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Pre-existing orthorhombic embryos-induced hexagonal-orthorhombic martensitic transformation in MnNiSi_(1-x)(CoNiGe)_x alloy

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Chinese Physics B 2024年第4期33卷 691-699页

作者：张婷婷龚元元鲁子骞徐锋 MIIT Key laboratory of Advanced Metallic and Intermetallic materials Technology School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China

The thermal-elastic martensitic transformation from high-temperature Ni_(2)In-type hexagonal structure to low-temperature TiNiSi-type orthorhombic structure has been widely studied in MnMX(M=Ni or Co,and X=Ge or Si)alloys.However,the answer to how the orthorhombic martensite nucleates and grows within the hexagonal parent is still unclear.In this work,the hexagonal-orthorhombic martensitic transformation in a Co and Ge co-substituted MnNiSi is investigated.One can find some orthorhombic laths embedded in the hexagonal parent at a temperature above the martensitic transformation start temperature(M_(s)).With the the sample cooing to M_(s),the laths turn broader,indicating that the martensitic transformation starts from these pre-existing orthorhombic laths.Microstructure observation suggests that these pre-existing orthorhombic laths do not originate from the hexagonal-orthorhombic martensitic transformation because of the difference between atomic occupations of doping elements in the hexagonal parent and those in the preexisting orthorhombic laths.The phenomenological crystallographic theory and experimental investigations prove that the pre-existing orthorhombic lath and generated orthorhombic martensite have the same crystallography relationship to the hexagonal parent.Therefore,the orthorhombic martensite can take these pre-existing laths as embryos and grow up.This work implies that the martensitic transformation in MnNiSi_(1-x)(CoNiGe)_(x) alloy is initiated by orthorhombic embryos.

关键词： martensitic transformation MnMX alloy orthorhombic embryo crystallography relationship

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Inhibiting shuttle effect of lithium polysulfides by double metal selenides for high-performance lithium-sulfur batteries

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Rare Metals 2024年第6期43卷 2546-2559页

作者： Lei Li Xue-Jing Yang Yi-Yang Li Bo Jin Hui Liu Meng-Yang Cui Dong-Bo Guan Xing-You Lang Qing Jiang Key laboratory of Automobile materials Ministry of Educationand College of Materials Science and EngineeringJilin University

Lithium-sulfur batteries（LSBs） have attracted the attention of more and more researchers due to the advantages of high energy density,environmental friendliness,and low production cost.However,the low electronic conductivity of active material and shuttling effect of lithium polysulfides（LiPSs） limit the commercial development of LSBs.To solve these problems,we design a core-shell composite with nitrogen-doped carbon（NC） and two types of selenides（FeSe2-NC@ZnSe-NC）.The FeSe2-NC@ZnSe-NC has a strong adsorption capacity,and can effectively adsorb LiPSs.At the same time,it also effectively alleviates the shuttling effect of LiPSs,and improves the utilization of the active substance during the charge/discharge reaction processes.The mechanism involved in FeSe2-NC@ZnSe-NC is demonstrated by both experiments and density-functional theory（DFT） calculations.The electrochemical test results indicate that LSB with S/FeSe2-NC@ZnSe-NC delivers an initial discharge capacity of 1260 mAh·g-1at 0.2C.And after 500 cycles at 1C,the capacity decay rate per cycle is 0.031%,and the capacity retention rate is 85%.The FeSe2-NC@ZnSe-NC core-shell structure verifies a rational strategy to construct an electrode material for high-performance LSBs.

关键词： Lithium–sulfur batteries Shuttling effect Metal selenide Nitrogen-doped carbon Lithium polysulfides

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Fast thermal responsive separators toward long-life and safe lithium metal batteries

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Nano Research 2024年第4期17卷 2746-2754页

