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Low-temperature dielectric relaxation associated with NbO_6 octahedron distortion in antimony modified potassium sodium niobate ceramics

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Journal of Materials Science & Technology 2022年第20期115卷 189-198页

作者： Nan Zhang Xiang Lv Xi-xiang Zhang Jing Lyu Shuo-Wang Yang jiagang wu Department of Materials Science Sichuan UniversityChengdu 610065China Division of Physical Science and Engineering King Abdullah University of Science and TechnologyThuwal 23955-6900Saudi Arabia Department of Chemistry National University of Singapore3 Science Drive 3117543Singapore Institute of High Performance Computing Agency for ScienceTechnology and Research1 Fusionopolis Way#16-16 Connexis138632Singapore

Although the antimony(Sb) has been widely used to modify potassium sodium niobate(KNN) ceramics for tailoring the phase structure and performance, the role of Sb still remains insufficiently understood,consequently hindering the understanding of the physical origin of high-performance KNN-based ceramics. Here, we combine the experiments and first-principles calculations to deeply reveal the effects of Sb on KNN ceramics. Our results reveal a re-entrant-like relaxation behavior near the rhombohedralorthorhombic(R-O) phase transition at the low content of Sb, which transforms into a canonical one at higher content of Sb. First-principles calculations show a significantly decreased difference in the bond length of six B-O bonds of Nb O6 octahedral in Sb-modified KNN ceramics compared to pristine KNN ceramics, responsible for the low-temperature re-entrant-like dielectric relaxation. Furthermore, the addition of Sb would soften the B-O repulsion and gradually break the long-range ferroelectric ordering,resulting in the occurrence of nanoscale domains and enhanced local heterogeneity. Finally, we find that the optimized piezoelectric properties are the trade-off between the long-range ferroelectric ordering and the local heterogeneity. Therefore, this work not only deeply reveals the effects of Sb on KNN ceramics from multi-scale perspectives but also helps the future composition design for achieving high piezoelectricity.

关键词： KNN-based ceramics Re-entrant-like relaxation Covalency Multiphase coexistence Local heterogeneity

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A novel lead-free relaxor with endotaxial nanostructures for capacitive energy storage

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SusMat 2024年第1期4卷 116-125页

作者： Xiaoyan Dong Tengfei Hu Xiaojunwu Jie Yin Zhengqian Fu jiagang wu College of Materials Science and Engineering Sichuan UniversityChengduP.R.China Analysis and Testing Center for Inorganic Materials Shanghai Institute of CeramicsChinese Academy of SciencesShanghaiP.R.China

Dielectric capacitors with a fast charging/discharging rate,high power density,and long-term stability are essential components in modern electrical ***,miniaturizing and integrating capacitors face a persistent challenge in improving their energy density(W_(rec))to satisfy the specifications of advanced electronic systems and *** this work,leveraging phase-field simulations,we judiciously designed a novel lead-free relaxor ferroelectric material for enhanced energy storage performance,featuring flexible distributed weakly polar endotaxial nanostructures(ENs)embedded within a strongly polar fluctuation *** matrix contributes to substantially enhanced polarization under an external electric field,and the randomly dispersed ENs effectively optimize breakdown phase proportion and provide a strong restoring force,which are advantageous in bolstering breakdown strength and minimizing ***,this relaxor ferroelectric system incorporating ENs achieves an exceptionally high W_(rec)value of 10.3 J/cm^(3),accompanied by a large energy storage efficiency(η)of 85.4%.This work introduces a promising avenue for designing new relaxor materials capable of capacitive energy storage with exceptional performance characteristics.

关键词： endotaxial nanostructure energy storage lead-free relaxor ferroelectric

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Magnitude and direction of temperature variability affect hospitalization for myocardial infarction and stroke:population-based evidence from Guangzhou,China

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Frontiers of Environmental Science & Engineering 2024年第3期18卷 1-11页

作者： Zhou Yang Murui Zheng Ze-Lin Yan Hui Liu Xiangyi Liu Jie-Qi Jin jiagang wu Chun-Quan Ou State Key Laboratory of Organ Failure Research Department of BiostatisticsGuangdong Provincial Key Laboratory of Tropical Disease ResearchSchool of Public HealthSouthern Medical UniversityGuangzhou 510515China Guangzhou Center for Disease Control and Prevention Guangzhou 510440China

