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A novel(Sm_(0.2)Eu_(0.2)Gd_(0.2)Ho_(0.2)Yb_(0.2))CrO_(3)high-entropy ceramic nanofiber as a negative temperature coefficient thermistor

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Journal of Rare Earths 2024年第10期42卷 1937-1942页

作者： Weijun Zhao Meng Zhang Liyan Xue Kaixian wang Fan Yang Jiuping Zhong Heng chen School of materials Sun Yat-sen UniversityShenzhen518107China Xiamen Institute of Rare Earth materials Haixi InstituteChinese Academy of SciencesXiamen361021China Xiamen key laboratory of Rare Earth Photoelectric Functional materials Xiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of SciencesXiamen361021China Fujian science&technology Innovation laboratory for Optoelectronic Information of china Fuzhou350108China advanced Energy science and technology Guangdong laboratory Huizhou516003China Sichuan Jcc Rare Earth metals New Material Co. Ltd.Chengdu610000China

The electrical properties of high-entropy ceramics(HECs)have been extensively studied in recent years due to their unique structural characteristics and fascinating functional properties induced by entropy *** high-entropy(Sm_(0.2)Eu_(0.2)Gd_(0.2)Ho_(0.2)Yb_(0.2))CrO_(3)(HE-RECrO_(3))nanofibers were prepared by electro *** work demonstrates that HE-RECrO_(3)nanofibe rs were successfully synthesized at a low temperature(800℃),which is approximately 400℃lower than the temperatures at which chromate ceramics were synthesized via the sol-gel method and the solid-state reaction *** resistivity of HE-RECrO_(3)nanofibers decreases exponentially with increasing temperature from 25 to600℃.The logarithm of the resistivity is linearly related to the inverse of the temperature,confirming the negative temperature coefficient property of HE-RECrO_(3)*** B_(25/50)value of the HERECrO_(3)nanofibers reaches 4072 *** conclusion,HE-RECrO_(3)nanofibers are expected to be potential candidates for negative-temperature-coefficient(NTC)thermistors.

关键词： Rare earths High-entropy ceramics Ceramic fiber materials Negative temperature coefficient thermistors

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Electron-distribution control via Pt/NC and MoC/NC dual junction:Boosted hydrogen electro-oxidation and theoretical study

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Journal of Energy Chemistry 2024年第1期88卷 513-520,I0011页

作者： Feng Zhou Xiaofeng Ke Yihuang chen Mei Zhao Yun Yang Youqing Dong Chao Zou Xi’an chen Huile Jin Lijie Zhang Shun wang key laboratory of Carbon materials of Zhejiang Province College of Chemistry and Materials EngineeringWenzhou UniversityWenzhou 325000ZhejiangChina Zhejiang Engineering Research Center for Electrochemical Energy materials and Devices Institute of New Materials&Industry TechnologyWenzhou UniversityWenzhou 325000ZhejiangChina

The scarcity,high cost and susceptibility to CO of Platinum severely restrict its application in alkaline hydrogen oxidation reaction(HOR).Hybridizing Pt with other transition metals provides an effective strategy to modulate its catalytic HOR performance,but at the cost of mass activity due to the coverage of modifiers on Pt ***,we constructed dual junctions'Pt/nitrogen-doped carbon(Pt/NC)andδ-MoC/NC to modify electronic structure of Pt via interfacial electron transfer to acquire Pt-MoC@NC catalyst with electron-deficient Pt nanoparticles,simultaneously endowing it with high mass activity and durability of alkaline ***,the unique structure of Pt-MoC@NC endows Pt with a high COtolerance at 1,000 ppm CO/H_(2),a quality that commercial Pt-C catalyst *** theoretical calculations not only confirm the diffusion of electrons from Pt/NC to Mo C/NC could occur,but also demonstrate the negative shift of Pt d-band center for the optimized binding energies of*H,*OH and CO.

