检索结果-南通市图书馆

Flexoelectricity enhanced water splitting and hydrogen evolution reaction on grain boundaries of monolayer transition metal dichalcogenides

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2022年第2期15卷 978-984页

作者： Mingjie Pu Dong Wang Zhuhua Zhang Yufeng Guo Wanlin Guo State Key Laboratory of Mechanics and Control of Mechanical Structures and MOE Key Laboratory for Intelligent Nano Materials and Devices College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China

Our extensive first-principles calculations reveal that the chemical activities of monolayer transition metal dichalcogenides(TMDs)MX_(2)(M=Mo or W,and X=Te,Se,or S)for water splitting and hydrogen evolution are modified and promoted on their grain boundaries(GBs)when in-plane tensile loadings are *** with monolayer TMDs without GBs,the flexoelectricity induced by nonuniform deformation and strain gradient significantly enhances the charge polarizations of X and M atoms at the GB sites of monolayer TMDs,which facilitates the dissociation of water molecules on the GB sites and reduces the reaction barrier of hydrogen evolution *** energy barriers of splitting water molecules and hydrogen adsorption free energies on the GB sites decrease with increasing the flexoelectric *** results highlight an attractive way of utilizing the flexoelectric effect of GB-containing TMDs to improve their surface catalytic capability for hydrogen generation.

关键词： flexoelectricity transition metal dichalcogenides grain boundaries water splitting hydrogen evolution reaction

Formation of I1 stacking fault by deformation defect evolution from grain boundaries in Mg

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2022年第10期10卷 2717-2729页

作者： Yong-Jie Hu Vaidehi Menon Liang Qi Department of Materials Science and Engineering University of MichiganAnn Arbor 48109USA Department of Materials Science and Engineering Drexel UniversityPhiladelphia 19104USA

I_(1)stacking faults(SFs)in Mg alloys are regarded as the nucleation sites ofdislocations that are critical for these alloys to achieve high *** it was proposed that the formation of I_(1)SFs requires the accumulations of a large number of vacancies,which are difficult to achieve at low *** this study,molecular dynamics(MD)and molecular statics(MS)simulations based on empirical interatomic potentials were applied to investigate the deformation defect evolutions from the symmetric tilt grain boundaries(GBs)in Mg and Mg-Y alloys under external loading along-*** results show the planar faults(PFs)on Pyramidal I planes first appear due to the nucleation and glide of(1/2 c+p)partial dislocations from GBs,where p=1/3(1010).These partial dislocations with pyramidal PFs interact with other defects,including pyramidal PFs themselves,GBs,and ppartial dislocations,generating a large amount of I_(1)*** analyses show the nucleation and growth of I_(1)SFs are achieved by atomic shuffle events and deformation defect reactions without the requirements of vacancy *** simulations also suggest the Y clusters at GBs can reduce the critical stress for the formation of pyramidal PFs and I_(1)SFs,which provide a possible reason for the experimental observations that Y promotes thedislocation activities.

关键词： Magnesium alloys I1 stacking faults dislocations grain boundaries Defect nucleation and evolution Molecular dynamics simulations

The Role of grain boundaries in Organic-Inorganic Hybrid Perovskite Solar Cells and its Current Enhancement Strategies:A Review

在线全文

学校读者我要写书评

暂无评论

Energy & Environmental Materials 2024年第4期7卷 175-204页

作者： Jindan Zhang Shicheng Tang Mengqi Zhu Zhenghong Li Zhibin Cheng Shengchang Xiang Zhangjing Zhang College of Chemistry and Materials Science Fujian Key Laboratory of Polymer MaterialsFujian Normal University32 Shangsan RoadFuzhou 350007China

grain boundaries(GBs)in perovskite polycrystalline films are the most sensitive place for the formation of the defect states and the accumulation of ***,abundant works have been carried out to explore their properties and then try to solve the induced ***,two important issues ***,the role of GBs in charge carrier dynamics is unclear due to their component complexity/defect tolerance nature and the insufficiency in testing *** works conclude that GBs are benign,while others consider GBs as carrier recombination *** for sure are the deterioration in ion transport and perovskite ***,to solve the known hazards of GBs,a lot of additives have been added to anchoring ions and passivate *** in most of those works,GBs and perovskite surfaces are treated in the same manner ignoring the fact that GB is essentially a homogeneous junction in a narrow and slender space,while surface is a heterogeneous junction with a stratified *** this review,we focus on works insight into GBs and additives for ***,we also discuss the prospects of the maturity of GB exploration toward upscaling the manufacture of perovskite photovoltaic and related optoelectronic devices.

