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Dielectric properties of low dielectric constant Ba_(0.60) Sr_(0.40)Mg_(0.15)Ti_(0.85)O_3-Mg_2TiO_4 composite thin films for tunable applications

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Chinese Science Bulletin 2009年第13期54卷 2235-2238页

作者： GAO LiNa zhai jiwei YAO Xi Functional Materials Research Laboratory Tongji University Shanghai 200092 China

Ba0.60Sr0.40Mg0.15Ti0.85O3-xmol%Mg2TiO4(x=0―40 mol%)(BSTM-MT) composite thin films were fabricated by sol-gel *** precursor solution of these composite thin films was prepared through mixing the Ba0.60Sr0.40Mg0.15Ti0.85O3 and Mg2TiO4 *** microstructures and dielectric tunability of composite thin films were *** dielectric constant of composite thin films can be tailored from 155 to 55 by changing the concentration of *** dielectric loss of these composite thin films were still kept below 0.01 and the tunability was above 20% at a dc-applied electric field of 500 kV/*** dielectric constant,low dielectric loss,and high tunability of this kind of composite thin films can be useful for potential microwave tunable applications.

关键词：低介电常数复合薄膜可调谐介电性能应用溶胶凝胶法低介电损耗薄膜制备

Microstructures and Dielectric Properties of Ba_(1-x)Sr_xTiO_3 Ceramics Doped with B_2O_3-Li_2O Glasses for LTCC Technology Applications

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Journal of Materials Science & Technology 2012年第3期28卷 280-284页

作者： Xiujian Chou Zhenyu Zhao Miaoxuan Du Jun Liu jiwei zhai Key Laboratory of Instrumentation Science&Dynamic Measurement Ministry of EducationNational Key Labora-tory of Science and Technology on Electronic Test and Measurement(North University of China)Taiyuan 030051China Functional Materials Research Laboratory Tongji UniversityShanghai 200092China

Ba1-xSrxTiO3 ceramics, doped with B2O3-Li2O glasses have been fabricated via a traditional ceramic process at a low sintering temperature of 900 ℃ using liquid-phase sintering aids. The microstructures and di- electric properties of B2O3-Li2O glasses doped Ba1-xSrxTiO3 ceramics have been investigated systemat- ically. The temperature dependence dielectric constant and loss reveals that B2O3-Li2O glasses doped Ba1-xSrxTiO3 ceramics have di？usion phase transformation characteristics. For 5 wt% B2O3-Li2O glasses doped Ba0.55Sr0.45TiO3 composites, the tunability is 15.4% under a dc-applied electric field of 30 kV/cm at 10 kHz; the dielectric loss can be controlled about 0.0025; and the Q value is 286. These composite ceramics sintered at low temperature with suitable dielectric constant, low dielectric loss, relatively high tunability and high Q value are promising candidates for multilayer low-temperature co-fired ceramics （LTCC） and potential microwave tunable devices applications.

关键词： Sintering Ferroelectricity Dielectric properties Microstructure

Fatigue-less relaxor ferroelectric thin films with high energy storage density via defect engineer

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Journal of Materials Science & Technology 2021年第18期77卷 178-186页

作者： Baijie Song Shuanghao Wu Hao Yan Kun Zhu Liuxue Xu Bo Shen jiwei zhai Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education Functional Materials Research LaboratorySchool of Materials Science and EngineeringTongji UniversityShanghai 201804China

Thin film capacitors with excellent energy storage performances,thermal stability and fatigue endurance are strongly desired in modern electrical and electronic ***,we design and prepare lead-free0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3BiFeO_(3)-x%Mn(x=0,0.5,1.5,2,3)thin films via sol-gel *** ions of divalent valence combine with oxygen vacancies,forming defect complex,which results in marked decline in leakage current and obvious enhancement in breakdown strength.A high energy storage density~47.6 J cm^(-3)and good efficiency~65.68%are simultaneously achieved in 2%Mn doped 0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3 BiFeO_(3)thin film ***,the 2%Mn-doped thin film exhibits excellent thermal stability in wide operating temperature range(35–115℃)and strong fatigue endurance behaviors after 108 *** above results demonstrate that 2%Mn-doped 0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3 BiFeO_(3)thin film capacitor with superior energy storage performances is a potential candidate for electrostatic energy storage.

