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Anomalous thermal expansion and enhanced magnetocaloric effect in<001>-textured mn_(x)Fe_(5-x)Si_(3) alloys

Rare metals 2024年第5期43卷 2263-2274页

作者： yong Gong Xue-Fei miao Tapas Samanta Chris Taake Jun Liu feng-Jiao Qian yan-yan Shao yu-Jing Zhang Qing-yong Ren Luana Caron feng Xu mIIT Key Laboratory of Advanced metallic and Intermetallic materials Technology School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing210094China Department of Physics Bielefeld University33501BielefeldGermany College of Physics Nanjing University of Aeronautics and AstronauticsNanjing210016China Institute of High Energy Physics Chinese Academy of SciencesBeijing100049China Spallation Neutron Source Science Center Dongguan523803China Guangdong-Hong Kong-macao Joint Laboratory for Neutron Scattering Science and Technology Dongguan523803China Department of Physics Bielefeld University33501BielefeldGermany Helmholtz-Zentrum Berlin für Materialien und Energie12489BerlinGermany

The development of zero and negative therma expansion(i.e.,ZTE and NTE)materials is of crucial importance to the control of undesirable thermal expansion for high-precision *** the present work,ZTE and NTE were obtained in directionally-solidified mn_(x)Fe_(5-x)Si_(3)alloys with a strongtexture,in striking contrast to positive thermal expansion in their isotropic counterparts magnetometry and in-situ X-ray diffraction(XRD)measurements were performed to uncover the origin of the anomalous thermal *** measurements indicate a strong easy-plane magnetocrystalline anisotropy in the textured samples,where the magnetic moments are aligned within the ab plane of the hexagonal structure Temperature-dependent XRD on the x=1 sample reveals a ZTE character in the ab plane that is coupled to a ferromagnetic *** a result,the macroscopic ZTE(~0.22×10^(-6)K^(-1))in the x=1 sample can be attributed to the microscopic magneto volume effect within the ab plane,which is realized by the introduction of the-textured ***,the competition between antiferromagnetic and ferromagnetic exchange coupling leads to NTE in textured x=1.5 and 2 ***,textured x=1 sample displays enhanced magnetocaloric properties as compared to the conventional counterparts with randomly-oriented *** this work demonstrates a new strategy toward the exploration of anomalous thermal expansion properties as well as the enhancement of magnetocaloric properties for materials with a strong magnetocrystalline anisotropy.

关键词： mnFeySis magnetocaloric effect magnetic phase transition Negative thermal expansion

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Influence of ammonium sulfate on the corrosion behavior of AZ31 magnesium alloy in chloride environment

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Journal of magnesium and Alloys 2024年第3期12卷 1082-1101页

作者： feng Ge Zhongyu Cui yue Liu Li Lei Xin Wang Hongzhi Cui School of materials Science and Engineering Ocean University of ChinaQingdao 266100China Beijing National Innovation Institute of Lightweight Ltd.Beijing 101499China

Electrochemical corrosion of AZ31 magnesium alloy in the NH_(4)^(+)-SO_(4)2−-Cl−environment is *** of NH_(4)^(+)overshadows that of Cl−as the(NH_(4))_(2)SO_(4) concentration is 0.005 m or higher,yielding an evolution from localized corrosion to uniform *** effect of NH_(4)^(+)can be attributed to that(i)NH_(4)^(+)dissolves the inner mgO and hinders the precipitation of mg(OH)_(2) and(ii)the buffering ability of NH_(4)^(+)provides H+,enhances the hydrogen evolution,and expedites the corrosion *** latter is demonstrated as the dominant factor with the results in unbuffered and buffered *** severe corrosion and hydrogen process in NH_(4)^(+)-containing solution results in a high Hads coverage and yields an inductive loop within the low ***,SO_(4)^(2−)is helpful in generating cracked but partially protective corrosion products,while Cl−could broaden the corrosion area beneath the corrosion product.

