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UltrahighQ Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)microwave dielectric ceramics for temperature-stable millimeter-wave dielectric resonator antennas

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Journal of Advanced Ceramics 2024年第2期13卷 155-165页

作者： Guoqiang He Yu Jiang Kaixin Song Yanjun Liu Yuan Nie Wenjie Zhang Ziqi Zhao Yinghan He Xinyue Ma Xiuli Chen Xu Li huanfu zhou Collaborative Innovation Centre for Exploration of Hidden Nonferrous Metal Deposits and Development of New Materials in Guangxi Key Laboratory of Nonferrous Materials and New Processing TechnologyMinistry of EducationSchool of Materials Science and EngineeringGuilin University of TechnologyGuilin 541004China College of Electronic Information Hangzhou Dianzi UniversityHangzhou 310018China

Microwave dielectric ceramics should be improved to advance mobile communication technologies *** this study,we prepared Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics with nonstoichiometric Sr^(2+)ratios based on our previously reported SrY_(2)O_(4) microwave dielectric ceramic,which has a low dielectric constant and an ultrahigh quality factor(Q value).The ceramic exhibited a 33.6% higher Q-by-frequency(Q×f)value(Q≈12,500)at x=0.02 than SrY_(2)O_(4).All Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics exhibited pure phase structures,although variations in crystal-plane spacings were *** ceramics are mainly composed of Sr-O,Y1-O,and Y_(2)-O octahedra,with the temperature coefficient of the resonant frequency(τ_(f))of the ceramic increasing with Y_(2)-O octahedral *** ceramic comprises uniform grains with a homogeneous elemental distribution,clear grain boundaries,and no obvious cavities at x=*** Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics exhibited good microwave dielectric properties,with optimal performance observed at x=0.02(dielectric constant(εr)=15.41,Q×f=112,375 GHz,and τ_(f)=-17.44 ppm/℃).The τ_(f) value was reduced to meet the temperaturestability requirements of 5G/6G communication systems by adding CaTiO_(3),with Sr_(1.02)Y_(2)O_(4.02)+2wt% CaTiO_(3) exhibiting ε_(r)=16.14,Q×f=51,004 GHz,andτf=0 ppm/℃.A dielectric resonator antenna prepared using Sr_(1.02)Y_(2)O_(4.02)+2wt%CaTiO_(3) exhibited a central frequency of 26.6 GHz,with a corresponding gain and efficiency of 3.66 dBi and 83.14%,***,Sr_(1.02)Y_(2)O_(4).02-based dielectric resonator antennas are suitable for use in 5G millimeter-wave band(24.5-27.5 GHz)applications.

关键词： millimeter wave microwave dielectric ceramics dielectric resonator antenna nonstoichiometric ratio

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内嵌Flash存储器可靠性评估方法的分析及应用

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电子与封装 2024年第7期24卷 43-49页

作者：周焕富刘伟周成中科芯集成电路有限公司江苏无锡214072

介绍了存储器分类及Flash存储器的基本结构,分析了非易失性存储器(NVM)可靠性试验标准的特点。从试验项目、试验条件、样品数量和数据图形等方面比较了JEDEC和AEC发布的NVM可靠性试验的标准和方法。以2款存储容量分别为64 kB和128 kB的... 详细信息

介绍了存储器分类及Flash存储器的基本结构,分析了非易失性存储器(NVM)可靠性试验标准的特点。从试验项目、试验条件、样品数量和数据图形等方面比较了JEDEC和AEC发布的NVM可靠性试验的标准和方法。以2款存储容量分别为64 kB和128 kB的MCU芯片为试验对象,依据JEDEC和AEC发布的试验标准和方法,设计了针对MCU芯片内嵌Flash存储器可靠性的评估试验,为Flash存储器的设计和验证工作提供参考。

