检索结果-内蒙古大学图书馆

SSRN 2022年

作者： Zhu, Xuejie Wang, Chenyu Zhang, Cong Wang, Ziyu Feng, Jiangshan Liu, Shengzhong Yang, Dong Laboratory of Applied Surface and Colloid Chemistry Ministry of Education School of Materials Science and Engineering Shaanxi Key Laboratory for Advanced Energy Devices Shaanxi Engineering Lab for Advanced Energy Technology Institute for Advanced Energy Materials Shaanxi Normal University Xi’an710119 China Dalian National Laboratory for Clean Energy IChEM Dalian Institute of Chemical Physics Chinese Academy of Sciences 457 Zhongshan Road Dalian116023 China Materials Science and Engineering Pennsylvania State University University ParkPA16802 United States

The stable black α-phase is the key to attaining high-efficiency formamidinium lead triiodide (FAPbI3) perovskite solar cells (PSCs). There have been some reports using different sizes of ions to stabilize α-phase FAPbI3;unfortunately, they often affect the bandgap, stability and carrier dynamics, in addition to increasing the number of carrier trap sites. Herein, we present 1-allyl-3-methylimidazolium-chloride (AMICl) ionic liquid to stabilize the α-phase of pure FAPbI3 perovskite without encountering the above adversities. It is found that the thermodynamic temperature of α-FAPbI3 is significantly reduced from 150 °C to 140 °C by using AMICl, and the absorption edge of FAPbI3 remains at 850 nm. The efficiency of a FAPbI3 device with AMICl is increased from 18.47% for the control device to 20.76%, one of the highest values among pure FAPbI3 solar cells. The high efficiency is attributed to the low trap density, long carrier lifetime and suppressed carrier recombination, thanks to the large grain size and good crystallinity of FAPbI3 generated by the formation of intermediate products from PbI2 and AMICl. Meanwhile, FAPbI3 solar cells with AMICl exhibit excellent environmental stability. The bare device without any encapsulation maintains about 87% of its initial value after being exposed to ambient for 24 days, significantly improved over the control device, which retains only about 53% of its initial efficiency under the same conditions. © 2022, The Authors. All rights reserved.

关键词： Efficiency

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Two-dimensional ferromagnetic superlattices

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National Science Review 2020年第4期7卷 745-754页

作者： Shanshan Liu Ke Yang Wenqing Liu Enze Zhang Zihan Li Xiaoqian Zhang Zhiming Liao Wen Zhang Jiabao Sun Yunkun Yang Han Gao Ce Huang Linfeng Ai Ping Kwan Johnny Wong ANDrew Thye Shen Wee Alpha T.N'Diaye Simon A.Morton Xufeng Kou Jin Zou Yongbing Xu Hua Wu Faxian Xiu State Key Laboratory of Surface Physics and Department of Physics Fudan University Institute for Nanoelectronic Devices and Quantum Computing Fudan University Laboratory for Computational Physical Sciences (MOE) Fudan University Department of Electronic Engineering Royal Holloway University of London School of Electronic Science and Engineering Nanjing University Materials Engineering The University of Queensland Department of Physics National University of Singapore Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore Lawrence Berkeley National Laboratory School of Information Science and Technology Shanghai Tech University Centre for Microscopy and Microanalysis The University of Queensland Collaborative Innovation Center of Advanced Microstructures

