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Intrinsic mechanical behavior of MgAgSb thermoelectric material:An ab initio study

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Journal of Materiomics 2020年第1期6卷 24-32页

作者： Guodong Li Qi An Umut Aydemir Sergey I.Morozov Bo Duan Pengcheng Zhai Qingjie Zhang william a.goddard Ⅲ Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics School of ScienceWuhan University of TechnologyWuhan430070China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan430070China Department of Chemical and Materials Engineering University of Nevada RenoRenoNV89557USA Department of Chemistry Koc UniversitySariyerIstanbul34450Turkey Boron and Advanced Materials Research Center Koc UniversitySariyerIstanbul34450Turkey Department of Computer Simulation and Nanotechnology South Ural State UniversityChelyabinsk454080Russia Materials and Process Simulation Center California Institute of TechnologyPasadenaCA91125USA

α-MgAgSb based thermoelectric(TE)device attracts much attention for its commercial application because it shows an extremely high conversion efficiency of ~8.5% under a temperature difference of 225 ***,the mechanical behavior of α-MgAgSb is another serious consideration for its engineering ***,we apply density functional theory(DFT)simulations to examine the intrinsic mechanical properties of all three MgAgSb phases,including elastic properties,shear-stress-shear-strain relationships,deformation and failure mechanism under ideal shear and biaxial shear *** find that the ideal shear strength of α-MgAgSb is 3.25 GPa along the most plausible(100)slip *** strength is higher than that of β-MgAgSb(0.80 GPa)and lower than that of γ-MgAgSb(3.43 GPa).The failure of α-MgAgSb arises from the stretching and breakage of MgeSb bond α-MgAgSb under pure shear load,while it arises from the softening of MgeAg bond and the breakage of AgeSb bond under biaxial shear *** suggests that the deformation mechanism changes significantly under different loading conditions.

关键词： MgAgSb thermoelectric materials Density functional theory Ideal strength Deformation mechanism

Ductile deformation mechanism in semiconductor α-Ag_(2)S

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npj Computational Materials 2018年第1期4卷 289-294页

作者： Guodong Li Qi An Sergey I.Morozov Bo Duan william a.goddard III Qingjie Zhang Pengcheng Zhai G.Jeffrey Snyder State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology430070 WuhanChina Department of Materials Science and Engineering Northwestern UniversityEvanstonIL 60208USA Department of Chemical and Materials Engineering University of Nevada RenoRenoNV 89557USA Department of Computer Simulation and Nanotechnology South Ural State UniversityChelyabinsk 454080Russia Materials and Process Simulation Center California Institute of TechnologyPasadenaCA 91125USA

Inorganic semiconductor α-Ag_(2)S exhibits a metal-like ductile behavior at room temperature,but the origin of this high ductility has not been fully explored *** on density function theory simulations on the intrinsic mechanical properties of α-Ag_(2)S,its underlying ductile mechanism is attributed to the following three factors:(i)the low ideal shear strength and multiple slip pathways under pressure,(ii)easy movement of Ag–S octagon framework without breaking Ag−S bonds,and(iii)a metallic Ag−Ag bond forms which suppresses the Ag-S frameworks from slipping and holds them *** easy slip pathways(or easy rearrangement of atoms without breaking bonds)in α-Ag_(2)S provide insight into the understanding of the plastic deformation mechanism of ductile semiconductor materials,which is beneficial for devising and developing flexible semiconductor materials and electronic devices.

