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Journal of Advanced Ceramics 2021年第4期10卷 809-819页

作者： Tianxiang YAN Kaiyuan CHEN Chengqi LI Min liu Jie WANG Liang FANG laijun liu College of Mechanical and Control Engineering&College of Materials Science and Engineering Guilin University of TechnologyGuilin 541004China Institute of Fluid Engineering Equipment Jiangsu Industrial Technology Research InstituteJiangsu UniversityZhenjiang 212013China Key Laboratory for RF Circuits and Systems Ministry of Education&Key Laboratory of Large Scale Integrated DesignHangzhou Dianzi UniversityHangzhou 310018China

(1-x)K_(0.5)Na_(0.5)Nb0_(3-x)Bi(Zn_(2/3)Nb_(1/3))0_(3)((1-x)KNN-xBZN,x=0.010,0.015,0.020,0.025,and 0.030)lead-free ceramics were fabricated via a traditional solid-state *** crystal structure,microstructure,dielectric,and conductivity behavior of this system were *** with X-ray diffraction(XRD)patterns,Rietveld refinement,and dielectric spectroscopy,an orthorhombic phase was determined for x=0.010,an orthorhombic-tetragonal mixed phase was identified for x=0.015,and a rhombohedral symmetry appears in 0.020≤x≤*** 0.98KNN-0.02BZN and 0.975KNN-0.025BZN ceramics exhibit stable permittivity and low dielectric loss tangent(tan)in wide temperature ranges owing to the combination of rhombohedral-tetragonal step-like feature and the diffuse phase transition from tetragonal to *** activation energies of dielectric relaxation and conductivity behavior at high temperatures initially decrease slightly,then drop sharply,and finally decline slowly,which could be attributed to microstructure morphologies and the concentration of oxygen vacancies.

关键词： ceramic crystal structure dielectric spectroscopy oxygen vacancies

Compositional modulation in ZnGa_(2)0_(4) via Zn^(2+)/Ge^(4+)co-doping to simultaneously lower sintering temperature and improve microwave dielectric properties

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Journal of Advanced Ceramics 2021年第6期10卷 1360-1370页

作者： Ying XIONG Hongyuan XIE Zhenggang RAO laijun liu Zhengfeng WANG Chunchun LI College of Information Science and Engineering Guilin University of TechnologyGuilin 541004China Guangxi Key Laboratory of Optical and Electronic Materials and Devices College of Material Science and EngineeringGuilin University of TechnologyGuilin 541004China School of Materials Science and Engineering Nanchang UniversityNanchang 330031China

AB_(2)O_(4)-type spinels with low relative permittivity(ε_(τ))and high quality factor(Q×f)are crucial to high-speed signal propagation *** this work,Zn^(2+)/Ge^(4+) co-doping to substitute Ga in ZnGa_(2)O_(4) was designed to lower the sintering temperature and adjust the thermal stability of resonance frequency ***_(1+2)Ga_(2-2x)Ge_(x)O_(4)(0.1≤x≤0.5)ceramics were synthesised by the conventional solid state ***^(2+)/Ge^(4+) co-substitution induced minimal variation in the macroscopical spinel structure,which effectively lowered the sintering temperature from 1385 to 1250℃.All compositions crystallized in a normal spinel structure and exhibited dense microstructures and excellent microwave dielectric *** compositional dependent quality factor was related to the microstructural variation,being confirmed by Raman features.A composition with x=0.3 shows the best dielectric properties with ε_(τ) ≈10.09,Q×f≈112,700 THz,and ε_(τ) ≈-75.6 ppm/℃.The negative τf value was further adjusted to be near-zero through the formation of composite ceramics with TiO_(2).

