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(K,Na)NbO_(3)-based lead-free ceramics with enhanced temperature-stable piezoelectricity and efficient red luminescence

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Journal of Advanced Ceramics 2023年第2期12卷 373-385页

作者： Qing liU Er PAN Fucai liU Jing-Feng Li School of Optoelectronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu 610054China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

There has been a surge of research interest in the promising lead-free potassium-sodium niobate(KNN)-based ceramics,applications of which could be significantly promoted by improving thermal stability of piezoelectricity.Besides,endowing the KNN-based ceramics with photoluminescence property by rare-earth-ion doping can make them more completive lead-free counterparts in potential applications such as novel multifunctional sensing devices.Herein,a novel KNN-based ceramic material doped with Eu was elaborately designed to simultaneously obtain enhanced temperaturestable piezoelectricity and good luminescence property.By the introduction of diffused phase transition and the modulation of unit cell distortion,a large piezoelectric strain coefficient(d^(*)_(33))with a small variation(590±59 pm/V)over a wide temperature range(from room temperature to 110℃)was realized.The optimal composition also exhibited a considerable piezoelectric coefficient(d_(33))with small fluctuation(330±33 pC/N)from 20 to 80℃.In addition to the enhanced temperature-stable piezoelectricity,the luminescence of these ceramics was slightly enhanced with the elevation of BaZrO_(3)(BZ)doping contents,which could be attributed to the increased compositional disorder and the decreased unit cell distortion of the matrix material.Moreover,an optical characteristic was more prominent at ultra-low temperatures.This work unprecedentedly provides a novel paradigm for the design of multifunctional KNN-based ceramics with enhanced temperature-stable piezoelectricity and good luminescence property,revealing the great potential of the rare-earth-element-doped KNN material for future applications in the novel multifunctional devices.

关键词： piezoelectric thermal stability rare-earth lead-free potassium-sodium niobate(KNN)

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Room-temperature thermoelectric materials: Challenges and a new paradigm

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Journal of Materiomics 2022年第2期8卷 427-436页

作者： Zhijia Han jing-Wei li feng Jiang Jiating Xia Bo-Ping Zhang Jing-Feng Li Weishu liu The Beijing Municipal Key Laboratory of New Energy Materials and Technologies School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing100083China Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen518055China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China Shenzhen Engineering Research Center for Novel Electronic Information Materials and Devices Southern University of Science and TechnologyShenzhenGuangdong518055China

Room-temperature thermoelectric materials provide promising solutions for energy harvesting from the environment,and deliver a maintenance-free power supply for the internet-of-things(IoTs).The currently available Bi_(2)Te_(3) family discovered in the 1950s,still dominates industrial applications,however,it has serious disadvantages of brittleness and the resource shortage of tellurium(1×10^(-3) ppm in the earth's crust).The novel Mg_(3)Sb_(2) family has received increasing attention as a promising alternative for room-temperature thermoelectric materials.In this review,the development timeline and fabrication strategies of the Mg 3 Sb 2 family are depicted.Moreover,an insightful comparison between the crystal-linity and band structures of Mg_(3)Sb_(2) and Bi_(2)Te_(3) is drawn.An outlook is presented to discuss challenges and new paradigms in designing room-temperature thermoelectric materials.

关键词： Thermoelectric materials Mg_(3)Sb_(2) Bi_(2)Te_(3) Chemical bond engineering

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Local Atomic Configuration in Pristine and A-Site Doped Silver Niobate Perovskite Antiferroelectrics

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Research 2022年第2期2022卷 203-212页

作者： jing Gao Wei li Jue liu Qian li Jing-Feng Li State Key Laboratory of New Ceramis and Fine Processing School of Materials Science and Engineering Tsinghua UniversityBeijing 10084China Neutron Scattering Division Onk Ridge National LaboratoryOak RidgeTenessee 37831USA