关键词： deformation ductile ductility

金属Pd催化NO还原形成NH_(3),N_(2)O和N_(2)的原子机制

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Chinese Journal of Chemical Physics 2023年第1期36卷 94-102,I0034-I0042,I0002页

作者：于沛平吴宇杨昊谢森 william a.goddard Ⅲ 程涛苏州大学功能纳米与软物质研究院江苏省碳基功能材料与器件高技术研究重点实验室苏州215123 美国加州理工学院美国光合成联合研究中心加利福利亚91125

工业污染物NO是对环境和人类健康的潜在威胁.因此,将NO选择性地催化还原成无害的N_(2)、NH_(3)或N_(2)O气体是非常有意义的.在许多催化剂中,金属钯已被证明在将NO还原为N_(2)的选择性方面是最有效的.然而,NO在Pd上的还原机制,特别是N-N... 详细信息

工业污染物NO是对环境和人类健康的潜在威胁.因此,将NO选择性地催化还原成无害的N_(2)、NH_(3)或N_(2)O气体是非常有意义的.在许多催化剂中,金属钯已被证明在将NO还原为N_(2)的选择性方面是最有效的.然而,NO在Pd上的还原机制,特别是N-N键的形成途径仍然不清楚,阻碍了新型催化剂的开发.本文基于密度泛函理论的量子力学计算,报道了还原NO形成NH_(3)、N_(2)O和N_(2)的反应路径中的所有基本反应步骤.结果表明,N_(2)O的形成是通过Eley-Rideal反应机制进行的.即在较高的NO^(*)表面覆盖率时,通过将一个吸附的NO^(*)与一个来自溶剂或气相的非吸附的NO结合,形成dimer-(NO)_(2)^(*)中间物,其N-N耦合势垒较低(0.58 eV).发现了dimer-(NO)_(2)^(*)将继续与溶剂中的NO反应,形成N_(2)O,这一点本文发现之前没有报道过.随着NO的消耗和溶剂中N_(2)O^(*)的形成,Langmuir-Hinshelwood(L-H)机制将占主导地位,N_(2)O^(*)将在低化学势垒(0.42 eV)下被还原,从而形成N_(2).相比之下,NH_(3)完全由L-H反应形成,它具有较高的化学势垒(0.87 eV).此外,本文报道了通过在NO^(*)吸附位点掺入另一个金属原子(M)以形成M/Pd,通过考察其对N-N键形成能和N_(2)^(*)结合能的影响,从而实现对产物选择性的调控.

关键词：一氧化氮还原计算模型电化学反应

Sulfur-doped graphene anchoring of ultrafine Au25 nanoclusters for electrocatalysis

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Nano Research 2021年第10期14卷 3509-3513页

作者： Mufan Li Bei Zhang Tao Cheng Sunmoon Yu Sheena Louisia Chubai Chen Shouping Chen Stefano Cestellos-Blanco william Agoddard III Peidong Yang Department of Chemistry University of CaliforniaBerkeleyCalifornia 94720USA Department of Materials Science and Engineering University of CaliforniaBerkeleyCalifornia 94720USA Chemical Science Division Lawrence Berkeley National LaboratoryBerkeleyCalifornia 94720USA Kavli Energy NanoScience Institute BerkeleyCalifornia 94720USA Materials and Process Simulation Center California Institute of TechnologyPasadenaCalifornia 91125USA

The biggest challenge of exploring the catalytic properties of under-coordinated nanoclusters is the issue of *** demonstrate herein that chemical dopants on sulfur-doped graphene(S-G)can be utilized to stabilize ultrafine(sub-2 nm)Au_(25)(PET)18 clusters to enable stable nitrogen reduction reaction(NRR)without significant structural *** Au_(25)@S-G exhibits an ammonia yield rate of 27.5μgNH_(3)·mgAu^(-1)·h^(-1)at-0.5 V with faradic efficiency of 2.3%.More importantly,the anchored clusters preserve~80%NRR activity after four days of continuous operation,a significant improvement over the 15%remaining ammonia production rate for clusters loaded on undoped graphene tested under the same *** labeling experiments confirmed the ammonia was a direct reaction product of N2 feeding gas instead of other chemical ***-situ X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy of post-reaction catalysts reveal that the sulfur dopant plays a critical role in stabilizing the chemical state and coordination environment of Au atoms in *** ReaxFF molecular dynamics(RMD)simulation confirmed the strong interaction between Au nanoclusters(NCs)and *** substrate-anchoring process could serve as an effective strategy to study ultrafine nanoclusters’electrocatalytic behavior while minimizing the destruction of the under-coordinated surface motif under harsh electrochemical reaction conditions.

