and catalytic properties of 2D defective systems is summarized.Central to the discussion is the understanding of electronic structure,optical properties,and reaction mechanisms to inform the rational design of photocatalysts based on 2D materials for enhanced photocatalytic performance.This mini-review aims to provide insights into the computational design of 2D defect systems tailored for efficient photocatalytic applications.
基金financially supported by the National Key R&D Program of China(No.2021YFC2202300)the National Natural Science Foundation of China(NSFC)(No.51974258)the National College Students Innovation and Entrepreneurship Training Program(No.S202210699134).
文摘Gold-platinum(Au-Pt)alloy has aroused considerable attention due to its ultra-low magnetic susceptibility(MS)in testing mass(TM)on spacecraft.However,the effect of Au content on the properties of the alloy has not yet been understood.In this study,the composition design of Au-Pt alloy with ultra-low MS was achieved through density functional theory(DFT)and experimental methods.The elastic,thermal properties and electronic structure were systematically investigated,the composition range was further optimized and Au75Pt25 was determined to be the most suitable alloy for TM material.The phase composition of this alloy after cold rolling and solid solution was characterized,indicating a single-phase FCC structure.In addition,there is a good validation between the experimental Vickers hardness and the DFT results.This work provides new insights into the compositional optimization of Au-Pt alloys and lays the foundation for alloy development.
基金the National Natural Science Foundation of China(Nos.51801045 and 52171113)the Key Laboratory of Materials Modification by Laser,Ion and Electron Beams,Ministry of Education,Dalian University of Technology(No.KF2002).
文摘To obtain the aluminum alloy with high thermal and mechanical properties,the effects of alloying elements and the second phases on the thermal conductivity of Al alloys were investigated by CALPHAD and first-principles calculation,respectively.The properties of the second phases,including Young's modulus,Poisson's ratio and minimum thermal conductivity,were systematically studied.Results show that the ranking order of the effects of the alloying elements on the thermal conductivity is Mg>Cu>Fe>Si,and for Al-12Si alloys,the mathematical model of the relationship between the alloying elements and the thermal conductivity can be expressed as λ=ax^(2)-bx+c when the second phase precipitates in the matrix.All kinds of ternary phases of Al-Fe-Si have higher deformation resistance,rigidity,theoretical hardness,Debye temperature and thermal conductivity than the other phases which possibly exist in the Al-12Si alloys.Based on the guidance of CALPHAD and first-principles calculation,the optimized chemical composition of Al alloy with high conductivity is Al-11.5Si-0.4Fe-0.2Mg(wt.%)with a thermal conductivity of 137.50 W·m^(-1)·K^(-1)and a hardness of 81.3 HBW.
基金Funded by National Key R&D Program of China(No.2021YFB3802300)the National Natural Science Foundation of China(No.52171045)the Joint Fund(No.8091B022108)。
文摘The mechanical and thermodynamic properties of W-Ti alloys(including W_(15)Ti_(1),W_(14)Ti_(2),W_(12)Ti_(4) and W_(8)Ti_(8) alloys)were investigated by the first-principles approach based on density functional theory.The results indicate that W-Ti alloys except W_(8)Ti_(8) are thermodynamically stable.The modulus and hardness of W-Ti alloys are smaller than those of pure tungsten and gradually decrease with increasing Ti concentration.However,their B/G ratios and Poisson's ratios exceed those of pure tungsten,suggesting that the introduction of Ti decreases the mechanical strength while enhancing the ductility of W-Ti alloys.The thermal expansion coefficients for W-Ti alloys all surpass those of pure tungsten,indicating that the introduction of titanium exacerbates the thermal expansion behavior of W-Ti alloys.Nevertheless,elevated pressure has the capacity to suppress the thermal expansion tendencies in titanium-doped tungsten alloys.This study offers theoretical insights for the design of nuclear materials by exploring the mechanical and thermodynamic properties of W-Ti alloys.