关键词： Hydrogen oxidation reaction Dual junctions CO-tolerance Platinum

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Geology and genesis of the Aqishan Pb-Zn deposit,NW china:Insights from mineralogy,geochemistry,and in situ U-Pb geochronology

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Geoscience Frontiers 2024年第5期15卷 489-514页

作者： Kang wang Yinhong wang Jun Deng Jiajun Liu Fangfang Zhang Wei Zhang Hui Zhang Wenxin Gu Hong chen State key laboratory of Geological Processes and Mineral Resources and School of Earth Sciences and ResourcesChina University of GeosciencesBeijing 100083China

The unique ore-forming processes and the key factors responsible for formation of skarn deposits are still obscure,and challenges exist in the determination of timing of Pb-Zn skarns owing to lacking suitable mineral *** we present detailed paragenesis,bulk geochemistry,in situ U-Pb dating of zircon and garnet,and garnet oxygen isotopes together with in situ zircon Hf-O isotopes from the newly discovered Aqishan Pb-Zn deposit in the southern Central Asian Orogenic Belt(CAOB),northwest *** comprehensive data set revealed a Late Carboniferous subduction-related distal Pb-Zn skarn system associated with the granitic ***-ore stage garnets are generally subhedral to euhedral with oscillatory zoning and show slightly fractionated rare earth element patterns with positive Eu anomalies that point to an infiltration metasomatism origin under high water/rock *** syn-ore stage sphalerite is typically enriched in Mn and Cd and has moderate Zn/Cd ratios(337–482),with a formation temperature of 265℃to 383℃,which indicate magmatic-hydrothermal *** isocons defined by P_(2)O_(5)decipher that the principal factors for skarn formation were elevated activities of Fe,Ca,and Si species,where remobilization of Pb metals,meanwhile,contributed to ore-forming budgets to mineralizing *** U-Pb dating of zircons from granite porphyry that occurs distal to the skarns and Pb-Zn orebodies shows that these intrusions emplaced at ca.311.3–310.6 Ma,recording the subduction of the Paleo-Tianshan oceanic *** garnets in close textural association with Pb-Zn sulfides yield indistinguishable in situ LA-ICP-MS U-Pb ages of 310.5±4.1 ***-rock geochemistry and in situ zircon Hf-O isotopes(δ^(18)O=4.6‰–6.0‰)indicate that the granite porphyry was derived from partial melting of juvenile crust and influenced by subducted oceanic *** isotope compositions of garnets(δ^(18)O=8.0‰–9.0‰)demonstrate that the equilibrated ore fluids

关键词： In situ U-Pb dating Garnet O isotopes Aqishan Pb-Zn deposit Skarn mineralization Southern CAOB

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Ligand effect in surface atomic sites of group VI B transition metals on ultrathin Pt nanowires for enhanced oxygen reduction

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Nano Research 2024年第6期17卷 5298-5304页

作者： Yuwei He Yueguang chen Renjie Wu zhihe Xiao Mengxian Li Chunfeng Shi Leyu wang State key laboratory of Chemical Resource Engineering College of ChemistryBeijing University of Chemical TechnologyBeijing 100029China State key laboratory of Petroleum Molecular and Process Engineering SINOPEC Research Institute of Petroleum Processing Co.Beijing 100083China

Increasing the utilization efficiency of platinum is critical for advancing proton exchange-membrane fuel cells(PEMFCs).Despite extensive research on catalysts for the cathodic oxygen reduction reaction(ORR),developing highly active and durable Pt-based catalysts that can suppress surface dealloying in corrosive acid conditions remains ***,we report a facile synthesis of bimetallic ultrathin PtM(M=Mo,W,and Cr)nanowires(NWs)composed of group VI B transition metal atomic sites anchored on the *** NWs possess uniform sizes and well-controlled atomic *** to PtW and PtCr catalysts,the PtMo0.05 NWs exhibit the highest half-wave potential of 0.935 V and a mass activity of 1.43 A·mgPt^(−1).Remarkably,they demonstrate a remarkable 23.8-fold enhancement in mass activity compared to commercial Pt/C for ORR,surpassing previously reported Pt-based ***,the PtMo NWs cathode in membrane electrode assembly tests achieves a remarkable peak power density of 1.443 W·cm^(−2)(H_(2)-O_(2)conditions at 80℃),which is 1.09 times that of commercial Pt/*** ligand effect in the bimetallic surface not only facilitates strong coupling between Mo(4d)and Pt(5d)atomic orbitals to hinder atom leaching but also modulates the d-states of active site,significantly optimizing the adsorption of key oxygen(*O and*OH)species and accelerating the rate-determining step in ORR pathways.