Relationships between nonoptimal temperatures and cardiovascular disease(CVD)mortality have been well ***,evidence of the association between temperature variability(TV)and CVD morbidity is *** study aimed to quantify the risk and burden of CVD-related hospitalization associated with the magnitude and direction of *** on meteorology and population-based hospitalizations for myocardial infarction(MI)and stroke were collected in Guangzhou,China,from 2013 to *** temperature variability(HTV)was measured as the standard deviation of hourly temperature records over specific exposure *** direction(upward or downward)of HTV was defined as the average daily mean temperature change relative to that of the previous day during the exposure ***-Poisson regression was applied to assess the impact of HTV after adjusting for the daily mean temperature,and the hospitalization fractions attributable to HTV were calculated.A 1℃-increase in HTV was significantly associated with a 2.24%and 1.72%increase in hospitalizations for MI and hemorrhagic stroke(HS)at lag 0–1 d,respectively,and a 1.55%increase in hospitalizations for ischemic stroke(IS)at lag 0–3 *** the study period,5.99%,4.64%,and 4.53%of MI,HS,and IS hospitalizations,respectively,were attributable to *** upward TV exerts acute effects on CVD hospital admissions,whereas the impact of downward TV generally *** findings highlight the importance of the magnitude and direction of temperature fluctuations,in addition to the mean level,in assessing the adverse health impacts of temperature variations.

关键词： Hourly temperature variability Cardiovascular Hospitalization Direction China

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Synergy of lead vacancies and morphotropic phase boundary to promote high piezoelectricity and temperature stability of PBZTN ceramics

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Journal of Materials Science & Technology 2023年第6期137卷 1-7页

作者： Wenbin Liu Ting Zheng Xuezheng Ruan Zhenyong Man Haoyue Xue Laiming Jiang Fuping Zhang Guorong Li jiagang wu Department of Materials Science Sichuan UniversityChengdu 610065China Shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 201800China Institute of Fluid Physics China Academy of Engineering PhysicsMianyang 621900China

The flourishing development of emerging electromechanical applications has stimulated an urgent demand for ferroelectric ceramics with high piezoelectric properties and broad temperature usage ***,it remains a challenge to simultaneously obtain good piezoelectricity and reliable temperature stability in lead zirconate titanate(PZT)-based piezoelectric *** solve this issue,a synergetic strategy was proposed to introduce lead vacancies through niobium doping and construct morphotropic phase boundary(MPB).In this work,Pb_(0.905)Ba_(0.085)(V Pb″)_(0.01)[(Zr_(x)Ti_(1-x))_(0.98)Nb_(0.02)]O_(3)(PBZTN-x)material system was *** comprehensive properties(d_(33)=864 pC/N,k_(p)=84%,T_(C)=201℃)and excellent temperature stability(less than 10%variation of electrical properties from 20℃ to 160℃)were obtained in PBZTN-0.540 *** piezoelectricity can be attributed to high extrinsic contribution(domain wall motion)induced by Pb^(2+)vacancies and the existence of nano-domains emerged at MPB,while excellent temperature stability is mainly attributed to the minimized local stress in the lattice and the stable domain structure.

关键词： Piezoelectricity Lead vacancies Morphotropic phase boundary Temperature stability

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Multiscale Structure Engineering for High-Performance Pb-Free Piezoceramics

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Accounts of Materials Research 2022年第4期3卷 461-471页

作者： Xiang Lv Ting Zheng Chunlin Zhao Jie Yin Haijun wu jiagang wu Department of Materials Science Sichuan UniversityChengdu 610064China State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China

CONSPECTUS:The increasing world energy crisis drives humans to harvest the energy in nature as much as possible without heavily damaging the ***,most of the energy in nature cannot be used ***,pursuing technologies or matter that can directly interconvert different energies has been one of the most cutting-edge fields in science and *** a magic ability exists in true-life piezoelectric materials that generate charge when being given a force and vice versa,rendering them highly promising for energy harvesting and conversion because of the tremendous mechanical energy on the earth,such as tide ***,piezoelectric materials,represented by the lead zirconate titanate(Pb(Zr,Ti)O_(3),PZT)family,have been largely used in various traditional and burgeoning fields,such as electronic information,biomedical treatment,and wearable flexible electronic devices,and are one of the most important favorites in multidisciplinary ***,Pb is highly *** by environmental protection and concern for human health,Pb-free piezoceramics are rapidly being developed to hopefully replace Pb-based *** particular,the renewal of Restriction of the use of certain Hazardous Substances(e.g.,RoHS 2),issued by the European Union,declared that replacement of PZT“...may be scientif ically and technologically practical to a certain degree...”.Therefore,developing high-performance Pb-free piezoceramics has become more urgent than *** this context,some Pb-free piezoceramics,represented by potassium sodium niobate((K,Na)NbO_(3),KNN),barium titanate(BaTiO_(3),BT),bismuth barium titanate((Bi,Na)TiO_(3),BNT),and bismuth ferrite(BiFeO_(3),BFO),stand out because of their unique or similar ***,several key challenges,including an inferior overall performance compared to Pb-based counterparts and an unclear structure−property relationship from multiscale viewpoints,have severely hindered the development of Pb-free piezoceramics for