关键词： magnesium alloy Ammonium corrosion Electrochemical kinetic parameter Anodic dissolution.

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Purity-dependent Lorenz number,electron hydrodynamics and electron-phonon coupling in WTe_(2)

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Science China(Physics,mechanics & Astronomy) 2024年第8期67卷 153-158页

作者： Wei Xie feng yang Liangcai Xu Xiaokang Li Zengwei Zhu Kamran Behnia Wuhan National High magnetic Field Center and School of Physics Huazhong University of Science and TechnologyWuhan 430074China Laboratoire de Physique et d’Etude des matériaux(ESPCI-CNRS-Sorbonne Université)PSL University Paris 75005France

We present a study of electrical and thermal transport in Weyl semimetal WTe_(2)down to 0.3 *** Wiedemann-Franz law holds below 2 K and a downward deviation starts *** deviation is more pronounced in cleaner samples,as expected in the hydrodynamic picture of electronic transport,where a fraction of electron-electron collisions conserve *** are the dominant heat carriers and their mean-free-path does not display a Knudsen *** is presumably a consequence of weak anharmonicity,as indicated by the temperature dependence of the specific *** momentum exchange between phonons and electrons leads to quantum oscillations of the phononic thermal ***-Grüneisen picture of electron-phonon scattering breaks down at low temperature when Umklapp ph-ph collisions cease to be a sink for electronic flow of *** with semi-metallic Sb shows that normal ph-ph collisions are amplified by *** both semimetals,at cryogenic temperature,e-ph collisions degrade the phononic flow of energy but not the electronic flow of momentum.

关键词： thermal conductivity Wiedemann-Franz law electron hydrodynamics electron-phonon coupling

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A data and physical model dual-driven based trajectory estimator for long-term navigation

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Defence Technology（防务技术） 2024年第10期40卷 78-90页

作者： Tao feng yu Liu yue yu Liang Chen Ruizhi Chen School of Communications and Information Engineering Chongqing University of Posts and TelecommunicationsChongqing400065China Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic UniversityHong Kong999077China Chongqing Key Laboratory of Autonomous Navigation and microsystem Chongqing University of Post and TelecommunicationsChongqing400065China State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing(LIESMARS)Wuhan UniversityWuhan430000China

Long-term navigation ability based on consumer-level wearable inertial sensors plays an essential role towards various emerging fields, for instance, smart healthcare, emergency rescue, soldier positioning et al. The performance of existing long-term navigation algorithm is limited by the cumulative error of inertial sensors, disturbed local magnetic field, and complex motion modes of the pedestrian. This paper develops a robust data and physical model dual-driven based trajectory estimation(DPDD-TE) framework, which can be applied for long-term navigation tasks. A Bi-directional Long Short-Term memory(Bi-LSTm) based quasi-static magnetic field(QSmF) detection algorithm is developed for extracting useful magnetic observation for heading calibration, and another Bi-LSTm is adopted for walking speed estimation by considering hybrid human motion information under a specific time period. In addition, a data and physical model dual-driven based multi-source fusion model is proposed to integrate basic INS mechanization and multi-level constraint and observations for maintaining accuracy under long-term navigation tasks, and enhanced by the magnetic and trajectory features assisted loop detection algorithm. Real-world experiments indicate that the proposed DPDD-TE outperforms than existing algorithms, and final estimated heading and positioning accuracy indexes reaches 5° and less than 2 m under the time period of 30 min, respectively.