关键词： Flash存储器擦写循环数据保持

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广西普通本科院校专业设置及调整的现状、问题与对策

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高教论坛 2024年第5期 76-81页

作者：李亚娟周焕福桂林理工大学广西桂林541004

专业设置情况、结构情况、建设情况等直接影响着人才培养质量。广西本科院校近年来取得了长足的发展,其专业设置日趋优化,总体来看学科门类设置齐全、专业种类不断增加、专业布点不断增多、专业增撤持续优化,但还存在专业设置专业种类... 详细信息

专业设置情况、结构情况、建设情况等直接影响着人才培养质量。广西本科院校近年来取得了长足的发展,其专业设置日趋优化,总体来看学科门类设置齐全、专业种类不断增加、专业布点不断增多、专业增撤持续优化,但还存在专业设置专业种类少而不精、趋同性、布局不尽合理、顶层设计不足等问题。着眼于专业及学校的高质量发展,广西普通本科院校在专业设置与调整方面,需要加强宏观调控科学设置专业、分析比较优势推动特色发展、对接产业需求优化专业结构、凝聚多方合力完善调整机制结构。

关键词：高质量发展广西本科院校专业设置与调整

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Sintering behavior,phase composition,microstructure,and dielectric characteristics of garnet-type Ca_(3)Fe_(2)Ge_(3)O_(12) microwave ceramics

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Journal of Materiomics 2023年第3期9卷 472-481页

作者： Guoqiang He Yanjun Liu huanfu zhou Xiuli Chen Key Laboratory of Nonferrous Materials and New Processing Technology Ministry of EducationSchool of Materials Science and EngineeringGuilin University of TechnologyGuilin541004China

This paper describes the solid-state production of a unique yellowish-grey microwave dielectric ceramic,Ca_(3)Fe_(2)Ge_(3)O_(12)(CFG).Rietveld refinement demonstrated that CFG corresponds to a cubic system(space group 230:Ia 3 d).The relative density of the ceramic initially increased and then decreased with the sintering temperature,reaching a maximum of 96.92%at 1330℃.According to scanning electron mi-croscopy and energy-dispersive spectroscopy results,the CFG ceramic grains are spherical and consistent in size;furthermore,they have distinct grain boundaries and a uniform distribution of the four con-stituent *** CFG ceramic has a superior crystal structure and a high crystallinity,according to transmission electron *** spectroscopy revealed that the Q×f value of the ceramic and the full width at half maximum of the Raman peak are negatively *** ceramic possesses the best overall dielectric characteristics after sintering at 1330℃for 4 h:ε_(r)=10.31,Q×f=82636 GHz,andτ_(f)=-45.66×10^(-6)℃^(-1),showing that it is a promising candidate for use in mobile devices.

关键词： Low permittivity Garnet-type structure Microwave dielectric properties Ca_(3)Fe_(2)Ge_(3)O_(12)

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Sintering behaviour and microwave dielectric properties of MgO-2B_(2)O_(3)--xwt%BaCu(B_(2)O_(5))-ywt%H_(3)BO_(3) ceramics

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Journal of Advanced Ceramics 2021年第6期10卷 1282-1290页

作者： Haiquan WANG Shixuan LI Kangguo WANG Xiuli CHEN huanfu zhou Collaborative Innovation Center for Exploration of Hidden Nonferrous Metal Deposits and Development of New Materials in Guangxi Key Laboratory of Nonferrous Materials and New Processing TechnologyMinistry of EducationSchool of Materials Science and EngineeringGuilin University of TechnologyGuilin 541004China

This study investigates the bulk density,sintering behaviour,and microwave dielectric properties of the MgO-2B_(2)O_(3) series ceramics synthesised by solid-state *** to the X-ray diffraction and microstructural analyses,the as-prepared MgO-2B_(2)O_(3) ceramics possess a single-phase structure with a rod-like *** effects of different quantities of H_(3)BO_(3) and BaCu(B_(2)O5)(BCB)on the bulk density,sintering behaviour,and microwave dielectric properties of the MgO-2B_(2)O_(3) ceramics were ***,the optimal sintering temperature was obtained by adding 30 wt%H_(3)BO_(3) and 8 wt%*** also reduced the sintering temperature to 825°***,the addition of 40 wt%H_(3)BO_(3) and 4 wt%BCB increased the quality factor,permittivity,and temperature coefficient of resonance frequency of MgO-2B_(2)O_(3) to 44,306 GHz(at 15 GHz),5.1,and-32 ppm/℃,*** properties make MgO-2B_(2)O_(3) a viable low-temperature co-fired ceramic with broad applications in microwave dielectrics.

