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Thermally stable polymer-ceramic composites for microwave antenna applications

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Journal of Advanced Ceramics 2016年第4期5卷 269-276页

作者： Li ZHANG Jie ZHANG zhenxing yue Longtu LI State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing 100084 China

Polymer-ceramic composites were prepared by twin screw melt extrusion with high-density polyethylene (HDPE) as the matrix and polystyrene-coated BaO-Nd2O3-TiO2 (BNT) ceramics as the filling ***,the incorporation of polystyrene (PS) by the coating route could significantly improve the thermal behaviors of the composites (HDPE-PS/BNT),besides the temperature stability of dielectric properties and thermal *** microwave dielectric properties of the composites were investigated *** results indicated that,as the volume fraction of BNT ceramic particles increased from 10 to 50 vol％ in the composites,the dielectric constant increased from 3.54 (9.23 GHz) to 13.14 (7.20 GHz),which can be beneficial for the miniaturization of microwave devices;the dielectric loss tangent was relatively low (0.0003-0.0012);more importantly,the ratio of PS to HDPE increased accordingly,making the composite containing 50 vol％ BNT ceramics have a low value of temperature coefficient of resonant frequency (τf =-11.2 ppm/℃) from-20 to 60 ℃.The GPS microstrip antennas were therefore designed and prepared from the HDPE-PS/BNT *** possessed good thermal stability (τf=23.6 ppm/℃) over a temperature range of-20 to 60 ℃,promising to meet the requirements of practical antenna applications.

关键词： polymer-ceramic composites microwave dielectric properties thermal stability GPS antenna

Crystal structure,chemical bond characteristics,infrared reflection spectrum,and microwave dielectric properties of Nd_(2)(Zr_(1−x)Ti_(x))_(3)(MoO_(4))_(9) ceramics

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Journal of Advanced Ceramics 2023年第1期12卷 82-92页

作者： Jian BAO Yuping ZHANG Hideo KIMURA Haitao WU zhenxing yue School of Environmental and Material Engineering Yantai UniversityYantai 264005China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Microwave dielectric ceramics(MWDCs)with low dielectric constant and low dielectric loss are desired in contemporary society,where the communication frequency is developing to high frequency(sub-6G).Herein,Nd_(2)(Zr_(1−x)Ti_(x))_(3)(MoO_(4))_(9)(NZ_(1−x)T_(x)M,x=0.02-0.10)ceramics were prepared through a solid-phase *** to X-ray diffraction(XRD)patterns,the ceramics could form a pure crystal structure with the R3c(167)space *** internal parameters affecting the properties of the ceramics were calculated and analyzed by employing Clausius-Mossotti relationship,Shannon’s rule,and Phillips-van Vechten-Levine(P-V-L)***,theoretical dielectric loss of the ceramics was measured and analyzed by a Fourier transform infrared(IR)radiation ***,when x=0.08 and sintered at 700℃,optimal microwave dielectric properties of the ceramics were obtained,including a dielectric constant(ε_(r))=10.94,Q·f=82,525 GHz(at 9.62 GHz),and near-zero resonant frequency temperature coefficient(τ_(f))=−12.99 ppm/℃.This study not only obtained an MWDC with excellent properties but also deeply analyzed the effects of Ti^(4+)on the microwave dielectric properties and chemical bond characteristics of Nd_(2)Zr_(3)(MoO_(4))_(9)(NZM),which laid a solid foundation for the development of rare-earth molybdate MWDC system.

关键词： microwave dielectric ceramics(MWDCs) Nd_(2)(Zr_(1−x)Ti_(x))_(3)(MoO_(4))_(9)(NZ_(1−x)T_(x)M) Phillips-van Vechten-Levine(P-V-L)theory theoretical dielectric loss

Structure,defects,and microwave dielectric properties of Al-doped and Al/Nd co-doped Ba_(4)Nd_(9.33)Ti_(18)O_(54)ceramics

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Journal of Advanced Ceramics 2022年第4期11卷 629-640页