关键词： ligand effect oxygen reduction reaction group VI B transition metal ultrathin nanowires multiple oxygen species

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Phase transition of multi-component(TiZrVNb)C ceramics—Part II:From single phase to multiple phases via adjusting V content

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Journal of advanced Ceramics 2024年第5期13卷 689-698页

作者： Qingyi Kong Lei chen Sijia Huo Kunxuan Li Wenyu Lu Yujin wang Yu Zhou Institute for advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150080China key laboratory of advanced Structure‒Function Integrated materials and Green Manufacturing technology Harbin Institute of TechnologyHarbin 150001China National key laboratory of Precision Hot Processing of metals Harbin Institute of TechnologyHarbin 150001China

To address the relatively mediocre mechanical properties of single-phase multi-component carbide ceramics,a phase transition from a single phase to multiple phases was proposed to achieve superior mechanical properties.A series of(TiZrV_(x)Nb)C_(0.8) ceramics with different V contents were fabricated by spark plasma sintering(SPS).The influence of the V content on the phase composition,microstructural evolution,and mechanical properties was investigated in *** transition behavior from a single phase to multiple phases is discovered and *** formation of the Zr-rich phase and Zr-poor phase can be attributed to the increase in lattice distortion and mixed enthalpy caused by the addition of V.A nanometer lamellar structure with a semi-coherent interface obtained via in situ decomposition is reported for the first time in multi-component carbide *** semi-coherent interfaces with high dislocation density and strain concentration effectively improve the mechanical properties,grain refinement,and multi-phase *** optimal comprehensive mechanical properties of the Vickers hardness(26.3 GPa),flexural strength(369 MPa),and fracture toughness(3.1 MPa·m^(1/2))were achieved for the sample with 20 mol%V.

关键词： multi-component ceramics multiple phases microstructure evolution phase decomposition mechanical properties

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In situ synthesis of polycrystalline cubic boron nitride in cBN-Al-Ti system with different Gd_(2)O_(3) additions

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Rare metals 2021年第5期40卷 1267-1274页

作者： Sheng-lin Zhong zhi-Kai Li Chao chen Chuan chen peng wang Yi Wu College of materials science and Engineering Guilin University of TechnologyGuilin 541004China

Polycrystalline cubic boron nitride was sintered under high temperature(1400℃)and high pressure(5.5 GPa)using an in situ synthesis *** composition,microstructure,relative density and mechanical properties of the polycrystalline cubic boron nitride(PcBN)with different contents of Gd_(2)O_(3) were studied by means of X-ray diffraction(XRD),scanning electron microscopy(SEM)and energy-dispersive spectroscopy(EDS).The results show that the phases of TiB_(2),TiN,AIN,AlTi_(2)N and GdB_(6) are formed through in situ synthesis of cBN-Al-Ti-Gd_(2)O_(3) *** the Gd_(2)O_(3) content increasing,the relative density increases and mechanical properties of PcBN begin to increase and then *** amount of Gd_(2)O_(3) can advance the formation of TiB_(2) and improve the aspect ratio of TiB_(2).When Gd_(2)O_(3) content is 1.0 wt%,the PcBN exhibits optimal comprehensive mechanical properties,with a microhardness of 33.35 GPa and a flexural strength of 972.37 MPa.

关键词： Polycrystalline cubic boron nitride(PcBN) TiB_(2) Rod crystal Rare earth oxides Mechanical properties

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Multidimensional regulation of Ti-Zr-Cr-Mn hydrogen storage alloys via Y partial substitution

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Nano Research 2024年第5期17卷 4211-4220页

作者： Haixiang Xiu Wanqiang Liu Dongming Yin Nan Ding Wenfeng Qiao Shaolei Zhao Long Liang Cong Liu Shaohua wang Qingshuang wang Bingbing chen Limin wang Yong cheng School of materials science and Engineering Changchun University of Science and TechnologyChangchun 130022China State key laboratory of Rare Earth Resources Utilization Changchun Institute of Applied ChemistryChinese Academy of Sciences(CAS)Changchun 130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026China Department of Energy science and Engineering Nanjing Tech UniversityNanjing 211816China National Engineering Research Center of Nonferrous metals materials and Products for New Energy GRINM Group Co.Ltd.Beijing 100088China GRIMAT Engineering Institute Co. Ltd.Beijing 101407China College of Life science and technology Changchun University of Science and TechnologyChangchun 130022China

