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Comparison of formation and evolution of radiation-induced defects in pure Ni and Ni-Co-Fe medium-entropy alloy

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Chinese Physics B 2022年第12期31卷 365-373页

作者： Lin Lang huiqiu deng Jiayou Tao Tengfei Yang Yeping Lin Wangyu Hu Key Laboratory of Hunan Province on Information Photonics and Freespace Optical Communications School of Physics and Electrical SciencesHunan Institute of Science and TechnologyYueyang 414006China School of Physics and Electronics Hunan UniversityChangsha 410082China College of Materials Science and Engineering Hunan UniversityChangsha 410082China

High-entropy alloys(HEAs)and medium-entropy alloys(MEAs)have attracted a great deal of attention for developing nuclear materials because of their excellent irradiation ***,formation and evolution of radiation-induced defects in Ni Co Fe MEA and pure Ni are investigated and compared using molecular dynamics *** is observed that the defect recombination rate of ternary Ni Co Fe MEA is higher than that of pure Ni,which is mainly because,in the process of cascade collision,the energy dissipated through atom displacement decreases with increasing the chemical ***,the heat peak phase lasts longer,and the recombination time of the radiation defects(interstitial atoms and vacancies)is likewise longer,with fewer deleterious ***,by studying the formation and evolution of dislocation loops in Ni-Co-Fe alloys and Ni,it is found that the stacking fault energy in Ni-Co-Fe decreases as the elemental composition increases,facilitating the formation of ideal stacking fault tetrahedron ***,these findings shed new light on studying the formation and evolution of radiation-induced defects in MEAs.

关键词： medium-entropy alloy molecular dynamics simulations radiation-induced defects stacking fault energy

Wire-in-Wire TiO_(2)/C Nanofibers Free-Standing Anodes for Li-Ion and K-Ion Batteries with Long Cycling Stability and High Capacity

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Nano-Micro Letters 2021年第7期13卷 91-104页

作者： Die Su Yi Pei Li Liu Zhixiao Liu Junfang Liu Min Yang Jiaxing Wen Jing Dai huiqiu deng Guozhong Cao National Base for International Science and Technology Cooperation National Local Joint Engineering Laboratory for Key Materials of New Energy Storage BatteryHunan Province Key Laboratory of Electrochemical Energy Storage and ConversionSchool of ChemistryXiangtan UniversityXiangtan 411105People’s Republic of China Department of Materials Science and Engineering University of WashingtonSeattleWA 98195-2120USA College of Materials Science and Engineering Hunan UniversityChangsha 410082People’s Republic of China School of Physics and Electronics Hunan UniversityChangsha 410082People’s Republic of China

Wearable and portable mobile phones play a critical role in the market, and one of the key technologies is the flexible electrode with high specific capacity and excellent mechanical flexibility. Herein, a wire-in-wire TiO_(2)/C nanofibers (TiO_(2) ww/CN) film is synthesized via electrospinning with selenium as a structural inducer. The interconnected carbon network and unique wire- in-wire nanostructure cannot only improve electronic conductivity and induce effective charge transports, but also bring a superior mechanic flexibility. Ulti-mately, TiO_(2) ww/CN film shows outstanding electrochemical performance as free-standing electrodes in Li/K ion batteries. It shows a discharge capacity as high as 303 mAh g^(−1) at 5 A g^(−1) after 6000 cycles in Li half-cells, and the unique structure is well-reserved after long-term cycling. Moreover, even TiO_(2) has a large diffusion barrier of K^(+), TiO_(2) ww/CN film demonstrates excellent perfor-mance (259 mAh g^(−1) at 0.05 A g^(−1) after 1000 cycles) in K half-cells owing to extraordinary pseudocapacitive contribution. The Li/K full cells consisted of TiO_(2) ww/CN film anode and LiFePO_(4)/Perylene-3,4,9,10-tetracarboxylic dianhydride cathode possess outstanding cycling stability and demonstrate practical application from lighting at least 19 LEDs. It is, therefore, expected that this material will find broad applications in portable and wearable Li/K-ion batteries.

