随着5G时代的到来，新一代微波通信技术对射频电路功耗提出更高要求。射频前端中无源器件功耗是微波通信系统能耗的关键，以通信基站为例，无源器件的功耗占系统总能耗40％以上，如何降低射频前端中微波无源器件的功耗已成为高性能通信系统的关键问题。低损耗介质陶瓷是构成低功耗微波无源器件的基础，借助现代化微观测试手段与计算仿真工具，探究晶体结构调控介电损耗的物理机制，揭示不同因素对介电损耗影响的一般规律，可以为发展新型超低损耗介质材料与器件提供理论指导。 目前，介质陶瓷的研究大多局限于报道材料性能，对微波介电响应机制的探索有待进一步完善。本文选取中介热点的复合钙钛矿结构Ba₃ZnNb₂O₉体系、尖晶石结构LiZnNbO₄与Li₂ZnTi₃O₈体系以及类铌酸盐结构Zn₃Nb₂O₈体系为研究对象，借助拉曼散射光谱、电子顺磁共振谱、太赫兹时域谱、交流阻抗谱等测试表征手段，结合Materials Studio、HFSS软件等计算仿真工具，对本征与非本征因素(有序度、晶格振动、氧空位以及相组成与分布形式)对介电损耗的影响规律进行了系统研究与定量分析，进而提出基于晶体结构与物相组成降低介质陶瓷介电损耗的理论方法。主要工作如下： (1)基于单相Ba₃ZnNb₂O₉体系，深入探究B位阳离子有序度与微波介电损耗之间的内在关联。本文首先通过Mo⁶⁺离子掺杂结合退火工艺显著改善Ba₃ZnNb₂O₉体系的B位阳离子1:2有序度，使该体系的品质因数提升70％。在此基础上进行如下分析：(a)基于复杂晶体P-V理论，对该体系1:2有序结构进行全面解析，探明该体系中有序度引起的键能变化及其与介电损耗之间的内在关联；(b)综合考虑配位环境对离子极化率的影响，针对Shannon离子极化率法则的局限性，引入化学键离子性计算方法，使介电常数理论值的计算精度大幅提升。最终，制备出Ba₃Zn(Nb₁.₉₉₂Mo₀.₀₀₈)O₉.₀₀₄样品具有ε〓=38.9，Qf=102,931 GHz， τ〓=-19.1 ppm／℃，有望满足下一代超低损耗微波通讯的应用需求。 (2)基于单相LiZnNbO₄体系，全面分析单一掺杂离子对晶格振动与氧空位影响及其与微波介电损耗之间的内在关联。本文首先通过适当含量的CO²⁺／Ni²⁺离子掺杂，提升LiZnNbO₄体系的原子堆积密度，显著改善该体系的品质因数。在此基础上进行如下分析：(a)结合群论与第一性原理计算，完成LiZnNbO₄体系拉曼模式的标定，并依据拉曼模式的变化探究掺杂离子在晶格中的占位方式；(b)基于介电损耗频率特性的测试与拟合结果，系统探究掺杂离子占位方式变化对LiZnNbO₄体系晶格振动与氧空位的影响及其对微波介电损耗的贡献。最终，制备出LiZn₀.₉₈M₀.₀₂NbO₄样品具有ε〓=～15，Qf>100,000 GHz，τ〓=-60 ppm／℃和较低的烧结温度Ts=995-1010℃，在高性能微波集成器件中具有潜在的应用价值。 (3)基于单相Li₂ZnTi₃O₈体系，系统研究施受主离子共同掺杂引起的晶格振动与氧空位变化及其与微波介电损耗之间的内在关联。本文首先选取不同的施主、受主离子，优化掺杂离子组合方式，实现对Li₂ZnTi₃O₈体系晶格振动与氧空位的调控，大幅提升该体系的品质因数。在此基础上进行如下分析：(a)综合利用XRD全谱拟合、电子顺磁共振与拉曼光谱等分析方法，深入研究不同掺杂离子组合对Li₂ZnTi〓M〓O₈体系晶体结构与氧空位的影响；(b)引入交流阻抗谱与太赫兹时域谱测试手段，探明该体系中晶格振动与氧空位频率响应特性及其对微波频段内介电损耗的定量贡献，进一步完善复合离子掺杂改性的理论基础。最终，制备出Li₂ZnTi〓M〓O₈样品具有ε〓=25.38，Qf=85,000 GHz，τ〓=-9 ppm／℃，为微波介质陶瓷的复合离子掺杂改性提供理论指导。 (4)在对单相体系介电损耗的影响机制与改性方式取得充分认识的基础上，本文进一步探究复相体系物相组成对微波介电损耗的影响。首先选取(1-x)(3ZnO-Nb₂O₅)-xGeO₂体系，通过改变GeO₂含量调控体系的物相组成，优化体系的微波介电性能。在此基础之上进行如下分析：(a)通过XRD多相精修的方式，探明(1-x)(3ZnO-Nb₂O₅)-xGeO₂体系的物相转变过程；(b)综合利用第一性原理计算与ZnO-Nb₂O₅-GeO₂三元相图，系统研究该体系的相变机制；(c)采用随机分布模型对该体系微波介电性能进行拟合，全面分析物相组成与微波介电性能之间的内在关联。最终，制备出2.73ZnO-0.91Nb₂O₅-0.09GeO₂样品具有ε〓=21.3， Qf=99,140 GHz，τ〓=-54 ppm／℃，为拓展高性能微波介质陶瓷体系提供新的思路。 (5)复相体系的微波介电损耗除受到物相组成的影响之外，还受到物相分布形式的影响。本文制备了一种新型的“三明治”结构Zn₃Nb₂O₈-TiO₂-Zn₃Nb₂O₈陶瓷，相比于传统的随机分布形式，该种结构在实现谐振频率温度系数调零的同时，降低了恶化介电损耗的TiO₂用量，使得该体系品质因数提升8倍。在此基础之上进行如下分析工作：(a)通过HFSS软件系统地分析电磁场在“三明治”结构不同介质层中的分布；(b)基于并联分布模型对该体系介电性能进行拟合，并从电磁场分布的角度全面探究“三明治”结构陶瓷中介电损耗的影响机制。最终，“三明治”结构的研究完善了叠层复合方式调节介电性能的理论基础，为高性能微波器件的设计提供新的方法。 关键词：微波介质陶瓷，离子有序度，晶格振动，氧空位，物相组成与分布

