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Heterogeneous GdTbDyCoAl high-entropy alloy with distinctive magnetocaloric effect induced by hydrogenation

Journal of Materials science & technology 2022年第14期109卷 147-156页

作者： Liliang Shao Lin Xue Qiang Luo Kuibo Yin Zirui Yuan Mingyun Zhu Tao Liang Qiaoshi Zeng Litao Sun Baolong Shen school of Materials science and Engineering Jiangsu Key Laboratory of Advanced Metallic MaterialsSoutheast UniversityNanjing 211189China SEU-FEI Nano-Pico Center Key Laboratory of MEMS of Ministry of EducationSchool of Electronic Science and EngineeringSoutheast UniversityNanjing 210018China College of Mechanics and Materials Hohai UniversityNanjing 211100China Center for High Pressure science and technology Advanced Research PudongShanghai 201203China

Developing novel magnetocaloric materials is of great significance for the applications of magnetic *** this study,we designed a heterogeneous rare-earth-based high-entropy alloy(HEA)comprising amorphous matrix,local crystal-like cluster and nanocrystalline dihydride with average size of 7.5 nm through isothermal *** heterogeneous structure can significantly tune the magnetocaloric effect of *** hydrogenation,the predominant exchange interaction transforms from ferromagnetic to antiferromagnetic with the disappearance of spin-glass-like behavior,and a complete second-order magnetic transition is *** with the Gd_(20)Tb_(18)Dy_(18)Co_(20)Al_(24) high-entropy metallic glass with a small number of nanocrystals,the maximum magnetic entropy change of the hydrogen-containing HEA is increased from 8.8 to 13.6 J kg^(-1)K^(-1) under applied magnetic field change of 5 T accompanying unobvious hysteresis and decreased magnetic transition temperature from 59 to 8 K,which is more promising as magnetic refrigerant at cryogenic *** work provides a novel concept of designing heterogeneous structure in terms of special cluster and preferential nanocrystalline to modulate the properties of metallic glasses.

关键词： High-entropy metallic glass Hydrogenation Heterogeneous structure Magnetocaloric effect

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Regulation of the quantum barrier and carrier transport toward high-efficiency quasi-2D Dion-Jacobson tin perovskite solar cells

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Journal of Energy Chemistry 2024年第8期95卷 200-207,I0005页

作者： Huanhuan Yao Chang Shi Tai Wu Shurong Wang Mingyu Yin Liming Ding Yong Hua Feng Hao school of Materials and Energy University of Electronic Science and Technology of ChinaChengdu 611731SichuanChina College of Chemistry and Molecular Engineering Peking UniversityBeijing 100871China Yunnan Key Laboratory for Micro/Nano Materials&technology School of Materials and EnergyYunnan UniversityKunming 650091YunnanChina Center for Excellence in Nanoscience(CAS) Key Laboratory of Nanosystem and Hierarchical Fabrication(CAS)National Center for Nanoscience and TechnologyBeijing 100190China

Quasi-2D Dion-Jacobson(DJ)tin halide perovskite has attracted much attention due to its elimination of Van der Waals gap and enhanced environmental ***,the bulky organic spacers usually form a natural quantum well structure,which brings a large quantum barrier and poor film quality,further limiting the carrier transport and device ***,we designed three organic spacers with different chain lengths(ethylenediamine(EDA),1,3-propanediamine(PDA),and 1,4-butanediamine(BDA))to investigate the quantum barrier *** and experimental characterizations indicate that EDA with short chain can reduce the lattice distortion and dielectric confinement effect,which is beneficial to the effective dissociation of excitons and the inhibition of trap-free non-radiative *** addition,EDA cation shows strong interaction with the inorganic octahedron,realizing large aggregates in precursor solution and high-quality films with improved structural ***,femtosecond transient absorption proves that EDA cations can also weaken the formation of small n-phases with large quantum barrier to achieve effective carrier transport between different ***,the quasi-2D DJ(EDA)FA_(9)Sn_(10)I_(31)solar cells achieves a 7.07%power conversion efficiency with good environment ***,this work sheds light on the regulation of the quantum barrier and carrier transport through the chain length of organic spacer for qua si-2D DJ lead-free perovskites.