关键词： ceramics spinel composition modulation dielectric properties

A low-firing melilite ceramic Ba2CuGe207 and compositional modulation on microwave dielectric properties through Mg substitution

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Journal of Advanced Ceramics 2021年第1期10卷 108-119页

作者： Changzhi YIN Zezong YU Longlong SHU laijun liu Yan CHEN Chunchun LI College of Information Science and Engineering Guilin University of TechnologyGuilin 541004China School of Materials Science and Engineering Nanchang UniversityNanchang 330031China Guangxi Universities Key Laboratory of Non-Ferrous Metal Oxide Electronic Functional Materials and Devices College of Material Science and EngineeringGuilin University of TechnologyGuilin 541004China

A melilite Ba2CuGe2O7 ceramic was characterized by low sintering temperature and moderate microwave dielectric *** at 960℃,the Ba2CuGe2O7 ceramic had a high relative density 97%,a low relative permittivity(εr)9.43,a quality factor(Q×f)of 20,000 GHz,and a temperature coefficient of resonance frequency(τf)-76 ppm/℃.To get a deep understanding of the relationship between composition,structure,and dielectric performances,magnesium substitution for copper in Ba2CuGe2O7 was *** of magnesium doping on the sintering behavior,crystal structure,and microwave dielectric properties were *** doping in Ba2CuGe2O7 caused negligible changes in the macroscopic crystal structure,grain morphology,and size distribution,while induced visible variation in the local structure as revealed by Raman *** dielectric properties exhibit a remarkable dependence on *** increasing the magnesium content,the relative permittivity featured a continuous decrease,while both the quality factor and the temperature coefficient of resonance frequency increased *** variations in dielectric performances were clarified in terms of the polarizability,packing fraction,and band valence theory.

关键词： ceramics dielectric properties melilite structure compositional modulation

Epitaxially strained SnTiO3 at finite temperatures

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Chinese Physics B 2018年第12期27卷 480-486页

作者： Dawei Wang laijun liu Jia liu Nan Zhang Xiaoyong Wei School of Microelectronics and State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong UniversityXi'an 710049China College of Materials Science and Engineering Guilin University of TechnologyGuilin 541004China State Key Laboratory for Mechanical Behavior of Materials &School of Materials Science and Engineering Xi'an Jiaotong UniversityXi'an 710049China Electronic Materials Research Laboratory-Key Laboratory of the Ministry of Education and International Center for Dielectric Research Xi'an Jiaotong University Xi'an 710049China

By combining the effective Hamiltonian approach and direct ab initio computation, we obtain the phase diagram of SnTiO3with respect to epitaxial strain and temperature. This demonstrates the complex features of the phase diagram and provides an insight into this system, which is a presumably simple perovskite. Two triple points, as shown in the phase diagram, may be exploited to achieve high-performance piezoelectric effects. Despite the inclusion of the degree of freedom related to oxygen octahedron tilting, the ferroelectric displacements dominate the structural phases over the whole misfit strain range. Finally, we show that SnTiO3can change from hard to soft ferroelectrics with the epitaxial strain.

关键词： SnTiO_3 phase diagram epitaxial strain

Achieving enhanced energy storage performance and ultra-fast discharge time in tungsten–bronze ceramic

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Journal of Advanced Ceramics 2024年第9期13卷 1349-1358页

作者： Yuejun Dan liupan Tang Wenzhi Ning Yingzhi Meng Changzheng Hu laijun liu Liang Fang Key Laboratory of New Processing Technology for Nonferrous Metal&Materials Ministry of EducationCollege of Materials Science and EngineeringGuilin University of TechnologyGuilin 541004China Guangxi Key Laboratory of Optical and Electronic Materials and Devices Guilin University of TechnologyGuilin 541004China Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources in Guangxi Guilin University of TechnologyGuilin 541004China

