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Plastic deformation analysis and forming quality prediction of tube N C bending

Chinese Journal of Aeronautics 2016年第5期29卷 1436-1444页

作者： Lu Shiqiang Fang Jun Wang Kelu National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology School of Aeronautical Manufacturing Engineering Nanchang Hangkong University Nanchang 330063 China Jiangxi Key Laboratory of Surface Engineering Jiangxi Science and Technology Normal University Nanchang 330013 China

Plane strain assumption and exponent hardening law are used to investigate the plastic deformation in tube bending. Some theoretical formulae including stress, curvature radius of neutral layer, angle of neutral layer deviation, bending moment, wall thickness variation and crosssection distortion, are developed to explain the phenomena in tube bending and their magnitudes are also determined. During unloading process, the springback angle is deduced using the virtual work principle, and springback radius is also given according to the length of the neutral layer which remains unchanged before and after springback. The theoretical formulae are validated by the experimental results or the validated simulation results in literature, which can be used to auicklv predict the forming aualitv of tube numerical control （NC） bending.

关键词： Forming quality Plane strain Tube NC bending Theoretical analysis Virtual work principle

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Front Cover: Hollow Structure VS2@Reduced Graphene Oxide (RGO) Architecture for Enhanced Sodium-Ion Battery Performance (ChemElectroChem 1/2020)

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ChemElectroChem 2019年第1期7卷

作者： Haimei Qi Lina Wang Tiantian Zuo Shunlan Deng Prof. Qi Li Prof. Zong-Huai Liu Prof. Peng Hu Prof. Xuexia He Key Laboratory of Applied Surface and Colloid Chemistry Shaanxi Normal University) Ministry of Education Xi'an 710062 China Shaanxi Engineering Lab for Advanced Energy Technology School of Materials Science and Engineering Shaanxi Normal University Xi' an 710119 China School of Physics Northwest University Xi'an 710069 China

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Coexistence of Ferromagnetic and Stripe-Type Antiferromagnetic Spin Fluctuations in YFe2Ge2

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Physical Review Letters 2019年第21期122卷 217003-217003页

作者： Hongliang Wo Qisi Wang Yao Shen Xiaowen Zhang Yiqing Hao Yu Feng Shoudong Shen Zheng He Bingying Pan Wenbin Wang K. Nakajima S. Ohira-Kawamura P. Steffens M. Boehm K. Schmalzl T. R. Forrest M. Matsuda Yang Zhao J. W. Lynn Zhiping Yin Jun Zhao State Key Laboratory of Surface Physics and Department of Physics Fudan University Shanghai 200433 China Institute of Nanoelectronic Devices and Quantum Computing Fudan University Shanghai 200433 China Materials and Life Science Division J-PARC Center Tokai Ibaraki 319-1195 Japan Institut Laue-Langevin 71 Avenue des Martyrs 38042 Grenoble Cedex 9 France Forschungszentrum Jülich GmbH. Jülich Centre for Neutron Science at ILL 71 Avenue des Martyrs 38000 Grenoble France Diamond Light Source Harwell Campus Didcot OX11 0DE United Kingdom Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA NIST Center for Neutron Research National Institute of Standards and Technology Gaithersburg Maryland 20899 USA Department of Materials Science and Engineering University of Maryland College Park Maryland 20742 USA Department of Physics and Center for Advanced Quantum Studies Beijing Normal University Beijing 100875 China Collaborative Innovation Center of Advanced Microstructures Nanjing 210093 China

We report neutron scattering measurements of single-crystalline YFe2Ge2 in the normal state, which has the same crystal structure as the 122 family of iron pnictide superconductors. YFe2Ge2 does not exhibit long-range magnetic order but exhibits strong spin fluctuations. Like the iron pnictides, YFe2Ge2 displays anisotropic stripe-type antiferromagnetic spin fluctuations at (π, 0, π). More interesting, however, is the observation of strong spin fluctuations at the in-plane ferromagnetic wave vector (0, 0, π). These ferromagnetic spin fluctuations are isotropic in the (H, K) plane, whose intensity exceeds that of stripe spin fluctuations. Both the ferromagnetic and stripe spin fluctuations remain gapless down to the lowest measured energies. Our results naturally explain the absence of magnetic order in YFe2Ge2 and also imply that the ferromagnetic correlations may be a key ingredient for iron-based materials.

