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Robust and Tunable Ferroelectricity in Ba/Co Codoped (K_(0.5)Na_(0.5))NbO_(3) Ceramics

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Chinese physics Letters 2024年第7期41卷 152-160页

作者：刘佳讯查节林杨玉龙吕笑梅胡雪莉阎朔吴子敬黄凤珍 national laboratory of solid state microstructures and school of physics Nanjing UniversityNanjing 210093China Collaborative Innovation Center of Advanced microstructures Nanjing UniversityNanjing 210093China

The 0.98(K_(0.5)Na_(0.5))NbO_(3)-0.02Ba(Nb_(0.5)Co_(0.5))O_(3-δ) ceramics with doped Ba^(2+) and Co^(2+) ions are fabricated,and the impacts of the thermal process are studied.Compared with the rapidly cooled (RC) sample,the slowly cooled (SC) sample possesses superior dielectric and ferroelectric properties,and an 11 K higher ferroelectricparaelectric phase transition temperature,which can be attributed to the structural characteristics such as the grain size and the degree of anisotropy.Heat treatment can reversibly modulate the content of the oxygen vacancies,and in turn the ferroelectric hysteresis loops of the samples.Finally,robust and tunable ferroelectric property is achieved in SC samples with good structural integrity.

关键词： ceramics ferroelectric treatment

Multifunctional cellular carbon foams derived from chitosan toward self-cleaning, thermal insulation, and highly efficient microwave absorption properties

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Nano Research 2024年第3期17卷 927-938页

作者： Beibei Zhan Yanling Hao Xiaosi Qi Yunpeng Qu Junfei Ding Jing-liang Yang Xiu Gong Yanli Chen Qiong Peng Wei Zhong College of physics Guizhou Province Key Laboratory for Photoelectrics Technology and ApplicationGuizhou UniversityGuiyang 550025China Minzu Normal University of Xingyi Xingyi 562400China national laboratory of solid state microstructures and Jiangsu Provincial laboratory for NanoTechnology Nanjing UniversityNanjing 210093China

To adapt the practical demand,designing and constructing the multifunctional microwave absorbers(MAs)is the key future direction of research and development.However,effective integrating the multiple functions into a single material remains a huge challenge.Herein,cellular carbon foams(CCFs)with different porous structures were elaborately designed and fabricated in high efficiency through a facile continuous freeze-drying and carbonization processes using a sustainable biomass chitosan as the precursor.The obtained results revealed that the thermal treated temperature and g-C_(3)N_(4) amount played a great impact on the carbonization degrees,pore sizes,and morphologies of CCFs,which led to their tunable electromagnetic(EM)parameters,improved conduction loss,and polarization loss abilities.Owing to the special cellular structure,the designed CCFs samples simultaneously displayed the strong absorption capabilities,broad absorption bandwidths,and thin matching thicknesses.Meanwhile,the as-prepared CCFs exhibited the strong hydrophobicity and good thermal insulation,endowing its attractive functions of self-cleaning and thermal insulation.Therefore,our findings not only presented a facile approach to produce different porous structures of CCFs,but also provided an effective strategy to develop multifunctional high-performance MAs on basis of three-dimensional CCFs.

关键词： multifunctional microwave absorbers carbon foams cellular structure self-cleaning thermal insulation

Fatigue-resistant Hydrogels

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Chemical Research in Chinese Universities 2024年第1期40卷 64-77页

作者： LI Luofei LEI Hai CAO Yi Collaborative Innovation Center of Advanced microstructures National Laboratory of Solid State MicrostructureDepartment of PhysicsNanjing UniversityNanjing 210093P.R.China Department of physics Zhejiang UniversityHangzhou 310027P.R.China

Hydrogels have been extensively studied for applications in various fields, such as tissue engineering and soft robotics, as determined by their mechanical properties. The mechanical design of hydrogels typically focuses on the modulus, toughness, and deformability. These characteristics play important roles and make great achievements for hydrogel use. In recent years, a growing body of research has concentrated on the fatigue property of hydrogels, which determines their resistance to crack propagation in the networks during cyclic mechanical loads for applications. However, knowledge of hydrogel fatigue behavior remains notably deficient. Here, we present a brief overview of the fatigue behavior of hydrogels, encompassing the general experimental methods to measure the fatigue property and fundamental theoretical calculation models. Then, we highlight multiple strategies to enhance the fatigue resistance of hydrogels. Finally, we present our perspectives on fatigue-resistant hydrogels, outstanding challenges and potential directions for future research.