关键词： Chain lengths Organic spacers Quantum well Carrier transport Lattice distortion

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Direct enantioselective reduction of C=C bond of β-polyfluoro-alkylated enones via asymmetric photoredox catalysis

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science china Chemistry 2024年第6期67卷 2016-2021页

作者： Linghong Zhang Jin Ma Xu Ban Xiaowei Zhao Yanli Yin Zhiyong Jiang Key Laboratory of Natural medicine and Immuno-Engineering of Henan Province Henan UniversityKaifeng475004China school of Chemistry and Chemical Engineering Henan Normal UniversityPingyuan LaboratoryXinxiang453007China College of Advanced Interdisciplinary science and technology Henan University of TechnologyZhengzhou450001China

Direct enantioselective reduction of the C=C bond ofβ-polyfluoro-alkylated enones is an important but long-pending subject in asymmetric ***,we report on the viability of visible light-driven cooperative photoredox and chiral hydrogenbonding catalysis to effectively address this challenge,as a variety of products are obtained in high yields(up to 85%)with good to excellent enantioselectivities(up to 98%ee).The formation of thermodynamically favorable enol intermediates after double single-electron reduction represents the center of the ***,the utility of the current method is validated by the convenient regio-specific and-diverse synthesis of various deuterated derivatives for these products using inexpensive D_(2)O as the deuterium source.

关键词： photoredox catalysis Br?nsted acids asymmetric reduction enantioselective protonation azaarenes

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Excitonic complexes and optical gain in two-dimensional molybdenum ditelluride well below the Mott transition

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Light(science & Applications) 2020年第1期9卷 1647-1656页

作者： Zhen Wang Hao Sun Qiyao Zhang Jiabin Feng Jianxing Zhang Yongzhuo Li Cun-Zheng Ning Department of electronic Engineering Tsinghua University100084 BeijingChina Frontier science Center for Quantum Information 100084 BeijingChina Beijing National Research Center for Information science and technology 100084 BeijingChina school of Electrical Computerand Energy EngineeringArizona State UniversityTempeAZ 85287USA

Semiconductors that can provide optical gain at extremely low carrier density levels are critically important for applications such as energy efficient ***,all current semiconductor lasers are based on traditional semiconductor materials that require extremely high density levels above the so-called Mott transition to realize optical *** new emerging 2D materials provide unprecedented opportunities for studying new excitonic physics and exploring new optical gain mechanisms at much lower density levels due to the strong Coulomb interaction and co-existence and mutual conversion of excitonic ***,we report a new gain mechanism involving charged excitons or trions in electrically gated 2D molybdenum ditelluride well below the Mott *** combined experimental and modelling study not only reveals the complex interplay of excitonic complexes well below the Mott transition but also establishes 2D materials as a new class of gain materials at densities 4-5 orders of magnitude lower than those of conventional semiconductors and provides a foundation for lasing at ultralow injection levels for future energy efficient photonic ***,our study could help reconcile recent conflicting results on 2D materials:While 2D material-based lasers have been demonstrated at extremely low densities with spectral features dominated by various excitonic complexes,optical gain was only observed in experiments at densities several orders of magnitude higher,beyond the Mott *** believe that our results could lead to more systematic studies on the relationship between the mutual conversion of excitonic species and the existence of optical gain well below the Mott transition.

关键词： optical complexes transition

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A High-Efficiency Broadband Superconducting Nanowire Single-Photon Detector with a Composite Optical Structure

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Chinese Physics Letters 2015年第3期32卷 145-148页

作者：顾敏康琳张蜡宝赵清源郏涛万超徐睿莹杨小忠吴培亨 Research Institute of Superconductor electronics School of Electronic Science and EngineeringNanjing University

Superconducting nanowire single-photon detectors （SNSPDs） with a composite optical structure composed of phase-grating and optical cavity structures are designed to enhance both the system detection efficiency and the response bandwidth. Numerical simulation by the finite-difference time-domain method shows that the photon absorption capacity of SNSPDs with a composite optical structure can be enhanced significantly by adjusting the parameters of the phase-grating and optical cavity structures at multiple frequency bands. The absorption capacity of the superconducting nanowires reaches 70%, 72%, 60.73%, 61.7%, 41.2%, and 46.5% at wavelengths of 684, 850, 732, 924, 1256, and 1426nm, respectively. The use of a composite optical structure reduces the total filling factor of superconducting nanowires to only 0.25, decreases the kinetic inductance of SNSPDs, and improves the count rates.

