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Twinning,phase boundary structure and development of high coercivity in Fe-rich Sm_(2)Co_(17)-type magnets

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Journal of Rare Earths 2022年第1期40卷 102-111页

作者： Haichen Wu Zhuang Liu Chaoyue Zhang Qiqi Yang Huanming Lu Guoxin Chen Xinming Wang Yong Li Renjie Chen Aru Yan Analytical Center Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 3 J5201China Key Laboratory of Magnetic materials and Devices Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China

The microstructure of twinning as well as the phase boundary between 1:5 H and 2:17 R phase in Fe-rich Sm_(2)Co_(17)-type magnets was characterized at atomic scale using nanobeam diffraction and highresolution STEM-HAADF imaging,and the reason for the dramatic increase of coercivity during slow cooling was investigated based on the microchemistry analysis.The twinning relationship in the 2:17 R phase originates from ordered substitution of Sm atoms by Co-Co atomic pairs on every three(3033)and(3033)planes,leading to formation of two corresponding equivalent twin variants.The basal plane of the 2:17 R phase,the 1:3 R platelet phase across the 2:17 R cell and the 1:5 H cell boundary phase between two adjacent 2:17 R cells all can act as effective twin boundary.The cell boundary phase is precipitated along the pyramidal habit plane,and a fully coherent phase boundary(PB)is formed between the 1:5 H and 2:17 R phases with the orientation relationship to be PB//(1121)1:5 H//(1011)_(2):17 R.The phase boundary may either be parallel to or intersect with the pyramidal planes occupied by Co-Co atomic pairs.The substantial increase of coercivity during slow cooling is ascribed to the development of large gradient of the elements concentration within the cell boundary phase,resulting in large gradient of domain wall energy,and thus the pinning strength of the cell boundary phase against magnetic domain wall motion is significantly enhanced.

关键词： Sm_(2)Co_(17)-type magnets Microstructure Twinning Phase boundary Coercivity Rare earths

Zr-MOFs loaded on polyurethane foam by polydopamine for enhanced dye adsorption

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Journal of Environmental Sciences 2021年第3期33卷 177-188页

作者： Jingjing Zhao Linqiong Xu Yaozhuo Su Hongwei Yu Hui Liu Shaoping Qian Wenge Zheng Yongqing Zhao School of materials Science and Chemical engineering Ningbo UniversityNingbo 315211China ningbo Key Lab of Polymer materials Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China School of materials Science and engineering Wuhan Institute of TechnologyWuhan 430205China

Zirconium-based metal-organic frameworks(Zr-MOFs)have attracted widespread attention due to their high specific surface area,high porosity,abundant metal active sites and excellent hydrothermal stability.However,Zr-MOFs materials are mostly powdery in nature and thus difficult to separate from aqueous media,which limits their application in wastewater treatment.In this study,PDA/Zr-MOFs/PU foam was constructed by growing Zr-MOFs nanoparticles on a dopamine-modified polyurethane foam substrate by in-situ hydrothermal synthesis as an adsorbent for removing dyes from wastewater.The results demonstrated that the polydopamine coating improves the dispersion of the Zr-MOFs nanoparticles on the substrate and enhances the interaction between the Zr-MOFs nanoparticles and the PU foam substrate.As a result,compared with Zr-MOFs/PU foam,the prepared PDA/ZrMOFs/PU foam exhibits higher adsorption capacity for crystal violet(CV)(63.38 mg/g)and rhodamine B(RB)(67.73 mg/g),with maximum adsorption efficiencies of CV and RB of 98.4%(pH=11)and 93.5%(pH=7),respectively,at a concentration of 10 mg/L.The PDA/Zr-MOFs/PU foam can simultaneously remove CV and RB from the mixed solution.Moreover,the PDA/ZrMOFs/PU foam still exhibits high stability and reusability after five cycles.

关键词： Metal-organic framework Polydopamine Polyurethane foam Dye

Non-associative learning behavior in mixed proton and electron conductor hybrid pseudo-diode

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Journal of materials Science & technology 2023年第29期160卷 204-213页

作者： Zhi Wen Shi Wei Sheng Wang Ling Ai Yan Li Xin Li Chen Hui Xiao Yu Heng Zeng Li Qiang Zhu School of Physical Science and technology Ningbo UniversityNingbo 315211China Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesNingbo 315201China

With inherent ionic priorities, mixed ion and electron conductor hybrid devices have been proposed for brain-inspired neuromorphic system applications, demonstrating interesting neuromorphic functions. Here, mixed proton and electron conductor (MPEC) hybrid oxide neuromorphic transistor is proposed by adopting aqueous solution-processed mesoporous silica coating (MSC)-based electrolyte as gate dielec- tric. With optical and electrical synergetic coupling behaviors, the device demonstrates typical synap- tic responses and transition between short-term plasticity and long-term plasticity. With unique field- configurable proton self-modulation behaviors, a pseudo-diode operation mode is demonstrated on the MPEC hybrid transistor. Moreover, the device demonstrates interesting non-associative learning, including habituation and sensitization behavior. The results show that the proposed MPEC hybrid oxide neuromor- phic transistor has great potential in the field of neuromorphic engineering and would have potential in the bionic visual perception platform .

