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Bismuth-based halide double perovskite Cs_(2)KBiCl_(6): Disorder and luminescence

Chinese Chemical Letters 2024年第5期35卷 504-508页

作者： Pan Liu Yanming Sun Alberto J.Fernández-Carrión Bowen Zhang Hui Fu lunhua he Xing Ming Congling Yin Xiaojun Kuang MOE Key Laboratory of New Processing Technology for Nonferrous Metal and Materials Guangxi Key Laboratory of Optic and Electronic Materials and DevicesCollege of Materials Science and EngineeringGuilin University of TechnologyGuilin 541004China Analytical Instrumentation Center College of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China Spallation Neutron Source Science Center Dongguan 523803China Chinese Academic of Science Institute of PhysicsBeijing National Laboratory for Condensed Matter PhysicsBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China College of Science Guilin University of TechnologyGuilin 541004China College of Chemistry and Bioengineering Guilin University of TechnologyGuilin 541004China

A new bismuth-based halide double perovskite Cs_(2)KBiCl_(6) was isolated successfully through solid-state reactions and investigated using X-ray and neutron *** than an ordered structure,the crystal structure consists of shifted Cs,K,Bi,and Cl sites from the ideal positions with fractional occupancy in compensation,leading to variable local coordination of Cs^(+)ions,as revealed by^(133)Cs solid-state nuclear magnetic resonance ***_(2)KBiCl_(6) displays volume hysteresis at 5-298 K range upon heating and *** Cs_(2)KBiCl_(6) has a direct bandgap of 3.35(2)eV and red-shift luminescence of around 600 nm upon Mn doping compared with the Na *** stabilization of disordered structure in Cs_(2)KBiCl_(6) is related to two factors including the large-sized K^(+)cation which prefers to coordinate with more than six Cl^(-),and the Bi^(3+)with 6s^(2) lone pair which has a preference for a local asymmetric *** findings could have general application and help to understand the structure and property of halide perovskites.

关键词： Halide perovskite Double perovskite Luminescence Disordered structure Direct bandgap

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基于空间分辨中子衍射方法的锂离子电池电化学反应均匀性研究

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储能科学与技术 2024年第1期13卷 72-81页

作者：童文欣黄中垣王睿邓司浩何伦华肖荫果北京大学深圳研究生院广东深圳518055 散裂中子源科学中心广东东莞523803 中国科学院物理研究所北京100190

锂离子电池作为一种具有复杂组成的电化学器件,其电化学反应的均匀性受多种因素影响,包括正负极材料成分、电池结构和制备工艺等。电池的局部电化学反应不均匀性将导致局部失效加剧,进而影响其电化学性能、循环稳定性和安全性。鉴于电... 详细信息

锂离子电池作为一种具有复杂组成的电化学器件,其电化学反应的均匀性受多种因素影响,包括正负极材料成分、电池结构和制备工艺等。电池的局部电化学反应不均匀性将导致局部失效加剧,进而影响其电化学性能、循环稳定性和安全性。鉴于电池拆解分析不但会破坏其电芯结构,改变电极材料的化学性质,进而影响分析结果的准确性,本工作介绍并应用无损的空间分辨飞行时间中子衍射方法,对大尺寸软包锂离子电池电化学反应分布的均匀性展开研究。通过采集和分析毫米尺度测试区域的中子衍射数据,获得了全电池在初始状态和失效状态下锂离子嵌入石墨负极过程中的相变信息,并构建了全电池不同位置处的石墨负极多相含量分布和归一化后负极中的锂浓度分布图。此外,结合高精度三维X射线断层扫描方法,从电池厚度、电流密度和电解质浓度等多个角度,分析和探讨了这些因素对锂离子电池电化学反应均匀性的影响。空间分辨中子粉末衍射方法可以对不同类型和不同形状的金属离子电池中的电化学反应均匀性进行快速直接的检测,为电池结构性能优化和技术改进提供强有力的技术支持。

