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Microwave dielectric high-entropy ceramic Li(Gd_(0.2)Ho_(0.2)Er_(0.2)Yb_(0.2)Lu_(0.2))GeO_(4) with stable temperature coefficient for low-temperature cofired ceramic technologies

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Journal of Materials Science & Technology 2021年第34期93卷 28-32页

作者： huaicheng xiang Lei Yao Junqi Chen Aihong Yang Haitao Yang Liang Fang Shenzhen Key Laboratory of Special Functional Materials Shenzhen Engineering Laboratory for Advanced Technology of CeramicsGuangdong Research Center for Interfacial Engineering of Functional MaterialsCollege of Materials Science and EngineeringShenzhen UniversityShenzhen 518060China Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province.College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China Guangxi Key Laboratory of Optical and Electronic Materials and Devices College of Materials Science and EngineeringGuilin University of TechnologyCuilin 541004China

High-entropy ceramics are new single-phase materials with at least four cation or anion *** large configurational entropy is believed to enhance the simultaneous solubility of many components,which can be used to optimize certain *** this work,a high-entropy oxide,Li(Gd_(0.2)Ho_(0.2)Er_(0.2)Yb_(0.2)Lu_(0.2))GeO_(4)(LRG)was explored as a microwave dielectric ceramic for lowtemperature cofired ceramic *** LRG high-entropy ceramic with an olivine structure formed in the sintering temperature range of 1020-1100℃.The minimal distortion(5×10^(-4))of the[RO_(6)]octahedron led to a stable temperature coefficient of resonant frequency(τf)of-5.3 to-2.9 ppm/℃.Optimal microwave dielectric properties were achieved in the high-entropy ceramics at 1080℃ for 4 h with a relative density of 94.9%,a relative permittivity(ε_(r))of 7.2,and a quality factor(Q×f)of 29000 GHz(at15.3 GHz).For low-temperature cofired ceramic technology applications,the sintering temperature of the LRG high-entropy ceramic was reduced to 900℃ by the addition of 3 wt%H_(3)BO_(3),which exhibited outstanding microwave dielectric properties(ε_(r)=7.6,Q×f=11700 GHz,and τ_(f)=-7.4 ppm/℃)and a good chemical compatibility with silver.

关键词： High-entropy ceramic Octahedral distortion Microwave dielectric properties Stableτ_(f)

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SrGa_(12)O_(19):The first low-ε_(r) Ga-based microwave dielectric ceramic with anomalous positiveτ_(f)

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Journal of Advanced Ceramics 2024年第9期13卷 1432-1441页

作者： Yang Yang Weishuang Fang Huixing Lin Jie Li huaicheng xiang Ying Tang Lei Li Liang Fang Guangxi Universities Key Laboratory of Non-ferrous Metal Oxide Electronic Functional Materials and Devices and Guangxi Key Laboratory of Optical and Electronic Materials and DevicesCollege of Materials Science and EngineeringGuilin University of TechnologyGuilin 541004China Key Laboratory of Inorganic Functional Material and Devices Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Laboratory of Dielectric Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310058China