关键词： gold nanoclusters sulfur-doped graphene nitrogen reduction reaction electrocatalysis anchoring effect

通过实验表征、计算机辅助结构解析和原子模拟对切尔西土壤腐植酸进行三维结构模拟

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腐植酸 2022年第5期 60-75页

作者： Mamadou S.Diallo Andre Simpson Paul Gassman Jean Loup Faulon James H.Johnson william a.goddard Patrick G.Hatcher 袁飞巩冠群(译) 加州理工学院贝克曼研究所139-74材料和工艺模拟中心加利福尼亚州帕萨迪纳91125 霍华德大学土木工程系华盛顿特区20059 多伦多大学斯卡伯勒学院物理科学系加拿大多伦多MIC 1A4 太平洋西北国家实验室环境分子科学实验室华盛顿州里奇兰99352 桑迪亚国家实验室计算生物学和进化计算部加利福尼亚州利弗莫尔94551-0969 俄亥俄州立大学化学系俄亥俄州哥伦布43210 中国矿业大学化工学院徐州221116

本文描述了一个用于开发腐植酸(HAs)三维结构模型的完整的实验和计算框架。这种方法结合了实验表征、计算机辅助结构解析(CASE)和原子模拟,生成与HAs的分析数据和热力学/结构特性相一致的所有三维结构模型或这些模型的代表性样本。从元... 详细信息

本文描述了一个用于开发腐植酸(HAs)三维结构模型的完整的实验和计算框架。这种方法结合了实验表征、计算机辅助结构解析(CASE)和原子模拟,生成与HAs的分析数据和热力学/结构特性相一致的所有三维结构模型或这些模型的代表性样本。从元素分析、漫反射傅里叶变换红外光谱、一维/二维~1H和C溶液核磁共振光谱和电喷雾电离四极杆飞行时间质谱(ESI QqTOF MS)中获得的结构数据,结合CASE程序SIGNATURE,生成了切尔西土壤腐植酸(HA)所有的三维结构模型。这些模型随后被用作初始三维结构,进行恒温恒压分子动力学模拟,以估算其体密度和Hildebrand溶解度参数。只有少数模型异构体显示出的分子组成和体热力学性质与实验数据一致。这些模型异构体的等摩尔混合物的模拟C核磁共振光谱与切尔西土壤HA的实测光谱相比有较好的一致性。

关键词：土壤多肽和蛋白质分子模拟碳水化合物核磁共振光谱

Suppression of discontinuous precipitation and strength improvement by Sc doping in Cu-6 wt%Ag alloys

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Journal of Materials Science & Technology 2023年第4期135卷 80-96页

作者： Bailing An Rongmei Niu Yan Xin william LStarch Zhaolong Xiang Yifeng Su Robert E.goddard Jun Lu Theo M.Siegrist Engang Wang Ke Han Key Laboratory of Electromagnetic Processing of Materials(Ministry of Education) Northeastern UniversityShenyang 110819China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China School of Metallurgy Northeastern UniversityShenyang 110819China National High Magnetic Field Laboratory Florida State UniversityTallahasseeFL 32310USA Oak Ridge National Laboratory Oak RidgeTN 37830USA FAMU-FSU College of Engineering TallahasseeFL 32310USA

In low-Ag Cu matrix alloys,the presence of coarse discontinuous precipitates may limit *** demonstrated that discontinuous precipitation was suppressed,and continuous precipitation was en-hanced by the doping of Cu-6 wt%Ag with Sc.A high-volume fraction of continuous precipitates,which nucleated on{111}planes,led to a 55 MPa increase in strength,with only a slight decrease in electri-cal *** addition of Sc inhibited the nucleation of discontinuous precipitates by causing the Sc and the Ag to co-segregate onto grain boundaries,thus forming a thin intermetallic compound layer between *** deformation,both discontinuous and continuous precipitates were drawn into Ag *** combination of deformation strain and doping caused an increase in density and a decrease in the diameter of Ag fibers,resulting in about 205 MPa increase in doped samples when the deformation strain reached *** thinner,denser Ag fibers in the doped samples also caused higher electron scatter-ing at interfaces,leading to electrical conductivity that was 11%IACS lower than in non-doped *** reference,100%IACS(International Annealed Copper Standard)is equivalent to 1.7241μΩcm.