基金Project supported by the Major Research Plan from the Ministry of Science and Technology of China(Grant No.2011CB921900)the China Postdoctoral Science Foundation(Grant Nos.20090460145 and 201003009)+2 种基金the Fundamental Research Funds for the Central Universities of China(Grant No.201012200053)the Science and Technology Program of Hunan Province of China (Grant No.2010DFJ411)the Science Development Foundation of Central South University,China(Grant Nos.08SDF02 and 09SDF09)
文摘A biosensor device, built from graphene nanoribbons （GNRs） with nanopores, was designed and studied by first- principles quantum transport simulation. We have demonstrated the intrinsic transport properties of the device and the effect of different nucleobases on device properties when they are located in the nanopores of GNRs. It was found that the device＇s current changes remarkably with the species of nucleobases, which originates from their different chemical compositions and coupling strengths with GNRs. In addition, our first-principles results clearly reveal that the distinguished ability of a device＇s current depends on the position of the pore to some extent. These results may present a new way to read off the nucleobases sequence of a single-stranded DNA （ssDNA） molecule by such GNRs-based device with designed nanopores
基金Project supported by the National Natural Science Foundation of China(52364044,52204364)Scientific Research Special Project for First-Class Disciplines of Education Department of Inner Mongolia Autonomous Region(YLXKZX-NKD-001,YLXKZX-NKD-011)Basic Scientific Research Business Expenses of Colleges and Universities of Inner Mongolia Autonomous Region(2023QNJS011)。
文摘Based on first-principles calculation framework,the surface model,anodic dissolution,cathodic oxygen absorption reaction,and other related electrochemical corrosion models of Fe-Ce system were constructed,and the influencing mechanism Ce doping on the corrosion resistance of Fe-Ce system in the Cl medium environment was analyzed.The results show that Ce doping on the first surface and subsurface inhibits the ionization of Fe atoms and greatly promotes the repassivation process of Fe matrix.Ce doping on the first layer is conducive to preventing the detachment of surface Fe atoms from Fe matrix and delaying the occurrence of corrosion.Ce atoms in the subsurface effectively increase the difficulty of Fe atoms detaching from the matrix at high Cl concentrations.When O diffusion is the controlling link of oxygen absorption reaction,Ce doping has no effects on the reaction rate of cathodic oxygen absorption.Ce doping enhances the electrochemical stability of Fe(100)1and reduces the anodic dissolution rate of Fe matrix,thereby improving its corrosion resistance.
基金supported by the National Natural Science Foundation of China(No.22373084,No.62201494)Hebei Natural Science Foundation(B2022203007)the Cultivation Project for Basic Research and Innovation of Yanshan University(2024LGZD002).
文摘The adsorption properties of a magnesium porphyrin(MgP)molecule on Au(111)surface covered with up to three lay-ers of sodium chloride(NaCl)were investigated by means of first-principles calculations.The most stable adsorption configuration of MgP on the NaCl/Au(111)heterosurfaces was found to be at the Cl-top site with a 20°angle between the[110]lattice direction of NaCl and the Mg–N bond of the molecule.Compared with MgP molecule adsorbed on bare Au(111),the inclusion of NaCl lay-ers can lead to a significant decrease in the adsorption energy of the MgP molecule.The exis-tence of NaCl layers also reduced the charge transfer between the molecule and the surface.For heterosurfaces with two or three monolayers of NaCl,the charge transfer was almost com-pletely suppressed.The obtained partial density of states(PDOS)showed that hybridization between the electronic structures of the adsorbed MgP molecule and the metal surface can be significantly suppressed when NaCl layers were added.For the heterosurface with three lay-ers of NaCl,the PDOS around the Fermi level was almost identical with that of the free molecule,suggesting the electronic structure of the MgP molecule was nicely preserved.Influ-ence of the NaCl layers on the electronic structure of the MgP molecule was mainly found for molecular orbitals(MOs)away from the Fermi level as a result of the large band gap of the NaCl layers.
基金supported by the National Natural Science Foun-dation of China(Grant Nos.12393831 and 12088101).