Dielectric ceramics with low permittivity(ε_(r)),high quality factor(Q×f),and near-zero resonant frequency(τ_(f))in the microwave bands are key materials used in fifth/sixth-generation(5G/6G)telecommunication,whileτ_(f) of most low-εr microwave dielectric ceramics is relatively *** this work,the first low-εr Ga-based ceramic SrGa_(12_O_(19) with an anomalous positiveτ_(f) was reported,and the causes of the positiveτ_(f),intrinsic polarization,and loss mechanism were systematically studied.X-ray diffraction(XRD)and transmission electron microscopy(TEM)revealed that the SrGa_(12_O_(19) ceramic formed a pure hexagonal magnetoplumbite structure with spinel blocks and rock-salt blocks stacked along the crystallographic *** sintered at 1430℃,it possessed the optimal microwave dielectric properties of a lowεr of 14.46,high Q×f of 64,705 GHz,and exceptional positiveτ_(f) of+55.7 ppm/℃,along with a low linear thermal expansion coefficient(αL)of 11.617 ppm/℃.The large positive deviation betweenεr andεr(C–M)of 45.31%resulted from the rattling effect of atoms in the rock-salt *** unique positiveτ_(f)(+55.7 ppm/℃)was governed by the rattling effect,resulting in a positiveταm(the temperature coefficient of ion polarizability)of 8.489 ppm/℃ and a large negative temperature coefficient of permittivity(τε)of−132.864 ppm/℃.Phillips–Vechten–Levine(P–V–L)chemical bond theory revealed greater contributions of the spinel block to bond ionicity(fi,52.95%),permittivity(ε,55.15%),bond energy(E,56.87%),and lattice energy(U,74.88%)than those of the rock-salt *** intrinsic dielectric properties were analyzed using infrared(IR)reflectivity *** favorable performance of the SrGa_(12_O_(19) ceramic indicated that it is a novelτ_(f) *** selection of compounds with different structural layer combinations provides a new idea for exploring excellent microwave dielectric ceramics.

关键词： magnetoplumbite microwave dielectric properties rattling effect chemical bond theory

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Effects of barium substitution on the sintering behavior,dielectric properties of Ca_(2)Nb_(2)O_(7) ferroelectric ceramics

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Journal of Advanced Dielectrics 2017年第2期7卷 36-40页

作者： Chunchun Li huaicheng xiang Yuandong Qin Liang Fang College of Information Science and Engineering Guilin University of Technology Guilin 541004P.R.China Guangxi New Future Information Industry Co.Ltd Beihai 536005 P.R.China State Key Laboratory Breeding Base of Nonferrous Metals and Specific Materials Processing Guangxi Universities Key Laboratory of Nonferrous Metal Oxide Electronic Functional Materials and Devices College of Material Science and Engineering Guilin University of Technology Guilin 541004P.R.China

Barium-doped Ca_(2)Nb_(2)O_(7)ceramics were prepared in the form of Ca_(2-x)Ba_(x)Nb_(2)O_(7)(0≤x≤0.6)by solid-state *** solubility limit of barium in Ca_(2)Nb_(2)O_(7)was found to be x=0.4 based on X-ray diffraction and Raman spectroscopy *** x≤0.4,Ca_(2-x)Ba_(x)Nb_(2)O_(7)solid solutions with a monoclinic perovskites-like layered structure(PLS)were formed,whereas beyond x=0.4,a secondary phase CaNb_(2)O_(6) was *** dielectric properties obviously depended on the barium *** increasing barium amount,the dielectric constant increased from 33.5 for pure Ca_(2)Nb_(2)O_(7)to 38.6 for x=0.4(f=1 MHz).The Curie temperature(T_(c)) of the x=0.1 sample was 1280±5℃.The phase transition was confirmed to be the second order.

关键词： Dielectric properties perovskites-like layered structure barium substitution

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Coupling of piezocatalysis and photocatalysis for efficient degradation of methylene blue by Bi_(0.9)Gd_(0.07)La_(0.03)FeO_(3) nanotubes

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Journal of Advanced Ceramics 2022年第7期11卷 1069-1081页

作者： Angom Devadatta MANI Jie LI Ziquan WANG Jiale ZHOU huaicheng xiang Jinlai ZHAO Libo DENG Haitao YANG Lei YAO Shenzhen Key Laboratory of Special Functional Materials Shenzhen Engineering Laboratory for Advanced Technology of CeramicsGuangdong Research Center for Interfacial Engineering of Functional MaterialsCollege of Materials Science and EngineeringShenzhen UniversityShenzhen 518071China Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China cCollege of Chemistry and Environmental Engineering Shenzhen UniversityShenzhen 518071China

