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Segregation of solute atoms in ZrC grain boundaries and their effects on Grain boundary strengths

Journal of Materials Science & Technology 2022年第6期101卷 234-241页

作者： Fu-Zhi Dai Yinjie Sun Yixiao Ren Huimin Xiang Yanchun Zhou Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China

ZrC is a promising candidate for the application in ultra-high temperature regime due to its unique combination of excellent properties,such as high melting point,good chemical inertness and high temperature stability.The rapid decrease of strength at high temperatures,however,is one of the obstacles that impedes its practical services.Strengthening of grain boundaries by solute segregation is believed to be an effective way to improve its high temperature performance.Therefore,the segregation tendency of ten solid solute atoms,including Sc,Ti,V,Cr,Y,Nb,Mo,Hf,Ta,W,in Zr C grain boundaries,and the strengthening/weakening effects on grain boundaries due to segregation are investigated by first-principles calculations.The segregation tendency is found dominated by the size effect,which is confirmed by both a qualitative analysis and a quantitative approach based on support vector regression.It means that big atoms tend to segregate to Grain boundary sites with local expansions,while small atoms tend to segregate to Grain boundary sites with local compressions.Simulations on stress-strain responses indicate that segregation of small atoms(Ti,V,Cr,Nb,Ta,Mo,W)can usually improve Grain boundary strengths by inducing compression strains to grain boundaries,even though there is also an exception.In contrast,segregation of Sc and Y will soften grain boundaries.The results reveal that strengthening of grain boundaries by solute segregation is a valuable avenue to enhance high temperature mechanical properties of ZrC,providing guidelines for further design of ZrC based materials.

关键词： ZrC Grain boundary Segregation Strength First-principles calculation Machine learning

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From protonation & Li-rich contamination to grain-boundary segregation: Evaluations of solvent-free vs. wet routes on preparing Li_(7)La_(3)Zr_(2)O_(12) solid electrolyte

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Journal of Energy Chemistry 2022年第10期31卷 223-239,I0005页

作者： Xiao Huang Yang Lu Yajun Niu Jiawen Tang Yongjian Zhou Yan Yang Bingbing Tian SZU-NUS Collaborative Innovation Center for Optoelectronic Science&Technology International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of EducationInstitute of Microscale OptoelectronicsShenzhen UniversityShenzhen 518060GuangdongChina Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology Department of Chemical EngineeringTsinghua UniversityBeijing 100084China Collaborative Innovation Center for Vessel Pollution Monitoring and Control Dalian Maritime UniversityDalian 116026LiaoningChina

Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO) has been recognized as a candidate solid electrolyte for high-safety Lianode based solid-state batteries because of its electro-chemical stability against Li-metal and high ionic conductivity. Solvent(e.g., isopropanol(IPA)) has been commonly applied for preparing LLZO powders and ceramics. However, the deterioration of the proton-exchange between LLZO and IPA/absorbed moisture during the mixing and tailoring route has aroused less attention. In this study, a solvent-free dry milling route was developed for preparing the LLZO powders and ceramics. For orthogonal four categories of samples prepared using solvent-free and IPA-assisted routes in the mixing and tailoring processes, the critical evaluation was conducted on the crystallinity, surficial morphology, and contamination of ascalcinated and as-tailored particles, the cross-sectional microstructure of green and sintered pellets,the morphology and electro-chemical properties of grain boundaries in ceramics, as well as the interfacial resistance and performance of Li anode based symmetric batteries. The wet route introduced Li-rich contaminations(e.g., Li OH·H)_(2)O and Li)_(2)CO)_(3)) onto the surfaces of LLZO particles and Li-Ta-O segregations at the adjacent and triangular grain boundaries. The LLZO solid electrolytes prepared through dry mixing in combination with the dry tailoring route without the use of any solvent were found to the optimal performance. The fundamental material properties in the whole LLZO preparation process were found, which are of guiding significance to the development of LLZO powder and ceramic production craft.