文摘Control of hyperfine interaction strength of shallow donors in Si is one of the central issues in realizing Kane quantum computers.First-principles calculations on the hyperfine Stark shift of shallow donors are challenging since large supercells are needed to accommodate the delocalized donor wave functions.In this work,we investigated the hyperfine Stark shift and its strain tunability for shallow donors P and As in Si using the potential patching method based on first-principles density functional theory calculations.The good agreement between our calculations and experimental results confirms that the potential patching method is a feasible and accurate first-principles approach for studying wave-function-related properties of shallow impurities,such as the Stark shift parameter.It is further shown that the application of strain expands the range of hyperfine Stark shift and helps improve the response of shallow donor based qubit gates.The results could be useful for developing quantum computing architectures based on shallow donors in Si.
基金Project supported by the National Natural Science Foundation of China(Grant No.62125402).
文摘Thermal expansion is crucial for various industrial processes and is increasingly the focus of research endeavors aimed at improving material performance.However,it is the continuous advancements in first-principles calculations that have enabled researchers to understand the microscopic origins of thermal expansion.In this study,we propose a coefficient of thermal expansion(CTE)calculation scheme based on self-consistent phonon theory,incorporating the fourth-order anharmonicity.We selected four structures(Si,CaZrF_(6),SrTiO_(3),NaBr)to investigate high-order anharmonicity’s impact on their CTEs,based on bonding types.The results indicate that our method goes beyond the second-order quasi-harmonic approximation and the third-order perturbation theory,aligning closely with experimental data.Furthermore,we observed that an increase in the ionicity of the structures leads to a more pronounced influence of high-order anharmonicity on CTE,with this effect primarily manifesting in variations of the Grüneisen parameter.Our research provides a theoretical foundation for accurately predicting and regulating the thermal expansion behavior of materials.
基金supported by the National Key Research and Development Program of China(No.2022YFB4600900).
文摘In this study,6061 aluminum alloy and galvanized steel fusion-brazed lap joints were obtained using a laser-arc hybrid heat source,and the effects of laser power variation on the microstructure,mechanical properties,and fracture mechanism of the joints were ana-lyzed.The results showed that the tensile shear load initially increased with rising laser power,followed by a decrease.At a laser power of 240 W,the maximum tensile shear load was 2479.8 N/cm and the weak section of joint was in the Al-Fe reaction layer con-sisting of Fe(Al,Si)_(3),Fe_(2)(Al,Si)_(5),and Fe(Al,Si)intermetallic compounds(IMCs).Computational results showed that the inherently high brittleness and hardness of Fe(Al,Si)_(3) and the high mismatch rates of Fe(Al,Si)_(3)/Al interfaces were the key factor leading to the failure of the joints at lower heat input.
基金supported by the National Natural Science Foundation of China(Grant No.51701180)the Foundation of the State Key Laboratory of Coal Conversion(Grant No.J22-23-103).
文摘MgO is one of the most abundant minerals in the Earth’s interior,and its structure and properties at high temperature and pressure are important for us to understand the composition and behavior in the deep Earth.In the present work,firstprinciples molecular dynamics calculations were performed to investigate the pressure-induced structural evolution of the MgO melts at 4000 K and 5000 K.The results predicted the liquid-solid phase boundaries,and the calculated viscosities of the melts may help us to understand the transport behavior under the corresponding Earth conditions.
基金supported by National Key R&D Program of China(No.2022YFB3705202)National Natural Science Foundation of China(Nos.51831008,52171049 and 52104330).
文摘Second period elements(B,C,N,and O)usually appear at the grain boundary(GB)and strongly affect the mechanical performance in austenitic stainless steels.Therefore,it is significant to investigate the effect of solute elements(B,C,N,and O)on the GB.The first-principles calculation based on the density function theory was applied to explore the effect of B,C,N,and O onγ-FeΣ5(210)[001]GB.The GB energy,the segregation energy,the Voronoi volume,and the theoretical tensile test were calculated to investigate the segregation behavior and the strengthening effect.The structural change and electronic evolution were also investigated by bond change,charge density distribution,and density of states.The results show that B is favored to segregate at the capped trigonal prism(CTP)position with a large void and has a strengthening effect on the GB strength,while O and N are preferred to locate at the octahedral(OCT)site and have an embrittling effect on GB cohesion.C can segregate at both the CTP site and the OCT location with little energy difference.As C segregates at the OCT site,it is beneficial for GB strength.However,it is detrimental at the CTP position.It can be seen that the influence of solutes is closely related to the element type and segregated position.