关键词： length A High-Efficiency Broadband Superconducting Nanowire Single-Photon Detector with a Composite Optical Structure

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A review of novel ternary nano-layered MAX phases reinforced AZ91D magnesium composite

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Journal of Magnesium and Alloys 2022年第6期10卷 1457-1475页

作者： Wantong Chen Wenbo Yu Chaosheng Ma Guozheng Ma Laiqi Zhang Haidou Wang Center of Materials science and Engineering School of Mechanical and Electronic Control EngineeringBeijing Jiaotong UniversityBeijing 100044China National Key Lab for Remanufacturing Army Academy of Armored ForcesBeijing 100072China State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing100083China

In recent decades, the demand for lightweight and high specific strength materials brings about the development of magnesium matrix composites. Different from some traditional binary ceramic particles, such as SiC, Al_(2)O_(3), the novel ternary nano-layered M_(n+1)AX_(n)(MAX)phase carbide or nitride ceramics exhibit metal-like properties and self-lubricate capacity(where “M” is an early transition metal, “A” belongs to the group A element, “X” is C or/and N, and n = 1–3). Ti_(2)AlC, as the representative of the MAX phase, was interestingly introduced into the magnesium matrix. Layered Ti_(2)AlC MAX phased reinforced AZ91D magnesium composites manufactured through the stir casting exhibit sufficient deformation capacity due to unique deformation behaviors of MAX, namely delamination and the formation of kinking band. Further,the Ti_(2)AlC-AZ91D composites exhibit a distinctive characteristic in strengthening mechanism, damping mechanism and tribological capacity due to the other special properties of MAX phase, such as self-lubricated property. Accordingly, to give a comprehensive understanding, we overviewed the fabrication process, microstructural characterization, mechanical properties, damping property and tribological capacity on these composites. In order to understand the A-site effect in MAX phase on the microstructure, we introduced another representative Ti_(3)SiC_(2)MAX phase to explain the interfacial evolution. In addition, due to the high aspect ratio of MAX, MAX particles could be orientationally regulated in Mg matrix by plastic deformation such as hot extrusion. Herein, we discussed the anisotropic mechanical and physical properties of the textured composites produced by hot extrusion. Moreover, the potential applications and future development trends of MAX phases reinforced magnesium matrix composites were also given and prospected.

关键词： Ternary MAX phases Magnesium composite Damping Mechanical properties Anisotropic Tribological capacity

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Materials properties and device applications of semiconducting bismuth oxyselenide

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InfoMat 2024年第6期6卷 31-63页

作者： Menglu Li Pei Chen Yan Zhao Mei Zhao Huaqian Leng Yong Wang Sharafat Ali Fazal Raziq Xiaoqiang Wu Jiabao Yi Haiyan Xiao Liang Qiao school of Physics University of Electronic Science and Technology of ChinaChengduSichuanthe Pepole's Republic of China Institute for Advanced Study Chengdu UniversityChengduthe Pepole's Republic of China Global Innovative Centre for Advanced Nanomaterials School of EngineeringCollege of EngineeringScience and EnvironmentThe University of NewcastleCallaghanNew South WalesAustralia

Layered two-dimensional(2D)materials have garnered marvelous attention in diverse fields,including sensors,capacitors,nanocomposites and transistors,owing to their distinctive structural morphologies and superior physicochemical ***,layered quasi-2D materials,especially layered bismuth oxyselenide(Bi2O2Se),are of particular interest,because of their different interlayer interactions from other layered 2D *** this basis,this material offers richer and more intriguing physics,including high electron mobility,sizeable bandgap,and remarkable thermal and chemical durability,rendering it an utterly prospective contender for use in advanced electronic and optoelectronic ***,this article reviews the recent advances related with ***,its structural characterization,band structure,and basic properties are briefly ***,the synthetic strategies for the preparation of Bi_(2)O_(2)Se are ***,the diverse applications of Bi2O2Se in the field of electronics and optoelectronics,photocatalytic,solar cells and sensing were summarized in ***,the challenges and future perspectives of Bi2O2Se are included.