关键词： Li_(7)La_(3)Zr_(2)O_(12) Solid electrolyte Solvent-free procedure Ion-exchange Grain boundary Fundamental material properties

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Fatigue crack propagation across Grain boundary of Al-Cu-Mg bicrystal based on crystal plasticity XFEM and cohesive zone model

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Journal of Materials Science & Technology 2022年第31期126卷 275-287页

作者： Qi Zhao Magd Abdel Wahab Yong Ling Zhiyi Liu School of Materials Science and Engineering Hubei University of Automotive TechnologyShiyan 442002China Faculty of Mechanical-Electrical and Computer Engineering School of Engineering and TechnologyVan Lang UniversityHo Chi Minh CityVietnam Soete Laboratory Faculty of Engineering and ArchitectureGhent UniversityTechnologiepark Zwijnaarde 903B-9052 ZwijnaardeBelgium School of Materials Science and Engineering Central South UniversityChangsha 410083China

In this paper,a methodology integrating crystal plasticity(CP),the eXtended finite element method(XFEM)and the cohesive zone model(CZM)is developed for an Al-Cu-Mg alloy to predict fatigue crack propagation(FCP)across Grain boundary(GB)of Al-Cu-Mg alloy during stageІІ.One GB model is incor-porated into FCP constitutive law to describe grain interaction at GB.A bicrystal containing GB is built up to simulate FCP behavior through L participated GBs.Modelling features including GB characteristic,cumulative plastic strain(CPS)distribution and crystal slipping evidence can be identified.The numer-ical results are compared with published experimental data to check the accuracy of model.This work demonstrates that the combination of CP containing GB constitutive laws,XFEM and CZM is a promising methodology in predicting twist angle-controlled crack deflection through GBs.

关键词： Grain boundary Twist angle Crystal plasticity Extended finite element method Fatigue crack propagation Cumulative plastic strain

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Tandem catalysis on adjacent active motifs of copper Grain boundary for efficient CO_(2) electroreduction toward C2 products

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Journal of Energy Chemistry 2022年第7期31卷 219-223,I0006页

作者： Tao Luo Kang Liu Junwei Fu Shanyong Chen Hongmei Li Junhua Hu Min Liu Hunan Joint International Research Center for Carbon Dioxide Resource Utilization State Key Laboratory of Powder MetallurgySchool of Physics and ElectronicsCentral South UniversityChangsha 410083HunanChina School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450002HenanChina

Copper (Cu) is a special electrocatalyst for CO_(2) reduction reaction (CO_(2)RR) to multi-carbon products.Experimentally introducing grain boundaries (GBs) into Cu-based catalysts is an efficient strategy to improve the selectivity of C^(2+) products.However,it is still elusive for the C^(2+) product generation on Cu GBs due to the complex active sites.In this work,we found that the tandem catalysis pathway on adjacent active motifs of Cu GB is responsible for the enhanced activity for C^(2+)production by first principles calculations.By electronic structure analysis shows,the d-band center of GB site is close to the Fermi level than Cu(100) facet,the Cu atomic sites at Grain boundary have shorter bond length and stronger bonding with*CO,which can enhance the adsorption of*CO at GB sites.Moreover,CO_(2)protonation is more favorable on the region Ⅲ motif (0.84 e V) than at Cu(100) site (1.35 e V).Meanwhile,the region Ⅱ motif also facilitate the C–C coupling (0.72 e V) compared to the Cu(100) motif (1.09 e V).Therefore,the region Ⅲ and Ⅱ motifs form a tandem catalysis pathway,which promotes the C^(2+)selectivity on Cu GBs.This work provides new insights into CO_(2)RR process.

关键词： Cu(100)facet Grain boundary CO_(2)electroreduction C2+products Tandem catalysis

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Synergistic effect of V_(2)O_(5)and Bi_(2)O_(3) on the Grain boundary structure of high-frequency NiCuZn ferrite ceramics

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Journal of Advanced Ceramics 2022年第6期11卷 912-921页

作者： Xiuyuan FAN Guohua BAI Zhenhua ZHANG Qiming CHEN Jiaying JINa Jiafeng XUa Xuefeng ZHANG Mi YAN School of Materials Science and Engineering State Key Laboratory of Silicon MaterialsKey Laboratory of Novel Materials for Information Technology of Zhejiang ProvinceZhejiang UniversityHangzhou 310027China Institute of Advanced Magnetic Materials College of Materials&Environmental EngineeringHangzhou Dianzi UniversityHangzhou 310012China

