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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

Polarizable Additive with Intermediate Chelation Strength for Stable Aqueous Zinc‑Ion Batteries

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Nano-Micro Letters 2024年第5期16卷 41-55页

作者： Yuting Xia Rongao Tong Jingxi Zhang Mingjie Xu Gang Shao Hailong Wang Yanhao Dong Chang‑An Wang state key Lab of new ceramics and fine processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084People’s Republic of China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001HenanPeople’s Republic of China

Aqueous zinc-ion batteries are promising due to inherent safety,low cost,low toxicity,and high volumetric capacity.However,issues of dendrites and side reactions between zinc metal anode and the electrolyte need to be solved for extended storage and cycle life.Here,we proposed that an electrolyte additive with an intermediate chelation strength of zinc ion—strong enough to exclude water molecules from the zinc metal-electrolyte interface and not too strong to cause a significant energy barrier for zinc ion dissociation—can benefit the electrochemical stability by suppressing hydrogen evolution reaction,overpotential growth,and den-drite formation.Penta-sodium diethylene-triaminepentaacetic acid salt was selected for such a purpose.It has a suitable chelating ability in aqueous solutions to adjust solvation sheath and can be readily polarized under electrical loading conditions to further improve the passivation.Zn||Zn symmetric cells can be stably operated over 3500 h at 1 mA cm^(-2).Zn||NH4V4O10 full cells with the additive show great cycling stability with 84.6%capacity retention after 500 cycles at 1 A g^(-1).Since the additive not only reduces H2 evolution and corrosion but also modifies Zn2+diffusion and deposition,highlyreversible Zn electrodes can be achieved as verified by the experimental results.Our work offers a practical approach to the logical design of reliable electrolytes for high-performance aqueous batteries.

关键词： Aqueous zinc-ion batteries Electrolyte additives DTPA-Na Chelation strength

Single-atom alloys prepared by two-step thermal evaporation

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Nano Research 2024年第4期17卷 2808-2813页

作者： Honglin Wang Jing Li Meirong Huang Jizhe Cui Zhiying Cheng Rong Yu Hongwei Zhu state key Lab of new ceramics and fine processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China state key Lab of Solid Waste Reuse for Building Materials Beijing Building Materials Academy of Science ResearchBeijing 100041China

Single-atom alloys(SAAs)have gained significant attention due to their remarkable atomic utilization efficiency,interactions between single atoms(SAs)and metal supports,and free-atom-like electronic structure of dopant elements.In this work,we observed the formation of SAs in pre-deposited metal particles by a two-step thermal evaporation technique,thereby establishing the first instance of discovering SAAs by thermal evaporation.The discovery of SAAs by thermal evaporation extends the range of SAAs preparation methods to include this traditional synthetic technique,which offers convenience,cost-efficiency,and universality.The formation mechanism of SAAs prepared using this technique was elucidated by density functional theory calculations.It was demonstrated that thermal evaporation can be utilized to prepare SAAs with multiple SAs,further highlighting its universal applicability.

关键词： single-atom alloys thermal evaporation density functional theory

Microstructures and characteristics of deep trap levels in ZnO varistors doped with Y_2O_3

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Science China(Technological Sciences) 2009年第12期52卷 3668-3673页

作者： LIU Jun 1 ,HU Jun 1 ,HE JinLiang 1 ,LIN YuanHua 2 &LONG WangCheng 1 1state key laboratory of Power Systems,Department of Electrical Engineering,Tsinghua University,Beijing 100084,China 2state key laboratory of new ceramics and fine processing,Department of Material Science and Engineering,Tsinghua University, Beijing 100084,China state key laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing China state key laboratory of new ceramics and fine processing Department of Material Science and Engineering Tsinghua University Beijing China

In this paper discussions on ZnO based varistor ceramics doped with different ratios of Y2O3 are presented.Analysis on the phase and microstructures of the samples indicates that an additional phase is detected in the samples doped with Y2O3,and the average grain size of the specimens decreases from about 9.2μm to 4.5μm,with an increase in the addition of Y2O3 from 0 mol%to 3 mol%.The corresponding varistor’s voltage gradient markedly increases from 462 V/mm to 2340 V/mm,while the nonlinear coefficient decreases from 22.3 to 11.5,respectively.Furthermore,the characteristics of deep trap levels in these ZnO samples are investigated by measuring their dielectric spectroscopies.The trap energy level and capture cross section evaluated by relaxation peak of the Cole-Cole plot vary slightly as the addition of Y2O3 increases.These traps may be ascribed to the intrinsic defects of ZnO lattice.

