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Al_2O_3-Coated Nano-SiC Particles Reinforced Al_2O_3 Matrix Composites

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Journal of Materials Science & Technology 2002年第6期18卷 541-543页

作者： Juxian ZHANG, Jinjun FENG and Longqiao GAObeijing vacuum electron.cs res.arch inst.tute, PO. Box 749 Ext. Box 33, beijing 100016, China beijing vacuum electron. res. inst. PO Box 749 Beijing 100016 China

Properties of Al2O3-coated nano-SiC have been compared with those of as-received SiC. The isoelectric point (IEP) of SiC changed from pH3.4 to pH7.3 after coating with the alumina precursor, which is close to that of alumina. Because both surfaces of coated SiC and AI2O3 possess higher positive charge at pH=4.5-5.0, they are uniformly dispersed in the two-phase aqueous suspensions, Then a mixed powder containing nano-SiC dispersed homogeneously into the Al2O3 matrix was achieved from flocculating the two-phase suspension. Finally, Al2O3/SiC nanocomposites were obtained by coating nano-SiC with Al2O3, in which the majority of SiC particles were located within the AI2O3 grains. The observation by transmission electron.microscopy (TEM) and the analysis by the X-ray photoelectron.spectroscopy (XPS) showed that cracks propagated towards the intragranular SiC rather than along grain boundaries.

关键词： Coated nano-SiC Colloidal processing Nanocomposites Intragranular structure Transgranular fracture

Enhancing Photovoltaic Performance of Nonfused-Ring electron.Acceptors via Asymmetric End-Group Engineering and Noncovalently Conformational Locks

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Chinese Journal of Chemistry 2024年第5期42卷 485-490页

作者： Bo Liu Congqi Li Xiaobin Gu Yinghui Han Zhixiang Wei Yunhao Cai Xin Zhang Hui Huang Yanping Huo School of Chemical Engineering and Light Industry Guangdong University of TechnologyGuangzhouGuangdong510006 China College of Materials Science and Opto-electron.c Technology & Center of Materials Science and Optoelectron.cs Engineering & CAS Center for Excellence in Topological Quantum Computation & CAS Key Laboratory of vacuum Physics University of Chinese Academy of SciencesBeijing100049 China College res.urces and Environment University of Chinese Academy of SciencesBeijing100049 China Center for Excellence in Nanoscience (CAS) & Key Laboratory of Nanosystem and Hierarchical Fabrication (CAS) National Center for Nanoscience and TechnologyBeijing100190 China

By employing the asymmetric end-group engineering,an asymmetric nonfused-ring electron.acceptor(NFREA)was designed and *** with the symmetric analogs(NoCA-17 and NoCA-18),NoCA-19 possesses broader light absorption range,more coplanarπ-conjugated backbone,and appropriate crystallinity according to the experimental and theoretical *** organic solar cells based on J52:NoCA-19 exhibited a power conversion efficiency as high as 12.26%,which is much higher than those of J52:NoCA-17(9.50%)and J52:NoCA-18(11.77%),mainly due to more efficient exciton dissociation,better and balanced charge mobility,suppres.ed recombination loss,shorter charge extraction time,longer charge carrier lifetimes,and more favorable blend film *** findings demonstrate the great potential of asymmetric end-group engineering in exploring low-cost and high-performance NFREAs.

关键词： Organic solar cells Nonfused-ring electron.acceptors Asymmetric end-group engineering Noncovalently conformational locks Low-cost acceptors

Direct observation of oxygen vacancy formation and migration over ceria surface by in situ environmental transmission electron.microscopy

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Journal of Rare Earths 2024年第4期42卷 676-682页

作者： Dawei Pang Wei Li Ningqiang Zhang Hong He Shengcheng Mao Yanhui Chen Liwei Cao Chong Li Ang Li Xiaodong Han beijing Key Laboratory of Solid Microstructure and Properties Department of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China beijing Key Laboratory for Green Catalysis and Separation The Faculty of Environment and LifeBeijing University of TechnologyBeijing10124China International Joint res.arch Laboratory for Quantum Functional Materials of Henan School of Physics and MicroelectronicsZhengzhou UniversityZhengzhou450001China

