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Strain manipulation of ferroelectric skyrmion bubbles in a freestanding PbTiO3 film: A phase field simulation

Physical Review B 2022年第22期105卷 224101-224101页

作者： Yixuan Zhang Qian Li Houbing Huang Jiawang Hong Xueyun Wang School of Aerospace Engineering Beijing Institute of Technology Beijing 100081 China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing 100084 China Advanced Research Institute of Multidisciplinary Science Beijing Institute of Technology Beijing 100081 China

So far nanoscale topological polar structures have been mainly observed in ferroelectric superlattices, nanodots, and complex heterostructures, originating from the intricate interplay of built-in electric field, polarization, strain, and their gradient-related energies. However, solid substrates hinder the continuous strain manipulation of the ferroelectric topological textures. Recently, a breakthrough in fabricating freestanding films has demonstrated the possibility of continuous strain manipulation, but there has been little experimental or theoretical investigation of whether polar topological structures exist in freestanding films. Herein, by performing phase field simulation on (PbTiO3)20/(SrTiO3)10 freestanding bilayers, we observed the stabilized ferroelectric skyrmion bubbles in a ferroelectric layer. A thickness-dependent phase diagram indicates that the skyrmion bubbles exist when the ferroelectric layer is between eight and 30 unit cells. Meanwhile, we demonstrated that the uniaxial strain is an effective way to manipulate the skyrmion bubble in freestanding films, which not only induces consolidation and rearrangement of skyrmion bubbles, but also induces a phase transition from the topological skyrmion bubble state to a standard a1/a2 domain state. These results provide us guidance with a mechanical approach to control topological polar structures in freestanding films.

关键词： Electric polarization Ferroelectric domains Phase-field modeling

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Saxs "Unveils" Porous Anodes for Potassium-Ion Batteries: Dynamic Evolution of Pore Structure in Fe@Fe 2 O 3 /Pcnfs Composite Nanofibers

SSRN

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SSRN 2023年

作者： Shi, Haiting Jinxi, Bao Xianyan, Wu Feng, Tian Shuaitong, Liang Shao, Ruiqi Jingjing, Shi Yingjie, Dong Xu, Zhiwei State Key Laboratory of Separation Membranes and Membrane Processes School of Textile Science and Engineering Tiangong University Tianjin300387 China College of Materials and Textile Engineering Nanotechnology Research Institute Jiaxing University Jiaxing314001 China Shanghai Synchrotron Radiation Facility Zhangjiang Lab Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai201204 China International Joint Laboratory of New Textile Materials and Textiles of Henan Province Zhongyuan University of Technology Zhengzhou450007 China

The porous structure plays a key role in improving the electrochemical performance of composite nanofibers. However, the dynamic evolution of the pore structure and its action during the ion intercalation/extraction process for the negative electrode is not clear. Herein, porous carbon nanofibers composites (Fe@Fe2O3/PCNFs) were prepared as the negative electrode materials for sodium/potassium-ion batteries. Electrochemical test findings revealed that the composites had good electrochemical characteristics, and the porous structure provided more pseudo-capacitive behaviors for the composite electrodes. After 1500 discharge/charge cycles at a current density of 1000 mA g-1, the specific capacities of the potassium-ion and sodium-ion batteries were 144.8 mAh g-1 and 157.8 mAh g-1, respectively. We innovatively used the synchrotron small-angle X-ray scattering (SAXS) technique to systematically investigate the kinetic process of potassium formation in composites and showed that the kinetic process of potassium reaction in composites can be divided into four stages, and the pores with smaller average diameter distribution are more sensitive to the changes of the reaction process. This work provides a new way to study the deposition kinetics of sodium/potassium in porous materials, which facilitates the design of porous structures and realizes the development of alkali metal ion-anode materials with higher energies. © 2023, The Authors. All rights reserved.