Mechanically exfoliated two-dimensional ferromagnetic materials(2 D FMs) possess long-range ferromagnetic order and topologically nontrivial skyrmions in few layers. However, because of the dimensionality effect, such few-layer systems usually exhibit much lower Curie temperature(TC) compared to their bulk counterparts. It is therefore of great interest to explore effective approaches to enhance their TC, particularly in wafer-scale for practical applications. Here, we report an interfacial proximity-induced high-TC2 D FM FeGe Te(FGT) via A-type antiferromagnetic material Cr Sb(CS) which strongly couples to FGT. A superlattice structure of(FGT/CS)n, where n stands for the period of FGT/CS heterostructure, has been successfully produced with sharp interfaces by molecular-beam epitaxy on 2-inch wafers. By performing elemental specific X-ray magnetic circular dichroism(XMCD) measurements, we have unequivocally discovered that TCof 4-layer FeGeTecan be significantly enhanced from 140 K to230 K because of the interfacial ferromagnetic coupling. Meanwhile, an inverse proximity effect occurs in the FGT/CS interface, driving the interfacial antiferromagnetic Cr Sb into a ferrimagnetic state as evidenced by double-switching behavior in hysteresis loops and the XMCD spectra. Density functional theory calculations show that the Fe-Te/Cr-Sb interface is strongly FM coupled and doping of the spin-polarized electrons by the interfacial Cr layer gives rise to the TCenhancement of the FeGeTefilms, in accordance with our XMCD measurements. Strikingly, by introducing rich Fe in a 4-layer FGT/CS superlattice, TCcan be further enhanced to near room temperature. Our results provide a feasible approach for enhancing the magnetic order of few-layer 2 D FMs in wafer-scale and render opportunities for realizing realistic ultra-thin spintronic devices.

关键词： 2D ferromagnetic material room temperature 2-inch Fe3GeTe2 film wafers proximity effect (Fe3GeTe2/CrSb)nsuperlattice

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Improvement of image-type very-low-energy-electron-diffraction spin polarimeter

arXiv

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arXiv 2023年

作者： Zha, Heming Liu, Wenjing Wang, Deyang Zhao, Bo Shen, XiaoPing Ye, Mao Qiao, Shan Center for Excellence in Superconducting Electronics State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai200050 China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing100049 China School of Physical Science and Technology ShanghaiTech University Shanghai201210 China Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai201210 China State Key Laboratory of Surface Physics Department of Physics Fudan University Shanghai200433 China

Spin- and angle-resolved photoemission spectroscopy (SARPES) with high efficiency and resolution plays a crucial role in exploring the fine spin-resolved band structures of quantum materials. Here we report the performance of SARPES instrument with a second-generation home-made multichannel very-low-energy-electron-diffraction (VLEED) spin polarimeter. Its energy and angular resolutions achieve 7.2 meV and 0.52°. We present the results of SARPES measurements of Bi(111) film to demonstrate its performance. Combined with the density functional theory (DFT) calculations, the spin polarization of the bulk states was confirmed from the spin-layer locking caused by the local inversion asymmetry. The surface states at binding energy of 0.77 eV are found with 1.0 ±0.11 spin polarization. The better resolutions and stability compared with the first-generation one provide a good platform to investigate the spin-polarized electronic states in materials. © 2023, CC BY-NC-SA.

关键词： Spin polarization

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Ab Initio Study of the Effects of Cr on Helium Behaviors in Fe–Ycr (Y = 9.38, 12.50 At.%) Austenitic Binary Alloys

SSRN

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SSRN 2022年

作者： Wan, Lei Ye, Xiaoqiu Gao, Tao School of Materials Science and Engineering Lanzhou University of Technology Gansu Lanzhou730050 China State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of Technology Gansu Lanzhou730050 China Science and Technology on Surface Physics and Chemistry Laboratory Sichuan Mianyang621907 China Institute of Atomic and Molecular Physics Sichuan University Sichuan Chengdu610065 China Key Laboratory of High Energy Density Physics and Technology of Ministry of Education Sichuan University Sichuan Chengdu610064 China

The effects of Cr on helium diffusion, capture ability, and the stability of He n V m (V means vacancy) complexes ( n = 0–6, m = 0–4) in Fe–YCr (Y = 9.38, 12.50 at.%) binary alloys are evaluated using density functional theory (DFT). We found that Cr played a significant dual role in helium migration. The diffusion of helium between octahedral or tetrahedral interstitials cannot pass through tetrahedral or octahedral gaps. The presence of Cr or the increase of Cr contents both prevents the trapping of helium atoms by vacancies. We have confirmed that Cr content has no obvious effect on the radiation expansion resistance of the alloy models. At a higher or lower n/m ratio, the spontaneous emission of He or SIAs (self-interstitial atoms), or vacancies are predicted. Our work provides necessary information and additional knowledge for the interpretation of complex experimental data, such as micropore formation, void swelling, etc. © 2022, The Authors. All rights reserved.