The extremely high structural tolerance of ceria to oxygen vacancies(Ov)has made it a desirable catalytic material for the hydrocarbon oxidation to chemicals and pharmaceuticals and the reduction of gaseous *** is proposed that the formation and diffusion of Ov originate from its outstanding reduction ***,the formation and diffusion process of Ov over the surface of ceria at the atomic level is still ***,the structural and valence evolution of CeO_(2)(111)surfaces in reductive,oxidative and vacuum environments from room temperature up to 700℃was studied with in situ aberration-corrected environmental transmission electron.microscopy(ETEM)*** is found to form under a high vacuum at elevated temperatures.however,the surface can recover to the initial state through the adsorption of oxygen atoms in an oxygen-contained ***,in hydrogen environment,the step-CeO_(2)(111)surface is not stable at elevated temperatures.thus,the steps tend to be eliminated with increasing *** with first-principles density function calculations(DFT),it is proposed that O-terminated surfaces would develop in a hypoxic environment due to the dynamic diffusion of Ov from the outer surface to the ***,in a reductive environment,H2 facilitates the formation and diffusion of Ov while Ce-terminated surfaces *** res.lts reveal dynamic atomic-scale interplay between the nanoceria surface and gas,thereby providing fundamental insights into the Ov-dependent reaction of nano-CeO_(2) during catalytic processes.

关键词： Ceria Direct observation In situ ETEM Oxygen vacancy Density function calculations Rareearths

Generation and Suppres.ion of Pendant Droplet Oscillation in electron.Beam Directed Energy Deposition

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Engineering 2024年第6期37卷 215-229页

作者： Zhiyue Liang Zhenyu Liao Haoyu Zhang Zixiang Li Li Wang Baohua Chang Dong Du Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationTsinghua UniversityBeijing 100084China

electron.beam–directed energy deposition(EB–DED)has emerged as a promising wire-based metal additive manufacturing ***,the effects of EBs on pendant droplets at wire tips have not yet been *** aim of this study is to enhance the understanding of this action by analyzing the mechanism of droplet *** pendant droplet oscillation phenomenon hinders the stable transfer of droplets to the molten pool and limits the feasibility of manufacturing complex lattice structures.by EB–***,another aim of this study is to create an oscillation suppres.ion *** escalating asymmetric amplitude is the main characteristic of droplet *** primary oscillationinducing force is the recoil force generated from the EB-acted local surface of the *** physical mechanism of this force is the rapid increase and uneven distribution of the local surface temperature caused by the partial action of the *** prerequisites for droplet oscillation include vacuum conditions,high power densities,and bypass wire feeding *** proposed EB–dynamic surrounding melting(DSM)method can be applied to conveniently and effectively suppres. oscillations,enable the accurate transfer of droplets to the molten pool,and achieve stable processes for preparing the strut elements of lattice *** the temperature and improving the uniformity of its distribution are the mechanisms of oscillation suppres.ion in EB–*** this study,the physical basis for interpreting the mechanism by which EBs act on droplets and the technical basis for using EB–DED to prepare complex lattice structure parts are provided.

关键词： Additive manufacturing electron.beam freeform fabrication In situ monitoring Pendant droplet

Multi-site Passivation of ZnO Metal Oxides via Biomolecules for Efficient and Highly Stable Organic Solar Cells

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Chinese Journal of Chemistry 2024年第14期42卷 1582-1592页