关键词：空间分辨中子衍射方法锂离子电池材料锂浓度分布电化学反应均匀性

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焊前预处理对钛合金厚板焊接残余应力的影响

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金属学报 2024年第8期60卷 1064-1078页

作者：周牧王倩王延绪翟梓融何伦华李昺马英杰雷家峰杨锐中国科学技术大学材料科学与工程学院沈阳110016 中国科学院金属研究所师昌绪先进材料创新中心沈阳110016 中国科学院金属研究所沈阳材料科学国家研究中心沈阳110016 上海科技大学智造系统工程中心上海201210 散裂中子源科学中心东莞523803 中国科学院物理研究所北京国家凝聚态物理学实验室北京100190

焊接残余应力是影响焊接成型及焊接部件服役的重要因素。为了优化焊接工艺和焊接接头微观结构,有效地减小焊接残余应力,本工作研究了焊前预处理工艺对电子束焊接钛合金厚板焊接接头组织、性能和残余应力的影响机制。对不同预处理工艺制... 详细信息

焊接残余应力是影响焊接成型及焊接部件服役的重要因素。为了优化焊接工艺和焊接接头微观结构,有效地减小焊接残余应力,本工作研究了焊前预处理工艺对电子束焊接钛合金厚板焊接接头组织、性能和残余应力的影响机制。对不同预处理工艺制备的钛合金焊接接头进行组织形貌表征,发现焊前预热显著增宽了焊接接头的熔合区和热影响区,粗化了两区域内的α片层,提高了焊接接头的强韧性匹配。采用中子衍射法、深孔法和轮廓法检测钛合金厚板电子束焊接头残余应力,对3种方法的检测结果进行对比分析,获得了焊接接头不同区域沿不同方向的残余应力分布。另外,对比了2种预热工艺焊接接头采用深孔法获得的残余应力结果,发现焊前预热可以显著降低焊接接头的残余应力。采用数值模拟计算了不同预热温度下温度场和应力场的变化情况,获得了不同预热温度条件下热应力的动态变化规律,揭示了预热降低残余应力的内在机理。对比2种预处理工艺焊接接头熔合区和热影响区的显微组织、元素分布和晶粒取向,进一步阐明了预热可以通过促进元素扩散和诱发变体选择降低β→α相变产生的应力集中。

关键词：钛合金残余应力中子衍射显微组织力学性能

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C-Type Antiferromagnetic Structure of Topological Semimetal CaMnSb2

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Chinese Physics Letters 2024年第03期41卷 119-125页

作者：李博曾旭涛徐千惠杨帆项俊森钟恒扬邓司浩何伦华徐菊萍殷雯鲁兴业刘慧颖胜献雷金文涛 School of Physics Beihang University Beijing National Laboratory for Condensed Matter Physics and Institute of PhysicsChinese Academy of Sciences Center for Advanced Quantum Studies and Department of Physics Beijing Normal University Spallation Neutron Source Science Center Songshan Lake Materials Laboratory

Determination of the magnetic structure and confirmation of the presence or absence of inversion （P） and time reversal （Τ） symmetry is imperative for correctly understanding the topological magnetic materials. he... 详细信息

关键词： Density functional theory

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深冷循环对SiC/Al复合材料宏微观残余应力的影响

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金属学报 2024年第8期60卷 1031-1042页

作者：谷黎明冯效铭于朝张峻凡刘振宇何伦华卢怀乐李小虎王晨张晓东肖伯律马宗义中国科学院金属研究所、师昌绪先进材料创新中心沈阳110016 中国科学技术大学、材料科学与工程学院沈阳110016 散裂中子源科学中心东莞523803 中国科学院物理研究所、北京凝聚态物理国家研究中心北京100190 松山湖材料实验室东莞523808 中国科学院高能物理研究所北京100049

铝基碳化硅(SiC/Al)复合材料因其高比模量、高比强度和良好尺寸稳定性等特点广泛应用于精密光学领域。SiC/Al复合材料热处理过程中产生的宏/微观残余应力是影响其尺寸稳定性的关键因素。为了阐明残余应力的降低方法和效果,提高精密光学... 详细信息