关键词： Diffusion

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Molecular-level imaging of hydrogen-bonded organic frameworks by cryogenic low-dose electron microscopy

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Green Chemical engineering 2025年

作者： Yikuan Liu Yanbin Chen Liwei Xia Shuo Zhang Zhangnan Zhong Liwei Wang Yujie Huang Xinru Jiang Mengru Bu Qunfeng Zhang Xiaonian Li Yihan Zhu Center for Electron Microscopy Zhejiang Key Laboratory of Surface and Interface Science and Engineering for Catalysts China-Saudi Arabia Joint Laboratory on Microscopic Structural Engineering of Advanced Materials State Key Laboratory of Green Technologies for Chemical Synthesis and Conversion and College of Chemical Engineering Zhejiang University of Technology Hangzhou 310014 China

The fundamental problems associated with structural inhomogeneities of hydrogen-bonded organic frameworks (HOFs), such as surface terminations and host-guest heterostructures that govern their functionalities and growth mechanisms, remain a critical gap in knowledge. This arises from the lack of advanced real-space structural characterization tools with molecular precision. By leveraging state-of-the-art cryogenic low-dose electron microscopy, this work overcomes the beam damage limitations of traditional techniques and elucidates the crystal structures, surface terminations, and host-guest structures of HOFs at molecular-level. Real-space observations confirm lateral crystal growth consistent with the terrace-ledge-kink (TLK) model, but deviate from the classical monomer-addition mechanism. Instead, we propose a nonclassical cooperative multisite monomer-addition mechanism, where simultaneous monomer addition at both framework and guest sites eventually drives crystal faceting.

关键词： Hydrogen-bonded organic framework Low-dose electron microscopy Cryo-EM surface termination Host-guest structure

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Small-Signal Disturbance Compensation Control for LCL-Type Grid-Connected Converter in Weak Grid

Small-Signal Disturbance Compensation Control for LCL-Type G...

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作者： Zhu, Donghai Zhou, Shiying Zou, Xudong Kang, Yong Zou, Kaifeng School of Electrical and Electronic Engineering State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China Wuhan Second Ship Design and Research Institute Wuhan430205 China Naval Aeronautical University Qingdao266041 China

When the three-phase LCL-type converter is attached to a weak grid, its grid current control will interact with a phase-locked loop (PLL), via the point of common coupling voltage. And, the PLL dynamic has a negative influence on the current control, rendering an undesired performance to grid current control, even leading to the instability issue, if no effective measure is employed. To mitigate this problem, this article proposes a simple and visualized small-signal disturbance compensation control method for the LCL-type grid-connected converter. First, the effect mechanism of PLL dynamic on the current control is analyzed, and the root of the small-signal disturbance caused by PLL dynamic is identified subsequently. Based on this, an improved control method is proposed to compensate the aforesaid PLL-introduced small-signal disturbance terms in current loop, and then, the negative effect of PLL dynamic on the grid current control can be effectively reduced in the weak grid, without modifying the PLL parameters and structure. Moreover, the method is not influenced by the circuit parameters change, and it is robust to the variation of grid impedance. Finally, the proposed method is validated by the experiment. © 1972-2012 IEEE.

关键词： Phase locked loops

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Site Sensitivity of Interfacial Charge Transfer and Photocatalytic Efficiency in Photocatalysis: Methanol Oxidation on Anatase TiO₂ Nanocrystals

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Angewandte Chemie - International Edition 2021年第11期60卷 6160-6169页

作者： Fu, Cong Li, Fei Zhang, Jiachen Li, Dan Qian, Kun Liu, Yong Tang, Junwang Fan, Fengtao Zhang, Qun Gong, Xue-Qing Huang, Weixin Hefei National Laboratory for Physical Sciences at the Microscale Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes CAS Key Laboratory of Materials for Energy Conversion and Department of Chemical Physics University of Science and Technology of China Heifei 230026 China Key Laboratory for Advanced Materials Centre for Computational Chemistry and Research Institute of Industrial Catalysis East China University of Science and Technology Shanghai 200237 China Hefei National Laboratory for Physical Sciences at the Microscale Department of Chemical Physics Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China Heifei 230026 China State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 China Department of Chemical Engineering University College London London WC1E 7JE United Kingdom Dalian National Laboratory for Clean Energy Dalian 116023 China