关键词： Pairing mechanisms Spin dynamics Superconducting phase transition High-temperature superconductors Pnictides Neutron scattering

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Novel type of ferroelectricity in brownmillerite structures: A first-principles study

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Physical Review Materials 2018年第8期2卷 084402-084402页

作者： Hao Tian Xiao-Yu Kuang Ai-Jie Mao Yurong Yang Hongjun Xiang Changsong Xu S. Omid Sayedaghaee Jorge Íñiguez L. Bellaiche Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China Physics Department and Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA National Laboratory of Solid State Microstructures College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 China Department of Physics Key Laboratory of Computational Physical Sciences (Ministry of Education) State Key Laboratory of Surface Physics Fudan University Shanghai 200433 China Microelectronics-Photonics Program and Physics Department University of Arkansas Fayetteville Arkansas 72701 USA Materials Research and Technology Department Luxembourg Institute of Science and Technology (LIST) 5 Avenue des Hauts-Fourneaux L-4362 Esch/Alzette Luxembourg

First-principles calculations are conducted on two magnetic brownmillerites, namely, Ca2Co2O5 and Sr2Co2O5. Both systems possess a previously overlooked polar Pmc21 phase that is low in energy. This ferroelectric state is even predicted to be the ground state of Sr2Co2O5, which therefore renders such material multiferroic. Strikingly, the ferroelectricity associated with this Pmc21 phase involves an original energetic coupling that is linear in the polar mode, quadratic in another distortion, and linear in a third mode. Such ferroelectricity is therefore of a novel type, since it differs from previously reported proper, improper, hybrid improper, and triggered kinds of ferroelectricity.

关键词： Defects Ferroelectricity First-principles calculations Crystal structures Multiferroics Oxides Density functional theory

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Revisiting spin cycloids in multiferroic BiFeO3

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Physical Review B 2018年第18期98卷 184420-184420页

作者： Bin Xu Bertrand Dupé Changsong Xu Hongjun Xiang L. Bellaiche School of Physical Science and Technology Soochow University Suzhou Jiangsu 215006 China Physics Department and Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA Institute of Physics INSPIRE Group Johannes Gutenberg-University Mainz 55128 Mainz Germany Key Laboratory of Computational Physical Sciences (Ministry of Education) State Key Laboratory of Surface Physics and Department of Physics Fudan University Shanghai 200433 China Collaborative Innovation Center of Advanced Microstructures Nanjing 210093 People's Republic of China

We revisit the inverse spin current model that has been previously used to explain the existence of magnetic cycloids in bulk multiferroic BiFeO3. Using a first-principles-based effective Hamiltonian method, and in combination with Monte Carlo simulations, we predict a magnetic phase diagram as a function of first- and second-nearest-neighbor interaction strength in the spin current model and show that, in contrast with previous understanding, both first and second nearest neighbors have to be taken into account to be in accordance with experimental findings, including the existence of type-1 and type-2 cycloids with, respectively, [11¯0] and [112¯] propagation directions, and the cycloid-to-antiferromagnetic transition under magnetic field. Other previously unknown magnetic arrangements are found in this phase diagram. The microscopic origins of all its magnetic phases are further explained in terms of the coexistence of single solutions of the spin current model having different weights (in magnitude and even sign).