作者： Pingan Li Zhifang Liu Yitong Peng Shanshan Yang Tao Meng Yunhuan Hu Yingjun Jiang Hao Sun Qi Li Xianluo Hu State Key laboratory of materials Processing and Die and Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Lithium metal batteries(LMBs)have been extensively investigated during the past decades because of their ultrahigh energy densities.With the increasing demand for energy density,however,the safety issue of LMBs has become a significant challenge.In particular,localized areas of increased temperature(namely,hotspots)may be induced and even exacerbated within LMBs by uneven current distribution,internal short circuits,or inadequate heat dissipation,which significantly sacrifices battery safety and cycle life.Here,we report the rational design and fabrication of a fast thermal responsive separator capable of inhibiting the growth of lithium dendrites and mitigating thermal propagation,thereby reducing the risk of thermal runaway.The as-achieved separator comprises both an electrospun membrane using a phase change material with superior thermal-storage ability and a thermally conductive modification layer of hexagonal boron nitride nanosheets with a fast heat-transfer feature.It is demonstrated that such a unique integration of heat conduction and heat storage enables the functional separator with attractive abilities to mitigate hotspots and inhibit the growth of lithium dendrites upon the cycling of LMBs.Moreover,pouch cells with the thermal-responsive separator,as well as numerical simulations,verify much enhanced safety and cycle life of LMBs.This work may offer a new conceptual design of intelligent separators that acts as a functional unit encapsulated within a single cell to boost in-situ thermal management,which will help to develop high-safety and energy-dense LMBs.

关键词： lithium metal batteries separators hotspots safety thermal management

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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 Engineering Huazhong University of Science and Technology

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 systematically. The 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 opposite. The 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 Mg2Si+Al-Mg IMCs phases not presented in the hypoeutectic Al-Si/AZ91D composites.Besides, increasing Si content, the thickness proportion of the T layer increased, forming an inconsistent preferred orientation of the MRL.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 composite. The fractures of the Al-xSi/AZ91D bimetallic composites transformed from the T layer into the E layer with the increase of the Si content. The improvement of the shear strength of the Al-xSi/AZ91D bimetallic composites was attributed to the synergistic action of the Mg2Si 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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Overcoming the Na-ion conductivity bottleneck for the cost-competitive chloride solid electrolytes

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Journal of Energy Chemistry 2024年第8期95卷 1-8页

作者： Lv Hu Hui Li Fang Chen Yating Liu Jinzhu Wang Cheng Ma Hefei National Research Center for Physical sciences at the Microscale CAS Key Laboratory of Materials for Energy Conversion Department of Materials Science and Engineering University of Science and Technology of China National Synchrotron Radiation laboratory

Chloride solid electrolytes possess multiple advantages for the construction of safe,energy-dense allsolid-state sodium batteries,but presently the chlorides with sufficiently high cost-competitiveness for commercialization almost all exhibit low Na-ion conductivities of around 10-5S cm-1or lower.Here,we report a chloride solid electrolyte,Na2.7ZFCl5.3O0.7,which reaches a Na-ion conductivity of2.29 × 10-4S cm-1at 25℃ without involving overly expensive raw materials such as rare-earth chlorides or Na2S.In addition to the efficient ion transport,Na2.7ZrCl5.3O0.7also shows an excellent deformability surpassing that of the widely studied Na3PS4,Na3SbS4,and Na2ZrCl6solid electrolytes.The combination of these advantages allows the all-solid-state cell based on Na2.7ZrCl5.3O0.7and NaCrO2to realize stable room-temperature cycling at a much higher specific current than those based on other non-viscoelastic chloride solid electrolytes in literature(120 mA g-1vs.12-55 mA g-1);after 100 cycles at such a high rate,the Na2.7ZFCl5.3O0.7-based cell can still deliver a discharge capacity of 80 mAh g-1at25℃.

关键词： All-solid-state sodium batteries Chlorides High voltage stability Ionic conductivities Solid electrolytes

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Carbon-based materials with combined functions of thermal management and electromagnetic protection: Preparation, mechanisms, properties, and applications

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Nano Research 2024年第3期17卷 883-903页

作者： Junwei Yue Yiyu Feng Mengmeng Qin Wei Feng School of materials science and Engineering and Tianjin Key laboratory of Composite and Functional materials Tianjin UniversityTianjin 300350China