High density and safe storage of hydrogen are the preconditions for the large-scale application of hydrogen ***,the hydrogen storage properties of Ti_(0.6)Zr_(0.4)Cr_(0.6)Mn_(1.4) alloys are systematically studied by introducing Y element instead of Ti element through vacuum arc *** the partial substitution of Y,a second phase of rare earth oxide is added in addition to the main suction hydrogen phase,C14 Laves *** to the unique properties of rare earth elements,the partial substitution of Y can not only improve the activation properties and plateau pressure of the alloys,but also increase the effective hydrogen storage capacity of the *** comprehensive properties of hydrogen storage alloys are improved by multidimensional regulation of rare earth *** them,Ti_(0.552)Y_(0.048)Zr_(0.4)Cr_(0.6)Mn_(1.4) has the best comprehensive *** alloy can absorb hydrogen without activation at room temperature and 5 MPa,with a maximum hydrogen storage capacity of 1.98 wt.%.At the same time,it reduces the stability of the hydride and the enthalpy change value,making it easier to release *** theoretical analysis and first-principle simulation,the results show that the substitution of Y element reduces the migration energy barrier of hydrogen and the structural stability of the system,which is conducive to hydrogen *** alloy has superior durability compared to the original alloy,and the capacity retention rate was 96.79%after 100 hydrogen absorption/desorption cycles.

关键词： AB_(2)-type hydrogen storage alloy rare earth element first-principles simulation multidimensional regulation

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Boron nitride microribbons strengthened and toughened alumina composite ceramics with excellent mechanical,dielectric,and thermal conductivity properties

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Journal of advanced Ceramics 2024年第4期13卷 496-506页

作者： Jilin wang Dongping Lu Weiping Xuan Yuchun Ji Ruiqi chen Shaofei Li Wenbiao Li Wenzhuo chen Shilin Tang Guoyuan Zheng Fei Long Guangxi key laboratory of Optical and Electronic materials and Devices Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of ResourcesSchool of Materials Science and EngineeringGuilin University of TechnologyGuilin 541004China key laboratory of New Processing technology for Nonferrous metals and materials of Ministry of Education Guilin University of TechnologyGuilin 541004China School of materials science and Engineering Peking UniversityBeijing 100871China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityKowloon 999077Hong KongChina

Aluminum oxide(Al_(2)O_(3))ceramics have been widely utilized as circuit substrates owing to their exceptional *** this study,boron nitride microribbon(BNMR)/Al_(2)O_(3)composite ceramics are prepared using spark plasma sintering(SPS).This study examines the effect of varying the amount of toughened phase BNMR on the density,mechanical properties,dielectric constant,and thermal conductivity of BNMR/Al_(2)O_(3)composite ceramics while also exploring the mechanisms behind the toughening and increased thermal conductivity of the fabricated *** results showed that for a BNMR content of 5 wt%,BNMR/Al_(2)O_(3)composite ceramics displayed more enhanced characteristics than pure Al_(2)O_(3)*** particular,the relative density,hardness,fracture toughness,and bending strength were 99.95%±0.025%,34.11±1.5 GPa,5.42±0.21 MPa·m^(1/2),and 375±2.5 MPa,*** values represent increases of 0.76%,70%,35%,and 25%,respectively,compared with the corresponding values for pure Al_(2)O_(3)***,during the SPS process,BNMRs are subjected to high temperatures and pressures,resulting in the bending and deformation of the Al_(2)O_(3)matrix;this leads to the formation of special thermal pathways within *** dielectric constant of the composite ceramics decreased by 25.6%,whereas the thermal conductivity increased by 45.6%compared with that of the pure Al_(2)O_(3)*** results of this study provide valuable insights into ways of enhancing the performance of Al_(2)O_(3)-based ceramic substrates by incorporating novel BNMRs as a second *** improvements are significant for potential applications in circuit substrates and related fields that require high-performance materials with improved mechanical properties and thermal conductivities.