关键词： Electric polarization Ferroelectricity Magnetic interactions Magnetic order Magnetic texture Magnetoelectric effect Multiferroics Monte Carlo methods

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Phase equilibrium of Cd_(1-x)Zn_xS alloys studied by first-principles calculations and Monte Carlo simulations

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Chinese Physics B 2016年第1期25卷 549-555页

作者：张付珍薛红涛汤富领李小康路文江冯煜东 State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Department of Materials Science and EngineeringLanzhou University of TechnologyLanzhou 730050China Science and Technology on Surface Engineering Laboratory Lanzhou Institute of PhysicsLanzhou 730000China

The first-principles calculations based on density functional theory combined with cluster expansion techniques and Monte Carlo （MC） simulations were used to study the phase diagrams of both wurtzite （WZ） and zinc-blende （ZB） Cdl_xZnxS alloys. All formation energies are positive for WZ and ZB Cdl-xZnxS alloys, which means that the Cdl-xZnxS alloys are unstable and have a tendency to phase separation. For WZ and ZB Cdl_xZnxS alloys, the consolute temperatures are 655 K and 604 K, respectively, and they both have an asymmetric miscibility gap. We obtained the spatial distributions of Cd and Zn atoms in WZ and ZB *** alloys at different temperatures by MC simulations. We found that both WZ and ZB phases of *** alloy exhibit phase segregation of Cd and Zn atoms at low temperature, which is consistent with the phase diagrams.

关键词： first-principles calculation Monte Carlo simulations phase separation spatial distribution

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Lattice structures and electronic properties of WZ-CuInS2/WZ-CdS interface from first-principles calculations

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Chinese Physics B 2016年第12期25卷 207-216页

作者：柳红霞汤富领薛红涛张宇程育汶冯煜东 State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Department of Materials Science and Engineering Lanzhou University of Technology Lanzhou 730050 China Science and Technology on Surface Engineering Laboratory Lanzhou Institute of Physics Lanzhou 730000 China

Using the first-principles plane-wave calculations within density functional theory, the perfect bi-layer and monolayer terminated WZ-CIS （100）/WZ-CdS （100） interfaces are investigated. After relaxation the atomic positions and the bond lengths change slightly on the two interfaces. The WZ-CIS/WZ-CdS interfaces can exist stably, when the interface bonding energies are -0.481 J/m2 （bi-layer terminated interface） and -0.677 J/m2 （monolayer terminated interface）. Via analysis of the density of states, difference charge density and Bader charges, no interface state is found near the Fermi level. The stronger adhesion of the monolayer terminated interface is attributed to more electron transformations and orbital hybridizations, promoting stable interfacial bonds between atoms than those on a bi-layer terminated interface.

关键词： first-principles calculation WZ-CIS/WZ-CdS interface density of states interface bonding en-ergy interface states

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Anorganische CsPbX3‐Perowskit‐Solarzellen: Fortschritte und Perspektiven

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Angewandte Chemie 2019年第44期131卷

作者： Jingru Zhang Gary Hodes Zhiwen Jin Shengzhong (Frank) Liu Key Laboratory of Applied Surface and Colloid Chemistry Ministry of Education Shaanxi Key Laboratory for Advanced Energy Devices Shaanxi Engineering Lab for Advanced Energy Technology School of Materials Science & Engineering Shaanxi Normal University Xi'an 710119 P. R. China Department of Materials and Interfaces Weizmann Institute of Science Rehovot 76100 Israel School of Physical Science and Technology & Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education Lanzhou University Lanzhou 730000 P. R. China Dalian National Laboratory for Clean Energy iChEM Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 P. R. China