关键词： ceramics piezoelectric bismuth

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Progress on the doping and phase boundary design of potassium–sodium niobate lead-free ceramics

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Journal of Advanced Dielectrics 2018年第3期8卷 1-16页

作者： Jie Xing Ting Zheng jiagang wu Dingquan Xiao Jianguo Zhu College of Materials Science and Engineering Sichuan University Chengdu 610064P.R.China

Potassium–sodium niobate(K,Na)NbO3/(KNN)lead-free ceramics have drawn vast amount of attention as one of the effective alternatives to lead-based *** recent years,the author’s group concentrated their work on KNN-based *** paper reviews the main obtained results in authors’laboratory on how to enhance the piezoelectric properties of KNN-based ceramics,including the ions or compounds substitution,the constructing and types of phase boundaries near room temperature,the investigation of other tools(sintering aids,synthesis technique,poling conditions)on *** the published papers up to now show the developing higher performance with maintaining high Curie temperature of KNN-based ceramics which has great potential for the future and is the key to success for the field.

关键词： Potassium-sodium niobate lead-free ceramic doping phase boundary piezoelectric properties

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Magnetoelectric coupling at microwave frequencies observed in bismuth ferrite-based multiferroics at room temperature

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Journal of Materials Science & Technology 2023年第6期137卷 100-103页

作者： Man Zhang Vladimir Koval Yu Shi Yajun Yue Chenglong Jia jiagang wu Giuseppe Viola Haixue Yan School of Engineering and Materials Science Queen Mary University of LondonMile End RoadLondon E14NSUK Institute of Materials Research Slovak Academy of SciencesWatsonova 47Kosice 04001Slovakia Key Laboratory for Magnetism and Magnetic Materials of MOE Lanzhou UniversityLanzhou 730000China Department of Chemistry Queen Mary University of LondonMile End RoadLondon E14NSUK Department of Materials Science Sichuan UniversityChengdu 610064China

***,In the search for advanced multifunctional materials for next generation sensors and logic devices,magnetoelectric multifer-roics exhibiting simultaneously ferromagnetism and ferroelectric-ity within the same phas... 详细信息

关键词： microwave coupling ferroelectric

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Potassium sodium niobate based lead-free ceramic for high-frequency ultrasound transducer applications

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Journal of Materiomics 2020年第3期6卷 513-522页

作者： Jie Xing Laiming Jiang Chunlin Zhao Zhi Tan Qian Xu jiagang wu Qiang Chen Dingquan Xiao Jianguo Zhu College of Materials Science and Engineering Sichuan University610064ChengduChina Roski Eye Institute Keck School of MedicineUniversity of Southern CaliforniaLos AngelesCA90033USA Key Laboratory of Deep Underground Science and Engineering(Ministry of Education) School of Architecture and EnvironmentSichuan UniversityChengdu610065China Sichuan Province Key Laboratory of Information Materials and Devices Application Chengdu University of Information Technology610103ChengduChina

The BiAlO_(3)(BA)and(Bi_(0.5)Na_(0.5))ZrO_(3)(BNZ)are selected to form a solid solution with(K_(0.48)Na_(0.52))NbO_(3) via traditional solid state technique to optimize the electrical performance and temperature stability of KNNbased lead-free ceramics,*** we show that doped BA has a great influence on phase structure,morphologies,and electrical *** XRD patterns and dielectric constant versus temperature curves reveal that an increase in the BA content results in a transform of phase structures from a coexistence state of rhombohedral,orthorhombic and tetragonal phases to pseudocubic *** to the construction of R-O-T phase boundary,optimized performances(T_(C)~336℃,d_(33)~306 pC/N,kp=0.48)are obtained in 0.962(K_(0.48)Na_(0.52))NbO_(3)-0.003BiAlO_(3)-0.035(Bi_(0.5)Na_(0.5))ZrO_(3)(KNN-3)*** on the sintered KNN-3 ceramic samples,high-frequency ultrasound imaging transducers are designed and fabricated,which exhibits a high center frequency of 24.5 MHz,a broad -6 dB bandwidth of 97% and a ***,the imaging characteristic of the lead-free transducers is demonstrated via ex vivo imaging of biological tissue *** environment friendly materials,the excellent electrical and acoustic performance of developed KNN-based ceramics has great potential for practical applications.