关键词： Relaxor ferroelectric thin films Energy storage density Defect engineer

Recent progress of ecofriendly perovskite-type dielectric ceramics for energy storage applications

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Journal of Advanced Dielectrics 2018年第6期8卷 43-60页

作者： Feng Li jiwei zhai Bo Shen Huarong Zeng Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education Functional Materials Research Laboratory School of Materials Science&Engineering Tongji University4800 Caoan road Shanghai 201804P.R.China Key Laboratory of Inorganic Functional Materials and Devices Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050 P.R.China University of Chinese Academy of Sciences Beijing 100049 P.R.China

Increasing concern has been focused on the search for ecofriendly dielectric ceramics to meet the extensive demands of pulsed *** to the advantages of high-energy storage density,efficiency,and excellent temperature stability,optimization of energy storage performance in dielectric ceramics has been a goal in the past *** review summarizes the recently reported progress in energy storage properties of typical perovskite-type lead-free *** advantages and shortcomings in the various kinds of ceramics are ***,future prospects are presented to provide some guidelines for the exploration of new materials.

关键词： Lead-free dielectric ceramics energy storage charge-discharge perovskite-type.

Polypyrrole random-coil induced permittivity from negative to positive in all-organic composite films

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Journal of Materiomics 2020年第2期6卷 348-354页

作者： Peng Wang Zhongbin Pan Mingkun Wang Shuangwu Huang Jinjun Liu jiwei zhai School of Materials Science and Chemical Engineering Ningbo UniversityNingboZhejiang315211China School of Materials Science&Engineering Tongji University4800 Caoan RoadShanghai201804China

Percolating composites with negative permittivity can be promising candidates for ***,novel all-organic composite films containing of random coil polypyrrole(PPy)and poly(-vinylidene fluoride)(PVDF)are fabricated via a solution casting *** random coil PPy is prepared by oxidative template assembly approach for the first *** experimental result indicates that the negative permittivity is easily adjusted through controlling the random coil PPy ***,the random coil PPy contents exceeded 7 wt% the negative permittivity appear attributed to the formation of 3D interconnected PPy *** facile approach not only opens a new way to preparing negative permittivity of all-organic composite films,but also points out a route to facilitate the practical applications of metamaterials.

关键词： Polypyrrole Composite films Random coil Negative permittivity

High depolarization temperature and superior piezoelectric performance with complex structural evolution in BiFeO_(3)-PbTiO_(3)-(Sr0.7Bi0.2,0.1)TiO_(3) systems

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Journal of Materiomics 2022年第6期8卷 1260-1268页

作者： Hongwei Shi Feng Li Xinliang Yang Mingsheng Long Lei Shan Chunchang Wang jiwei zhai Information Materials and Intelligent Sensing Laboratory of Anhui Province Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of EducationInstitutes of Physical Science and Information TechnologyAnhui UniversityHefei230601China Laboratory of Dielectric Functional Materials School of Materials Science and EngineeringAnhui UniversityHefei230601China School of Materials Science&Engineering Tongji University4800 Caoan RoadShanghai201804China

Bismuth ferriteebased ferroelectric ceramics are considered strong competitors in highetemperature piezoelectric applications that benefits from their high depolarization temperature(Td),but problems of large conductivity and low piezoelectric coefficient(d33)should be ***_(3)ePbTiO_(3)ex(Sr0.7Bi0.2,0.1)TiO_(3)(BFePTexSBT)ternary system are designed in this work that successfully resolves this tough *** refinements show that this system exhibits multiphase coexistence with complex structural transition among rhombohedral,tetragonal and pseudocubic ***,a high Td~320℃ and d33~236℃/N are synergistically optimized in x=0.20 composition near pseudoephase boundary,which are indicated by multiescale techniques(phase structure,dielectric analysis etc.).What'smore,dual electrostrain peaks appear at separate phase boundaries for x=0.20 and 0.66 compositions with distinct piezo/ferroelectric *** law and piezoelectric force microscopy analysis clarify that the optimal electrostrain performance for both critical compositions are dominated by intrinsic(x=0.20)and extrinsic(x=0.66)contributions,*** work not only provides a new BFePTexSBT system with a high Td and superior d33 that are promising candidates in highetemperature actuator and sensor applications,but also presents a possibility of multiphaseecoexistence established exotic macroscopic performances.