High-frequency soft magnetic ferrite ceramics are desired in miniaturized and efficient power electronics but remain extremely challenging to deploy on account of the power loss(Pcv)at megahertz frequencies.Here,we prepared NiCuZn ferrite with superior high-frequency properties by V_(2)O_(5)and Bi_(2)O_(3)synergistic doping,which proves to be a potent pathway to reduce Pcv of the ferrite at megahertz frequencies.The sample doped with 800 ppm V_(2)O_(5)and 800 ppm Bi_(2)O_(3)yielded the most optimized magnetic properties with a Pcv of 113 kW/m^(3)(10 MHz,5 mT,25℃),an initial permeability(μi)of 89,and a saturation induction(Bs)of 340 mT,which is at the forefront of the reported results.These outstanding properties are closely related to the notable Grain boundary structure,which features a new type of nano-Bi_(2)Fe_(4)O_(9)phase around ferrite grains and a Ca/Si/V/O amorphous layer.Our results indicate great strides in correlating the Grain boundary structure with multiple-ion doping and set the scene for the developing high-frequency soft magnet ferrites.

关键词： NiCuZn ferrite megahertz application Grain boundary Bi_(2)Fe_(4)O_(9) ion doping

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Grain boundary Passivation Modulated by Molecular Doping for High-Performance Perovskite Solar Cells

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Journal of Renewable Materials 2022年第12期10卷 3505-3519页

作者： Yangyang Hao Yue Liu Guorui Cao College of Che mical and Engineering Qingdao University of Science and TechnologyQingdao266042China

Aiming to reduce the defects of perovskite film and improve carrier transport,an organic small molecule,benzo[d]isothiazol-3(2H)-one 1,1-dioxide(OBS),is introduced as an additive in the solution-processing of perovskite and prepare uniform perovskite films with a continuous distribution of OBS at grain boundaries.Fourier trans-form infrared spectroscopy and X-ray photoelectron spectroscopy are conducted to reveal the interactions of hydrogen bonding and coordina tion bonding between OBS and perovskite.Various characterizations(including X-ray diffraction,UV-vis spectroscopy,electrochemical impedance spectroscopy,etc.)are conducted to uncover the effect of OBS on device performance.Consequently,high efficiency of 23.26%is obtained for the OBS-treated device,while the control device shows only a companion efficiency of 21.60%.

关键词： Perovskite solar cells organic small molecule Grain boundary hydrogen bonding coordination bonding

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Atomic study of hydrogen behaviors at∑3(111)Grain boundary in equiatomic CoCrNi and CoCrNiFe alloys

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Tungsten 2022年第3期4卷 239-247页

作者： Hua-Qing Guan Yan-Mei Jing Shao-Song Huang Key Laboratory of Material Modification by Laser Ion and Electron Beams(Dalian University of Technology)Ministry of EducationDalian116024China

High-entropy alloys are potential advanced structural materials for applications in nuclear energy due to their proved high irradiation performance.However,exposing components made of structure materials to service conditions under certain nuclear environments may induce hydrogen embrittlement(HE)as one of the typical failure mechanisms.In this work,we performed density functional theory(DFT)calculations to examine the role of specific element species in HE mechanism in CoCrNi and CoCrNiFe alloys.The solution energy,binding energy and diffusion barrier of H atoms at∑3 GBs(GBs is short for grain boundaries)are presented.Based on the DFT data,we found that Cr limits the H atom to a specific potential position,thus suppresses H segregation.The dipole moment interaction between H and Fe atoms weakens the binding of H atoms.The lattice distortion effect-induced trapping for H provides higher H diffusion barriers at∑3 GBs than that in pure Ni.