关键词： Potassium

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Unconventional excitonic states with phonon sidebands in layered silicon diphosphide (Jun, 10.1038/s41563-022-01285-3, 2022)

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NATURE materials 2022年第10期21卷 1212-1212页

作者： Zhou, Ling Huang, Junwei Windgaetter, Lukas Ong, Chin Shen Zhao, Xiaoxu Zhang, Caorong Tang, Ming Li, Zeya Qiu, Caiyu Latini, Simone Lu, Yangfan Wu, Di Gou, Huiyang Wee, Andrew T. S. Hosono, Hideo Louie, Steven G. Tang, Peizhe Rubio, Angel Yuan, Hongtao National Laboratory of Solid State Microstructures Jiangsu Key Laboratory of Artificial Functional Materials College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing China Max Planck Institute for the Structure and Dynamics of Matter Center for Free Electron Laser Science Hamburg Germany School of Materials Science and Engineering Beihang University Beijing China Center for Computational Quantum Physics Simons Foundation Flatiron Institute New York NY USA Department of Physics University of California Berkeley CA USA Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley CA USA School of Materials Science and Engineering Peking University Beijing China Materials Research Center for Element Strategy Tokyo Institute of Technology Yokohama Japan College of Materials Science and Engineering National Engineering Research Center for Magnesium Alloys Chongqing University Chongqing China Center for High Pressure Science and Technology Advanced Research Beijing China Department of Physics National University of Singapore Singapore Singapore

Complex correlated states emerging from many-body interactions between quasiparticles (electrons, excitons and phonons) are at the core of condensed matter physics and material science. In low-dimensional materials, quantum confinement affects the electronic, and subsequently, optical properties for these correlated states. Here, by combining photoluminescence, optical reflection measurements and ab initio theoretical calculations, we demonstrate an unconventional excitonic state and its bound phonon sideband in layered silicon diphosphide (SiP2), where the bound electron–hole pair is composed of electrons confined within one-dimensional phosphorus–phosphorus chains and holes extended in two-dimensional SiP2layers. The excitonic state and emergent phonon sideband show linear dichroism and large energy redshifts with increasing temperature. Our ab initio many-body calculations confirm that the observed phonon sideband results from the correlated interaction between excitons and optical phonons. With these results, we propose layered SiP2as a platform for the study of excitonic physics and many-particle effects.

关键词： Silicon compounds

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Interface engineering of phase separation in SrRuO3/SrTiO3 hybrid superlattices

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Physical Review B 2022年第2期106卷 024424-024424页

作者： Zhangzhang Cui Yingying Zhang Xiaofang Zhai Hanghui Chen Yi-De Chuang Jinghua Guo Zhengping Fu Zhengcao Li Yalin Lu Hefei National Research Center for Physical Sciences at the Microscale and Department of Materials Science and Engineering University of Science and Technology of China Hefei Anhui 230026 China Anhui Laboratory of Advanced Photon Science and Technology University of Science and Technology of China Hefei Anhui 230026 China State Key Laboratory for New Ceramics and Fine Processing Key Laboratory of Advanced Materials of Ministry of Education School of Materials Science and Engineering Tsinghua University Beijing 100084 China School of Physical Science and Technology ShanghaiTech University Shanghai 201210 China NYU-ECNU Institute of Physics NYU Shanghai Shanghai 200122 China Department of Physics New York University New York New York 10003 USA Advanced Light Source Lawrence Berkeley National Laboratory Berkeley California 94720 USA

Most observed phase separation phenomena in complex oxides occur in systems with chemical dopants or structural defects, and theories have established the strong connection between phase separation and the random distribution of chemical dopants. Recent experiments on fabricated high-quality oxide superlattices also confirmed that the phase separation is suppressed in the clean systems without chemical disorders. Thus far, phase separation in strongly correlated oxides without the need of chemical dopants or structural defects has not been fully demonstrated. Here, we have built chemically ordered hybrid superlattices using prototypical SrRuO3 and SrTiO3 perovskite oxides. Contrary to previous understandings, we observe phase separation of two magnetic phases with different spin easy axes. We elucidate this phenomenon through first-principles calculations that the hybrid superlattices have a spontaneous structural instability, leading to a coexistence of ferromagnetic and antiferromagnetic phases. Our findings provide an alternative pathway other than chemical doping to introduce phase separation in correlated oxides and imply that phase separation can exist in clean systems without the need of chemical disorders.