Photocatalytic degradation of organic pollutants is of great significance for wastewater remediation but is still hindered by the poor catalytic efficiency of the ***,we report a strategy to simultaneously introduce piezocatalysis and to enhance the intrinsic photocatalysis in a single catalyst,which improved the performance for catalytic degradation of methylene blue(MB)***,piezoelectric BiFeO_(3)(BFO)nanotube doped with different contents of Gd and La(Bi_(0.9)(GdxLa_(1−x))0.1FeO_(3))were produced by *** doping led to a higher concentration of surface oxygen vacancy(OV)in Bi_(0.9)Gd_(0.07)La_(0.03)FeO_(3),which effectively increased the piezoelectric field due to the deformation of BFO,and suppressed the recombination of photon-generated electron–hole *** Bi_(0.9)Gd_(0.07)La_(0.03)FeO_(3)nanotube showed excellent catalytic performance under simultaneous light irradiation and ultrasonic excitation,giving an extraordinary 95%degradation of MB within 90 *** findings suggest that the piezoelectric effect combined with defect engineering can enhance the catalytic performance of Bi_(0.9)Gd_(0.07)La_(0.03)FeO_(3)*** could potentially be extended to other catalytic systems for high-performance pollutant treatment.

关键词： photocatalysis piezocatalysis sonophotocatalysis oxygen vacancy(OV)

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Preparation, crystal structure, and dielectric characterization of Li_(2)W_(2)O_(7) ceramic at RF and microwave frequency range

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Journal of Advanced Dielectrics 2017年第1期7卷 1-5页

作者： Jinwu Chen Chunchun Li Dan Wang huaicheng xiang Liang Fang State Key Laboratory Breeding Base of Nonferrous metals and specific Materials Processing Guangxi Universities Key Laboratory of Non-Ferrous Metal Oxide Electronic Functional Materials and Devices College of Material Science and Engineering Guilin University of Technology Guilin 541004P.R.China School of Mechanical Engineering Guilin University of Aerospace Technology Guilin 541004P.R.China Guangxi New Future Information Industry Co.Ltd Beihai 536005P.R.China

Single phase Li_(2)W_(2)O_(7) with anorthic structure was prepared by the conventional solid-state reaction method at 550℃ and the anorthic structure was stable up to 660℃.The dielectric properties at radio frequency(RF)and microwave frequency range were *** sample sintered at 640℃ exhibited the optimum microwave dielectric properties with a relative permittivity of 12.2,a quality factor value of 17,700 GHz(at 9.8 GHz),and a temperature coefficient of the resonant frequency of232 ppm/℃ as well as a high relative density~94.1%.Chemical compatibility measurement indicated Li_(2)W_(2)O_(7) did not react with aluminum electrodes when sintered at 640℃ for 4 h.

关键词： Microwave dielectric ceramics LTCC anorthic structure

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加强学习　改进作风与时俱进　深化改革——项怀诚部长在全国财政工作会议闭幕式上的讲话

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中国资产评估 2002年第1期 6-9页

作者：项怀诚财政部

党的十五届六中全会要求，“全党要坚持讲学习、讲政治、讲正气，在推进党的思想建设、组织建设的同时，把加强和改进党的作风建设放在更加突出的位置，切实抓紧抓好。”改进和加强财政部门作风建设，总的要求是深入贯彻十五届六中全会... 详细信息

党的十五届六中全会要求，“全党要坚持讲学习、讲政治、讲正气，在推进党的思想建设、组织建设的同时，把加强和改进党的作风建设放在更加突出的位置，切实抓紧抓好。”改进和加强财政部门作风建设，总的要求是深入贯彻十五届六中全会《决定》精神，按照“八个坚持，八个反对?（共4页)

关键词：中国财政工作党的建设作风建设世界观工作方法群众利益

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Ca_(3–x)Mg_(x)Yb_(2)Ge_(3)O_(12)(0≤x≤3)石榴石的A位Rattling效应与微波介电性能

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硅酸盐学报 2023年第4期51卷 872-881页

作者：唐莹相怀成李洁方亮桂林理工大学材料科学与工程学院有色金属及材料加工新技术教育部重点实验室广西光电材料与器件重点实验室广西桂林541004 桂林理工大学理学院广西桂林541004