关键词： Long-term navigation Wearable inertial sensors Bi-LSTm QSmF Data and physical model dual-driven

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Numerical Analysis of Perforation during Hydraulic Fracture Initiation Based on Continuous-Discontinuous Element method

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Computer modeling in Engineering & Sciences 2024年第8期140卷 2103-2129页

作者： Rui Zhang Lixiang Wang Jing Li Chun feng yiming Zhang School of Civil and Transportation Engineering Hebei University of TechnologyTianjin300401China Key Laboratory for mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing100190China School of Civil Engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou310018China Jinyun Institute Zhejiang Sci-Tech UniversityLishui321400China

Perforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing *** perforation designs is critical for augmenting the efficacy of hydraulic fracturing and boosting oil or gas *** this study,we employ a hybrid finite-discrete element method,known as the continuous–discontinuous element method(CDEm),to simulate the initiation of post-perforation hydraulic fractures and to derive enhanced design *** model incorporates the four most prevalent perforation geometries,as delineated in an engineering technical ***-world perforations deviate from the ideal cylindrical shape,exhibiting variable cross-sectional profiles that typically manifest as an initial constriction followed by an expansion,a feature consistent across all four perforation *** simulations take into account variations in perforation hole geometries,cross-sectional diameters,and perforation *** findings show that perforations generated by the 39g DP3 HmX perforating bullet yield the lowest breakdown pressure,which inversely correlates with increases in sectional diameter and perforation ***,this study reveals the relationship between breakdown pressure and fracture degree,providing valuable insights for engineers and designers to refine perforation strategies.

关键词： Hydraulic fracturing real perforation shape breakdown pressure perforation layout design CDEm

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Controlling of coordination state of Ru_(x)N_(y) clusters for efficient oxygen reduction electrocatalysis

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Nano Research 2024年第3期17卷 1035-1041页

作者： Weiyang Fu yihuan yu Tongtong Liu yinliang Cao Zhengping Zhang feng Wang State Key Laboratory of Chemical Resource Engineering Beijing Key Laboratory of Electrochemical Process and Technology for MaterialsBeijing University of Chemical TechnologyBeijing 100029China Beijing Advanced Innovation Center for Soft matter Science and Engineering Beijing University of Chemical TechnologyBeijing 100029China Zhejiang Tianneng Hydrogen Energy Technology Co. Ltd.Huzhou 313100China

Ruthenium(Ru)is an attractive potential alternative to platinum as an electrocatalyst for the oxygen reduction reaction(ORR),in virtue of its high catalytic selectivity and relatively low *** this work,a series of well-dispersed nitrogen-coordinated Ru-clusters on carbon black(Ru_(x)N_(y)/C)were prepared by pyrolyzing different Ru-containing sandwich compounds as the Ru *** higher thermal stability of these complexed sandwich precursors(bis(1,2,3,4,5-pentamethylcyclopentadienyl)Ru(II)monomer,dichloro(p-cymene)Ru(II)dimer,and chloro(1,2,3,4,5-pentamethylcyclopentadienyl)Ru(II)tetramer)affords the control of coordinated state for the resulting Ru-clusters,in comparison of that derived from ruthenium *** the pyrolysis treatment,the Ru coordinated state in Ru_(x)N_(y)/C,with the Ru–N and Ru–Ru bonds,still showed the structural inheritance from the Ru(II)monomer,dimer,and tetramer,but using ruthenium chlorides as the Ru source resulted in the nanoscale Ru *** ORR testing exhibited that the Ru_(x)N_(y)/C sample derived from the Ru(II)tetramer(Ru_(x)N_(y)/C-T)presents the higher catalytic activity than the other obtained samples in either alkaline or acidic *** in the acidic electrolyte,Ru_(x)N_(y)/C-T shows the comparable ORR activity to that of Pt/C catalysts,and it shows the superior tolerance against methanol and *** X-ray absorption spectroscopy and density functional theory calculations demonstrate that these tetra-nuclear Ru-clusters could be the most active site due to their broadened d-orbital bands and lower energy d-band center than those of other subnano species and nanocrystals,and their favorable yeager-type adsorption of O_(2)-molecules is also contributed to promoting O–O bond cleavage and accelerating the ORR process.