关键词： Hydrogel Fatigue-resistant Fracture

Clions accelerating interface charge transfer in a Si/InSFaradaic junction photocathode for solar seawater splitting

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Science China Chemistry 2024年

作者： Jun Luo Ruotong Bao Hongzheng Dong Ye Fu Dongjian Jiang Bo Wang Yuzhan Zheng Qiong Wang Wenjun Luo Zhigang Zou Eco-materials and Renewable Energy Research Center (ERERC) Jiangsu Key Laboratory for Nano Technology National Laboratory of Solid State Microstructures College of Engineering and Applied Sciences Nanjing University national laboratory of solid state microstructures and Department of physics Nanjing University

Photoelectrocatalytic seawater splitting is a promising low-cost method to produce green hydrogen in a large scale.The effects of Cl-ions in seawater on the performance of a photoanode have been reported in previous studies.However,few researches have been done on the roles of Cl-ions in a photocathode.Herein,for the first time,we find that Cl-ions in the electrolyte improve the photocurrent of a Si/In2S3photocathode by 50%at-0.6 VRHE.An in-situ X-ray photoelectron spectroscopy （XPS） characterization combined with the time-of-flight secondary-ion mass spectrometry by simulating photoelectrochemical conditions was used to investigate the interface charge transfer mechanism.The results suggest that there is an In+32S3–x（OH）2xlayer on the surface of In2S3in the phosphate buffer solution （PBS） electrolyte,which plays a role as an interface charge transfer mediator in the Si/In2S3photocathode.The In+32S3–x（OH）2xsurface layer becomes In+32S3–x（Cl）2xin the PBS electrolyte with NaCl and accelerates the charge transfer rate at the In2S3/electrolyte interface.These results offer a new concept of regulating interface charge transfer mediator to enhance the performance of photoelectrocatalytic seawater splitting for hydrogen production.

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Electrical uniformity analyses on 12-inch Si-based Hf0.5Zr0.5O2 ferroelectric capacitor devices by atomic layer deposition

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Progress in Natural Science:Materials International 2024年第3期34卷 598-605页

作者： Wen-Juan Ding Yu Liu Zhi-Qiang Xiao Li Gao Yu-Chen Li Lin Zhu Xiang Li Wei-Min Li Shuang Chen Ai-Dong Li national laboratory of solid state microstructures College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced MicrostructuresNanjing University Jiangsu Leadmicro Nano-Technology Co. Ltd. Semiconductor Manufacturing North China Corp. Kuang Yaming Honors school Nanjing University

The study on the uniformity of electrical performance of large wafer-scale Hf0.5Zr0.5O2（HZO） ferroelectric capacitors is still lacking yet now. In this work, TiN/HZO/TiN metal-ferroelectric-metal（MFM） devices on 12-inch silicon wafers have been fabricated by thermal atomic layer deposition. The correlation of thickness uniformity with device-to-device variation of electrical properties and yield of the 12-inch MFM system was investigated. It was found that the uniformity of ferroelectric properties is closely related to the variation of HZO thickness of the MFM system, the concentration of oxygen vacancies in the micro-region of the HZO film, and the ferroelectric phase micro-distribution on 12-inch Si wafer. This work provides some important information for the performance optimization of HfO2-based ferroelectric random access memories.

关键词： 12-Inch Si wafer Atomic layer deposition Electrical uniformity Ferroelectric random access memory Hf0.5Zr0.5O2 ferroelectric thin film

Creation and annihilation of artificial magnetic skyrmions with the electric field

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Chinese physics B 2024年第3期33卷 132-137页

作者：程军孙亮张一可吉同舟曹荣幸缪冰锋赵永刚丁海峰 national laboratory of solid state microstructures and Department of physics Nanjing UniversityNanjing 210093China Collaborative Innovation Center of Advanced microstructures Nanjing UniversityNanjing 210093China Department of physics State Key Laboratory of Low-Dimensional Quantum PhysicsTsinghua UniversityBeijing 100084China Frontier Science Center for Quantum Information Tsinghua UniversityBeijing 100084China College of Electrical Energy and Power EngineeringYangzhou UniversityYangzhou 225127China

Recent theory and experiments show that artificial magnetic skyrmions can be stabilized at room temperature without the need for the external magnetic field,casting strong potentials for the device applications.In this work,we study the electric field manipulation of artificial magnetic skyrmions imprinted by Co disks on CoPt multilayers utilizing the micromagnetic simulations.We find that the reversible annihilation and creation of skyrmions can be realized with the electric field via the strain mediated magnetoelastic coupling.In addition,we also demonstrate controllable manipulation of individual skyrmion,which opens a new platform for constructing magnetic field-free and low-energy dissipation skyrmion based media.