关键词： bismuth oxyselenide device applications preparation methods properties two-dimensional material

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Surface grain refinement mechanism of SMA490BW steel cross joints by ultrasonic impact treatment

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International Journal of Minerals,Metallurgy and Materials 2017年第4期24卷 410-414页

作者： Bo-lin He Lei Xiong Ming-ming Jiang Ying-xia Yu Li Li school of Mechanical & electronic Engineering East China Jiaotong University Nanchang 330013 China

Ultrasonic impact treatment (UIT) is a postweld technique for improving the fatigue strength of welded joints. This technique makes use of ultrasonic vibration to impact and plastically deform a weld toe and can achieve surface grain refinement of the weld toe, which is considered as the main reason for the improvement of fatigue strength. In this paper, the microstructure of the surface of a treated weld toe was observed by metallographic microscopy and transmission electron microscopy (TEM). The results show that UIT could produce severe plastic deformation on the surface layer of the weld toe and the maximum depth of plastic deformation extended to approximately 260 μm beneath the treated surface. Repeated processing could exacerbate the plastic deformation on the surface layer, resulting in finer grains. We can conclude that the surface grain refinement mechanism of SMA490BW welded joints is related to the high density of dislocation tangles and dislocation walls. © 2017, university of science and technology Beijing and Springer-Verlag Berlin Heidelberg.

关键词： Grain size and shape High resolution transmission electron microscopy Joints (structural components) Plastic deformation Transmission electron microscopy Ultrasonic applications Ultrasonic effects Weathering steel Welding Welds

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Transport property of topological crystalline insulator SnTe(100)and ferrimagnetic insulator heterostructures

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Journal of Materials science & technology 2022年第36期131卷 204-211页

作者： Anqi Zhang Daheng Liu Teng Yang Song Ma Zhidong Zhang Shenyang National Laboratory for Materials science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China school of Materials science and Engineering University of Science and Technology of ChinaShenyang 110016China

Topological crystalline insulator(TCI)SnTe is a potential material for quantum electronic devices because of its attractive inherent sensitivity of band topology and highly mobile characteristic of Dirac *** proximity effect at the interface of SnTe film can affect the topological surface transport and may result in novel quantum magneto-electric ***,we study the magnetoelectrical transport properties of SnTe thin films grown on ferrimagnetic insulators Eu_3Fe_5O_(12)(110)(EuIG(110))and Y_(3)Fe_(5)O_(12)(111)(YIG(111))single-crystal underlayers by molecular beam *** magnetic resistance(LMR)is observed in SnTe/Eu IG heterostructures in the low field range,which is different from the weak antilocalization(WAL)characteristic of SnTe/YIG ***,the double carrier characteristic with the coexistence of holes and electrons in SnTe/Eu IG heterostructure is quite different from the holes as main carriers in SnTe/YIG,although the SnTe layer remains the same crystal plane(100)in the two *** LMR in SnTe/Eu IG is attributed to the topological surface Dirac electrons and disordered domain distribution in the SnTe layer which is in sharp contrast to the WAL of SnTe/YIG with ordered domain distribution in the SnTe *** present studies of transport properties not only provide a fundamental understanding of the transport mechanism of TCI and magnetite insulator heterostructure but also display the promising application probability for tunable topological electronic devices.

关键词： Topological crystalline insulator Ferrimagnetic insulators Linear magnetoresistance Electrical transport Molecular beam epitaxy

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Predicting Moral Elevation Conveyed in Danmaku Comments Using EEGs

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Cyborg and Bionic Systems 2023年第1期4卷 217-224页

作者： Chenhao Bao Xin Hu Dan Zhang Zhao Lv Jingjing Chen Department of electronic Engineering Tsinghua UniversityBeijing 100084China Department of Biomedical Engineering Johns Hopkins UniversityBaltimoreMDUSA Department of Psychiatry School of MedicineUniversity of PittsburghPittsburghPAUSA Department of Psychology School of Social SciencesTsinghua UniversityBeijing 100084China school of Computer science and technology Anhui UniversityHefei 230601China

Moral elevation,the emotion that arises when individuals observe others’moral behaviors,plays an important role in determining moral behaviors in real *** recent research has demonstrated the potential to decode basic emotions with brain signals,there has been limited exploration of affective computing for moral elevation,an emotion related to social *** address this gap,we recorded electroencephalography(EEG)signals from 23 participants while they viewed videos that were expected to elicit moral *** than 30,000 danmaku comments were extracted as a crowdsourcing tagging method to label moral elevation continuously at a 1-s temporal ***,by employing power spectra features and the least absolute shrinkage and selection operator regularized regression analyses,we achieved a promising prediction performance for moral elevation(prediction r=0.44±0.11).Our findings indicate that it is possible to decode moral elevation using EEG ***,the small-sample neural data can predict the continuous moral elevation experience conveyed in danmaku comments from a large population.

关键词： EEG prediction absolute

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