The rapid development of capacitors with high energy density and efficiency has been driven by advanced electronic systems and innovative pulsed power *** this study,we prepared Sr_(4.5−x)Ba_(x)Sm_(0.5)Zr_(0.5)Nb_(9.5)O_(30)(x=2.5,3,3.5,4,4.5)dielectric ceramics,which exhibited structural distortion due to the co-occupation of Ba^(2+),Sr^(2+),and Sm^(3+)in the A-site and the partial substitution of Nb^(5+)by Zr^(4+)in the *** ordered/disordered distribution due to these distortions thus generated polar nanoregions(PNRs)and induced a relaxation ferroelectric behavior,which was verified by the high-resolution transmission electron *** the use of the Vogel–Fulcher and Maxwell–Boltzmann equations,we found that easy inversion and small dipole sizes are crucial for achieving high energy storage density and *** Sr_(4.5−x)Ba_(x)Sm_(0.5)Zr_(0.5)Nb_(9.5)O_(30)(x=3.5)dielectric ceramic displayed a ferroelectric/paraelectric transition near room *** ferroelectric testing revealed large energy storage density(Wrec=4.31 J·cm^(−3))and high efficiency(η=93.8%)at 310 kV·cm−***,Sr_(4.5−x)Ba_(x)Sm_(0.5)Zr_(0.5)Nb_(9.5)O_(30)(x=4.5)exhibited higher breakdown field strength due to its large resistivity and small grain *** led to energy storage density of approximately 5.3 J·cm^(−3)at 460 kV·cm^(−1).Additionally,Sr_(4.5−x)Ba_(x)Sm_(0.5)Zr_(0.5)Nb_(9.5)O_(30)(x=3.5)demonstrated current density(CD)of approximately 713.38 A·cm^(−2)and power density(PD)of approximately 87.51 MW·cm^(−3),with ultrafast discharge time of 34 ns and excellent discharge energy density(Wdis)of approximately 2.27 J·cm^(−3).Overall,this study presents a promising approach for developing dielectric ceramic materials that hold potential for applications in innovative pulsed power components.

关键词： large energy storage high efficiency ultra-fast discharge time tungsten-bronze structure

Dielectric Properties of Unfilled Tetragonal Tungsten Bronze Ba4PrFe(0.5)Nb(9.5)O(30) Ceramics

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Journal of Wuhan University of Technology(Materials Science) 2017年第4期32卷 904-909页

作者：胡长征 ZHU Qihua SUN Zhen GUO Zhe liu laijun FANG Liang Ministry-province Jointly-constructed Cultivation Base for State Key Laboratory of Processing for Non-ferrous Metal and Featured Materials Guangxi Zhuang Autonomous Region Guilin University of Technology Key Laboratory of New Processing Technology for Nonferrous Metals and Materials Ministry of Education Guilin University of Technology Guangxi Universities Key Laboratory of Non-ferrous Metal Oxide Electronic Functional Materials and Devices College of Material Science and Engineering Guilin University of Technology

In order to found new dielectrics ceramics in tungsten bronze structure, unfilled tungsten bronze（TB） ceramics with nominal formula Ba4PrFe（0.5）Nb（9.5）O（30） were prepared by the solid state reaction method. The microstructure and dielectric properties were studied using powder X-ray diffraction, field emission scanning electron microscope, and variable temperature dielectric test system. The results show that the ceramics have a single phase and belong to the space group of P4bm with the cell of a = b = 12.4839（3）？, c = 3.9409（5）？, V = 614.192（2）？3. The frequency dependent dielectrics properties show that the ceramics have a Debye-like relaxation at room temperature, while the temperature dependent dielectrics properties indicate that the ceramics are a relaxor and the relaxation is due to the nanopolars and oxygen vacancies. The ceramics have a potential application in electronic ceramics as temperature-stable multilayer ceramic capacitors.