 With the advent of 5G era, the new generation of microwave communication technology puts higher demands on the power consumption of RF circuits. The power consumption of passive components in the RF front-end is an important component of the energy consumption in microwave communication. Taking the communication base station as an example, the energy consumption of the passive components accounts for more than 40% of the system. Dielectric ceramics are the basis of microwave passive components. Therefore, exploring the physical mechanism and revealing the influence of different factors on dielectric loss can provide theoretical guidance for the development of ultra-low loss dielectric materials and devices. At present, researches on dielectric ceramics were limited to the microwave performance, while the internal and external factors affecting the dielectric properties were inadequate. Here, works were carried out on it. At first, Ba₃ZnNb₂O₉,LiZnNbO₄, Li₂ZnTi₃O₈ and Zn₃Nb₂O₈ system were prepared and the dielectric properties were improved by optimizing the preparing process, phase compositions and microstructure. Then, the effects of intrinsic and extrinsic factors on dielectric loss were studied by Raman scattering, SEM, EPR, THz time domain spectroscopy, impedance spectroscopy, Materials Studio and HFSS. Finally, theoretical methods based on crystal structure and phase compositions were proposed to reduce the loss of dielectric ceramics. Firstly, Ba₃ZnNb₂O₉ ceramics were prepared and the intrinsic correlation between 1:2 order and microwave dielectric loss was explored:(a)Appropriate content of Mo⁶⁺ and annealing process were applied to improve the 1:2 order and reduce the intrinsic loss of Ba₃Zn(Nb〓Mo〓)O〓ceramics;(b)The ordered structure of Ba₃Zn(Nb〓Mo〓)O〓 was analyzed, and the intrinsic relationship between order degree and quality factor was elucidated based on the bond energy of Nb-O;(c)Due to the influence of coordination field, the Shannon rules was no longer applicable. And, chemical bond ionic was introduced to predict theoretical dielectric constant, which was highly consistent with the measured value;(d)Ba₃Zn(Nb₁.₉₉₂Mo₀.₀₀₈)O₉.₀₀₄ ceramics with ε〓=38.9, Qf=102,931 GHz, τ〓=-19.1 ppm/℃ were obtained, which was expected to meet the application requirements of ultra-low loss microwave communication. Secondly,LiZnNbO₄ ceramics were prepared, the effects of Co²⁺/Ni²⁺ ions on lattice vibration/oxygen vacancies and microwave dielectric loss were studied: (a)Appropriate content of Co²⁺/Ni²⁺ enteredLiZnNbO₄ system would increase the atomic bulk density and improve the quality factor; (b)Based on the group theory and first-principles calculation, Raman modes ofLiZnNbO₄ system were confirmed. And, Co²⁺/Ni²⁺ occupations inLiZnNbO₄ were explored according to the change of Raman modes; (c)The dielectric loss frequency characteristics of LiZn〓M〓NbO₄ were measured and fitted with the modified Q v.s. f relation. By this way, the effect of Co²⁺/Ni²⁺ on the lattice vibration and oxygen vacancy and its contribution to the microwave dielectric loss were systematically investigated; (d)LiZn₀.