基金supported by National Natural Science Foundation of China(Grant No.52074095)Guizhou Provincial Basic Research Program(Natural Science)(Grant No.QKHJC-ZK[2023]YB072)+2 种基金Guizhou Provincial Key Technology R&D Program(Grant No.QKHZC[2023]YB404)Guizhou Provincial Key Technology R&D Program(Grant No.QKHZC[2022]YB053)The numerical calculation of the first-principles was supported and assisted by the High-Performance Computing Center of Guizhou University.
文摘The influence mechanism of trace Nb on the corrosion resistance of surface corrosion products of high-strength anti-seismic rebar in the simulated marine environment was studied by combining first-principles calculations with corrosion mass loss method,surface analysis,cross-sectional analysis,quantitative analysis,and electrochemical test.The results demonstrated that the addition of trace Nb effectively improved the compactness and stability of surface corrosion layer of rebar,and the corrosion resistance of corrosion layer increased with the increase in Nb content.The beneficial effect of Nb content on the corrosion layer summarized two important key points.Firstly,the addition of Nb was beneficial to promoting the improvement in the structural stability of α-FeOOH,and α-FeOOH structure of solid solution Nb atoms was beneficial to strengthening the fixation of Cl atoms,thus increasing α/(β+γ)ratio,total impedance value,and corrosion potential.Secondly,the formation of Nb oxides can not only repair the corrosion layer,but also play a role in the fixation Cl atoms,resulting in the improvement in corrosion resistance of corrosion layer.
基金supported by the Postdoctoral Fellowship Program(Grade A)of China Postdoctoral Science Foundation(No.BX20240429)the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2024ZD1004007)+3 种基金the National Key R&D Program of China(Nos.2022YFC2904502 and 2022YFC2904501)the National Natural Science Foundation of China(No.52204298)the Major Science and Technology Projects in Yunnan Province(No.202202AB080012)the High Performance Computing Center of Central South University。
文摘Herein,a first-principles investigation was innovatively conducted to research the surface oxidation of ZnS-like sphalerite in the absence and presence of H_(2)O .The findings showed that single O_(2) was preferred to be dissociated adsorption on sphalerite surface by generating SAO and Zn AO bonds,and the S atom on the surface was the most energy-supported site for O_(2) adsorption,on which a≡Zn-O-S-O-Zn≡structure will be formed.However,dissociated adsorption of single H_(2)O will not happen.It was preferred to be adsorbed on the top Zn atom on sphalerite surface in molecular form through Zn-O bond.Besides,sphalerite oxidation can occur as if O_(2) was present regardless of the presence of H_(2)O ,and when H_(2)O and O_(2) coexisted,the formation of sulfur oxide(SO_(2) )needed a lower energy barrier and it was easier to form on sphalerite surface than that only O_(2) existed.In the absence of H_(2)O ,when SO_(2) was generated,further oxidation of which would form neutral zinc sulfate.In the presence of H_(2)O ,the formation of SO_(2) on sphalerite surface was easier and the rate of further oxidation to form sulfate was also greater.Consequently,the occurrence of sphalerite oxidation was accelerated.
基金supported by the Fund of Education Department of Shaanxi Provincial Government(No.23JP172)the National Natural Science Foundation of China(No.22309189)financial support from Xiaomi Young Talents Program.