关键词： ruthenium clusters coordination environment sandwich compounds electrocatalysis oxygen reduction reaction

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Highly oriented mXene/polyvinyl alcohol films prepared by scalable layer-by-layer blade coating for efficient electromagnetic interference shielding and infrared stealth

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Nano Research 2024年第6期17卷 5651-5660页

作者： Jingyu Dong Zhaoyang Li Congqi Liu Bing Zhou Chuntai Liu uezhan feng State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentNational Engineering Research Center for Advanced Polymer Processing TechnologyZhengzhou UniversityZhengzhou 450002China Shangqiu Normal University Shangqiu 476000China

Controlling the orientation of two-dimensional mXene within layered films is essential to optimize or tune their mechanical properties and electromagnetic interference shielding(EmI)performance,but achieving the high orientation mXene layers on an industrial scale remains a challenging *** this paper,a scalable layer-by-layer blade coating(LbLBC)method was employed to fabricate highly oriented mXene/polyvinyl alcohol(PVA)*** the LbLBC process,mXene/PVA colloid suffered a strong shearing effect,which induced the ordered alignment of mXene nanosheets along the direction of the blade *** orientation of mXene can be effectively adjusted by changing the scraping gap of LbLBC,achieving a maximum Herman orientation factor f of *** a result,the mechanical properties and EmI performance of the as-prepared mXene/PVA films are in direct proportion to their orientation,with the optimal values of tensile strength of 145.5 mPa,fracture strain of 19.6%,toughness of 17.7 mJ·m^(−3),and EmI shielding effectiveness of 36.7 ***,the inherently low mid-infrared(mid-IR)emissivity of mXene,combined with the densely oriented structure affords the composite films with IR stealth,resulting in a substantial decrease from 150 to 66.1℃in the radiative temperature of a ***,these scalable mXene/PVA films exhibit remarkable potential for integration into the next generation of multifunctional protective camouflage materials.

关键词： mXene nanosheets densely oriented structure layer-by-layer blade coating electromagnetic interference shielding infrared stealth

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microstructure evolution,mechanical properties and fracture behavior of Al-xSi/AZ91D bimetallic composites prepared by a compound casting

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Journal of magnesium and Alloys 2024年第5期12卷 1944-1964页

作者： Guangyu Li Wenming Jiang feng Guan Junwen Zhu yang yu Zitian Fan State Key Laboratory of materials Processing and Die&mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

In this paper,the effect of the Si content on microstructure evolution,mechanical properties,and fracture behavior of the Al-xSi/AZ91D bimetallic composites prepared by compound casting was investigated *** obtained results showed that all the Al-xSi/AZ91D bimetallic composites had a metallurgical reaction layer(mRL),whose thickness increased with increasing Si content for the hypoeutectic Al-Si/AZ91D composites,while the hypereutectic Al-Si/AZ91D composites were *** mRL included eutectic layer(E layer),intermetallic compound layer(ImC layer)and transition region layer(T layer).In the ImC layer,the hypereutectic Al-Si/AZ91D composites contained some Si solid solution and flocculent mg_(2)Si+Al-mg ImCs phases not presented in the hypoeutectic Al-Si/AZ91D ***,increasing Si content,the thickness proportion of the T layer increased,forming an inconsistent preferred orientation of the *** shear strengths of the Al-xSi/AZ91D bimetallic composites enhanced with increasing Si content,and the Al-15Si/AZ91D composite obtained a maximum shear strength of 58.6 mPa,which was 73.4% higher than the Al-6Si/AZ91D *** fractures of the Al-xSi/AZ91D bimetallic composites transformed from the T layer into the E layer with the increase of the Si *** improvement of the shear strength of the Al-xSi/AZ91D bimetallic composites was attributed to the synergistic action of the mg_(2)Si particle reinforcement,the reduction of oxidizing inclusions and the ratio of Al-mg ImCs as well as the orientation change of the mRL.