关键词： Sc doping Grain boundary segregation Precipitation Strength Electrical conductivity Plastic deformation

Optically monitoring and controlling nanoscale topography during semiconductor etching

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Light(Science & Applications) 2012年第1期1卷 41-46页

作者： Chris Edwards Amir Arbabi Gabriel Popescu Lynford L goddard Department of Electrical and Computer Engineering University of Illinois at Urbana-ChampaignUrbanaIL 61801USA

We present epi-diffraction phase microscopy(epi-DPM)as a non-destructive optical method for monitoring semiconductor fabrication processes in real time and with nanometer level *** method uses a compact Mach–Zehnder interferometer to recover quantitative amplitude and phase maps of the field reflected by the *** low temporal noise of 0.6 nm per pixel at 8.93 frames per second enabled us to collect a three-dimensional movie showing the dynamics of wet etching and thereby accurately quantify non-uniformities in the etch rate both across the sample and over *** displaying a gray-scale digital image on the sample with a computer projector,we performed photochemical etching to define arrays of microlenses while simultaneously monitoring their etch profiles with epi-DPM.

关键词： microscopy nanoscale metrology photochemical etching quantitative phase imaging semiconductor process monitoring

Field load testing of copper extraction aeration pipes under simulated high heap pile

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International Journal of Mining Science and Technology 2013年第5期23卷 751-756页

作者： Shad M.Sargand Teruhisa Masada Jim goddard Civil Engineering Department Ohio University

Recently a research team at Ohio University,USA,conducted a unique full-scale feld load test to simulate the aeration pipe installations at a copper extraction mine operated in *** overliner material taken from the mine was used in recreating the in situ *** heaters were utilized to raise the temperature inside each pipe to simulate the essential element of the copper extraction *** maximum vertical deflection reached by the test pipes was close to 20%,when the simulated heap pile height was 80 *** plastic pipes and the overliner material were also tested in the *** on the results,the maximum heap pile fll depth was recommended for the aeration *** results indicated that the vertical deflection was the primary performance index for the aeration pipes installed in heap piles at ***,the pipe made of polypropylene resin was super.

关键词： Copper extraction Aeration pipe Heap pile Field load test Laboratory testing

Realization of palladium-based optomechanical cantilever hydrogen sensor

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Microsystems & Nanoengineering 2017年第1期3卷 367-372页

作者： Steven J.McKeown Xiaozhen Wang Xin Yu Lynford L.goddard Photonic Systems Laboratory Department of Electrical and Computer EngineeringMicro and Nanotechnology LabUniversity of Illinois at Urbana-Champaign208 North Wright StreetMNTL 2254UrbanaIL 61801USA

Hydrogen has attracted attention as an alternative fuel source and as an energy storage ***,the flammability of hydrogen at low concentrations makes it a safety ***,gas concentration measurements are a vital safety *** we present the experimental realization of a palladium thin film cantilever optomechanical hydrogen gas *** measured the instantaneous shape of the cantilever to nanometer-level accuracy using diffraction phase ***,we were able to quantify changes in the curvature of the cantilever as a function of hydrogen concentration and observed that the sensor’s minimum detection limit was well below the 250 *** of our test *** the change in curvature versus the hydrogen curve for calibration,we accurately determined the hydrogen concentrations for a random sequence of *** addition,we calculated the change in film stress as a function of hydrogen concentration and observed a greater sensitivity at lower concentrations.

关键词： hydrogen detection imaging and sensing interference microscopy optomechanics optical sensors surface dynamics