Photocatalytic oxidation of methanol on various anatase TiO2 nanocrystals was studied by in situ and time-resolved characterizations and DFT calculations. surface site and resulting surface adsorbates affect the surfa... 详细信息

Photocatalytic oxidation of methanol on various anatase TiO₂ nanocrystals was studied by in situ and time-resolved characterizations and DFT calculations. surface site and resulting surface adsorbates affect the surface band bending/bulk-to-surface charge migration processes and interfacial electronic structure/interfacial charge transfer processes. TiO₂ nanocrystals predominantly enclosed by the {001} facets expose a high density of reactive fourfold-coordinated Ti sites (Ti_4c) at which CH₃OH molecules dissociate to form the CH₃O adsorbate (CH₃O(a)_Ti4c). CH₃O(a)_Ti4c localized density of states are almost at the valence band maximum of TiO₂ surface, facilitating the interfacial hole transfer process;CH₃O(a)_Ti4c with a high coverage promotes upward surface band bending, facilitating bulk-to-surface hole migration. CH₃O(a)_Ti4c exhibits the highest photocatalytic oxidation rate constant. TiO₂ nanocrystals enclosed by the {001} facets are most active in photocatalytic methanol oxidation. © 2020 Wiley-VCH GmbH

关键词： electronic structure methanol nanocrystals surface chemistry surface photochemistry

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High detectivity photodetectors based on perovskite nanowires with suppressed surface defects

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Photonics Research 2020年第12期8卷 1862-1874页

作者： GUOHUI LI RUI GAO YUE HAN AIPING ZHAI YUCHENG LIU YUE TIAN BINING TIAN YUYING HAO SHENGZHONG LIU YUCHENG WU YANXIA CUI College of Physics and Optoelectronics Key Laboratory of Advanced Transducers and Intelligent Control System of Ministry of EducationKey Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of EducationTaiyuan University of TechnologyTaiyuan 030024China Key Laboratory of Applied Surface and Colloid Chemistry MOEShaanxi Key Laboratory for Advanced Energy DevicesShaanxi Engineering Laboratory for Advanced Energy TechnologySchool of Materials Science and EngineeringShaanxi Normal UniversityXi’an 710119China Dalian National Laboratory for Clean Energy iChEMDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China University of Chinese Academy of Sciences Beijing 100049China

Solution-processable,single-crystalline perovskite nanowires are ideal candidates for developing low-cost photodetectors,but their detectivities are limited due to a high level of unintentional *** the surfaceinitiated solution-growth method,we fabricated high-quality,single-crystalline,defects-suppressed MAPbI_(3) nanowires,which possess atomically smooth side surfaces with a surface roughness of 0.27 nm,corresponding to a carrier lifetime of 112.9 *** forming ohmic MAPbI_(3)∕Au contacts through the dry contact method,highperformance metal–semiconductor–metal photodetectors have been demonstrated with a record large linear dynamic range of 157 dB along with a record high detectivity of 1.2×10^(14) Jones at an illumination power density of 5.5 nW∕cm^(2).Such superior photodetector performance metrics are attributed to,first,the defects-suppressed property of the as-grown MAPbI_(3) nanowires,which leads to a quite low noise current in the dark,and second,the ohmic contact between MAPbI_(3) and Au interfaces,which gives rise to an improved responsivity compared with the Schottky contact *** realized high-performance MAPbI_(3) nanowire photodetector advances the development of low-cost photodetectors and has potential applications in weak-signal photodetection.