The proliferation of high-power,highly informationized,and highly integrated electronic devices and weapons equipment has given rise to increasingly conspicuous issues about electromagnetic(EM)pollution and thermal accumulation.These issues,in turn,impose constraints on the performance of such equipment and jeopardize personnel safety.Carbon materials,owing to their diverse and modifiable structures,offer adjustable thermal and electric conductivity,rendering them highly promising for applications in fields such as thermal management and EM protection which have garnered extensive research and review.The pursuit of integrated device and equipment development has elevated the demand for multifunctional materials,prompting significant research into carbon-based composite materials that include both thermal management and EM protection functionalities.Notably,there are no relevant reviews on this topic at present.Consequently,this work consolidates research findings from recent years on carbon matrix composites exhibiting dual attributes of thermal management and EM protection.These attributes include thermally conductive electromagnetic interference(EMI)shielding materials,thermally insulating EMI shielding materials,thermally conductive EM wave(EMW)absorbing materials,and thermally insulating EMW absorbing materials.The paper elucidates the fundamental principles underpinning thermal conduction,thermal insulation,EMW absorbing,and EMI shielding.Additionally,it engages in discussions surrounding areas of contention,design strategies,and the functional properties of various material designs.Ultimately,the paper concludes by presenting the challenges encountered and potential research strategies about composites endowed with both thermal management and EM protection functionalities,while also envisaging the development of novel multifunctional EM protection materials.

关键词： carbon-based composites electromagnetic interference shielding microwave absorption thermal conduction thermal insulation

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Exceptional electrostrain with minimal hysteresis and superior temperature stability under low electric field in KNN-based lead-free piezoceramics

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Journal of Advanced Ceramics 2024年第3期13卷 364-372页

作者： Huan Liu Yijin Hao Ziqi Yang Tianyi Feng Bin Su Xin Zhang Mengping Xue Bo-Ping Zhang Jing-Feng Li Beijing Municipal Key laboratory of New Energy materials and Technologies School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing 100083China State Key laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Over the past two decades,(K_(0.5)Na_(0.5))NbO_(3)(KNN)-based lead-free piezoelectric ceramics have made significant progress.However,attaining a high electrostrain with remarkable temperature stability and minimal hysteresis under low electric fields has remained a significant challenge.To address this long-standing issue,we have employed a collaborative approach that combines defect engineering,phase engineering,and relaxation engineering.The LKNNS-6BZH ceramic,when sintered at T_(sint)=1170℃,demonstrates an impressive electrostrain with a d_(33) value of 0.276%and 1379 pm·V^(-1)under 20 kV·cm^(-1),which is comparable to or even surpasses that of other lead-free and Pb(Zr,Ti)O_(3)ceramics.Importantly,the electrostrain performance of this ceramic remains stable up to a temperature of 125℃,with the lowest hysteresis observed at 9.73%under 40 kV·cm^(-1).These excellent overall performances are attributed to the presence of defect dipoles involving V′_(A)-V∙∙_(O) and B′_(Nb)-V∙∙O,the coexistence of R-O-T multiphase,and the tuning of the trade-off between long-range ordering and local heterogeneity.This work provides a lead-free alternative for piezoelectric actuators and a paradigm for designing piezoelectric materials with outstanding comprehensive performance under low electric fields.

关键词： lead-free piezoelectric ceramics temperature stability electrostrain potassium sodium niobate low hysteresis

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Hydrolysis mechanism of YbB_(2)C_(2)and the microstructure of the carbon derived from the hydrolysis reaction

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Journal of materials science & Technology 2024年第4期171卷 209-221页