关键词： Free-standing TiO_(2)/C nanofiber Li-ion battery K-ion battery First-principles calculation Full cells

Shock-induced migration of asymmetry tilt grain boundary in iron bicrystal: A case study of Σ3 [110]

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Chinese Physics B 2019年第12期28卷 273-279页

作者： Xueyang Zhang Kun Wang Jun Chen Wangyu Hu Wenjun Zhu Shifang Xiao huiqiu deng Mengqiu Cai Department of Applied Physics School of Physics and ElectronicsHunan UniversityChangsha 410082China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing 100088China Center for Applied Physics and Technology Peking UniversityBeijing 100087China College of Materials Science and Engineering Hunan UniversityChangsha 410082China National Key Laboratory of Shock Wave and Detonation Physics Institute of Fluid PhysicsMianyang 621900China

Many of our previous studies have discussed the shock response of symmetrical grain boundaries in iron *** this paper, the molecular dynamics simulation of an iron bicrystal containing Σ3 [110] asymmetry tilt grain boundary(ATGB) under shock-loading is performed. We find that the shock response of asymmetric grain boundaries is quite different from that of symmetric grain boundaries. Especially, our simulation proves that shock can induce migration of asymmetric grain boundary in iron. We also find that the shape and local structure of grain boundary(GB) would not be changed during shock-induced migration of Σ3 [110] ATGB, while the phase transformation near the GB could affect migration of GB. The most important discovery is that the shock-induced shear stress difference between two sides of GB is the key factor leading to GB migration. Our simulation involves a variety of piston velocities, and the migration of GB seems to be less sensitive to the piston velocity. Finally, the kinetics of GB migration at lattice level is discussed. Our work firstly reports the simulation of shock-induced grain boundary migration in iron. It is of great significance to the theory of GB migration and material engineering.

关键词： shock-loading grain boundary migration iron phase transition

A strategy to improve the electrochemical performance of Ni-rich positive electrodes:Na/F-co-doped LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2)

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Chinese Physics B 2021年第7期30卷 184-191页

作者： Hui Wan Zhixiao Liu Guangdong Liu Shuaiyu Yi Fei Gao huiqiu deng Dingwang Yuan Wangyu Hu College of Materials Science and Engineering Hunan UniversityChangsha 410082China School of Physics and Electronics Hunan UniversityChangsha 410082China Department of Nuclear Engineering and Radiological Sciences University of MichiganAnn ArborMI 48109USA

Ni-rich layered lithium transition metal oxides LiNi_xMn_yCo_zO_(2)(1-y-z≥0.6)are promising candidates for cathode materials,but their practical applications are hindered by high-voltage instability and fast capacity *** density functional theory calculations,we demonstrate that Na-,F-doping,and Na/F-co-doping can stabilize the structure and result into a higher open circuit voltage than pristine LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2)(NMC622)during the charging process,which may attain greater discharge capacity.F doping may inhibit the diffusion of Li ions at the beginning and end of charging;Na doping may improve Li ion diffusion due to the increase in Li layer spacing,consistent with prior ***/F-codoping into NMC622 promotes rate performance and reduces irreversible phase transitions for two reasons:(i)a synergistic effect between Na and F can effectively restrain the Ni/Li mixing and then enhances the mobility of Li ions and(ii)Ni/Li mixing hinders the Ni ions to migrate into Li layers and thus,stabilizes the *** study proposes that a layer cathode material with high electrochemical performance can be achieved via rational dopant modification,which is a promising strategy for designing efficient Li ion batteries.

关键词： Li ion batteries ion diffusion Na/F-co-doping first-principles calculations

Density functional theory study of active sites and reaction mechanism of ORR on Pt surfaces under anhydrous conditions

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Chinese Journal of Catalysis 2022年第12期43卷 3126-3133页

作者： Guangdong Liu huiqiu deng Jeffrey Greeley Zhenhua Zeng School of Physics and Electronics Hunan UniversityChangsha 410082HunanChina Davidson School of Chemical Engineering Purdue UniversityWest LafayetteIN 47907USA

Identifying active sites and catalytic mechanism of the oxygen reduction reaction under anhydrous conditions are crucial for the development of next generation proton exchange membrane fuel cells(PEMFCs)operated at a temperature>100℃.Here,by employing density functional theory calculations,we studied ORR on flat and stepped Pt(111)surfaces with both(110)and(100)type of *** found that,in contrast to ORR under hydrous conditions,(111)terrace sites are not active for ORR under anhydrous conditions,because of weakened binding of ORR intermediates induced by O*accumulation on the *** the other hand,step edges,which are generally not active for ORR under hydrous conditions,are predicted to be the active sites for ORR under anhydrous *** them,(110)type step edge with a unique configuration of accumulated O stabilizes O_(2)adsorption and facilitates O_(2)dissociation,which lead an overpotential<0.4 *** improve ORR catalysts in high-temperature PEMFCs,it is desirable to maximize(110)step edge sites that present between two(111)facets of nanoparticles.