关键词： low-temperature co-fired ceramics(LTCC) sintering temperature MgO-2B_(2)O_(3) H_(3)BO_(3) microwave dielectrics temperature coefficient of resonance frequency

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Mass Production of Bi3NbO7/Bi2Zn(2/3)Nb(4/3)O7 Composites and Their Visible-light Photocatalytic Activity

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Journal of Wuhan University of Technology(Materials Science) 2017年第2期32卷 403-407页

作者：彭代江 ZOU Zhengguang HE Jinyun 龙飞 MO Shuyi zhou huanfu School of Chemistry and Chemical Engineering Guangxi University Nanning 530004 China Key Laboratory of Nonferrous Materials and New Processing Technology Ministry of Education Guilin University of Technology Guilin 541004 China Guangxi Key Laboratory of New Energy and Building Energy Saving Guilin University of Technology Guilin 541004 China

Series Bi3NbO7/Bi2Zn（2/3）Nb（4/3）O7 （BN/BZN） composites were synthesized through a facile solid state reaction method. The products were characterized by X-ray diffraction（XRD）, field emission scanning electron microscopy（FE-SEM） and UV-vis diffuse reflectance spectroscopy（DRS）. When BN： BZN=0.1 mole ratio, the BN/BZN composite showed the best visible-light-driven photocatalytic performance, which decomposed nearly 100% of Rh B（10 ppm, p H=3-4） within 40 min. The results demonstrated that in-situ solid state synthesis of BN/BZN composites could be an efficient strategy to develop new photocatalyst for environmental remediation.

关键词： visible-light-driven photocatalyst Bi3NbO7/Bi2Zn(2/3)Nb(4/3)O7 composites solid state reaction method

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Phase evolution, microstructure, electric properties of (Ba1–xBi0.67xNa0.33x)(Ti1–xBi0.33xSn0.67x)O3 ceramics

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Journal of Advanced Ceramics 2019年第3期8卷 427-437页

作者： Xiuli CHEN Xu LI huanfu zhou Jie SUN Xiaoxia LI Xiao YAN Congcong SUN Junpeng SHI Collaborative Innovation Center for Exploration of Hidden Nonferrous Metal Deposits and Development of New Materials in Guangxi Key Laboratory of Nonferrous Materials and New Processing Technology Ministry of Education School of Materials Science and Engineering Guilin University of Technology

(Ba1–xBi0.67xNa0.33x)(Ti1–xBi0.33xSn0.67x)O3(abbreviated as BBNTBS,0.02≤x≤0.12)ceramics were fabricated via a traditional solid state reaction *** phase transition of BBNTBS from tetragonal to pseudo cubic is demonstrated by XRD and Raman *** BBNTBS(x=0.1)ceramics have decent properties with a highεr(~2250),smallΔε/ε25℃ values of±15%over a wide temperature range from–58 to 171℃,and low tanδ≤0.02 from 10 to 200℃.The basic mechanisms of conduction and relaxation processes in the high temperature region were thermal activation,and oxygen vacancies might be the ionic charge transport ***,BBNTBS(x=0.1)exhibited decent energy storage density(Jd=0.58 J/cm3)and excellent thermal stability(the variation of Jd is less than 3% in the temperature range of 25–120℃),which could be a potential candidate for high energy density capacitors.