关键词： Magnetic anisotropy Magnetotransport Phase separation Complex oxides Superlattices

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Evaluating the present and future of organic batteries

Nature Reviews Clean Technology

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Nature Reviews Clean technology 2025年 1-18页

作者： Huichao Dai Linnan Guan Minglei Mao Chengliang Wang School of Integrated Circuits State Key Laboratory of New Textile Materials and Advanced Processing Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education) Huazhong University of Science and Technology Wuhan China

The surge in electricity demand and the pursuit of sustainability position organic batteries as potential alternatives to conventional inorganic systems. In this Review, we quantitatively and mechanistically analyse the inherent characteristics of organic materials in comparison to inorganic materials and compare the electrochemical performance of organic and inorganic batteries. Owing to their weak intermolecular interactions (bond energy <100 kJ mol−1), light weight (density <2 g cm−3), high flexibility (Young’s modulus <10 GPa), high and non-selective ion diffusion coefficients (up to 10−8–10−9cm2s−1), low synthesis temperatures (<200 °C) and potentially high specific capacity, organic batteries might find application in high-specific-energy, large-scale, flexible devices or operating under extreme conditions such as ultrafast charging (higher than 10 C) and a wide temperature range (from −60 °C to 70 °C). Designability of organic electrode materials offers flexibility to tailor the properties of active materials to the requirements of different applications. Moreover, the optimization of the components and design packaging of organic batteries should also be considered in the development of large-scale cells. To advance practical applications, more attention should be paid to the sustainability, scalability and implementation aspects of organic batteries as well as performance standards, policies and regulations.

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Influence of Co on the microstructure and mechanical properties of M42 high-speed steel 2

Influence of Co on the microstructure and mechanical propert...

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2nd International Conference on advanced materials and Chemical Engineering, AMCE 2022

作者： Wang, Shunduo Chen, Yunbo Pan, Peng Lin, Zhenghua Zuo, Lingli China Academy of Machinery Science and Technology Beijing100044 China Beijing National Innovation Institute of Lightweight Ltd. Beijing100083 China State Key Laboratory for Advanced Forming Technology and Equipment Beijing100083 China Fujian Hengerda New Materials Ltd. Putian351142 China

M42 high-speed steel (W2Mo9Cr4VCo8) is a kind of high cobalt super-hard high-speed steel (HSS), which is extensively used in various cutting tool materials, but because of the high price of cobalt, high cobalt HSS does not bring good economic benefits. In this thesis, the consequences of various cobalt contents (0.0%, 2.0%, 4.0%, 6.0%, 8.0%) on the organization and mechanical properties of M42 HSS have been studied. The microstructure of HSS was analyzed by OM, SEM, and EDS, and the Rockwell hardness test, impact toughness test, and flexural strength test were conducted. The results show that cobalt helps to increase the nucleation rate of eutectic carbide precipitation and hinder its growth during tempering of HSS and refine the size of eutectic carbide, and the tempering hardness can be maintained above 68 HRC when the cobalt content is 4%-8%;however, cobalt also significantly reduces the impact toughness of HSS, and each 2% increase in cobalt impact toughness decreases about 4 J·cm-2. From the point of view of cobalt savings, cobalt content of 4%, high-speed steel tempering hardness, impact toughness, and other mechanical properties can be at a higher level. © Published under licence by IOP Publishing Ltd.

关键词： Eutectics

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Phase Equilibria at 500ºC of the Mg-Nd-Zn System in the Region of < 50 At%Nd

SSRN

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SSRN 2022年

作者： Xu, Honghui Wang, Peisheng He, Wei State Key Laboratory of Powder Metallurgy Central South University Changsha410083 China MOE Key Laboratory of New Processing Technology for Nonferrous Metals and Materials Guangxi Key Laboratory of Processing for Non-Ferrous Metals and Featured Materials School of Resources Environment and Materials Guangxi University Nanning530004 China

关键词： X ray diffraction

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Achieving Enhanced Electrochemical Performance for Cobalt-Free Layered Cathode Material by Al Doping

SSRN

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SSRN 2023年

作者： Huang, Yunhui Ma, Mingyuan Yang, Dan Ji, Yongsheng Qie, Long Liu, Zhikang Institute of New Energy Vehicles School of Materials Science and Engineering Tongji University Shanghai201804 China State Key Laboratory of Material Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan430074 China

We introduce a facile strategy to greatly improve the electrochemical reversibility of cobalt-free cathode material by doping trace quantity of Al in LiNi0.65Mn0.35O2. X-ray diffraction and X-ray photoelectron spectroscopy results reveal that Al doping reduces the cation disorder consequently and hence increases structural stability. Electrochemical measurements show that rate capability and cycling stability are remarkably enhanced by Al doping. Al-doped LiNi0.65Mn0.35O2 exhibits the optimized electrochemical performance with a capacity retention of 94.2% after 200 cycles at 2 C in voltage range of 2.75–4.2 V in cylindrical full cell, demonstrating that Al-doped cathode exhibits enhanced cyclability and reduced polarization during charge/discharge process. Moreover, the full cell shows good low-temperature performance with more than 70% capacity retention at -20 °C. The improved performances can be ascribed to the enhanced stability in layered structure of the Co-free material by the support of doped Al ions. © 2023, The Authors. All rights reserved.