关键词： boron nitride microribbons/aluminum oxide(BNMRs/Al_(2)O_(3))composite ceramics boron nitride microribbon(BNMR) spark plasma sintering(SPS) strengthening and toughening thermal conductivity

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Phase evolution,hydrogen storage thermodynamics,and kinetics of ternary Mg_(98)Ho_(1.5)Fe_(0.5) alloy

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Journal of Rare Earths 2024年第9期42卷 1800-1808,I0006页

作者： Jinming Liu Hui Yong Yang Zhao Shuai wang Yiwan chen Baosheng Liu Jifan Hu Yanghuan Zhang College of materials science and Engineering Taiyuan University of Science and TechnologyTaiyuan030024China china Institute of Ocean Engineering(Tsing Tao) Qingdao266000China key laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources Inner Mongolia University of Science and TechnologyBaotou014010China

Rare earth elements and transition metals have been found to improve the hydrogen storage characteristics of magnesium-based *** study investigated the Mg-Ho-Fe(MHF) ternary alloy prepared using the vacuum induction melting technique.X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),pressure-composition-temperature(PCT),and differential scanning calorimetry(DSC) were used to analyze the alloy's phase transitions,microstructure,thermodynamics,and kinetic *** results reveal that the Mg_(98)Ho_(1.5)Fe_(0.5) alloy forms a solid solution with Ho and Fe in the magnesium *** hydrogen absorption,the activated alloy transforms into a mixture of Mg/MgH_(2) phases and nanoscale HoH_(2) ***,only the MgH_(2) phase decomposes during hydrogen desorption,while the HoH_(2) phase remains unchanged,exhibiting a positive catalytic *** alloy demonstrates excellent hydrogen absorption kinetics,achieving a capacity of 5.56 wt% H_(2) within 10 min at 360℃,owing to the combined catalytic effects of Ho and *** activation energy for hydrogen desorption is found to be 135.87 kJ/mol,which is lower than that of the activation energies of pure MgH_(2) and MgFe alloys,indicating an enhancement in desorption ***,the enthalpy and entropy changes for hydrogen absorption and desorption are determined to be-70.51 kJ/mol H_(2),-125.62 J/(K·mol) H_(2),72.83 kJ/mol H_(2),and 128.95 J/(K·mol) H_(2),***,it is worth noting that the thermodynamic properties of the alloy are improved due to the catalytic effect of Ho and Fe.

关键词： Rare earths Magnesium-based hydrogen storage Hydrogen storage thermodynamics Hydrogen storage kinetics

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Theoretical analysis of the elastic Kelvin-Helmholtz instability in explosive weldings

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Defence technology（防务技术） 2024年第2期32卷 521-528页

作者： Yuanbo Sun Jianning Gou cheng wang Qiang Zhou Rui Liu pengwan chen Tonghui Yang Xiang Zhao State key laboratory of Explosion science and technology Beijing Institute of TechnologyBeijing100081China beijing HIWING Scientific and Technological Information Institute Beijing100084China School of Aerospace Engineering Tsinghua UniversityBeijing100084China

By considering the joint effects of the Kelvin-Helmholtz(KH) and Rayleigh-Taylor(RT) instabilities, this paper presents an interpretation of the wavy patterns that occur in explosive welding. It is assumed that the elasticity of the material at the interface effectively determines the wavelength, because explosive welding is basically a solid-state welding process. To this end, an analytical model of elastic hydrodynamic instabilities is proposed, and the most unstable mode is selected in the solid phase. Similar approaches have been widely used to study the interfacial behavior of solid metals in high-energy-density physics. By comparing the experimental and theoretical results, it is concluded that thermal softening,which significantly reduces the shear modulus, is necessary and sufficient for successful welding. The thermal softening is verified by theoretical analysis of the increase in temperature due to the impacting and sliding of the flyer and base plates, and some experimental observations are qualitatively *** summary, the combined effect of the KH and RT instabilities in solids determines the wavy morphology, and our theoretical results are in good qualitative agreement with experimental and numerical observations.

关键词： Explosive welding Hydrodynamic instabilities Elasticity

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