关键词： skyrmions magnetic anisotropy micromagnetic simulations

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Individual dynamics and local heterogeneity provide a microscopic view of the epidemic spreading

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Chinese physics B 2024年第5期33卷 656-663页

作者：朱友源沈瑞哲董昊王炜 Kuang Yaming Honors school Nanjing UniversityNanjing 210023China Collaborative Innovation Center of Advanced microstructures National Laboratory of Solid State MicrostructureSchool of PhysicsNanjing UniversityNanjing 210093China Institute for Brain Sciences Nanjing UniversityNanjing 210023China state Key laboratory of Analytical Chemistry for Life Science Nanjing UniversityNanjing 210023China

The COVID-19 pandemic has caused severe global disasters,highlighting the importance of understanding the details and trends of epidemic transmission in order to introduce efficient intervention measures.While the widely used deterministic compartmental models have qualitatively presented continuous “analytical” insight and captured some transmission features,their treatment usually lacks spatiotemporal variation.Here,we propose a stochastic individual dynamical(SID)model to mimic the random and heterogeneous nature of epidemic propagation.The SID model provides a unifying framework for representing the spatiotemporal variations of epidemic development by tracking the movements of each individual.Using this model,we reproduce the infection curves for COVID-19 cases in different areas globally and find the local dynamics and heterogeneity at the individual level that affect the disease outbreak.The macroscopic trend of virus spreading is clearly illustrated from the microscopic perspective,enabling a quantitative assessment of different interventions.Seemingly,this model is also applicable to studying stochastic processes at the “meter scale”,e.g.,human society’s collective dynamics.

关键词： Brownian motion epidemic spreading heterogeneity

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Quantum dynamics within curved thin layers with deviation

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Chinese physics B 2024年第7期33卷 502-507页

作者：程润赵浩罗翠柏周璇王必利李延标王骏 physics Department of Basic Department Army Engineering University of PLANanjing 211101China national laboratory of solid state Microstructure Collaborative Innovation Center of Advanced Microstructuresand School of PhysicsNanjing UniversityNanjing 210093China school of physics and Electronics Hunan UniversityChangsha 410082China Department of physics Anhui Normal UniversityWuhu 241002China

Combining the deviation between thin layers' adjacent surfaces with the confining potential method applied to the quantum curved systems,we derive the effective Schr?dinger equation describing the particle constrained within a curved layer,accompanied by a general geometric potential V_(gq) composed of a compression-corrected geometric potential V_(gq)~*and a novel potential V_(gq)~(**) brought by the deviation.Applying this analysis to the cylindrical layer emerges two types of deviation-induced geometric potential,resulting from the the cases of slant deviation and tangent deviation,respectively,which strongly renormalizes the purely geometric potential and contribute to the energy spectrum based on a very substantial deepening of bound states they offer.

关键词： confining potential method quantum mechanics curved thin layer

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Alloyed Pt-Sn nanoparticles on hierarchical nitrogen-doped carbon nanocages for advanced glycerol electrooxidation

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Nano Research 2024年第5期17卷 4055-4061页

作者： Jietao Jiang Liqi Zhou Fengfei Xu Guanghai Chen Xiaoyu Liu Zhen Shen Lijun Yang Qiang Wu Xizhang Wang Zheng Hu Key laboratory of Mesoscopic Chemistry of MOE Jiangsu Provincial Laboratory for NanotechnologySchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China national laboratory of solid state microstructures Jiangsu Key Laboratory of Artificial Functional MaterialsCollege of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China

Glycerol is an alternative sustainable fuel for fuel cells,and efficient electrocatalyst is crucial for glycerol oxidation reaction(GOR).The promising Pt catalysts are subject to the inadequate capability of C-C bond cleavage and the susceptibility to poisoning.Herein,Pt-Sn alloyed nanoparticles are immobilized on hierarchical nitrogen-doped carbon nanocages(hNCNCs)by convenient ethylene glycol reduction and subsequent thermal reduction.The optimal Pt_(3)Sn/hNCNC catalyst exhibits excellent GOR performance with a high mass activity(5.9 A·mg_(Pt)^(-1)),which is 2.7 and 5.4 times higher than that of Pt/hNCNC and commercial Pt/C,respectively.Such an enhancement can be mainly ascribed to the increased anti-poisoning and C-C bond cleavage capability due to the Pt_(3)Sn alloying effect and Sn-enriched surface,the high dispersion of Pt_(3)Sn active species due to N-participation,as well as the high accessibility of Pt_(3)Sn active species due to the three-dimensional(3D)hierarchical architecture of hNCNC.This study provides an effective GOR electrocatalyst and convenient approach for catalyst preparation.

关键词： Pt_(3)Sn alloy hierarchical nitrogen-doped carbon nanocages glycerol electrooxidation anti-poisoning C-C bond cleavage