Antiferroelectrics have attracted increasing research interests in recent years due to both their great potential in energy storage applications and intriguing structural characteristics.However,the links between the electrical properties and structural characteristics of distorted perovskite antiferroelectrics are yet to be fully deciphered.Here,we adopt local-structure methods to elucidate the nanoscale atomic structure of AgNbO,-based antiferroelectrics and their structural evolution upon La doping.The local structural features including interatomic distance distributions and atomic displacements have been analyzed using neutron small-box pair distribution function(PDF)refinement in conjunction with large-box Reverse Monte Carlo modelling.Our results highlight the correlation of cation displacements in AgNbo,and its disruption by the incorporation of La,apparently in corroboration with the observed anomalous dielectric properties.Spatial ordering of cation vacancies is observed in La-doped AgNbo,samples,which coordinates with oxygen octahedral tilting to relieve lattice strain.These results provide renewed insights into the atomic structure and antiferroelectric phase instabilities of AgNbO,and relevant perovskite materials,further lending versatile opportunities for enhancing their functionalities.

关键词： properties. perovskite Configuration

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Delineating complex ferroelectric domain structures via second harmonic generation spectral imaging

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Journal of Materiomics 2023年第2期9卷 395-402页

作者： Wei li Yunpeng Ma Tianyi feng Ziwan Du Yixuan liu Sergei VKalinin Jing-Feng Li Qian li State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China Department of Materials Science and Engineering University of Tennessee KnoxvilleKnoxvilleTN37996USA

Understanding the mechanisms and spatial correlations of crystallographic symmetry breaking in ferroelectric materials is essential to tuning their functional properties.While optical second harmonic generation(SHG)has long been utilized in ferroelectric studies,its capability for probing complex polar materials has yet to be fully realized.Here,we develop a SHG spectral imaging method implemented on a home-designed laser-scanning SHG microscope,and demonstrate its application for a model system of(K,Na)NbO3 single crystals.Supervised model fitting analysis produces comprehensive information about the polarization vector orientations and relative fractions of constituent domain variants as well as their thermal evolution across the polymorphic phase transitions.Multiple domains and phases are clearly delineated at different temperatures,suggesting the phase competitions in(K,Na)NbO3.Besides,we show that unsupervised matrix decomposition analysis can quickly and faithfully reveal domain configurations without a priori knowledge about specific material systems.The SHG spectral imaging method can be readily extended to other ferroelectric materials with potentials to be further enhanced.

关键词： Second harmonic generation Ferroelectrics Domain structure Bayes linear unmixing

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Bi2Te3-based applied thermoelectric materials:research advances and new challenges

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National Science Review 2020年第12期7卷 1856-1858页

作者： Jun Pei Bowen Cai Hua-Lu Zhuang Jing-Feng Li State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua University

Thermoelectric (TE) materials can directly exchange heat and electricity in the solid state.TE devices that do not contain moving parts or produce emissions have been commercialized as electronic coolers and temperatu... 详细信息

关键词： PERFORMANCE

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Low-cost and environmentally benign selenides as promising thermoelectric materials

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Journal of Materiomics 2018年第4期4卷 304-320页

作者： Tian-Ran Wei Chao-feng Wu Fu li Jing-Feng Li State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of ScienceShanghai200050China Shenzhen Key Laboratory of Advanced Thin Films and Applications College of Physics and EnergyShenzhen UniversityShenzhen518060China Advanced Materials Institute Graduate School at ShenzhenTsinghua UniversityShenzhen518055China

Developing high-efficiency materials with earth-abundant and low-toxicity elements has become a popular trend in the field of thermoelectrics.Among these compounds,oxides and sulfides,the lighter,cheaper and green analogies of tellurides,have been extensively investigated and summarized as well defined classes.Nonetheless,the vast family of selenides with better electrical performance,lower thermal conductivity and higher thermoelectric efficiency have not been specially discussed.Here in this review,we present recent advances in binary and multinary selenide thermoelectric materials,covering traditional PbSe,liquid-like Cu_(2)Se,layered SnSe,diamond-like and disordered multinary compounds.The features of selenides are discussed based on both environmental concerns and from the perspective of chemical bonding,transport properties and performance.Emphasis is put on the“compositionstructure-processing-performance”relationship,and some interesting issues are addressed.Finally,challenges for thermoelectric selenides are discussed,and possible optimization strategies are also suggested.