关键词： ZnO varistors Y2O3 electrical properties deep trap levels

Engineering neuroregenerative microenvironment via aligned hydrogel-assisted magnetic stimulation for complete spinal cord injury repair

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Engineered Regeneration

Engineered Regeneration 2024年第2期5卷 139-152页

作者： Chun-Yi Yang Zhe Meng Zhijun He Pengchao Ma Zhaohui Hou Kunkoo Kim Jingsong Lu Kaiyuan Yang Guihuai Wang Xiumei Wang state key laboratory of new ceramics and fine processing Key Laboratory of Advanced Materials of Ministry of EducationSchool of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Department of Neurosurgery Beijing Tsinghua Changgung HospitalSchool of Clinical MedicineTsinghua UniversityBeijing102218China

Utilizing biomaterials in tissue engineering has shown considerable promise for tissue regeneration,particularly through delivering multimodel cell-regulatory signals,including the material-related signals and extrinsic stimuli.In this research,we developed a magnetic-responsive aligned nanofiber fibrin hydrogel(MAFG),integrating the structured alignment of nanofibers and the pliability of fibrin hydrogel with an external magnetic field.This design aimed to enhance the regenerative response in spinal cord injury treatment.A medium-strength magnetic field,aligned with the spinal cord,was applied to aid motor function recovery in rats with spinal cord injuries.The use of MAFG in this context not only intensified the effect of the magnetic field but also encouraged the activation and differentiation of native neural stem cells.Furthermore,this method effectively steered macrophage polarization towards a beneficial M2 phenotype,addressing immune dysregulation at the injury site.The parallel application of magnetic field stimulation through MAFG in a spinal cord injury model contributed to the concurrent promotion of neurogenesis,angiogenesis,and immunomodulation,resulting in marked improvement in motor function in rats.This investigation underscores the therapeutic potential of magnetic field stimulation and highlights how aligning this stimulation with the spinal cord can significantly enhance the regenerative milieu at the injury site.

关键词： Angiogenesis Neurogenesis Immunomodulation Magnetic-responsive hydrogel Magnetic stimulation

Bioprinting of inorganic-biomaterial/neural-stem-cell constructs for multiple tissue regeneration and functional recovery

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National Science Review 2024年第4期11卷 228-244页

作者： Hongjian Zhang Chen Qin Zhe Shi Jianmin Xue Jianxin Hao Jinzhou Huang Lin Du Hongxu Lu Chengtie Wu state key laboratory of High Performance ceramics and Superfine Microstructure Shanghai Institute of Ceramics Chinese Academy of Sciences Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences

Tissue regeneration is a complicated process that relies on the coordinated effort of the nervous, vascular and immune systems. While the nervous system plays a crucial role in tissue regeneration, current tissue engineering approaches mainly focus on restoring the function of injury-related cells, neglecting the guidance provided by nerves. This has led to unsatisfactory therapeutic outcomes. Herein, we propose a new generation of engineered neural constructs from the perspective of neural induction, which offers a versatile platform for promoting multiple tissue regeneration. Specifically, neural constructs consist of inorganic biomaterials and neural stem cells(NSCs), where the inorganic biomaterials endows NSCs with enhanced biological activities including proliferation and neural differentiation. Through animal experiments, we show the effectiveness of neural constructs in repairing central nervous system injuries with function recovery. More importantly, neural constructs also stimulate osteogenesis, angiogenesis and neuromuscular junction formation, thus promoting the regeneration of bone and skeletal muscle, exhibiting its versatile therapeutic performance. These findings suggest that the inorganic-biomaterial/NSC-based neural platform represents a promising avenue for inducing the regeneration and function recovery of varying tissues and organs.

关键词： 3D bioprinting neural stem cells inorganic biomaterials neural constructs multiple tissue regeneration

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反铁磁成像的叠层相位恢复方法

Science Bulletin 2024年第4期69卷 466-472页

作者：崔吉哲沙浩治杨文峰于荣 School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China MOE key laboratory of Advanced Materials Tsinghua UniversityBeijing 100084China state key laboratory of new ceramics and fine processing Tsinghua UniversityBeijing 100084China

Antiferromagnetic imaging is critical for understanding and optimizing the properties of antiferromagnetic materials and devices.Despite the widespread use of high-energy electrons for atomic-scale imaging,they have low sensitivity to spin textures.Typically,the magnetic contribution to the phase of a highenergy electron wave is weaker than one percent of the electrostatic potential.Here,we demonstrate direct imaging of antiferromagnetic lattice through precise phase retrieval via electron ptychography,paving the way for magnetic lattice imaging of antiferromagnetic materials and devices.