文摘Extensive first-principles calculations have been performed to examine the electrochemical properties of Na-ion-intercalatable heterostructures formed by transitional metal dichalcogenides(MS_(2),where M=Ti,V,Nb and Mo)and blue phosphorus(BlueP),which have been reported as potential anode materials for rechargeable sodium-ion batteries.Upon formation of heterostructures,much improved structural stabilities have observed compared with the pristine MS_(2) and BlueP.Metallic T-TiS_(2),T-MoS_(2),H(T)-VS_(2) and H(T)-NbS_(2) would retain the conductive character after formation of heterostructures with BlueP,however,HTiS_(2)/BlueP and H-MoS_(2)/BlueP would undergo a semiconductor to metallic transition accompanied by Na intercalation.Moreover,the presence of relatively low diffusion barriers ranging from 0.04 eV to 0.08 eV,coupled with the suitable average open-circuit voltage spanning from 0.12 eV to 0.89 eV,guarantee exceptional charge-discharge rates and ensure the safety of battery performance.Among these heterostructures,H(T)-NbS_(2)/BlueP and T-TiS_(2)/BlueP exhibit best Na adsorption ability of up to 4 layers,corresponding to theoretical capacities of 570.2 and 746.7 mAh/g,respectively.These encouraging properties indicate that T-TiS_(2)/BlueP and H(T)-NbS_(2)/BlueP could serve as suitable anode materials for high-performance sodiumion batteries.
基金supported by the National Natural Science Foundation of China(Nos.41474067,12174352).
文摘The lattice thermal conductivity(κ_(latt))of mantle minerals plays a crucial role in the heat flow and temperature distribution within the Earth.MgSiO_(3)akimotoite is stable at the bottom of the mantle transition zone;it transitions to MgSiO_(3)perovskite(MgPv).Inκ_(latt)this work,we carry out a study of the of MgSiO_(3)akimotoite for pressures up to 25 GPa and temperatures up to 2500 K,based onκ_(latt)first-principles calculations combined with lattice dynamics theory.At 300 K and 25 GPa,the of MgSiO_(3)akimotoite is 37.66 W m^(-1)K^(-1),κ_(latt)larger than that of MgPv(13.46 W m^(-1)K^(-1)),which implies that the phase transition explains the reduction in.At 300 K,the pressureκ_(latt)κ_(latt)dependence of is 0.68 W m^(-1)K^(-1)GPa-1,stronger than that of MgPv(0.48 W m^(-1)K^(-1)GPa-1).The azimuthal anisotropy in of MgSiO_(3)akimotoite decreases from 45.5%at 0 GPa to 28.94%at 25 GPa,while the variation trend is opposite to that of MgPv.In MgSiO_(3)κ_(latt)akimotoite,Fe incorporating in the mineral leads to a decrease in and an increase in azimuthal anisotropy.Along the geotherm,theκ_(latt)of MgSiO_(3)akimotoite is lower than that of ringwoodite,which would suggest that MgSiO_(3)akimotoite slows down heat conduction at the bottom of mantle transition zone.These findings are useful for determining the thermal structure of,and understanding heat transfer in,the interior of the Earth.
基金supported by the National Natural Science Foundation of China under Grant No.12404093the China Postdoctoral Science Foundation under Grant No.2021M702915.
文摘As a new layered semiconductor material,Bi_(2)SeO_(5) has shown potential in the field of ultraviolet electronic devices in recent years because of its unique crystal structure and wide band gap.In this paper,the crystal structure,electronic structure,and thermodynamic stability of Bi_(2)SeO_(5) are studied based on first-principles calculations.The ultraviolet luminescence property of BiSe defect is predicated from defect property,which provides theoretical basis for experimental design of high-performance Bi2SeO5 photoelectric devices.
基金support from the National Natural Science Foundation of China(52174290).
文摘To explain the influence mechanism of MgO on the consolidation and reduction characteristics of roasted iron pellets,the properties and structure of pellets were investigated from multi-dimensions.It indicated that the MgO addition decreased the reduction swelling index(RSI)and reduction degree of pellets in both CO and H_(2)atmospheres.During the stepwise reduction process of Fe2O3→Fe3O4→FeO,the reduction behaviour of pellets in CO and H_(2)was similar,while the reduction rate of pellets in H_(2)atmosphere was almost twice as high as that in CO atmosphere.During the stepwise reduction process of FeO→Fe,the RSI of pellets showed a logarithmic increase in CO atmosphere and a linear decrease in H_(2)atmosphere.As investigated by first-principles calculations,C and Fe mainly formed chemical bonds,and the CO reduction process released energy,promoting the formation of iron whiskers.However,H and Fe produced weak physical adsorption,and the H_(2)reduction process was endothermic,inhibiting the generation of iron whiskers.With Mg2+doping in FexO,the nucleation region of iron whiskers expanded in CO reduction process,and the morphology of iron whiskers transformed from“slender”to“stocky,”reducing RSI of the pellets.