关键词： Oxygen reduction Active site Anhydrous condition High-temperature PEMFCs Density functional theory

Modification of short-range repulsive interactions in ReaxFF reactive force field for Fe–Ni–Al alloy

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Chinese Physics B 2021年第8期30卷 113-119页

作者： Huaqiang Chen Lin Lang Shuaiyu Yi Jinlong Du Guangdong Liu Lixia Liu Yufei Wang Yuehui Wang huiqiu deng Engang Fu State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China Department of Applied Physics School of Physics and ElectronicsHunan UniversityChangsha 410082China Department of Chemistry and Biology University of Electronic Science and Technology of China Zhongshan InstituteZhongshan 528402China

The short-range repulsive interactions of any force field must be modified to be applicable for high energy atomic collisions because of extremely far from equilibrium state when used in molecular dynamics(MD)*** this work,the short-range repulsive interaction of a reactive force field(ReaxFF),describing Fe-Ni-Al alloy system,is well modified by adding a tabulated function form based on Ziegler-Biersack-Littmark(ZBL)*** modified interaction covers three ranges,including short range,smooth range,and primordial *** short range is totally predominated by ZBL *** primordial range means the interactions in this range is the as-is ReaxFF with no *** smooth range links the short-range ZBL and primordial-range ReaxFF potentials with a taper *** energies and forces are guaranteed to be continuous,and qualified to the consistent requirement in *** modified force field is applicable for simulations of energetic particle bombardments and reproducing point defects'booming and recombination effectively.

关键词： molecular dynamics force field modification Fe–Ni–Al alloy irradiation

Vacancies and Antisites in B2 FeAl and DO_3 Fe_3Al with a Modified Analytic EAM Model

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Journal of Materials Science & Technology 2001年第6期17卷 601-604页

作者： Xiaolin SHU, Wan gyu HU, Hanning XIAO and huiqiu deng College of Materials Science and Engineering, Hunan University, Changsha 410082, China Ban gwei ZHANG International Centre of Materials Physics, Chinese Academy of Sciences, S Hunan Univ Coll Mat Sci & Engn Changsha 410082 Peoples R China Chinese Acad Sci Int Ctr Mat Phys Shenyang 110016 Peoples R China

A simple modified analytic EAM model for bcc Fe and fcc Al was used to calculate the lattice constant and elastic constants of B2 FeAl and DO3 Fe3Al alloys. The formation energies of ... 详细信息

A simple modified analytic EAM model for bcc Fe and fcc Al was used to calculate the lattice constant and elastic constants of B2 FeAl and DO3 Fe3Al alloys. The formation energies of vacancy and antisite were also calculated. The present calculations are in agreement with the experimental data and the theoretical results obtained by other authors.

关键词： Al DO Fe Vacancies and Antisites in B2 FeAl and DO3 Fe3Al with a Modified Analytic EAM Model EAM

核-壳结构Ag-Au纳米颗粒合金化行为的分子动力学

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稀有金属材料与工程 2013年第11期42卷 2321-2325页

作者：党敏肖时芳邓辉球邓磊胡望宇湖南大学湖南长沙410082

利用分子动力学方法和改进分析型嵌入原子势函数模拟了核-壳结构Ag-Au纳米颗粒的合金化行为,从原子扩散、微观结构演变以及合金化程度等方面对比分析了壳层厚度对合金化行为的影响。结果表明,壳层较薄时,核-壳界面处原子扩散现象显著,... 详细信息

利用分子动力学方法和改进分析型嵌入原子势函数模拟了核-壳结构Ag-Au纳米颗粒的合金化行为,从原子扩散、微观结构演变以及合金化程度等方面对比分析了壳层厚度对合金化行为的影响。结果表明,壳层较薄时,核-壳界面处原子扩散现象显著,内核表现出多面体形貌,表层Au、Ag原子完全混合。壳层较厚时,表面原子以扩散为主,整个颗粒表面为多面体结构,但内核保持初始球状结构。通过层错生长方式使形貌发生了改变。壳层越薄,体系合金化程度越高。

关键词：纳米颗粒合金化行为核-壳结构分子动力学

Robust Pseudo-capacitive Li-I2 Battery Enabled by Catalytic, Adsorptive N-doped Graphene Interlayer

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Robust Pseudo-capacitive Li-I2 Battery Enabled by Catalytic,...