作者： Irfan Ismail Maria Khalil Xiaomei Gao Xingze Chen Muhammad Jawad Rong Huang Zhiyun Li Emmanuel Acheampong Tsiwah Wei-shi Li Qun Luo Chang-Qi Ma i-Lab&Printable electron.cs res.arch Center Suzhou Institute of Nano-Tech and Nano-Bionics(SINANO)Chinese Academy of Sciences(CAS)SuzhouJiangsu215123 China University of Chinese Academy of Sciences(UCAS) Beijing100040 China School of Nano-Tech and Nano-Bionics University of Science and Technology of China(USTC)HefeiAnhui230027 China Shanghai inst.tute of Organic Chemistry(SIOC) Chinese Academy of Sciences(CAS)Shanghai200032 China vacuum Interconnected Nanotech Workstation(Nano-X) SuzhouJiangsu215123 China

ZnO nanoparticles(nps)among metal oxide(MOs)are proven to be essential electron.transporting layers(ETLs)applied in organic solar cells(OSCs).However,intrinsic defects,interfacial charge recombination,and catalytic behavior towards the active layer res.rict the applications of ZnO nps for efficient and long-term stable *** commonly available biomolecule cytidine 5'-monophosphate(CMP-OH)with phosphonic acid,its salt cytidine 5'-monophosphate disodium salt(CMP-ONa)with a phosphate group as an anchoring group and conjugated terminal functional in both analogous molecules provide carrier transfer bridge at bottom interface of the active *** theoretical investigations and characterizations have discovered the multi-site coordination of CMP-OH towards acceptor molecules and ZnO *** dual-side alignment of CMP analogous molecules hinders interfacial charge recombination and enhances charge transfer potential at ***,PM6:L8-BO-based OSCs with modified ETL obtain 18.13%efficiency,12%higher than that of unmodified *** higher efficiency,CMP-OH-based OSC devices illustrate remarkably improved thermal stability for 500 h at 85℃with 72%of initial PCE and operation stability for 2000 h with 90.1%of initial *** work reveals the passivation mechanism of multi-anchoring groups towards MOs and single-functional groups towards the active layer to optimize the interface for efficient and highly stable OSCs.

关键词： Organic solar cells Nanoparticles Nucleotides Interfacial interactions Surface chemistry Multi-site passivation

Tungsten separation behavior on preparation of high-purity cerium by combined vacuum gravity sedimentation-directional solidification

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Journal of Rare Earths 2024年第6期42卷 1182-1186,I0007页

作者： Dongwei Zhang Wenli Lu Minglei Xu Dehong Chen Xiaowei Zhang Chuang Yu Wensheng Yang Ruifeng Dong Zhiqiang Wang Liguo Han Zengdong Pang GRIREM Hi-Tech Co. Ltd.Langfang065201China National Engineering res.arch Center for Rare Earth China GRINM Group Co.Ltd.Beijing100088China GRIREM Advanced Materials Co. Ltd.Beijing100088China

In light of the difficult removal of harmful impurity tungsten(W)in Ce metal,in this paper a combined vacuum gravity sedimentation-directional solidification method was innovatively designed and the W separation behavior was *** reducing the electron.beam power inst.ntly and gradually at reduction rates of 1,3 and 5 kW/min,it is found that W is enriched at the bottom of ingots as the melt *** enrichment effect is much better than that of single purification method and the enrichment degree increases as the beam reduction rate decreases,attributed to the k0(W)>1 andρ(W)>ρ(Ce).Overall,the minimum content of W impurity can decrease from 630 to 0.1 ppm at the top of the ingot,and the purity of Ce increases from 99.932 wt%to 99.995 wt%by this combined ***,this paper provides a new method for the removal of high density and low evaporation coefficient impurities in low vapor pres.ure rare earth metals.

关键词： Cerium electron.beam melting Directional solidification Gravity sedimentation Rare earths

Free radicals trigger the closure of open pores.in lignin-derived hard carbons toward improved sodium-storage capacity

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Journal of Energy Chemistry 2024年第7期94卷 551-559页