关键词： Potassium sodium niobate Lead free piezoceramics Thermal stability Ultrasound imaging transducers

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Ultra-slim electrostrains with superior temperature-stability in leadfree sodium niobate-based ferroelectric perovskite

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Journal of Materiomics 2022年第6期8卷 1230-1238页

作者： Ruiyi Jing Qingyuan Hu Leiyang Zhang Yuan Sun jiagang wu D.O.Alikin V.Ya Shur Xiaoyong Wei Hongliang Du Yunfei Chang Li Jin Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education&International Center for Dielectric ResearchSchool of Electronic Science and EngineeringXi'an Jiaotong UniversityXi'an710049China Functional Materials and Acousto-Optic Instruments Institute School of Instrumentation Science and EngineeringHarbin Institute of TechnologyHarbin150080China Department of Materials Science Sichuan UniversityChengdu610065China School of Natural Sciences and Mathematics Ural Federal UniversityEkaterinburg620000Russia Multifunctional Electronic Ceramics Laboratory College of EngineeringXi'an International UniversityXi'an710077China

Large electrostrains with high temperature stability and low hysteresis are essential for applications in high-precision actuator ***,achieving simultaneously all three of the aforementioned features in ferroelectric ceramics remains a considerable *** this work,we firstly report a high unipolar electrostrain(0.12%at 60 kV/cm)in(1ex)NaNbO_(3)-x[(Ba0.85Ca0.15)(Zr_(0.1)Ti_(0.9))O_(3)](NN-xBCZT)ferroelectric polycrystalline ceramics with excellent thermal stability(variation less than 10%in the temperature range of 30-160℃)and ultra-low hysteresis(<6%).Secondly,the high-field electrostrain response is dominated by the intrinsic electrostrictive effect,which may account for more than 80%of the ***,due to the thermal stability of the polarization in the pure tetragonal phase,the large electrostrain demonstrates extraordinarily high stability from room temperature to 140℃.Finally,in-situ piezoelectric force microscopy reveals ultra-highly stable domain structures,which also guarantee the thermal stability of the electrostrain in(NN-xBCZT ferroelectrics *** study not only clarifies the origin of thermally stable electrostrain in NN-xBCZT ferroelectric perovskite in terms of electrostrictive effect,but also provides ideas for developing applicable ferroelectric ceramic materials used in actuator devices with excellent thermal stability.

关键词： Electrostrain Electrostriction NaNbO_(3) Polarization

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铌酸钾钠基无铅压电陶瓷的发展与展望

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四川师范大学学报（自然科学版） 2019年第2期42卷 143-153页

作者：吴家刚四川大学材料科学与工程学院四川成都610065

压电陶瓷材料作为一类重要的高技术新材料,对我国国民经济和国防建设具有重大战略意义.目前市场上大量使用的是以锆钛酸铅(PZT)为主的有铅压电陶瓷,该类陶瓷虽然电学性能优异、廉价易制取、可实现大规模工业化生产,但其中含有大量的Pb元... 详细信息

压电陶瓷材料作为一类重要的高技术新材料,对我国国民经济和国防建设具有重大战略意义.目前市场上大量使用的是以锆钛酸铅(PZT)为主的有铅压电陶瓷,该类陶瓷虽然电学性能优异、廉价易制取、可实现大规模工业化生产,但其中含有大量的Pb元素,会对人体健康和生态环境造成极大危害.随着可持续发展战略的提出和人们对生态环境保护的日益关注,可见PZT陶瓷已经不符合环境友好的需求,能否找到一种电学性能和PZT陶瓷相媲美甚至更优异的无铅压电陶瓷材料,成为了各国学者争相研究的热点问题.我国肖定全教授早在1998年就提出"环境协调性铁电压电陶瓷"的概念.在各级项目的大力资助下,取得许多非常重要的进展,使得我国科学工作者在国际无铅压电材料研究领域占有重要地位.结合作者自己的科研工作,重点阐述铌酸钾钠基无铅压电陶瓷的相界设计,并提出一类新型相界设计新思路,极大提升该类陶瓷的压电性能.结合自己近年的相关工作和国内外研究进展,就其发展现状进行客观的分析,并对其面临的机遇与挑战提出一些自己的看法.

关键词：无铅压电陶瓷铌酸钾钠相界设计性能调控稳定性

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