关键词： Al/mg bimetallic composites Si content mg_(2)Si reinforcement microstructure mechanical properties Fracture behavior

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Effect of Frequency on Degradation in BOPP Films Under Repetitively Pulsed Voltage

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1280-1290页

作者： Chuansheng Zhang yu feng Fei Kong Bangdou Huang Cheng Zhang Tao Shao Beijing International S&T Cooperation Base for Plasma Science and Energy Conversion Institute of Electrical EngineeringChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Operating conditions of film capacitors are complex,and the problem of film insulation failure caused by repetitively pulsed voltage is becoming ever *** of the film under repetitively pulsed voltage cannot be accurately evaluated by the average breakdown electric *** this paper,the effects of pulsed electric field and pulse repetition frequency on the breakdown in biaxially oriented polypropylene(BOPP)films are *** phases of BOPP degradation are proposed based on the voltage amplitude,i.e.,maintenance(m),decline(D),and near-zero(N).Evolution of the BOPP film from degradation to breakdown at different frequencies is ***,transition of discharge mode and elemental composition of the film are *** results show continuous heat generation under repetitive microsecond pulses is the dominant factor for degradation of BOPP *** number of applied pulses and the repetitive stressing time decrease exponentially with increase of *** research can be contributed to the safe and reliable operation of capacitors.

关键词： Aging breakdown film capacitor polypropylene repetitive pulse

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Synchronous deprotonation–protonation for mechanically robust chitin/aramid nanofibers conductive aerogel with excellent pressure sensing, thermal management, and electromagnetic interference shielding

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Nano Research 2024年第3期17卷 2038-2049页

作者： Xinxin Zhang Kunpeng Qian Jianhui Fang Sineenat Thaiboonrod miao miao Xin feng Department of Chemistry College of SciencesShanghai UniversityShanghai 200444China Research Center of Nano Science and Technology College of SciencesShanghai UniversityShanghai 200444China School of materials Sciences and Engineering Shanghai UniversityShanghai 200444China National Nanotechnology Center(NANOTEC) National Science and Technology Development Agency(NSTDA)Thailand Science ParkPathum Thani 12120Thailand

Aerogels with regularly porous structure and uniformly distributed conductive networks have received extensive attention in wearable electronic sensors,electromagnetic shielding,and so ***,the poor mechanical properties of the emerging nanofibers-based aerogels are limited in practical *** this work,we developed a synchronous deprotonation–protonation method in the KOH/dimethyl sulfoxide(DmSO)system at room temperature for achieving chitin cross-linked aramid nanofibers(CANFs)rather than chitin nanofibers(ChNFs)and aramid nanofibers(ANFs)separately by using chitin and aramid pulp as raw *** freeze-drying process,the cross-linked chitin/aramid nanofibers(CA)aerogel exhibited the synergetic properties of ChNF and ANF by the dual-nanofiber compensation *** mechanical stress of CA aerogel was 170 kPa at 80%compressive strain,increased by 750%compared with pure ChNF ***,the compressibility of CA aerogel was somewhat improved compared to ANF *** enhancement verified that the crosslinking reaction between ANF and ChNF during the synchronous deprotonation process was ***,the conductive aerogels with uniform porous structure(CA-m)were successfully obtained by vacuum impregnating CA aerogels in Ti_(3)C_(2)T_(x) mXene solution,displaying low thermal conductivity(0.01 W/(m·K)),high electromagnetic interference(EmI)shielding effectiveness(SE)(75 dB),flame retardant,and heat ***,the as-obtained CA-m aerogels were also applied as a pressure sensor with excellent compression cycle stability and superior human motion monitoring *** a result,the dual-nanofiber based conductive aerogels have great potentials in flexible/wearable electronics,EmI shielding,flame retardant,and heat insulation.

关键词： synchronous deprotonation–protonation electromagnetic interference(EmI)shielding flame retardant heat insulation pressure sensing

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