作者： Wen-Jun Ji Zong-Lin Yi Ming-Xin Song Xiao-Qian Guo Yi-Lin Wang Yi-Xuan Mao Fang-Yuan Su Jing-Peng Chen Xian-Xian Wei Li-Jing Xie Cheng-Meng Chen CAS Key Laboratory of Carbon Materials Institute of Coal ChemistryChinese Academy of SciencesTaiyuan 030001ShanxiChina University of Chinese Academy of Sciences Beijing 100049China Center of Materials Science and Optoelectron.cs Engineering University of Chinese Academy of SciencesBeijing 100049China School of Environment and Safety Taiyuan University of Science and TechnologyTaiyuan 030001ShanxiChina

The chemical activation of various precursors is effective for creating additional closed pores.in hard carbons for sodium ***,the formation mechanism of closed pores.under the influence of pore-forming agents is not well ***,an effective chemical activation followed by a high-temperature self-healing strategy is employed to generate interconnected closed pores.in lignin-derived hard carbon(HCs).By systematic experimental design combined with electron.paramagnetic res.onance spectroscopy,it can be found that the content of free radicals in the carbon matrix influences the closure of open pores.at high *** high activation temperature(>700 C)leads to a low free radical concentration,making it difficult to achieve self-healing of open pores.at high *** activation at 700°C,a balance between pore making and self-healing is achieved in the final hard carbon.A large number of free radicals triggers rapid growth and aggregation of carbon microcrys-tals,blocking pre-formed open micropores.and creating additional interconnected closed pores.in as-obtained hard *** a res.lt,the optimized carbon anode(LK-700-1300)delivers a high reversible capacity of 330.8 mA h g^(-1) at 0.03 A g^(-1),which is an increase of 86 mA h g^(-1) compared to the pristine lignin-derived carbon anode(L-700-1300),and exhibits a good rate performance(202.1 mA h g^(-1) at 1 A g^(-1)).This work provides a universal and effective guidance for tuning closed pores.of hard carbons from otherprecursors.

关键词： Hard carbon Chemical activation Free radical Self-healing Closed pores.Sodium ion batteries

Real-Time Observation of inst.ntaneous ac Stark Shift of a vacuum Using a Zeptosecond Laser Pulse

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Chinese Physics Letters 2024年第1期41卷 11-15页

作者：苏丹丹江淼 Key Laboratory for Laser Plasmas(Ministry of Education)and School of Physics and Astronomy Collaborative Innovation Center for IFSA(CICIFSA)Shanghai Jiao Tong UniversityShanghai 200240China School of Science China University of Mining and TechnologyBeijing 100083China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyBeijing 100083China

Based on the numerical solution of the time-dependent Dirac equation,we propose a method to observe in real time the ac Stark shift of a vacuum driven by an ultra-intense laser *** overlapping the ultra-intense pump pulse with another zeptosecond probe pulse whose photon energy is smaller than 2mc^(2),electron.positron pair creation can be controlled by tuning the time delay between the pump and probe *** the pair creation rate depends sensitively on the inst.ntaneous vacuum potential,one can reconstruct the ac Stark shift of the vacuum potential according to the time-delay-dependent pair creation rate.

关键词： pump tuning vacuum

EXPERIMENTAL STUDY OF VELOCITY SPREAD IN A CYCLOIDING electron.BEAM

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电子科学学刊(英文版) 1984年第2期1卷 121-131页

作者：蔡熙章 beijing vacuum electron.Device res.arch inst.tute

The paper describes briefly the effect of electron.velocity spread on the principal operating para-meters of a gyrotron.A method of reducing velocity spread is discussed,and a new method of mea-suring electron.velocity spread in a cycloiding electron.beam is *** use of a high precisionradial-gauge and multilobe collector,the distribution of the beam transverse velocity of a gyrotronis accurately *** with other methods conventionally used in this country and abroadsuch as those using retarding-field,pin-hole collector,this method is characterized by the fact that thespace charge effect would not modify the experimental res.lts,and the beam velocity spread of a gyrotronunder real operating conditions can be *** order to characterize the beam in an overall man-ner,a new concept of relative density velocity spread is introduced in this *** experimental workhas been performed on a special electron.beam analyser with advanced design.

关键词： spread gauge briefly collector characterize BEAM longitudinal radial transverse usage