关键词： Thermoelectric materials Selenides Transport properties

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Probing bundle-wise abnormalities in patients infected with human immunodeficiency virus using fixel-based analysis:new insights into neurocognitive impairments

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Chinese Medical Journal 2023年第18期136卷 2178-2186页

作者： jing Zhao Bin jing Jiaojiao liu feng Chen Ye Wu Hongjun li School of Biological Science and Medical Engineering Beihang UniversityBeijing 100069China Department of Radiology Beijing Youan HospitalCapital Medical UniversityBeijing 100069China School of Biomedical Engineering Capital Medical UniversityBeijing 100069China Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application School of Biomedical EngineeringCapital Medical UniversityBeijing 100069China School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjingJiangsu 210094China

Background:Changes in white matter(WM)underlie the neurocognitive damages induced by a human immunodeficiency virus(HIV)infection.This study aimed to examine using a bundle-associated fixel-based analysis(FBA)pipeline for investigating the microstructural and macrostructural alterations in the WM of the brain of HIV patients.Methods:This study collected 93 HIV infected patients and 45 age/education/handedness matched healthy controls(HCs)at the Beijing Youan Hospital between January 1,2016 and December 30,2016.All HIV patients underwent neurocognitive evaluation and laboratory testing followed by magnetic resonance imaging(MRI)scanning.In order to detect the bundle-wise WM abnormalities accurately,a specific WM bundle template with 56 tracts of interest was firstly generated by an automated fiber clustering method using a subset of subjects.Fixel-based analysis was used to investigate bundle-wise differences between HIV patients and HCs in three perspectives:fiber density(FD),fiber cross-section(FC),and fiber density and cross-section(FDC).The between-group differences were detected by a two-sample t-test with the false discovery rate(FDR)correction(Pling age and gender.Results:Among FD,FC and FDC,FD was the only metric that showed significant bundle-wise alterations in HIV patients compared to HCs.Increased FD values were observed in the bilateral fronto pontine tract,corona radiata frontal,left arcuate fasciculus,left corona radiata parietal,left superior longitudinal fasciculus III,and right superficial frontal parietal(SFP)(all FDR P<0.05).In bundle-wise covariance network,HIV patients displayed decreased FD and increased FC covarying patterns

关键词： Human immunodeficiency virus Diffusion tensor imaging White matter bundle Fixel-based analysis Covariance network

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Role of β2-glycoprotein I in the pathogenesis of the antiphospholipid syndrome

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Rheumatology & Autoimmunity 2023年第3期3卷 131-139页

作者： jing li Xiangrui Zhu Juan feng Department of Endocrinology Beijing ChaoYang HospitalCapital Medical UniversityBeijingChina Department of Physiology and Pathophysiology School of Basic Medical SciencesPeking UniversityBeijingChina Department of Integration of Chinese and Western Medicine School of Basic Medical SciencesPeking UniversityBeijingChina

Antiphospholipid syndrome(APS)is typically characterized by increased levels of three classes of antiphospholipid antibodies,namely lupus anticoagulant,anti-β2-glycoprotein I(anti-β2GPI),and anticardiolipin antibodies.β2-Glycoprotein(β2GPI)is a phospholipid-binding protein composed of five domains(DI-V)and a major antigen in APS.β2GPI is expressed on the surfaces of several cell types,including endothelial cells,monocytes,trophoblast cells,and platelets.Its binding to the anti-β2GPI antibody triggers downstream signaling events and ultimately exerts a variety of cellular effects.β2GPI modulates hemostasis and the complement system,as well as playing an important role in APS-associated vascular injury.Therefore,studying β2GPI will help elucidate the pathogenesis of APS and improve the treatment of patients with this condition.This review will mainly focus on the structure and function of β2GPI,as well as its implication in the pathogenesis of APS.