作者： Weijia GUO Zhiyu MA Yu LUO Yugu CHEN zhenxing yue Longtu LI State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Low-loss tungsten–bronze microwave dielectric ceramics are dielectric materials with potential application value for miniaturized dielectric filters and antennas in the fifth-generation(5G)communication *** this work,a novel Al/Nd co-doping method of Ba_(4)Nd_(9.33)Ti_(18)O_(54)(BNT)ceramics with a chemical formula of Ba_(4)Nd_(9.33+z/3)Ti_(18−z)Al_(z)O_(54)(BNT–AN,0≤z≤2)was proposed to improve the dielectric properties through structural and defect *** with Al-doped ceramics(Ba_(4)Nd_(9.33)Ti_(18−z)Al_(4z/3)O_(54),BNT–A,0≤z≤2)for comparison,the ceramics were prepared by a solid state *** is found that Al/Nd co-doping method has a significant effect on improving the dielectric properties compared with Al *** the doping amount z increased,the relative dielectric constant(εr)and the temperature coefficient of resonant frequency(τf)of the ceramics decreased,and the Q×f values of the ceramics obviously increased when z≤*** microwave dielectric properties ofεr=72.2,Q×f=16,480 GHz,andτf=+14.3 ppm/℃were achieved in BNT–AN ceramics with z=*** spectroscopy and thermally stimulated depolarization current(TSDC)technique were firstly combined to analyze the structures and defects in microwave dielectric *** is shown that the improvement on Q×f values was originated from the decrease in the strength of the A-site cation vibration and the concentration of oxygen vacancies(VO××),demonstrating the effect and mechanism underlying for structural and defect modulation on the performance improvement of microwave dielectric ceramics.

关键词： microwave dielectric ceramics Ba4Nd9.33Ti18O54(BNT) Al and Al/Nd doping structural and defect modulation

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Sintering characteristics, crystal structure and dielectric properties of cobalt-tungsten doped molybdate-based ceramics at microwave frequency

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Journal of Materiomics 2022年第5期8卷 949-957页

作者： Jian Bao Yuping Zhang Haitao Wu Yuanyuan Zhou zhenxing yue School of Environmental and Material Engineering Yantai UniversityYantai264005ShandongChina School of Materials Science and Engineering University of JinanJinan250022ShandongChina State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China

In this study,a sequence of Ce_(2)[Zr_(1-x)(Co_(1/2)W_(1/2))_(x)]_(3)(MoO_(4))_(9)(CZ_(1-x)(CW)_(x)M)(x=0.02e0.10)ceramics with excellent microwave dielectric properties were obtained by the traditional solid-phase *** crystal structure,dielectric properties,and chemical bond characters of the ceramics were characterized and analyzed.X-ray diffraction and Rietveld refinement analysis show that CZ_(1-x)(CW)_(x)M could form a single-phase of the triangular crystal system in the entire doping *** microstructure of the ceramic samples was obtained by scanning electron *** sintering temperature was reduced and the gain of the sample was refined as the increase of doping ion ***,the intrinsic factors affecting the properties of CZ_(1-x)(CW)_(x)M were analyzed by employing P-V-L theory and through in-depth infrared *** x was 0.04 and the sintering temperature was 750C,the best dielectric properties of the samples were achieved,includingεr=9.95,Q·f=80,803 GHz(at 9.99 GHz),and tf=-9.10 ppm/℃.

关键词： Ce_(2)[Zr_(1-x)(Co_(1/2)W_(1/2))_(x)]_(3)(MoO_(4))_(9) Rietveld refinement P-V-L theory Infrared analysis

Structure characteristics and microwave dielectric properties of Pr_(2)(Zr_(1-x)Ti_(x))_(3)(MoO_(4))_(9) solid solution ceramic with a stable temperature coefficient

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Journal of Materials Science & Technology 2022年第21期116卷 121-129页