关键词： unfilled tetragonal tungsten bronze dielectric properties ceramic

Giant electrocaloric effect in BiFeO_(3) and La codoped PbZr_(0.7)Ti_(0.3)O_(3) epitaxial thin films in a broad temperature range

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Journal of Materiomics 2022年第1期8卷 156-165页

作者： Miaomiao Zhang laijun liu Rusen Yang Ping Yu Qi Zhang Biaolin Peng Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured Materials Center on Nanoenergy ResearchGuangxi UniversityNanning530004China Guangxi Key Laboratory of Optical and Electronic Materials and Devices Guilin University of TechnologyGuilin541004China School of Advanced Materials and Nanotechnology Xidian UniversityXi'an710126China College of Material Science and Engineering Sichuan UniversityChengdu610064China BCMaterials Basque Centre for MaterialsApplications and NanostructuresUPV/EHU Science Park48940LeioaSpain IKERBASQUE Basque Foundation for SciencePlaza Euskadi5Bilbao48009Spain

Ferroelectric thin/thick films with large electrocaloric(EC)effect are critical for solid state cooling ***,large positive EC effects with two EC peaks in a broad temperature range(~100 K)were obtained in 0.95Pb_(0.92)La_(0.08)(Zr_(0.70)Ti_(0.30))_(0.98)O_(3)-0.05BiFeO_(3)(BFO-La-codoped PZT)epitaxial thin films deposited on the(100),(110)and(111)oriented SrTiO_(3)(STO)substrates by a sol-gel *** thin film deposited on the(111)oriented STO substrate exhibited a stronger EC effect(~20.6 K at 1956 kV/cm)near room ***,the thin films deposited on the(100)and(110)oriented STO substrates exhibited a stronger EC effect(~18.8 K at 1852 kV/cm and~20.8 K at 1230 kV/cm,respectively)around the peak of the dielectric permittivity(T_(m),~375 K).Particularly,as the direction of the applied electric field was switched(E<0),the DT of the(100)-oriented thin films around T_(m) was enhanced significantly from 18.8 K to 38.1 *** self-induced-poling during the preparing process maybe plays a key role on the magic *** can be concluded that the BFO-La-codoped PZT epitaxial thin films are promising candidates for application in the next solid-state cooling devices.

关键词： Sol-gel Epitaxial thin film Electrocaloric effect Self-induce-poled

Large electrostrain in Bi_(1/2)Na_(1/2)TiO_(3)-based relaxor ferroelectrics:A case study of Bi_(1/2)Na_(1/2)TiO3-Bi_(1/2)K_(1/2)TiO_(3)-Bi(Ni_(2/3)Nb_(1/3))O_(3) ceramics

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Journal of Materiomics 2021年第3期7卷 593-602页

作者： Guangzhi Dong Huiqing Fan laijun liu Pengrong Ren Zhenxiang Cheng Shujun Zhang State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an710072China Institute for Superconducting and Electronic Materials Australia Institute of Innovative MaterialsUniversity of WollongongWollongong2522Australia College of Materials Science and Engineering Guilin University of TechnologyGuilin541004China Shaanxi Province Key Laboratory for Electrical Materials and Infiltration Technology School of Materials Science and EngineeringXi’an University of TechnologyXi’an710048China

(1-x)(0.8Bi_(1/2)Na_(1/2)TiO3-0.2Bi_(1/2)K_(1/2)TiO3)-xBi(Ni_(2/3)Nb_(1/3))O3(BNKT-xBNN)solid solution ceramics were fabricated by high temperature solid-state reaction *** the compositions possess relaxor ferroelectric features,among which the ergodic BNKT-0.02BNN exhibits large repeatable electrostrain value Suni¼0.51%at electric field of 65 kV/cm,with high piezoelectric stain coefficient d33*of 890 pm/V at 45 kV/cm,while the non-ergodic compositions present unrepeatable large strain *** on the electric field-composition phase diagram,the repeatability of strain response in ergodic compositions can be attributed to the reversible electric-field-induced phase *** addition,the effects of BNN contents on the macroscopic strain properties are explored by analyzing the existing states of the polar regions with corresponding thermal evolutions and electric-field-induced phase *** research is expected to guide the design of lead free relaxor ferroelectric materials with desired electrostrain properties.