关键词： additives charge carrier dynamics grain boundaries perovskite solar cells

Microstructure of Carbides at grain boundaries in Nickel Based Superalloys

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2012年第11期28卷 1031-1038页

作者： Xiaoming Dong Xiaoli Zhang Kui Du Yizhou Zhou Tao Jin Hengqiang Ye Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

It is well known that carbides at grain boundaries play an nickel based superalloys. In order to deeply understand the mportant role in affecting mechanical properties of relationship between grain boundary structures and properties, in this work, we have investigated the microstructure of grain boundaries with different misorienta- tion angles in bicrystals of nickel based superalloys. It is found that the bicrystals with smaller misorientation angles contain denser M23C6 but sparse MC particles at grain boundaries, and this kind of bicrystals presents longer stress rupture lives. It was observed that MC carbides were decorated by M23C6 and M6C particles at grain boundaries. The formation of these carbide particles, therefore, is likely due to the local fluctuation of chemical composition around MC carbides. In addition, the orientation relationships between MC carbides and γ/γ1 matrix were also determined.

关键词： Electron microscopy Ni based superalloys grain boundaries Orientation relationship

Enhancement of oxygen reduction reaction activity by grain boundaries in platinum nanostructures

在线全文

学校读者我要写书评

暂无评论

Nano Research 2020年第12期13卷 3310-3314页

作者： Enbo Zhu Wang Xue Shiyi Wang Xucheng Yan Jingxuan Zhou Yang Liu Jin Cai Ershuai Liu Qingying Jia Xiangfeng Duan Yujing Li Hendrik Heinz Yu Huang Department of Materials Science and Engineering University of CaliforniaLos AngelesCA90095USA School of Materials Science and Engineering Beijing Institute of TechnologyBeijing100081China Department of Chemistry and Biochemistry University of CaliforniaLos AngelesCA90095USA Department of Chemical and Biological Engineering University of Colorado BoulderBoulderCO80309USA Department of Chemistry and Chemical Biology Northeastern UniversityBostonMA02115USA California NanoSystems Institute University of CaliforniaLos AngelesCA90095USA

Systematic control of grain boundary densities in various platinum(Pt)nanostructures was achieved by specific peptide-assisted assembly and coagulation of nanocrystals.A positive quadratic correlation was observed between the oxygen reduction reaction(ORR)specific activities of the Pt nanostructures and the grain boundary densities on their *** to commercial Pt/C,the grain-boundary-rich strain-free Pt ultrathin nanoplates demonstrated a 15.5 times higher specific activity and a 13.7 times higher mass *** studies suggested that the specific activity of ORR was proportional to the resident number and the resident time of oxygen on the catalyst surface,both of which correlate positively with grain boundary density,leading to improved ORR activities.

关键词： oxygen reduction reaction nanowire peptide grain boundaries

Behaviors of Lanthanum and Cerium on grain boundaries in Carbon Manganese Clean Steel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Rare Earths 2007年第4期25卷 485-489页

作者：林勤郭锋朱兴元 Department of Physical Chemistry University of Science and Technology Beijing Inner Mongolia University of Technology Wuhan University of Technology

The behaviors of La and Ce on gram boundaries in carbon manganese clean steel were investigated by high-reso- lution transmission elecetron microscope （HRTEM）, scanning elecetron microscopy（SEM ）, energy dispersive spectrometer （EDS） and X-ray diffraction（XRD） analysis. The existing forms of rare earths （RE） in clean steel were as follows： dissolved in sohd solution, forming inclusion or second phase containing RE （RE-Fe-P, La-P, Fe-La eutectic and Fe-Ce phase）. The dissolved La or Ce segregated at grain boundaries. The segregation of both S and P at gram boundaries was reduced with suitable RE content. The impact toughness of the steel was improved obviously. La and Ce had effecets on purifying molten steel and modifying inclusions in clean steel, whereas with excessive La or Ce, La-Fe-P, La-P and Fe-La eutecetic phase or Ce-Fe-P and Fe-Ce intermetallic compound would form along grain boundaries, causing the impact energy to decrease significantly.