关键词： Cathodes

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Phase Equilibria at 500ºC of the Mg-Nd-Zn System in the Region from 0 to 50 At%Nd

SSRN

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SSRN 2022年

作者： Wang, Peisheng He, Wei Xu, Honghui State Key Laboratory of Powder Metallurgy Central South University Changsha410083 China MOE Key Laboratory of New Processing Technology for Nonferrous Metals and Materials Guangxi Key Laboratory of Processing for Non-Ferrous Metals and Featured Materials School of Resources Environment and Materials Guangxi University Nanning530004 China

The phase equilibria at 500 ºC of the Mg–Nd–Zn system in the region below 50 at.% Nd were investigated with equilibrated alloys via the electron probe microanalysis and X-ray diffraction. And the isothermal section was constructed. Ten ternary phases, tao1 to tao9 and T-NdMg12, were found at 500 ºC. Among them, the tao8 and tao9 are the newly found ternary compounds. The tao7 is a metastable phase. The T-NdMg12 phase is considered to be the Zn-stabilized Mnl2Th-type NdMg12 phase. Its composition ranges was measured to be Nd7.6-7.7Mg84.5-88.7Zn3.7-7.8. The homogeneity ranges of the eight stable ternary compounds (tao1 to tao6, tao8 and tao9) were well determined. The solubility of the third elements in the binary compounds of the three binary systems was also well measured. The lattice parameters of the tao1, tao2 and tao5 phases were determined to be a = 0.9709 (3) nm / b = 1.1253 (4) nm / c = 0.9545 (3) nm at Nd7.8Mg57.0 Zn35.2 (tao1), a =1.46234 (1) nm / c =0.8706 (1) nm at Nd7.1Mg28.5Zn64.4 (tao2) and a = 2.0883 (2) nm at Nd16.7Mg18.5Zn64.8 (tao5), respectively. © 2022, The Authors. All rights reserved.

关键词： Electron probe microanalysis

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CoS2/V2O3 Heterostructure with Coffee Ground Derived Carbon as Superior Composite Anodes of Sodium-Ion Batteries

SSRN

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SSRN 2023年

作者： Xue, Yongqi Wu, Jun Cheng, Zhiqun Xu, Congxin Cai, Yurong Ni, Wenbin Zhou, Xiaochong College of Electronics and Information Hangzhou Dianzi University Hangzhou310018 China The Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education National Engineering Lab for Textile Fiber Materials and Processing Technology School of Materials Science and Engineering Zhejiang Sci-Tech University Hangzhou310018 China Huzhou Horizontal Na Energy Technology Co. Ltd Chengye Intelligent Center No. 819 Xisaishan Road Longxi Street Huzhou313000 China

The poor ion transport kinetics and serious volumetric change of transition metal sulfides hinder their electrochemical applications. In this study, we introduced a heterostructure between CoS2 and V2O3 as an anode of sodium-ion batteries (SIBs) via a feasible hydrothermal method combining with a biomass carbon derived from coffee grounds (CG). The as-prepared CoS2/V2O3-CG composite retained a reversible capacity of 464.5 mAh g-1 after 300 cycles at 0.5 A g-1, exhibited an excellent rate capability of up to 8 A g-1 and a remarkable long-cycling life of over 2,000 cycles at 2 A g-1 with a capacity decay rate of less than 0.041% per cycle. The kinetic analysis indicated that CoS2/V2O3-CG composite exhibited a superior capacitive behavior, making it a high Na+ diffusion coefficient in SIBs. The enhanced electrochemical performances of composite can be primarily attributed to the CoS2/V2O3 heterostructure and porous biomass-derived carbon, which offers a built-in electric field and a large surface area, and effectively alleviates the volumetric expansion effect. © 2023, The Authors. All rights reserved.

关键词： Anodes

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