₉₈M₀.₀₂NbO₄ ceramics with ε〓=～15, Qf> 100,000 GHz, τ〓=-60 ppm/℃, T〓=995-1010℃ was prepared and expected to used in the LTCC devices. Thirdly, Li₂ZnTi₃O₈ ceramics were prepared, the effects of acceptor/donor ions on lattice vibration/oxygen vacancies and microwave dielectric loss were investigated: (a)Different donor and acceptor ions were selected, and the doping method was optimized to regulate the lattice vibration and oxygen vacancies in Li₂ZnTi₃O₈ ceramics. As a result, the quality factor of the system was greatly improved; (b)The influency of different doping ions on crystal structure of Li₂〓ZnTi〓M〓O₈ system was analysized according to XRD refinement, Electron paramagnetic resonance and Raman spectroscopy; (c)AC impedance spectrum and THz time-domain spectrum were collected and fitted, then the frequency response curves of lattice vibration and oxygen vacancy were calculated. Then, it can be concluded that lattice vibration contributed 80% of the dielectric loss, and the conduction loss contributed the remaining parts (20%). Moreover, (l-x)(3Zn0-Nb₂O₅)-xGeO₂ ceramics were investigated with regard to the preparation, phase composition and microwave dielectric properties: (a)Appropriate content of GeO₂ could modify the phase composition and improve the microwave dielectric properties of the systems; (b)The phase transition mechanism of (l-x)(3Zn0-Nb₂O₅)-xGeO₂ ceramics were systematically studied based on the coordination environment and ternary phase diagram; (c)The factors affecting microwave dielectric properties of (l-x)(3Zn0-Nb₂O₅)-xGeO₂ ceramics were analyzed by random distribution model and the intrinsic correlation between phase composition and microwave dielectric properties was clarified. At last, a novel sandwich Zn₃Nb₂O₈-TiO₂-Zn₃Nb₂O₈ ceramics was prepared and the effects of phase distribution on microwave dielectric loss were studied: (a)Compared with samples with random phase distribution, the TiO₂ content required to achieve the near-zero temperature coefficient of the resonant frequency in sandwich Zn₃Nb₂O₈-TiO₂-Zn₃Nb₂O₈ ceramics was greatly reduced. As a result, the quality factor was improved by 8 times; (b)The electromagnetic fields in sandwich Zn₃Nb₂O₈-TiO₂-Zn₃Nb₂O₈ ceramics were simulated by HFSS; (c)The microwave dielectric properties were theoretically simulated and the anomalous phenomena in dielectric constant and loss were investigated from the perspective of electromagnetic field distribution. KEY WORDS: Microwave dielectric ceramics, Lattice vibration, Oxygen vacancy, Ordering degree, Phase composition and distribution