关键词： lanthanum cerium grain boundaries carbon manganese clean steel rare earths

Spatially Resolved Analytical Electron Microscopy at grain boundaries of α-Al_2O_3

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2002年第2期18卷 189-190页

作者： S.Nufer, A.G.Marinopoulos, C.Elsasser, W.Kurtz and M.RuhleMax-Planck-Institut fur Metallforschung, Seestr. 92, D-70174 Stuttgart, Germany [ Manuscript received October 16, 2001] Max-Planck-Inst. für Metall. D-70174 Stuttgart Seestr. 92 Germany

In this work the electronic structure and the impurity excess of the basal and rhombohedral twin grain boundaries are investigated, using electron energy loss spectroscopy (EELS) and energy dispersive X-ray spectroscopy (EDXS). The measurability of electronic structures of the twin grain boundaries are discussed by comparing theoretical density of states (DOS) from bulk material with interfacial DOS, obtained from local density functional theory (LDFT) calculations.

关键词： grain boundaries Alumina (α-Al2O3) Local density function theory (LDFT) Electron energy loss spectroscopy (EELS)

An Elasticity Model Considering grain boundaries and Tensile Orientations for Directionally Solidified Superalloys

在线全文

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2019年第4期36卷 652-662页

作者： XIAO Jianfeng ZHANG Hongjian WEN Weidong CUI Haitao Aero-engine Thermal Environment and Structure Key Laboratory of Ministry of Industry and Information Technology Jiangsu Province Key Laboratory of Aerospace Power SystemState Key Laboratory of Mechanics and Control of Mechanical StructuresCollege of Energy & Power EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China

In order to investigate the elastic properties of directionally solidified(DS)superalloys,an elasticity model called boundaries elastic model(GBE model),considering grain boundaries and tensile orientations,is proposed in this *** assumptions are adopted in the GBE model:(1)The displacement of grains,which moves along the perpendicular direction,is restricted by the grain boundaries;(2)grain boundaries influence region(GBIR)is formed around the grain *** on the single crystal(SC)calculation method of elastic properties,the GBE model can well predict macroscopic equivalent elastic modulus(Young’s modulus)of DS superalloys under different tensile orientations *** demonstrate the correctness of the GBE model,3D finite element simulation is adopted and tensile experiments on a Ni3Al?base DS superalloy(IC10)along five tensile orientations are carried ***,the grain boundaries are observed by light microscopy and transmission electron microscope(TEM).Therefore,the GBE model is proved to be feasible by comparing the simulated results with the experiments.

关键词： directionally solidified superalloys single crystal Young’s modulus grain boundaries

The role of grain boundaries in solid-state Li-metal batteries

在线全文

学校读者我要写书评

暂无评论

Materials Futures 2023年第1期2卷 104-120页

作者： Emily Milan Mauro Pasta Department of Materials University of OxfordOxford OX13PHUnited Kingdom The Faraday Institution Didcot OX110RAUnited Kingdom

Despite the potential advantages promised by solid-state batteries,the success of solid-state electrolytes has not yet been fully *** is due in part to the lower ionic conductivity of solid *** many solid superionic conductors,grain boundaries are found to be ionically resistive and hence contribute to this lower ionic ***,in spite of the hope that solid electrolytes would inhibit lithium filaments,in most scenarios their growth is still observed,and in some polycrystalline systems this is suggested to occur along grain *** is apparent that grain boundaries affect the performance of solid-state electrolytes,however a deeper understanding is *** this perspective,the current theories relating to grain boundaries in solid-state electrolytes are explored,as well as addressing some of the challenges which arise when trying to investigate their *** are presented as a possible solution to reduce the effect of grain boundaries in *** research directions are suggested which will aid in both understanding the role of grain boundaries,and diminishing their contribution in cases where they are detrimental.

关键词： solid electrolytes grain boundaries lithium growth glasses