作者： Huanrong Tian Jinjie Zheng Lintao Liu Haitao Wu Hideo Kimura Yizhong Lu zhenxing yue School of Environmental and Material Engineering Yantai UniversityYantai 264005China School of Materials Science and Engineering University of JinanJinan 250022China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Pr_(2)(Zr_(1−x)Ti_(x))_(3)(MoO_(4))_(9)(x=0.1-1.0)ceramics were prepared via a conventional solid-state method,the dependence of crystal structure and bond characteristics on microwave dielectric properties was investigated *** X-ray diffraction patterns indicated that the single-phase Pr_(2)Zr_(3)(MoO_(4))_(9)structure was formed in all the *** the Ti^(4+)content increased,the lattice volume gradually decreased,which was ascribed to the fact that the ionic radius of Ti^(4+)was smaller than that of Zr^(4+).Notably,outstanding microwave dielectric properties withεr of 10.73-16.35,Q·f values of 80,696-18,726 GHz and minorτ_(f) values−14.1-−2.6 ppm/℃were achieved in Pr_(2)(Zr_(1−x)Ti_(x))_(3)(MoO_(4))_(9)***ε_(r) increased with the rising x values,which was associated with the increase ofα/Vm *** decreasing Q·f was affected by the decline of lattice energy of[Zr/TiO_(6)]***τf value was dominated by[Zr/TiO_(6)]octahedral distortion,Mo-O bond energy,bond strength and B-site bond ***,infrared reflection spectra suggested that the properties were mainly caused by the absorption of phonon,and the dielectric loss could be further reduced by optimizing the experimental process.

关键词： Pr_(2)(Zr_(1-x)Ti_(x))_(3)(MoO_(4))_(9) Normalized bond length Bond characteristics Raman spectra

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Single-cell network analysis reveals gene expression programs for Arabidopsis root development and metabolism

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Plant Communications 2024年第8期5卷 32-49页

作者： Ershang Han zhenxing Geng yue Qin yuewei Wang Shisong Ma MOE Key Laboratory for Cellular Dynamics School of Life SciencesDivision of Life Sciences and MedicineUniversity of Science and Technology of ChinaInnovation Academy for Seed DesignChinese Academy of SciencesHefei 230027China School of Data Science University of Science and Technology of ChinaHefei 230027China

Single-cell RNA-sequencing datasets of Arabidopsis roots have been generated,but related comprehensive gene co-expression network analyses are *** conducted a single-cell gene co-expression network analysis with publicly available scRNA-seq datasets of Arabidopsis roots using a SingleCellGGM *** analysis identified 149 gene co-expression modules,which we considered to be gene expression programs(GEPs).By examining their spatiotemporal expression,we identified GEPs specifically expressed in major root cell types along their developmental *** GEPs define gene programs regulating root cell development at different stages and are enriched with relevant developmental *** examples,a GEP specific for the quiescent center(QC)contains 20 genes regulating QC and stem cell niche homeostasis,and four GEPs are expressed in sieve elements(SEs)from early to late developmental stages,with the early-stage GEP containing 17 known SE developmental *** also identified GEPs for metabolic pathways with cell-type-specific expression,suggesting the existence of cell-type-specific metabolism in *** the GEPs,we discovered and verified a columellaspecific gene,NRL27,as a regulator of the auxin-related root gravitropism *** analysis thus systematically reveals GEPs that regulate Arabidopsis root development and metabolism and provides ample resources for root biology studies.

关键词： single-cell RNA sequencing single-cell gene co-expression network analysis gene expression program Arabidopsis root development NRL27 gravitropism

Large electrostrictive effect and strong photoluminescence properties in Sm_(2)O_(3)-modified lead-free potassium sodium niobate-based piezoelectric ceramics

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Journal of Materiomics 2020年第4期6卷 768-780页

作者： Wei Li Jigong Hao Peng Fu Juan Du Peng Li Chengchao Hu Wei Li zhenxing yue School of Materials Science and Engineering Liaocheng UniversityLiaocheng252059China State Key Laboratory of New Ceramic and Fine Processing Tsinghua UniversityBeijing100084China

In this work,the phase transition behavior and electrostrictive and photoluminescence properties of Sm_(2)O_(3)-modified 0.965(K_(0.48)Na_(0.52))(Nb_(0.95)Sb_(0.05))e_(0.035)Bi_(0.5)(Na_(0.82)K_(0.18))_(0.5)HfO_(3)(KNNSe0.035BNKH)ceramics were *** showed that the phase structure of the Sm2O3-modified ceramics evolved from coexisting orthogonal and tetragonal ferroelectric phases to a relaxor pseudocubic phase along with the strong destruction of the long-range ferroelectric *** switching in Smmodified ceramics with a relaxor pseudocubic phase became difficult,evident from the PFM ***,large electrostrictive effect with an electrostrictive coefficient of 0.022 m4/C2 was obtained in 1.0 mol%Sm-modified *** regard to long-term stability,the materials exhibited temperature-independent(20-100℃)and fatiguefree(up to 105 cycles)behavior,which guarantees their application in various *** KNNSe0.035BNKHexSm ceramics have the advantages of photoluminescence performance with bright orange emission under 407 nm visible light ***,KNNS0.035BNKHxSm ceramics have broad application prospects in multifunction devices due to their large electrostrictive effect,excellent photoluminescence performance,and long-term stability.