关键词： BiFeO_(3)-based Piezoelectric Electrostrain Multiphaseecoexistence Domain switching

Excellent energy storage performance of niobate-based glass-ceramics via introduction of nucleating agent

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Journal of Materiomics 2022年第4期8卷 763-771页

作者： Changshuai Liu Shufeng Xie Hairui Bai Fei Yan Tongtong Fu Bo Shen jiwei zhai Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education Functional Materials Research LaboratorySchool of Materials Science and EngineeringTongji UniversityShanghai201804China

For glass-ceramics, how to realize the collaborative optimization of BDS and permittivity is the key toimprove the energy storage density. In this work, ZrO2 is introduced into BPKNAS glass-ceramics asnucleating agent to promote crystal development of glass-ceramics and then achieve high *** 1.5 mol% ZrO2 is added, the glass-ceramics have the highest permittivity (~128.59) and meanwhilepossess high BDS (1948.90 kV/cm) due to the dense microstructure. Therefore, BPKNAS-1.5ZrO2 glass-ceramics has the highest theoretical energy storage density (21.62 J/cm3). Moreover, the permittivityvariation of BPKNAS-1.5ZrO2 glass-ceramics is less than 6 % in the wide temperature range from 80 to300 C, showing excellent temperature stability. In addition, BPKNAS-1.5ZrO2 glass-ceramics possessesultrahigh power density, which reaches up to 382.40 MW/cm3 in overdamped circuit. The above evi-dence shows that BPKNAS-1.5ZrO2 glass-ceramics with ultrahigh energy storage density and powerdensity is very competitive in the field of energy storage applications.

关键词： Glass-ceramics Nucleating agent Permittivity Energy storage density

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电介质储能材料

硅酸盐学报 2024年第4期52卷 1171-1172页

作者：翟继卫同济大学材料科学与工程学院功能材料研究所上海201804

电介质电容器是一种通过电介质在外加电场作用下的极化以及正负电荷的分离来储存能量的储能系统。与燃料电池、锂离子电池、超级电容器等通过离子迁移或化学反应实现能量转换的化学储能系统相比,电介质电容器由于其储能过程不涉及离子... 详细信息

电介质电容器是一种通过电介质在外加电场作用下的极化以及正负电荷的分离来储存能量的储能系统。与燃料电池、锂离子电池、超级电容器等通过离子迁移或化学反应实现能量转换的化学储能系统相比,电介质电容器由于其储能过程不涉及离子迁移扩散和化学反应,充放电反应迅速,功率密度极高,在许多需要快速充放电和高功率密度的应用场景中具有突出优势。

关键词：电介质电容器能量存储

Temperature-insensitive KNN-based ceramics by elevating O-T phase transition temperature and crystal texture

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Journal of Materiomics 2023年第2期9卷 261-268页

作者： Shuo Gao Peng Li Jiawei Qu Mingze Sun Jigong Hao Peng Fu Zhongbin Pan jiwei zhai Wei Li School of Materials Science and Engineering Liaocheng UniversityLiaocheng252059China School of Materials Science and Chemical Engineering Ningbo UniversityNingbo315211China School of Materials Science and Engineering Tongji UniversityShanghai201804China

The inferior temperature stability of piezoelectric response is the main drawback of KNN-based ***,the Ba-doped 0.97(K0.48Na0.52)(Nb0.96Sb0.04)O3-0.03Bax(Bi0.5Ag0.5)1-xZrO3(abbreviated as KNNSBxBAZ)textured ceramics were prepared by the template grain growth(TGG)*** comprehensive properties(d33¼(406±15)pC/N,TC=274℃,strain is 0.17%)were achieved in KNNSBxBAZ textured ceramics with x=***,its piezoelectric and strain properties also show superior temperature stability(d33 maintained within±20%change in awide temperature range from 25℃to 200℃and strain variation was less than 5%in the temperature range from room temperature to 165℃).The high O-T phase transition temperature(TO-T is 110℃)induced by incorporating Ba ions accounts for the enhanced temperature stability of piezoelectric *** addition,the crystal texture always maintains the contribution of piezoelectric anisotropy to the piezoelectric properties during elevated temperature,which significantly improved the temperature stability of piezoelectric *** work provides an effective strategy for simultaneously achieving high piezoelectric response and excellent temperature stability in KNN-based ceramics.

关键词： Textured ceramics Ba modification Piezoelectric properties Temperature stability