关键词： Hydrogen embrittlement Grain boundary DFT High-entropy alloy

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Atomic origin of spin-valve magnetoresistance at the SrRuO3 Grain boundary

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National Science Review 2020年第4期7卷 755-762页

作者： Xujing Li Li Yin Zhengxun Lai Mei Wu Yu Sheng Lei Zhang Yuanwei Sun Shulin Chen Xiaomei Li Jingmin Zhang Yuehui Li Kaihui Liu Kaiyou Wang Dapeng Yu Xuedong Bai Wenbo Mi Peng Gao Electron Microscopy Laboratory School of Physics Peking University Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology School of Science Tianjin University International Center for Quantum Materials Peking University State Key Laboratory of Superlattices and Microstructures Institute of Semiconductors Chinese Academy of Sciences State Key Laboratory for Artificial Microstructure & Mesoscopic Physics School of Physics Peking University Collaborative Innovation Centre of Quantum Matter College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology

Defects exist ubiquitously in crystal materials, and usually exhibit a very different nature from the bulk matrix.Hence, their presence can have significant impacts on the properties of devices.Although it is well accepted that the properties of defects are determined by their unique atomic environments, the precise knowledge of such relationships is far from clear for most oxides because of the complexity of defects and difficulties in characterization.Here, we fabricate a 36.8°Sr RuO3Grain boundary of which the transport measurements show a spin-valve magnetoresistance.We identify its atomic arrangement, including oxygen,using scanning transmission electron microscopy and spectroscopy.Based on the as-obtained atomic structure, the density functional theory calculations suggest that the spin-valve magnetoresistance occurs because of dramatically reduced magnetic moments at the boundary.The ability to manipulate magnetic properties at the nanometer scale via defect control allows new strategies to design magnetic/electronic devices with low-dimensional magnetic order.

关键词： spin-valve magnetic defects electron microscopy Grain boundary

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Clarifying the roles of Grain boundary and grain orientation on the corrosion and discharge processes of α-Mg based Mg-Li alloys for primary Mg-air batteries

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Journal of Materials Science & Technology 2021年第3期62卷 128-138页

作者： Huabao Yang Liang Wu Bin Jiang Wenjun Liu Jiangfeng Song Guangsheng Huang Dingfei Zhang Fusheng Pan State Key Laboratory of Mechanical Transmissions College of Materials Science and EngineeringChongqing UniversityChongqing400044China Chongqing Academy of Science and Technology Chongqing401123China College of Materials Science and Engineering Chongqing University of TechnologyChongqing400054China

The corrosion behavior at open circuit potential(OCP)and discharge properties under applied anodic currents of twoα-Mg based Mg-Li alloys,i.e.,LAZ131 and LAZ531,with different microstructural features for primary Mg-air batteries are investigated.The results show that the grain boundaries contribute equally to the corrosion and discharge processes,which are attacked preferentially than the grain interiors and accelerate the dissolution processes ofα-Mg based Mg-Li alloys.The(10-10)/(11-20)orientated grains are attacked preferentially than the(0002)orientated grains on the corrosion and discharge process.The increased corrosion rate and improved discharge properties are attributed to the refinement of grain size,decreased content of(0002)orientated grains and increased content of(10-10)/(11-20)orientated grains.Of those,the LAZ531 alloy possesses high and steady discharge voltage at small discharge current density for long time,with the values of 1.4801 V at 2.5 mA cm^(-2)and 1.3742 V at 10 mA cm^(-2).

关键词： Grain boundary grain orientation Corrosion behavior Discharge property Mg-air battery

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Effects of impurity elements on SiC Grain boundary stability and corrosion

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Nuclear Science and Techniques 2021年第11期32卷 77-95页

作者： Jun Hui Bao-Liang Zhang Tao Liu Min Liu Wen-Guan Liu Sino-French Institute of Nuclear Engineering and Technology Sun Yat-Sen UniversityZhuhai 519082China China Institute of Atomic Energy Beijing 102413China

grain boundaries(GBs)have critical influences on the stability and properties of various materials.In this study,first-principles calculations were performed to determine the effects of four metallic impurities(Ni,Al,Bi,and Pb)and three nonmetallic impurities(H,O,and N)on the GBs of silicon carbide(SiC),using the ∑5(210)GBs as models.The GB energy and segregation energy(SE)were calculated to identify the effects of impurities on the GB stability.Electronic interactions considerably influenced the bonding effects of SiC.The formation of weak bonds resulted in the corrosion and embrittlement of GBs.The co-segregation of Bi,Pb,and O was also investigated in detail.

关键词： SiC First-principles calculation Grain boundary Impurity atom Co-segregation

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