关键词： BNT Electrostrain Mechanism Lead free Relaxor ferroelectric Phase diagrams

Entropy regulation in LaNbO_(4)-based fergusonite to implement high-temperature phase transition and promising dielectric properties

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Journal of Advanced Ceramics 2023年第5期12卷 1067-1080页

作者： Deqin Chen Na Yan Xuefeng Cao Fengrong Li laijun liu Qinghua Shen Huanfu Zhou Chunchun Li Guangxi University Key Laboratory of Non-ferrous Metal Oxide Electronic Functional Materials and Devices College of Material Science and EngineeringGuilin University of TechnologyGuilin 541004China Guangxi Key Laboratory of Embedded Technology and Intelligent System Guilin University of TechnologyGuilin 541004China

High-entropy effect is a novel design strategy to optimize properties and explore novel *** this work,(La_(1/5)Nd_(1/5)Sm_(1/5)Ho_(1/5)Y_(1/5))NbO_(4)(5RNO)high-entropy microwave dielectric ceramics were successfully prepared in the sintering temperature(S.T.)range of 1210–1290℃via a solid-phase reaction route,and medium-entropy(La_(1/3)Nd_(1/3)Sm_(1/3))NbO_(4) and(La_(1/4)Nd_(1/4)Sm_(1/4)Ho_(1/4))NbO_(4)(3RNO and 4RNO)ceramics were *** effects of the entropy(S)on crystal structure,phase transition,and dielectric performance were *** entropy increase yields a significant increase in a phase transition temperature(from monoclinic fergusonite to tetragonal scheelite structure).Optimal microwave dielectric properties were achieved in the high-entropy ceramics(5RNO)at the sintering temperature of 1270℃for 4 h with a relative density of 98.2%and microwave dielectric properties of dielectric permittirity(ε_(r))=19.48,quality factor(Q×f)=47,770 GHz,and resonant frequency temperature coefficient(τ_(f))=–13.50 ppm/℃.This work opens an avenue for the exploration of novel microwave dielectric material and property optimization via entropy engineering.

关键词： high-entropy ceramics microwave dielectric property ion disorder far-infrared

Constructing Nanoscale Topology on the Surface of Microfibers Inhibits Fibroblast Fibrosis

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Advanced Fiber Materials 2022年第5期4卷 1219-1232页

作者： Yongjie Jiao Xiaojing Li Jinjie Chen Chaojing Li laijun liu Xingxing liu Fujun Wang Guang Chen Lu Wang Key Laboratory of Textile Science and Technology Ministry of EducationCollege of TextilesDonghua UniversityShanghai 201620China Healthcare Department of Taizhou Hospital Affiliated to Wenzhou Medical University(Zhejiang Province Taizhou Hospital) Taizhou 317000China Department of Vascular Surgery Taizhou Hospital Affiliated to Wenzhou Medical University(Zhejiang Province Taizhou Hospital)Taizhou 317000China

Fibrosis is a common problem in soft tissue regeneration,often caused by the differentiation of fibroblasts into *** of the nanoscale topology that regulates the mechanical transduction of cells,nanofibers or nanoparticles are commonly used to modulate fibroblast ***,the strength of nanofibers is insufficient,and the physi-ological toxicity of nanoparticles still remains to be *** this study,self-induced crystallization was used to construct nano-protrusions on the random and aligned polycaprolactone microfibers to regulate the behavior of *** results revealed that the mechanical properties of microfibers with a nanoscale topology were *** staining manifested that nano-protrusions impeded the activation of integrins and vinculins,thereby inhibiting the nuclear transfer of Yes-associated protein,resulting in a decrease in the expression ofα-smooth muscle *** topology of microfibers hampered the activation of the Rho/ROCK signalling *** general,we used a simple process to con-struct a fibrous scaffold with a micro-nano multilevel *** structure can hinder the transformation of fibroblasts into myofibroblasts on both random and aligned fibers,which is expected to prevent fibrosis.

关键词： Electrospinning Topology Fibroblast Fibrosis