伴随着6G 通信的发展，雷达遥感、检测成像等多个领域向太赫兹频段拓展，获取材料在该频段的介电常数显得愈发重要。本文基于NR 迭代法提取了太赫兹频率下样品的复介电常数，分析了迭代法的初值选取对提取结果的影响。在325~500 GHz 频段(Y 频段)搭建了一套由矢量网络分析仪(VNA)、扩频模块和四抛物面镜组成的8f 准光系统，实现散射参数S 2 1 的自由空间测量。由电磁波传输模型推导出复介电常数与S 2 1 之间的关系式， 利用迭代法提取出了特氟龙(Teflon)、丙烯腈-丁二烯-苯乙烯共聚物(ABS)和聚甲基丙烯酸甲酯(PMMA)样品的复介电常数谱，与其他文献报道的结果一致，验证了系统和方法的有效性。

介电性能描述了水泥基材料中的极化现象，即正负电荷中心发生分离的现象。目前，国内外学者针对通用硅酸盐水泥基材料的低频介电性能开展了大量研究，涉及水泥基材料的微结构、水泥水化过程、受力状态等，但缺少对最新成果的归纳整理和综合评述。本文通过综述近20年来国内外学者对通用硅酸盐水泥基材料低频介电性能的最新研究成果，对介电常数的测量方法进行介绍，分析了通用硅酸盐水泥基材料中的极化机理，讨论了骨料、水灰比、应力/应变和温度等因素对通用硅酸盐水泥基材料介电性能的影响规律。结果表明：孔隙溶液中的离子是影响通用硅酸盐水泥基材料介电性能的主要原因，通过离子的移动形成的电偶极子以串联的方式连接。骨料和外掺物通过影响微结构影响介电性能。温度升高和压应力会增强介电性能，温度降低和拉应力会减弱介电性能。最后针对今后需要深入开展的相关研究提出建议。

In this report, the processes of texture formation in grain-oriented ferroelectric ceramics based on layer-structured ferroelectric Bi₄Ti₃O₂ (LSBT) prepared by hot forging method are considered. The microstructural and X-ray methods revealed the axial textured formation in ferroelectric ceramic that are used to estimate the orientation factor of ceramics. For the first time, the domain structure changes when poling the anisotropic ferroelectric ceramics are investigated. The anisotropy of electromechanical, piezoelectric and ferroelectric properties of ferroelectric ceramics due to the crystal texture existence in it is studied. The aim of this study is to study the processes of crystalline texture formation in polycrystalline BLSF and to establish the dependence of the electrophysical properties of ceramics on the degree of texturing. Ceramics were textured using the hot stamping (HS) method developed at the Research Institute of Physics. The mechanism of the method is that the workpiece is subjected to uniaxial pressure and free radial deformation occurs due to the plastic flow of the material until the workpiece fills the free volume of the mold, which is created by placing the workpiece in the mold with a gap. The study of the microstructure of ceramics showed that an increase in the firing temperature in the range 950–1050∘C causes a sharp decrease in porosity and increases the density to 7.95 g/cm3, which is 98% of theoretical. An X-ray analysis was performed and microstructural studies were carried out, which revealed the formation of an axial texture in ceramics. The features of the switching processes of textured ceramics are revealed. The characteristics of the polarization switching of ceramics in the directions parallel and perpendicular (⊥) of the pressure axis during hot processing were obtained from the dielectric hysteresis P(E) loops, i.e., axis axial texture. The ⊥-cut ceramics are characterized by a more complete polarization switching, which is associated with the additional orientation of the (001) crystallographic planes in the textured material, as well as the presence of a threshold switching field. In the temperature range from -196 to + 600∘C, the anisotropy of the electro physical properties of ceramics due to the presence of a crystalline texture in it was studied. The dielectric constant, electrical conductivity, piezoelectric and elastic coefficients were measured for sections of ceramics of different orientations relative to the axis of the texture. The anisotropy of the dielectric constant and electrical conductivity manifests itself weakly at room temperature and increases sharply when approaching the Curie temperature. In the temperature range +20–400∘C, the high thermal stability of the piezoelectric module d33, measured by the quasistatic method, was established.