关键词： Sintering Ferroelectric properties Piezoelectric properties Actuators

Lattice vibrational characteristics,crystal structures and dielectric properties of non-stoichiometric Nd_((1+x))(Mg_(1/2)Sn_(1/2))O_(3) ceramics

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Journal of Materiomics 2020年第3期6卷 476-484页

作者： Zhikai Cao En-Cai Xiao Xue-Hui Li zhenxing yue Guohua Chen Ying Chen Kaixin Song Huanfu Zhou Ze-Ming Qi Feng Shi School of Material Science&Engineering Shandong University of Science and TechnologyQingdao266590China College of Arts and Design Shandong Jiaotong UniversityJinan250357China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China Guangxi Key Laboratory of Information Materials Guilin University of Electronic TechnologyGuilin541004China Key Laboratory of Inorganic Functional Materials and Devices Shanghai Institute of CeramicsChinese Academy of Sciences1295 Dingxi RoadShanghai200050China School of Electronics Information Hangzhou Dianzi UniversityHangzhou310018China Guangxi Ministry-Province Jointly-Constructed Cultivation Base for State Key Laboratory of Processing for Non-ferrous Metal and Featured Materials School of Materials Science and EngineeringGuilin University of TechnologyGuilin541004China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei230029China Key Laboratory of Processing and Testing Technology of Glass&Functional Ceramics of Shandong Province School of Materials Science and EngineeringQilu University of Technology(Shandong Academy of Sciences)Jinan250353China

Non-stoichiometric Nd_((1+x))(Mg_(1/2)Sn_(1/2))O_(3)(-0.04=x≤0.04,NMS)ceramics were fabricated via a conventional solid-state reaction *** structures and morphologies were investigated by Xray diffraction(XRD)and scanning electron microscopy(SEM),*** main crystalline phase is monoclinic Nd(Mg_(1/2)Sn_(1/2))O_(3) with a double perovskite structure(P21/n space group)for the NMS system proved by *** sample at x=0.01 has the best crystallinity and evenly distributed crystal grains observed by *** optimum performances(ε_(r)=19.87,Q×f=41840 GHz,f=12.05 GHz)are obtained at x=*** vibrational modes of the Raman spectra were assigned and illustrated,in *** dielectric properties obtained by fitting infrared reflectance spectra with the help of four-parameter semi-quantum model are consistent with the calculated values by microscopic polarization and damping *** reverse translational vibration of the NdeMgO_(6),the F_(5u)^((5)) mode,provides the greatest contribution to the dielectric *** relationships between crystal structures and dielectric properties were mainly established using lattice vibrational modes as a media.

关键词： Microwave dielectric ceramics Non-stoichiometric Lattice vibrational characteristics Crystal structures Dielectric properties

Research on effects of hydrostatic pressure on the dielectric property of Pb(Zn_(1/3)Nb_(2/3))O_3-BaTiO_3-PbTiO_3 relaxor ferroelectric ceramics

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Chinese Science Bulletin 2002年第6期47卷 513-518页

作者： XU Zhuo, ZHENG Shuguang, yue zhenxing, FENG Yujun, JIN An & YAO XiElectronic Materials Research Laboratory (EMRL), Xi’an Jiaotong University, Xi’an 710049, China Electronic Materials Research Laboratory (EMRL) Xi’an Jiaotong University Xi’an China

The dielectric properties of Pb(Zn1/3Nb2/3)O3-BaTiO3-PbTiO3 relaxor ferroelectric ceramics near the rhombohedral and tetragonal phase boundary were investigated under hydrostatic pressure. It was found that hydrostatic pressure made their phase transition temperature Tc and the peak temperature Tm decreased, and the frequency dispersion and relaxor behavior enhanced. In these disorder systems of composite pervoskite structures, there appeared polar clusters or nanodomains. The unique physical characteristics, which made the relaxor behavior enhanced, is that the correlation length among these nanodo- mains decreases greatly with the pressure increasing.

关键词： hydrostatic pressure relaxor ferroelectric dielectric-temperature spectrum.

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