Perowskite auf Halogenidbasis haben sich aufgrund ihrer hervorragenden optoelektronischen Eigenschaften zu einem der wichtigsten Themen in der Photovoltaik‐Forschung entwickelt. Insbesondere wurden bei organisch‐anorganischen Perowskit‐Solarzellen (PSCs) rasche Fortschritte beim Wirkungsgrad (PCE, power conversion efficiency) erreicht, mit einem derzeitigen Rekordwert von 23.7 % PCE. Die an sich instabile Beschaffenheit dieser Materialien, insbesondere gegenüber Feuchtigkeit und Wärme, stellt jedoch ein Problem bezüglich ihrer Langzeitstabilität dar. Der Ersatz der fragilen organischen Gruppe durch robustere anorganische Cs + ‐Kationen ergibt Caesiumbleihalogenide CsPbX 3 (X=Halogenid), die thermisch viel stabiler und meist auch stabiler gegen andere Faktoren sind. Seit dem ersten Bericht im Jahr 2015 ist der PCE von CsPbX 3 ‐basierten PSCs von 2.9 % bis auf heute 17.1 % mit deutlich verbesserter Stabilität gestiegen. In diesem Aufsatz sollen die bisherigen Ergebnisse auf dem Gebiet zusammenfasst und Lösungen für Entwicklungsengpässe vorgeschlagen werden.

关键词： Caesiumbleihalogenid Halogenidperowskite Photovoltaik Solarzellen Wirkungsgrad

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Grain Boundaries: Nanoassembly Growth Model for Subdomain and Grain Boundary Formation in 1T′ Layered ReS2(Adv. Funct. Mater. 49/2019)

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advanced Functional Materials 2019年第49期29卷

作者： Xiaobo Li Xiao Wang Jinhua Hong Dongyan Liu Qingliang Feng Zhibin Lei Kaihui Liu Feng Ding Hua Xu Key Laboratory of Applied Surface and Colloid Chemistry Ministry of Education Shaanxi Key Laboratory for Advanced Energy Devices Shaanxi Engineering Lab for Advanced Energy Technology School of Materials Science and Engineering Shaanxi Normal University Xi'an 710119 P. R. China Center for Multidimensional Carbon Materials Institute for Basic Science School of Materials Science and Engineering Ulsan National Institute of Science and Technology Ulsan 44919 South Korea Nanostructures Research Laboratory Japan Fine Ceramics Center Atsuta Nagoya 456‐8587 Japan School of Science Northwestern Polytechnical University Xi'an 710072 P. R. China State Key Laboratory for Mesoscopic Physics Collaborative Innovation Center of Quantum Matter School of Physics Peking University Beijing 100871 China

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Block poly(arylene ether sulfone) copolymers bearing quaterinized aromatic pendants: Synthesis, property and stability

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International Journal of Hydrogen Energy 2017年第42期42卷 26320-26332页

作者： Xueliang Zhang Pei Chen Qian Shi Songsong Li Feixiang Gong Xinbing Chen Zhongwei An Key Laboratory of Applied Surface and Colloid Chemistry (MOE) Shaanxi Key Laboratory for Advanced Energy Devices Shaanxi Engineering Lab for Advanced Energy Technology School of Materials Science and Engineering Shaanxi Normal University Xi'an 710119 PR China Xi'an Modern Chemistry Research Institute Xi'an 710065 PR China

Block poly(arylene ether sulfone) copolymers caring pendent benzyl-quaternary ammonium groups were prepared through multiple-step reaction pathways that involve pre-polycondensation, block copolycondensation, bromomethylation and Menshutkin reactions. The copolymer ionomer based anion exchange membranes (AEMs) with ion exchange capacity (IEC) from 0.75 to 1.10 mequiv g −1 display relatively large hydroxide conductivities of 45.9–66.1 mS cm −1 at 80 °C, which are ascribed to the distinct hydrophobic/hydrophilic microphase separation resulted from the block copolymer structures and side-chain type hydrophilic segments. Compared to the corresponding random copolymer based AEM, the block ones have obviously higher stability and larger hydroxide conductivity due to the well-connected ionic nanochannels. Among the AEMs, bQPAE-x7y32 with IEC of 1.10 mequiv g −1 gives the best performance with high hydroxide conductivity of 66.1 mS cm −1 , low methanol permeability of 4.9 × 10 −7 cm 2 s −1 , large φ of 4.6 × 10 4 Scm −3 s, as well as good alkaline stability, respectively.

关键词： Anion exchange membrane Block poly(arylene ether sulfone) copolymer Alkaline stability Microphase separation Hydroxide conductivity

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