微波介质陶瓷是5G/6G通讯技术的关键基础材料,具有高品质因数(Q×f)、低介电常数(εr)以及近零谐振频率温度系数(τf)的材料已逐渐成为研究与开发的重点。通过固相反应法制备了系列Ca_(3-x)Mg_(x)Yb_(2)Ge_(3)O_(12)(0≤x≤3)石榴石陶... 详细信息

微波介质陶瓷是5G/6G通讯技术的关键基础材料,具有高品质因数(Q×f)、低介电常数(εr)以及近零谐振频率温度系数(τf)的材料已逐渐成为研究与开发的重点。通过固相反应法制备了系列Ca_(3-x)Mg_(x)Yb_(2)Ge_(3)O_(12)(0≤x≤3)石榴石陶瓷。当0≤x≤2时,样品为正石榴石结构,相对介电常数εr逐渐从10.3增加至11.8,品质因数Q×f值逐渐从98000 GHz降低到78000 GHz,谐振频率温度系数τf在(-40~-56)×10^(–6)/℃之间波动。当2

关键词：微波介质陶瓷 Rattling效应石榴石介电性能

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财政部部长项怀诚:以优异成绩为新世纪开局

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人民论坛 2001年第1期 6-8页

作者：项怀诚财政部

国家财政部部长项怀诚日前接受中央电视台《经济半小时》栏目记者专访,首次对1998年以来中央决定实施的“积极的财政政策”的内涵、意义及作用进行阐释,其推心置腹,其幽默诙谐,给人留下深刻印象。

关键词：财政部项怀诚财政政策中国财政支出公共财政

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杂谈喝茶

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中国茶叶 2010年第4期32卷 41-42页

作者：项怀诚

老话说：开门七件事，柴米油盐酱醋茶？茶在开门七件事中长期以来不是太受重视的。随着经济的发展，茶在提高人们生活质量方面起着独特的作用.

关键词：喝茶生活质量开门醋茶米油中长酱盐

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Tectonic modes of mantle convection and their implications for Earth's tectonic evolution based on three-dimensional numerical simulations

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Science China Earth Sciences 2025年第1期68卷 270-296页

作者： Song xiang Jinshui HUANG Bingcheng WU School of Earth and Space Sciences University of Science and Technology of China CAS Center of Excellence in Comparative Planetary Studies

Five tectonic modes of mantle convection are obtained and analyzed with three-dimensional numerical models in a spherical shell domain. The five tectonic convective modes are non-plate mobile-lid, plate-like mobile-lid, episodic plate-like mobile-lid, episodic stagnant-lid, and stagnant-lid convective modes, respectively. The typical characteristics of these five tectonic modes and their numerical classification criteria based on plateness, mobility, and their standard deviations are presented and discussed. The results show that the yield stress of the lithosphere has profound effects on the tectonic convective *** the gradual increase of yield stress, the tectonic mode of mantle convection changes from one to another sequentially through the aforementioned five modes. Additionally, as the Rayleigh number increases, the range of yield stress for the platelike mobile-lid convective mode decreases, and the dimensionless transition stress between different tectonic modes ***, the dimensional transition stress between the non-plate mobile-lid convective mode and plate-like mobile-lid convective mode increases with the increase of Rayleigh number, but decreases between other tectonic modes. Furthermore, we find that the transition stress between different tectonic modes is inversely proportional to the internal heating rate, with the transition stress decreasing as the internal heating rate increases. The fitting analysis of the transition stress between tectonic modes shows that Earth's current plate tectonics correspond to a lithospheric yield stress of 150–250 MPa, which aligns with the strength of serpentinized mantle rock determined by experimental petrography. If the Archean mantle was 300°C warmer than it is today, then the Earth was in an episodic stagnant-lid convective mode. The tectonic evolution of the Earth's surface is closely related to the lithospheric strength and the process of thermal evolution. If the lithospheric strength w

关键词： Tectonic mode of mantle convection Plate-like mobile-lid convection Episodic plate-like mobile-lid convection Episodic stagnant-lid convection Plate tectonics and tectonic evolution of the Earth

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