关键词： nanowires perovskite surface

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Revealing the Microscopic Mechanism of Elementary Vortex Pinning in Superconductors

arXiv

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arXiv 2024年

作者： Chen, C. Liu, Y. Chen, Y. Hu, Y.N. Zhang, T.Z. Li, D. Wang, X. Wang, C.X. Lu, Z.Y.W. Zhang, Y.H. Zhang, Q.L. Dong, X.L. Wang, R. Feng, D.L. Zhang, T. Department of Physics State Key Laboratory of Surface Physics and Advanced Material Laboratory Fudan University Shanghai200438 China New Cornerstone Laboratory National Synchrotron Radiation Laboratory School of Nuclear Science and Technology University of Science and Technology of China Hefei230027 China National Laboratory of Solid State Microstructures Department of Physics Nanjing University Nanjing210093 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing100190 China Hefei National Laboratory Hefei230088 China Collaborative Innovation Center for Advanced Microstructures Nanjing210093 China Shanghai Research Center for Quantum Sciences Shanghai201315 China School of Physical Sciences University of Chinese Academy of Sciences Beijing100049 China Songshan Lake Materials Laboratory Guangdong Dongguan523808 China Zhejiang Institute of Photoelectronics & Zhejiang Institute for Advanced Light Source Zhejiang Normal University Jinhua321004 China Interdisciplinary Materials Research Center School of Materials Science and Engineering Tongji University Shanghai201804 China

Vortex pinning is a crucial factor that determines the critical current of practical superconductors and enables their diverse applications. However, the underlying mechanism of vortex pinning has long been elusive, lacking a clear microscopic explanation. Here using high-resolution scanning tunneling microscopy, we studied single vortex pinning induced by point defect in layered FeSe-based superconductors. We found the defect-vortex interaction drives low-energy vortex bound states away from EF, creating a "mini" gap that effectively lowers the system energy and enhances pinning. By measuring the local density-of-states, we directly obtained the elementary pinning energy and estimated the pinning force via the spatial gradient of pinning energy. The results are consistent with bulk critical current measurement. Furthermore, we show that a general microscopic quantum model incorporating defect-vortex interaction can naturally capture our observation. It suggests that the local pairing near pinned vortex core is actually enhanced compared to unpinned vortex, which is beyond the traditional understanding that non-superconducting regions pin vortices. Our study thus unveils a general microscopic mechanism of vortex pinning in superconductors, and provides insights for enhancing the critical current of practical superconductors. © 2024, CC BY.

关键词： Vortex flow

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Origin of enhanced stability in thiocyanate substituted α-FAPbI3 analogues

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Science China Chemistry 2019年第7期62卷 866-874页

作者： Zhuo Xu Ming Chen Shengzhong (Frank) Liu Key Laboratory of Applied Surface and Colloid Chemistry National Ministry of EducationShaanxi Key Laboratory for Advanced Energy DevicesShaanxi Engineering Lab for Advanced Energy TechnologyInstitute for Advanced Energy MaterialsSchool of Materials Science and Engineering Shaanxi Normal University Xi'an 710119 China State Key Laboratory of Catalysis Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 China

In the past few years,hybrid perovskites have emerged as the most promising photovoltaic materials due to their excellent optoelectronic properties,and easy fabrication ***,the long-term stability is still the main obstacle for their commercial ***,thiocyanate-doped hybrid perovskites have shown enhanced stability and impressive efficiency,but the reason is still ***,we discussed the enhanced stability of SCN-substituted pseudocubic FABX3(B=Pb^2+,Sn^2+;X=I^–,Br^–,and Cl^–)based on the density functional *** a series of calculations of Bader charge transfer,vacancy formation energies of different kinds of vacancies,decomposition enthalpy,phonon density of states,and ab initio molecular dynamics simulation,we conclude that the incorporation of SCN–can stabilize pseudocubic FABX3,and attribute the enhanced stability mainly to two factors:(1)the strong interaction between Pb^2+/Sn^2+and SCN^–,as well as the strong hydrogen bonding between FA+and X^–/SCN^–,and(2)the structural tilting induced by the incorporation of SCN^–.These findings provide alternative method for tuning the poor stability of pseudocubic FABX3,as well as for obtaining high-performance solar cells.

关键词： thiocyanate stability formamidinium perovskites density-functional theory

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