关键词： structure thermal stability energy storage

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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

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Realizing enhanced energy storage and hardness performances in 0.90NaNbO_(3)-0.10Bi(Zn_(0.5)Sn_(0.5))O_(3)ceramics

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Journal of Advanced Ceramics 2022年第5期11卷 729-741页

作者： Xiaoyan DONG Xu LI Hongyun CHEN Qinpeng DONG Jiaming WANG Xiang WANG Yue PAN Xiuli CHEN huanfu zhou Collaborative Innovation Center for Exploration of Hidden Nonferrous Metal Deposits and Development of New Materials in Guangxi Key Laboratory of Nonferrous Materials and New Processing TechnologyMinistry of EducationSchool of Materials Science and EngineeringGuilin University of TechnologyGuilin 541004China College of Materials Science and Engineering Sichuan UniversityChengdu 610064China

Ceramic dielectric capacitors have a broad scope of application in pulsed power supply *** behavior has manifested decent energy storage capabilities in dielectric materials due to its fast polarization *** addition,an ultrahigh energy storage density can also be achieved in NaNbO_(3)(NN)-based ceramics by combining antiferroelectric and relaxor *** of the existing reports about lead-free dielectric ceramics,nevertheless,still lack the relevant research about domain evolution and relaxor ***,a novel lead-free solid solution,(1-x)NaNbO_(3)-xBi(Zn_(0.5)Sn_(0.5))O_(3)(abbreviated as xBZS,x=0.05,0.10,0.15,and 0.20)was designed to analyze the domain evolution and relaxor *** evolutions in xBZS ceramics confirmed the contribution of the relaxor behavior to their decent energy storage characteristics caused by the fast polarization rotation according to the low energy barrier of polar nanoregions(PNRs).Consequently,a high energy storage density of 3.14 J/cm^(3)and energy efficiency of 83.30%are simultaneously available with 0.10 BZS ceramics,together with stable energy storage properties over a large temperature range(20-100℃)and a wide frequency range(1-200 Hz).Additionally,for practical applications,the 0.10 BZS ceramics display a high discharge energy storage density(W_(dis)≈1.05 J/cm^(3)),fast discharge rate(t_(0.9)≈60.60 ns),and high hardness(H≈5.49 GPa).This study offers significant insights on the mechanisms of high performance lead-free ceramic energy storage materials.

关键词： energy storage NaNbO3(NN)-based domain evolutions hardness

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Enhanced thermal and frequency stability and decent fatigue endurance in lead-free NaNbO_(3) -based ceramics with high energy storage density and efficiency

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Journal of Materiomics 2022年第2期8卷 489-497页

作者： Hongyun Chen Junpeng Shi Xiaoyan Dong Feihong Pang Hailin Zhang Xiuli Chen huanfu zhou School of Materials Science and Engineering Guilin University of TechnologyGuilin 541004China

Lead-free ceramic capacitors have the application prospect in the dielectric pulse power system due to the advantages of large dielectric constant,lower dielectric loss and good temperature ***-theless,most reported dielectric ceramics have limitation of realizing large energy storage density(W_(rec))and high energy storage efficiency(h)simultaneously due to the low breakdown electric field(E_(b)),low maximum polarization and large remanent polarization(P_(r)).These issues above can be settled by raising the bulk resistivity of dielectric ceramics and optimizing domain ***,we designed a new system by doping(Bi_(0.5)Na_(0.5))_(0.7)Sr_(0.3)TiO_(3) into 0.9NaNbO_(3)-0.1Bi(Ni_(0.5)Zr_(0.5))O_(3) ceramics,which simulta-neously obtained a higher bulk resistivity by decreasing the grain size and achieved a smaller P_(r) by optimizing domain structure,thus the better E_(b) of 530 kV/cm and W_(rec) of 6.43 J/cm^(3) were achieved,h was improved from 34%to 82%.Besides,the 0.4BNST ceramics show excellent temperature,frequency and fatigue stability under the conditions of 20-180℃,1-100 Hz and 104 cycles,***-while,superior power density(P_(D)=107 MW/cm^(3)),large current density(C_(D)=1070 A/cm^(2))and discharge speed(1.025 m s)were achieved in 0.4BNST ***,the charge-discharge performance displayed good temperature stability in the temperature range of 30℃-180℃.The above results indicated that the ceramics have potential practical value in the field of energy storage capacitor.

关键词： Breakdown electric field Excellent dielectric stability Charge-discharge performance Potential value

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