关键词： Mixed proton and electron conductor hybrid Oxide neuromorphic transistors Non-associative learning Pseudo-diode

Bioinspired tactile perception platform with information encryption function

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Chinese Physics B 2022年第9期31卷 636-643页

作者：石智文任征宇王伟胜肖惠曾俞衡竺立强 School of Physical Science and technology Ningbo UniversityNingbo 315211China Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesNingbo 315201China

Mimicking tactile perception is critical to the development of advanced interactive neuromorphic platforms.Inspired by cutaneous perceptual functions,a bionic tactile perceptual platform is proposed.PDMS-based tactile sensors act as bionic skin touch receptors.Flexible indium tin oxide neuromorphic transistors fabricated with a single-step mask pro-cessing act as artificial synapses.Thus,the tactile perceptual platform possesses the ability of information processing.Interestingly,the flexible tactile perception platform can find applications in information encryption and decryption.With adoption of cipher,signal transmitted by the perception platform is encrypted.Thus,the security of information transmis-sion is effectively improved.The flexible tactile perceptual platform would have potentials in cognitive wearable devices,advanced human-machine interaction system,and intelligent bionic robots.

关键词： flexible oxide neuromorphic transistor tactile perception platform information encryption

MAX phase forming mechanism of M-Al-C(M=Ti,V,Cr)coatings:In-situ X-ray diffraction and first-principle calculations

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Journal of materials Science & technology 2023年第12期143卷 140-152页

作者： Jianghuai Yuan Zhenyu Wang Guanshui Ma Xiaojing Bai Yong Li Xiaoying Cheng Peiling Ke Aiying Wang Key Laboratory of Marine materials and Related Technologies Zhejiang Key Laboratory of Marine Materials and Protective TechnologiesNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China School of materials Science and engineering Shanghai UniversityShanghai 200444China School of materials Science and engineering Anyang Institute of TechnologyAnyang 455000China Analytical Center Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China

The interesting hybrid properties of ceramics and metals induced by unique nano-laminated structures make the M_(n+1)AX n(MAX)phase attractive as a potential protective coating for vital structural compo-nents in harsh systems.However,an extremely narrow phase-forming region makes it difficult to prepare MAX phase coatings with high purity,which is required to obtain coatings with high-temperature anti-oxidation capabilities.This work describes the dependence of the phase evolution in deposited M-Al-C(M=Ti,V,Cr)coatings as a function on temperature using in-situ X-ray diffraction analysis.Compared to V_(2)AlC and Cr_(2)AlC MAX phase coatings,the Ti_(2)AlC coating displayed a higher phase-forming tempera-ture accompanied by a lack of any intermediate phases before the appearance of the Ti_(2)AlC MAX phase.The results of the first-principle calculations correlated with the experience in which Ti_(2)AlC exhibited the largest formation energy and density of states.The effect of the phase compositions of these three MAX phase coatings on mechanical properties were also investigated using ex-situ Vickers and nano-indenter tests,demonstrating the improved mechanical properties with good stability at high temperatures.These findings provide a deeper understanding of the phase-forming mechanism of MAX phase coatings to guide the preparation of high-purity MAX phase coatings and the optimization of MAX phase coatings with expected intermediate phases such as Cr_(2)C,V_(2)C etc.,as well as their application as protective coat-ings in temperature-related harsh environments.

关键词： MAX phase coating Phase-formation mechanism In-situ X-ray diffraction First-principle calculations Mechanical properties

High magnetic energy product in isotropic nanocomposite powders with high percent of soft phase towards ultrastrong magnets

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Journal of materials Science & technology 2023年第13期144卷 161-167页

作者： Longfei Ma Wei Quan Jinkui Fan Yanbai Chen Qiang Zheng Baoru Bian Jian Zhang Juan Du institute of materials School of Materials Science and EngineeringShanghai UniversityShanghai 200444China ningbo institute of Material technology&engineering Chinese Academy of SciencesNingbo 315201China

Nanostructure of magnetically hard and soft materials is fascinating for exploring next-generation ul-trastrong permanent magnets with less expensive rare-earth elements.However,the resulting hard/soft nanocomposites often exhibit a low remanence/energy product due to the challenge in obtaining ideal phase components and appropriate soft phase fraction.In this work,a novel microstructure of multiple phases consisting of 1:5 phase and 1:3 phase as main hard phase,and a high ratio of Fe(Co)(27 wt.%-48 wt.%)as soft phase was obtained in Sm-Co(Fe)/Fe nanocomposite magnet.The grain size of both hard and soft phases below 15 nm was observed.The optimal energy product for Sm-Co(Fe)/Fe(Co)nanocom-posite is 2.1 times(an increment of 107%)of the corresponding single-hard-phase powders without soft phase.It reports that the isotropic nanocomposite powders exhibit a record of magnetic energy product larger than 25 MGOe(the highest value is 28.6 MGOe).The high performance and the microstructure achieved in this work for the isotropic powders will shed light on and provide a good premise for syn-thesizing high performance anisotropic bulk nanocomposite magnets.