在新一代高速无线通信技术推动下, 低温共烧陶瓷技术(LTCC)正处于重大变革时期。采用低介电常数(K)、低损耗、谐振频率温度稳定型LTCC作为高频基板材料, 可以满足无线技术高速率、低延时、高可靠的需求, 是当前热点研究之一。因此商用基板材料的现状和一些候选材料的研究工作被主要评述, 重点对玻璃/陶瓷体系、氧化物助烧体系、氟化物助烧体系、本征低温烧结体系等低K值LTCC材料的组成、结构特征、介电性能、热膨胀系数等具体指标及相应优缺点进行了讨论。同时介绍了一些热门体系的改性工作及其毫米波适用性, 最后对未来低K值LTCC材料的发展进行展望。

以纳米晶掺杂复合体系为例，研究该类多组分光学材料的有效介电系数随复合体系结构和组分介电系数的变化，进而分析有效介质理论的适用条件。假定纳米晶被周期性掺杂到背景晶体中，且均为各向同性材料。借助转移矩阵理论研究发现，当纳米晶和背景晶体的介电系数相差较大时，有效介电系数会表现出波长依赖性。此外，发现复合体系在其光学能隙处没有有效介电系数，说明此时基于等效介质思想的有效介质理论均不适合描述复合体系的光学性质，这是因为在物理上均一的光学材料无法形成光学能隙。

为替代矢量网络分析仪，形成一套专用于闭式谐振腔的测量系统，本文采用频谱分析仪模块和跟踪发生器模块，基于C++和VISA 库函数进行系统控制，使两模块可以同步收发射频信号，实现闭式谐振腔谐振频率和Q 值的测量功能，最终实现微波介质材料的介电常数的测量，形成一套一体化闭式谐振腔介电常数测量系统。该系统与矢量网络分析仪对比测量微波介质陶瓷材料K65， 介电常数的相对误差为5.5×10- 3， tanδ 的相对误差为-3.74×10- 2； 对比测量材料K35，介电常数的相对误差为-1.69×10- 3，tanδ 的相对误差为1.08×10- 1。测量结果相对误差较小，介电常数的相对误差小于0.01，tanδ 的相对误差小于0.5，说明一体化介电常数测量系统的测量结果准确，可用于闭式谐振腔方法下的介电常数测量，也可推广用于其他介电常数测量系统。

The comparative analysis of the dielectric properties of bismuth-containing pyrochlores with different manifestation of atomic order/disorder was carried out. We examined the dielectric properties (including behavior in electric fields) of two pyrochlore compounds: BZN (presumably a composition close to Bi1.5Zn0.5Nb1.5O6.5) ceramics with chemical disorder in both A and B cation sublattices and Bi₂Ti₂O₇ single crystal with fully chemical ordered structure. The fundamental differences between the dielectric properties of the BZN ceramics and Bi₂Ti₂O₇ single crystal were shown. In particular, in the dielectric relaxation behavior (which cannot be described via Arrhenius law in the Bi₂Ti₂O7) or in the influence of the electric fields on the dielectric permittivity (splitting of the field-cooled and zero-field-cooled behaviors was observed for Bi₂Ti₂O₇ below estimated freezing temperature). The results of this study highlights the special role of Bi₂Ti₂O₇ as a candidate material for studying aspects of geometric frustration related with pyrochlore structure in non-magnetic medium and specifies the future directions of research.The comparative analysis of the dielectric properties of bismuth-containing pyrochlores with different manifestation of atomic order/disorder was carried out. We examined the dielectric properties (including behavior in electric fields) of two pyrochlore compounds: BZN (presumably a composition close to Bi1.5Zn0.5Nb1.5O6.5) ceramics with chemical disorder in both A and B cation sublattices and Bi₂Ti₂O₇ single crystal with fully chemical ordered structure. The fundamental differences between the dielectric properties of the BZN ceramics and Bi₂Ti₂O₇ single crystal were shown. In particular, in the dielectric relaxation behavior (which cannot be described via Arrhenius law in the Bi₂Ti₂O7) or in the influence of the electric fields on the dielectric permittivity (splitting of the field-cooled and zero-field-cooled behaviors was observed for Bi₂Ti₂O₇ below estimated freezing temperature). The results of this study highlights the special role of Bi₂Ti₂O₇ as a candidate material for studying aspects of geometric frustration related with pyrochlore structure in non-magnetic medium and specifies the future directions of research.

基于相干探测的太赫兹频域光谱仪(THz-FDS)是国际上正在发展的一种高分辨率太赫兹光谱测量与分析系统。本团队搭建了连续波透射式THz-FDS和反射式THz-FDS系统，并利用两种系统对固体、液体和气体样品进行测量，介绍了测量数据的分析处理方法。采用透射式THz-FDS系统对比研究了极值法和希尔伯特变换法提取样品折射率的特性，同时将希尔伯特变换法用于处理系统信号，准确获取了乳糖一水合物的折射率，并获得了极高的频率分辨率；采用透射式THz-FDS系统结合传输矩阵法，消除了测量液体样品过程中的Fabry-Pérot谐振，成功获得了非极性有机液体样品正己烷和环己烷的折射率。在反射式THz-FDS系统的研究方面，通过自参考方法准确获得了甲醇和乙醇在太赫兹频段的介电常数；研究了单减Kramers-Kronig (SSKK)估计相位误差的方法，成功提取了固体掺杂硅样品在太赫兹频段的折射率和吸收系数，测量和计算数据与前人研究结果基本吻合。本研究为频域太赫兹光谱技术的发展与应用奠定了基础。