基金financially supported by the National Natural Science Foundation of China(No.52171141)the Fund of Natural Science Special(Special Post)Research Foundation of Guizhou University(No.2023-032)the Fund of Research Foundation of Guizhou University(No.2024-33)
文摘Currently,the development of high-efficiency two-dimensional(2D)transistors is still hindered by the limited availability of suitable semiconductors and the contact resistance between the metal contact and the 2D semiconductors.Endeavors to address these challenges are highly desired.In this study,we conducted a comprehensive exploration of the potential 2D transition metal dinitrides(TMN_(2)s,TM=all the 3d,4d and 5d transition metals)with hexagonal(h-)and trigonal(t-)phases through systematic first-principles calculations.Among all h-TMN_(2)s and t-TMN_(2)s structures,we identified 8 TMN_(2)s that exhibit dynamical and thermal stability at room temperature.Of these,the h-TiN_(2),h-ZrN_(2)and h-HfN_(2)arefound to be semiconductors,and their direct bang gap,calculated at the HSE06 level,are 1.48,1.96 and 2.64 eV,respectively.The electron and hole mobility(μ_(e)andμ_(h))of these three structures exceed 1×10^(4)and1×10^(3)cm^(2)·V^(-1)·s^(-1),respectively.Especially,theμeof h-TiN_(2)amounts to 2.5×10^(4)cm^(2)·V^(-1)·s^(-1),and theμhof h-ZrN_(2)reaches to 7.7×10^(3)cm^(2)·V^(-1)·s^(-1).Importantly,unlike the MoS_(2)system,h-TMN_(2)forms Ohm contacts with both transition metals(e.g.,Cu)and 2D metals(e.g.,graphene),with tunneling possibilities exceeding 50%in the Cu system.These outstanding intrinsic semiconductor properties and contact characteristics exhibited by h-TMN_(2)highlight the immense potential of transition metal dinitrides in driving the advancement of next-generation information devices.Our findings significantly broaden the range of 2D materials and provide valuable insights for the development of high-eficiency 2D information devices.
基金sponsored by Major Science and Technology Project of the Yunnan Provincial Department of Science and Technology(202502AB080011)Yunnan Province Industrial High-Tech Project(202403AA080015)Special Science and Technology Research Project of Yunnan Province for the South Asia and Southeast Asia Innovation Center(202403AP140006).
文摘Ag/Al_(2)O_(3) powders are highly effective catalytic materials utilized in the epoxidation of ethylene to produce ethylene oxide.One of the critical challenges in this catalytic process is the stability of nano-sized Ag particles,especially during high-temperature catalysis.However,this issue can be effectively addressed through in-situ reaction synthesis.To gain a deeper understanding of the underlying mechanisms,the phase transformation process and the thermodynamic mechanism of the oxidation reaction in the Ag/Al_(2)O_(3) system have been investigated using firstprinciples thermodynamic calculations in conjunction with traditional thermodynamic data.These calculations,whose accuracy has been verified,provide valuable insights into the behavior of Ag and Al under different conditions.The results indicate that,during AgAl solid-solution oxidation,Ag-containing Al preferentially forms the stable intermediate phase Ag2Al instead of undergoing direct oxidation;this pathway becomes thermodynamically more favorable at higher Ag concentrations.With increasing temperature,Ag2Al is further oxidized to yield Ag and Al_(2)O_(3).It is also found that above 237℃,Ag2O and AgAlO2 become unstable.The overall reaction pathway is solid solution→Ag2Al→Ag+Al_(2)O_(3).This comprehensive study provides a robust theoretical calculation basis for the development and optimization of in-situ reaction-synthesized Ag/Al_(2)O_(3) powder composite materials,which have significant potential for practical applications in catalysis.