关键词： antiphospholipid syndrome coagulation complement inflammation β2-glycoprotein I

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High thermoelectric figure of merit ZT>1 in SnS polycrystals

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Journal of Materiomics 2020年第1期6卷 77-85页

作者： Asfandiyar Bowen Cai li-Dong Zhao Jing-Feng Li State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China School of Materials Science and Engineering Beihang UniversityBeijing100191China

Eco-friendly tin sulfide(SnS)has attracted increasing attention in the thermoelectric community because of its elemental abundance and analogous crystal structure to SnSe as a new thermoelectric material.However,so far no high dimensionless thermoelectric figure of merit ZT>1 was reported in SnS polycrystals.This work found an effective strategy for enhancing the thermoelectric performance of ptype polycrystalline SnS by Ag doping and vacancy engineering,leading to three orders of magnitude increase in carrier concentration and optimized effective mass and carrier mobility.As a result of the enhanced electrical conductivity,three times higher power factor ~3.85 μW/cm K^(2) at 877 K is realized in Sn_(0.995)Ag_(0.005)S sample.Interestingly,nanostructuring with Ag nano-precipitates were formed in the Agdoped SnS sample.Moreover,with introducing Sn vacancies in the crystal structure of Sn_(0.995-vac)Ag_(0.005)S,the power factor further enhanced to~4.25 μW/cm K^(2).In addition to the low-frequency phonons scattering by Ag nano-precipitates,dislocations strengthens the scattering of mid-frequency phonon,leading to an ultralow lattice thermal conductivity <0.5 W/m K above 800 K and a record high ZT up to 1.1 at 877 K in Sn_(0.99)Ag_(0.005)S polycrystals.

关键词： Thermoelectric tin sulfide Spark plasma sintering Nanoprecipitation Dislocation

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Heavy Precipitation over the jing–Jin–Ji Region in Early October: What Controls Its Interannual Variability?

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Journal of Meteorological Research 2022年第4期36卷 586-600页

作者： jing feng Tim li Ji WANG linna ZHANG Key Laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate andEnvironmental Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC–FEMD)Nanjing University of Information Science&TechnologyNanjing 210044China Beijing Meteorological Information Center China Meteorological AdministrationBeijing 100089China International Pacific Research Center and Department of Atmospheric Sciences School of Ocean and Earth Science and TechnologyUniversity of Hawaii at ManoaHonoluluHawaii 96822USA Beijing Municipal Climate Center Beijing 100089China Beijing Meteorological Observatory Beijing 100089China

Heavy regional precipitation(HRP)over Beijing,Tianjin,and Hebei Province(the jing–Jin–Ji region or JJJ)in early October(1–10 October)is a high-impact climate event because of travel and outdoor activities by exceptionally large population during the Chinese National Day Holidays(CNDH).What causes the year-to-year variation of the HRP during early October is investigated through an observational analysis.It is found that the HRP arises from moisture transport by southerly anomalies to the west of an anomalous low-level anticyclone over the subtropical northwestern Pacific(SNWP).Sensitivity numerical experiments reveal that the low-level anticyclonic anomaly is caused by a dipole heating pattern over tropical western and central Pacific associated with a La Niña-like SST anomaly(SSTA)pattern in the Pacific and by a negative heating anomaly over North Europe.The latter connects the SNWP anticyclone through a Rossby wave train.Anomalous ascent associated with a positive heating anomaly over the tropical western Pacific may strengthen the local Hadley Cell,contributing to maintenance of the low-level anomalous anticyclone over SNWP and extending westwards of the western Pacific subtropical high(WPSH).Therefore,both the tropical Pacific and midlatitude heating signals over North Europe may be potential predictors for HRP forecast in the JJJ region in early October.

关键词： heavy regional precipitation(HRP)in jing–Jin–Ji(JJJ) Beijing Tianjin and Hebei Province water vapor(WV)transport Rossby wave train diabatic heating anomalies La Niña-like SST anomaly

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