关键词： Antiferromagnetic imaging Magnetic lattice Ptychography Electron microscopy

Morphology effect on catalytic performance of ebullated-bed residue hydrotreating over Ni-Mo/Al_(2)O_(3)catalyst:a kinetic modeling study

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Green Chemical Engineering 2024年第1期5卷 60-67页

作者： Zhe Liu Juncong Yuan Zongzhuang Sun Xiang Feng Yibin Liu Huihong Zhu Chong Peng Chaohe Yang state key laboratory of Heavy Oil processing China University of PetroleumQingdao266580China Dalian Research Institute of Petroleum and Petrochemicals SINOPECDalian116045China state key laboratory of fine Chemicals Dalian University of TechnologyDalian116024China

Upgrading of vacuum residue is of prime industrial significance due to the increasing demand for light oils.Elucidating the effect of catalyst morphology on vacuum residue hydrotreating performance by kinetic modeling is therefore of great importance.Herein,kinetic analysis of hydrodemetallization(HDM)and hydrodeconradsoncarbon-residue(HDCCR)performances on industrial Ni-Mo/Al_(2)O_(3)catalysts with spherical and cylindrical morphologies in ebullated-bed were evaluated for more than 1600 h.It was found that the percentage of light impurities easier to be removed on spherical catalysts were 78.20%and 39.43%in HDM and HDCCR reactions,respectively,higher than 65.20%and 17.50%on cylindrical catalysts.This suggests that catalyst morphology affects the impurity removal ability and the impurity properties,resulting in better hydrotreating performance of spherical catalysts.This work not only combines catalyst morphology with impurity removal capability through kinetic modeling,but also provides new insights into the design of efficient hydrotreating catalysts.

关键词： Morphology effect Kinetic analysis Vacuum residue Hydrotreating

Simultaneously enhancing the strength and ductility of as-extruded AlN/AZ91 composites via nano-precipitation and pyramidal slip

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Journal of Materials Science & Technology 2024年第5期172卷 240-254页

作者： Bin Zhang Yunxia Sun Tuo Liang Yunzhen Li Tian Li Jingchao Wang Ruiru Cai Changlin Yang state key laboratory of Solidification processing Northwestern Polytechnical UniversityXi’an 710072China

Age hardening is often used to optimize the mechanical properties of as-deformed Mg-based materials in industry,whereas the improvement of strength is usually accompanied by the significant loss of ductility,which hinders the application of Mg-based materials in structural components.In the present work,high strength-ductility synergy(the yield strength of 263±9 MPa,ultimate tensile strength of 398±7 MPa and elongation to fracture of 34%±1%)was realized in as-extruded AlN/AZ91 composites after optimiz-ing aging processes.Microstructural characterization shows that AlN particles induced a large number of geometrically necessary dislocations around the AlN/Mg interface during extrusion,which decreased the nucleation barrier and provided more heterogeneous nucleation sites forγ-Mg 17 Al 12 continuous precipi-tation.Meanwhile,95%of residual dislocations in as-extruded AlN/AZ91 composites were annihilated dur-ing peak-aging,suppressing the growth and coarsening of continuous precipitates.Therefore,high density of nano-sizedγ-Mg 17 Al 12 continuous precipitates was produced in as-extruded AlN/AZ91 composites af-ter peak-aging.During tension,gliding dislocations bypassed sphericalγ-Mg 17 Al 12 nano-precipitates by Orowan looping rather than cutting mechanism,which induced a strong block on dislocation motion.So high yield strength was mainly attributed to the high density of non-shearableγ-Mg 17 Al 12 nano-precipitates with spherical morphology,which was different from other Mg-Al-based systems.The results of texture evolution and slip trace analysis demonstrated that the suppression of extension twinning and less basal slip was due to the enhanced activity of pyramidalc+aslip in as-extruded AlN/AZ91 com-posites after peak-aging during the room temperature tension,meanwhile,the dislocation density of as-extruded AlN/AZ91 composites was significantly decreased during peak-aging,then higher elongation to fracture was achieved.

关键词： Magnesium matrix composites Mechanical properties Precipitation Deformation mechanisms Non-basal slip