作者： Zhihui Li Hao Zhang Jixin Chen Jiemin Wang Xiaohui Wang Jinxing Yang Chao Zhang Zerong Zhang Hongyang Liu Fei Huang Meishuan Li Fei Li 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 Shanghai Key laboratory for High Temperature materials and Precision Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Carbide-derived carbon(CDC)materials have gained great attention due to the excellent properties for various potential applications.Here,graphite crystal is formed during a room-temperature hydrolysis pro-cess of layered compound YbB_(2)C_(2).The formation mechanism can be demonstrated by a YbB_(2)C_(2)molecular cell:Yb^(3+)acts as a cathode where H_(2)O molecule is reduced to H atom and OH^(−)ion,while(B_(2)C_(2))^(3−)acts as an anode where OH−ion is oxidized to O atom.Then,YbB_(2)C_(2)molecular cell begins to disintegrate,i.e.,Yb^(3+)ion,B and C atoms dissociate from the molecular cell.The as-produced C atoms combine to form graphite crystal.The initial graphite crystal is a cabbage-like microsphere,and then it gradually disintegrates and transforms into layered graphite.In addition,YbB_(6),Yb_(3)(OH)_(3)n(BO_(3))_((3-n))sol,hydrogen,hydrocarbons,and carbon oxides form simultaneously.Our method provides a general and inexpensive route to obtain carbide-derived graphite crystal.

关键词： Carbide-derived carbon YbB_(2)C_(2) Hydrolysis Molecular cell First-principles calculations

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Inducing piezoelectricity in distorted rutile TiO_(2)for enhanced tetracycline hydrochloride degradation through photopiezocatalysis

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Journal of Advanced Ceramics 2024年第3期13卷 323-331页

作者： Taotao Xia Lizhen Lu Haoyu Zhang Jinghui Wang Zonghe Huang Hongyang Wang Weiyi Yang Shuang Gao Qi Li Key laboratory of Advanced Technologies of materials(Ministry of Education) School of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Shenyang National laboratory for materials science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Various material design strategies have been developed to enhance photocatalytic performance of TiO_(2).However,no report is available on applications of the photopiezocatalysis strategy on TiO_(2)due to its lack of piezoelectricity.Here we developed a low-temperature molten salt etching process to create rutile TiO_(2)nanoparticles by etching[MgO_(6)]octahedrons away from MgTiO_(3)by molten NH_(4)Cl,during which a lattice distortion occurred in TiO_(2).The lattice distortion broke the structure symmetry of rutile TiO_(2)and subsequently endowed these rutile TiO_(2)nanoparticles with an unusual piezoelectric response with the maximum effective piezoelectric coefficient(d_(33))of~41.6 pm/V,which had not previously been found in TiO_(2)photocatalysts.Thus,the photopiezocatalysis strategy was applied for the first time to enhance the photocatalytic performance of these TiO_(2)nanoparticles.The creation of lattice distortion to induce piezoelectricity could be extended to other photocatalysts that the photopiezocatalysis strategy has not been applied to and may generate novel functionalities for various technical applications.

关键词： photocatalysis TiO_(2) piezocatalysis molten salt etching process photopiezocatalysis

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Improvement for creep strength of a second-generation single crystal superalloy by design of heat treatments

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Rare Metals 2024年第1期43卷 342-350页

作者： Wan-Shun Xia Xin-Bao Zhao Jia-Chen Xu Quan-Zhao Yue Qing-Qing Ding Huan-Chang Duan Yue-Feng Gu Hong-Bin Bei Ze Zhang Institute of Superalloys science and Technology School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027China State Key laboratory of Silicon and Advanced materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027China

Design of heat treatments is related to the key technology for development of nickel-based single crystal superalloys(Ni-SXs). Based on the full understanding of the solidification characteristics, this work applies optimization design of heat treatments for a second-generation Ni-SX. Microstructure evolution and creep properties are compared in the material under conventional/standard(Std.) and optimized(Opt.) treatments. For the Std. sample,strong dendritic segregations determine inconsistent microstructure evolution in the dendritic(D) and interdendritic region(ID), while the latter serves as weak area to have the prior microcrack initiation, damaging overall performance of the alloy. The Opt. treatment applies higher homogenization temperature, leading to overall reduced segregations, while not inducing incipient melting. A lower temperature of first-step ageing is used to lower the size ofγ'particles. These help to form the more uniform microstructure in dendritic and interdendritic region and relieve the inconsistent microstructure evolution. The balanced local strength makes ID no longer as the weak area,thus restricting microcrack initiation. Great improvement of high temperature and low stress property is obtained by this progress, leading to the pronounced increase of creep rupture life under 1100 °C/140 MPa.

关键词： Single crystal superalloy Heat treatment Segregation Solidification Creep property

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