随着电子领域的发展，市场对集成化、小型化和高可靠性的电子器件提出更高要求。高端多层陶瓷电容器(MLCC)因其更高的电容量、更小的尺寸和更低的损耗而备受青睐，但目前我国仍主要依赖进口，发展受限于内部介电材料。为解决这一问题，本论文综合大量介电材料的研究，选取巨介电材料Bi_2/3Cu₃Ti₄O₁₂ (BCTO)陶瓷作为研究对象，采用掺杂改性的方法制备了Bi_2/3Cu₃(InTa)_x/2Ti_4-xO₁₂ (BCT(IT)O)和Bi_2/3Cu₃(InNb)_x/2Ti_4-xO₁₂ (BCT(IN)O)两种体系陶瓷，旨在保留较高介电常数的同时有效降低介电损耗，以期获得兼具高介电性能和非线性特性的介电材料。并通过对两种陶瓷体系的系统分析，揭示了三五价离子及不同掺杂量对BCTO陶瓷介电和非线性性能的影响机理。

首先，通过在BCTO陶瓷的Ti⁴⁺位共掺杂In³⁺和Ta⁵⁺，不仅显著提高了BCTO陶瓷的介电性能，同时非线性性能也有显著升高。其中，组分IT0.04表现出最高的介电常数和最低的介电损耗，分别为8×10⁴和0.095 (在1 kHz下)，同时具有较高的非线性系数(5.824)。在基于BCT(IT)O陶瓷的研究基础上，通过引入In³⁺和Nb⁵⁺对BCTO陶瓷进行改性。所有In³⁺、Nb⁵⁺共掺组分的介电常数在整个测试频率范围内较纯BCTO均明显提升，其中最高可达1.7×10⁵ (IN0.005)。同时，共掺In³⁺、Nb⁵⁺还有效降低了BCTO陶瓷的介电损耗，并显著提高了其非线性系数。其中，组分IN0.04和IN0.08介电损耗在中低频范围内较纯BCTO均明显降低。

随后，对造成BCT(IT)O和BCT(IN)O陶瓷均表现出优异介电性能的原因进行了探究。结果显示，BCT(IT)O和BCT(IN)O陶瓷在低频下的巨介电性能来源于内部阻挡层电容(IBLC)和表面阻挡层电容(SBLC)机制共同作用，而在中高频下的巨介电性能来源于IBLC机制作用。其中，IBLC机制产生的原因来源于BCTO陶瓷晶粒与晶界响应共同作用。BCT(IN)O陶瓷相较于BCT(IT)O陶瓷表现出更好的介电性能，这可以归因于BCT(IN)O陶瓷的IBLC效应贡献高于BCT(IT)O陶瓷。另外，BCTO陶瓷的电极接触电阻与晶体内部电阻之间存在显著差异，这种差异是导致SBLC机制产生的原因。而BCTO陶瓷与电极之间功函数的差异是造成其巨大的电极接触电阻的主要原因。

此外，在BCT(IN)O陶瓷的研究中发现，陶瓷表层与陶瓷内部元素价态信息存在巨大差异。而这种差异是造成IBLC机制中晶粒半导化的主要原因，并建立核壳模型对这一现象进行解释。同时，造成BCT(IN)O陶瓷同时兼具高介电常数和低介电损耗这一现象，除IBLC和SBLC机制作用外，还与电子钉扎偶极子缺陷存在关联。

With the development of the electronic field, the market puts forward higher requirements for integrated, miniaturized and high-reliability electronic devices. High-end multilayer ceramic capacitor (MLCC) is favored for its higher capacitance, smaller size and lower loss, but China is still mainly dependent on imports, and development is limited by internal dielectric materials. In order to solve this problem, a large number of dielectric materials are studied in this paper, and Bi_2/3Cu₃Ti₄O₁₂ (BCTO) ceramic is selected as the research object. Bi_2/3Cu₃(InTa)_x/2Ti_4-xO₁₂ (BCT(IT)O) and Bi_2/3Cu₃(InNb)_x/2Ti_4-xO₁₂ (BCT(IN)O) were prepared by doping modification to effectively reduce dielectric loss while retaining high dielectric constant. In order to obtain dielectric materials with high dielectric properties and nonlinear characteristics. Through the systematic analysis of the two ceramic systems, the influence mechanism of tripentavalent ions and different doping amounts on the dielectric and nonlinear properties of BCTO ceramics was revealed.

Firstly, by co-doping In³⁺ and Ta⁵⁺ in Ti⁴⁺ position of BCTO ceramics, not only the dielectric properties of BCTO ceramics are significantly improved, but also the nonlinear properties are significantly increased. Among them, the component IT0.04 exhibits the highest dielectric constant and the lowest dielectric loss (8×10⁴ and 0.095 (at 1 kHz), respectively), and has a high nonlinear coefficient (5.824). Based on the research of BCT(IT)O ceramics, BCTO ceramics were modified by introducing In³⁺ and Nb⁵⁺. The permittivity of all In³⁺ and Nb⁵⁺ co-doped components is significantly higher than that of pure BCTO in the whole test frequency range, and the highest permittivity is 1.7×10⁵ (IN0.005). At the same time, the In³⁺ and Nb⁵⁺ co-doped BCTO ceramics can effectively reduce the dielectric loss and significantly improve the nonlinear coefficient. The dielectric losses of IN0.04 and IN0.08 are significantly lower than those of pure BCTO in the low if range.

Subsequently, the reasons for the excellent dielectric properties of both BCT(IT)O and BCT(IN)O ceramics were investigated. The results show that the great dielectric properties of BCT(IT)O and BCT(IN)O ceramics at low frequencies are due to the interaction of internal barrier layer capacitance (IBLC) and surface barrier layer capacitance (SBLC), while the great dielectric properties at middle and high frequencies are due to the IBLC mechanism. The IBLC mechanism is caused by the interaction between grain and grain boundary response of BCTO ceramics. BCT(IN)O ceramics exhibit better dielectric properties than BCT(IT)O ceramics, which can be attributed to the higher IBLC effect contribution of BCT(IN)O ceramics than BCT(IT)O ceramics. In addition, there is a significant difference between the electrode contact resistance of BCTO ceramics and the internal resistance of the crystal, and this difference is the cause of the SBLC mechanism. The difference of work function between BCTO ceramic and electrode is the main reason for its huge electrode contact resistance.

IN addition, in the study of BCT(IN)O ceramics, it is found that there is a huge difference in the valence information of the elements in the ceramic surface and the ceramic interior. This difference is the main reason of grain semiconducting in IBLC mechanism, and the core-shell model is established to explain this phenomenon. IN addition to the IBLC and SBLC mechanisms, the phenomenon of high dielectric constant and low dielectric loss of BCT(IN)O ceramics is also related to the defects of electronic pinning dipoles.