铝基碳化硅(SiC/Al)复合材料因其高比模量、高比强度和良好尺寸稳定性等特点广泛应用于精密光学领域。SiC/Al复合材料热处理过程中产生的宏/微观残余应力是影响其尺寸稳定性的关键因素。为了阐明残余应力的降低方法和效果,提高精密光学零件的尺寸稳定性,本工作使用中子衍射和有限元模拟,分析了深冷循环处理对于体积分数为35%的SiC/6092Al复合材料在退火状态下宏微观残余应力的影响,研究了深冷循环次数、样品尺寸、增强相颗粒尺寸和深冷循环温度差等影响因素。结果表明,深冷循环能引起基体塑性应变,从而显著降低退火态SiC/Al复合材料的相应力,并且随着深冷循环次数的增加,单次循环相应力降低效果减弱。深冷循环导致的塑性应变集中在颗粒周围的基体,主要影响颗粒和周围基体的相应力大小,与样品尺寸无明显关联,并且深冷循环不增加退火态样品的宏观残余应力。复合材料多次深冷循环后的相应力降低量与SiC颗粒尺寸无关,并且,多次深冷循环对相应力的降低效果与深冷循环温度差关系较小,100~-196℃和200~-196℃进行多次深冷循环对相应力的改变十分接近。

关键词：深冷循环中子衍射残余应力有限元方法代表性体积单元

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Structure and magnetic properties of the S=3/2 zigzag spin chain antiferromagnet BaCoTe_(2)O_(7)

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Science China(Physics,Mechanics & Astronomy) 2021年第8期64卷 91-97页

作者： Lisi Li Xunwu Hu Zengjia Liu Jia Yu Benyuan Cheng Sihao Deng lunhua he Kun Cao Dao-Xin Yao Meng Wang Center for Neutron Science and Technology School of PhysicsSun Yat-sen UniversityGuangzhou 510275China Shanghai Institute of Laser Plasma Shanghai 201800China Center for High Pressure Science and Technology Advanced Research Shanghai 201203China Spallation Neutron Source Science Center Dongguan 523803China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China

We report a study of the structure and magnetic properties of the S=3/2 zigzag spin chain compound BaCoTe_(2)O_(7).Neutron diffraction measurements show that it crystallizes in the noncentrosymmetric space group Ama2 with a canted↑↑↓↓spin structure along the quasi-one-dimensional zigzag chain and a moment size of 1.89(2)μBat 2 *** magnetic susceptibility and specific heat measurements yield an antiferromagnetic phase transition at TN=6.2 K.A negative Curie-Weiss temperature,ΘCW=-74.7(2) K,and an empirical frustration parameter,f=|ΘCW|/TN≈12,are obtained by fitting the magnetic susceptibility,indicating antiferromagnetic interactions and strong magnetic *** ultraviolet-visible absorption spectroscopy and first-principles calculations,an indirect band gap of 2.68(2) eV is *** propose that the canted zigzag spin chain of BaCoTe_(2)O_(7) may produce a change in the polarization via the exchange-striction mechanism.

关键词： antiferromagnet zigzag spin chain magnetic frustration spin structure

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Physical design of target station and neutron instruments for China Spallation Neutron Source

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Science China(Physics,Mechanics & Astronomy) 2013年第12期56卷 2410-2424页

作者： WANG FangWei LIANG TianJiao YIN Wen YU QuanZhi he lunhua TAO JuZhou ZHU Tao JIA XueJun ZHANG ShaoYing Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences Dongguan Branch Institute of High Energy PhysicsChinese Academy of Sciences

The China Spallation Neutron Source(CSNS)is the first accelerator-based multidiscipline user facility to produce pulsed neutrons by tungsten target under collision of a pulsed proton beam with a beam power of 100 kW at a repetition rate of 25 *** this paper,we focus on the physical design of CSNS target station and neutron *** optimized design,the flat tungsten target and the compact target-moderator-reflector coupling enhance effective cold and thermal neutron output from *** wing-type moderators supply four different characteristics of neutrons to 19 beamlines primarily for neutron scattering *** of neutron instruments are conceptually planned for total 20 beamlines,the configuration and specification have been determined for three day-one neutron *** designs are optimized for the Phase I of 100 kW with a upgradable capacity to 500 kW.