关键词： Nanocomposite Sm-Co(Fe)/Fe(Co) Microstructure Phase composition Phase fraction Magnetic energy product

Robust YAG:Ce single crystal for ultra-high efficiency laser lighting

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Journal of Rare Earths 2022年第5期40卷 717-724,I0002页

作者： Yaqian Zhang Jianming Liu Yujie Zhang Haisheng Yang Yanxia Yu Qingyun He Xiaojuan Liang Yongfu Liu Weidong Xiang College of Chemistry and materials engineering Wenzhou UniversityWenzhou 325035China Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesNingbo 315201China

At present,solid-state laser-driven lighting fabricated with blue laser diode(LD)and phosphor has been greatly developed in high-power lighting applications.The major obstacle is the luminescence saturation threshold of the fluorescence conversion material(YAG:Ce).In this work,we successfully prepared a series of high-quality and robust YAG:Ce single crystals.With high quantum efficiency(QE=92%),regular crystal structure and high thermal conductivity,the single-crystal has excellent ability to deal with high radiation flux and thermal accumulation generated by high power.Matching the single-crystal with the laser,the luminous efficiency up to 274 lm/W and saturation threshold of 12 W/mm^(2) were obtained.In addition,the influence of Ce doping concentration and sample processing conditions on the indicators in laser-driven white lighting was systematically studied.The results are of great significance and are believed to promote the development of solid-state laser-driven lighting.

关键词： YAG:Ce Single-crystal Laser diodes Luminous efficiency Saturation threshold Rare earths

Facile access to C-N bonds via unexpected side reactions of Knoevenagel condensation and their application in high-efficiency organic solar cells

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Science China Chemistry 2024年第1期67卷 323-329页

作者： Daobin Yang Shuncheng Yang Hongqian Wang Lin Xie Pengyu Yan Ziyi Ge Zhejiang engineering Research Center for Energy Optoelectronic materials and Devices Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China School of materials Science and Chemical engineering Ningbo UniversityNingbo 315211China Center of materials Science and Optoelectronics engineering University of Chinese Academy of SciencesBeijing 100049China

The construction of C-N bonds is of great importance in the fields of biology,medicine,chemistry and materials science.Here,the replacement of organic base from pyridine to piperidine in the Knoevenagel condensation process unexpectedly yields a series of novel organic molecules containing C-N bonds.Interestingly,the synthesis method does not require any external transition-metals catalysis,and photo-/electro-catalysis.Additionally,when the new compound 1b is added as a third component to a well-known binary system of PM6:Y6,the efficiency of the organic solar cell is significantly improved,resulting in an outstanding efficiency of 18.0%,which is one of the highest values reported to date for PM6:Y6-based ternary organic solar cells.

关键词： C-N bonds Knoevenagel condensation cross-coupling reaction third component organic solar cells

Effects of Pr-Cu-Ti intergranular addition on microstructure and magnetic properties of heavy-rare-earth-free Nd-Fe-B sintered magnets

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Journal of Rare Earths 2022年第5期40卷 778-783,I0004页

作者： Jinhao Zhu Guangfei Ding Bo Zheng Haichen Wu Lei Jin Zhehuan Jin Shuai Guo Renjie Chen Aru Yan CAS Key Laboratory of Magnetic materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application TechnologyNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China University of Chinese Academy of Sciences Beijing 100049China Analytical Center Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China

By intergranular addition of Pr-Cu-Ti alloy powders in the Nd-Fe-B sintered magnets with the normal B component,we propose an approach to the optimization of grain boundary and local Nd-Fe-B composition system.The coercivity is enhanced from 1.42 to 1.86 T,while further addition leads to a reduction in remanence and coercivity.The analyses of phase composition reveal that Ti mainly exists in the form of metallic Ti alloy,and part of Ti combines with B to form the TiB2 phase after the liquid phase sintering process.This process results in a consumption of B in the local Nd-Fe-B composition system and a change of the grain boundary component,which contributes to the formation process of the RE_(6)(Fe,M)_(14) phase after the annealing process.Therefore,with the modification of grain boundary and composition system,the intergranular addition of Pr-Cu-Ti induces the generation of continuous thin grain boundary phases.It promotes the intergrain exchange decoupling,increasing the coercivity in the annealed magnet.While the excess addition results in the segregation of TiB_(2),as well as the precipitation of TiB_(2) into the Nd-Fe-B phase,which leads to structural defects.Thus,the further effort for the addition alloy with Ti to reduce the deterioration of the microstructure will lead to further improvement in magnetic properties.

关键词： Nd-Fe-B sintered magnet Magnetic properties Grain boundary Microstructures Rare earths