关键词： neutron scattering spallation neutron source neutron diffraction neutron shielding

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Grain size and structure distortion characterization of α-MgAgSb thermoelectric material by powder diffraction

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Chinese Physics B 2020年第10期29卷 388-391页

作者： Xiyang Li Zhigang Zhang lunhua he Maxim Avdeev Yang Ren Huaizhou Zhao Fangwei Wang Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 101408China Songshan Lake Materials Laboratory Dongguan 523808China Australian Nuclear Science and Technology Organisation Lucas HeightsNSW 2234Australia X-ray Science Division Argonne National LaboratoryArgonneIL 60439USA

Nanostructuring, structure distortion, and/or disorder are the main manipulation techniques to reduce the lattice thermal conductivity and improve the figure of merit of thermoelectric materials. A single-phase α-MgAgSb sample, MgAg0.97Sb0.99, with high thermoelectric performance in near room temperature region was synthesized through a high-energy ball milling with a hot-pressing method. here, we report the average grain size of 24–28 nm and the accurate structure distortion, which are characterized by high-resolution neutron diffraction and synchrotron x-ray diffraction with Rietveld refinement data analysis. Both the small grain size and the structure distortion have a contribution to the low lattice thermal conductivity in MgAg0.97Sb0.99.

关键词： diffraction grain size structure distortion thermoelectric material

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Neutron-based characterization techniques for lithium-ion battery research

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Chinese Physics B 2020年第1期29卷 40-61页

作者： Enyue Zhao Zhi-Gang Zhang Xiyang Li lunhua he Xiqian Yu Hong Li Fangwei Wang Songshan Lake Materials Laboratory Dongguan 523808China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 101408China China Spallation Neutron Source(CSNS) Dongguan 523808China

During the past decades,Li-ion batteries have been one of the most important energy storage ***-scale energy storage requires Li-ion batteries which possess high energy density,low cost,and high *** than advanced battery materials,in-depth understanding of the intrinsic mechanism correlated with cell reaction is also essential for the development of high-performance Li-ion *** characterization techniques,especially neutron-based techniques,have greatly promoted Li-ion battery *** this review,the characteristics or capabilities of various neutron-based characterization techniques,including elastic neutron scattering,quasi-elastic neutron scattering,neutron imaging,and inelastic neutron scattering,for the related Li-ion-battery researches are *** design of in-situ/operando environment is also *** comprehensive survey on neutron-based characterizations for mechanism understanding will provide guidance for the further study of high-performance Li-ion batteries.

关键词： Li-ion battery neutron scattering characterization technique

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Magnetic field enhanced thermal conductivity and origin of large thermopower in layered cobaltates

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Journal of Materiomics 2023年第6期9卷 1048-1055页

作者： Yinong Yin Fanfan Shi Guo-Qiang Liu Ashutosh Tiwari Jiazheng Hao lunhua he Dan Liu Jianfeng Cai Xiaojian Tan Jun Jiang Baogen Shen Department of Physics Beijing Technology and Business UniversityBeijing100048China Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesZhejiang315201China Department of Materials Science and Engineering University of UtahSalt Lake CityUT84112USA Institute of High Energy Physics Chinese Academy of SciencesBeijing100049China Spallation Neutron Source Science Center(SNSSC) Dongguan523803China State Key Laboratory of Magnetism Institute of PhysicsChinese Academy of SciencesBeijing100190China

Cobalt oxide,as one of the most fascinating examples of correlated electronic system,exhibits several exotic transport characteristics,such as superconductivity,charge ordering,and topological *** this study,we are reporting the observation of another intriguing transport phenomenon in calcium ***,under a large magnetic field of 7 T,we observed an anomalously enhanced thermal conductivity that was accompanied with a largely suppressed *** observation reveals a hitherto undiscovered correlation between the two transport *** the premise of heisenberg model,we have shown that the observed experimental results can be explained consistently only if the magnon excitation is taken into *** study offers an insight into the puzzling origin of large thermopower observed in layered cobaltates and provides a specific strategy for further optimization of thermopower.

关键词： Calcium cobaltates Thermal conductivity Spin-wave Spin entropy

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