电子元器件向集成化、微型化的方向发展，开发具有宽工作范围的高性能介电电 容器具有良好的应用前景。钙钛矿功能陶瓷具有的众多物理性能满足上述需求但其较 低的储能密度及温度稳定性限制其发展。本研究以改善钙钛矿无铅陶瓷的介电及铁电 性能为目的，优选钛酸铋钠、钛酸钡及铌酸钠体系作为研究对象，通过引入阳离子空 位来改性陶瓷并对其结构、微观形貌等进行表征，具体内容如下： 采用固相法制备了钛酸铋钠基陶瓷 0.54Bi0.5Na0.5TiO3-0.06BaTiO3-0.4Bi0.2Sr0.7Ti1- 1.25xNbxO3 和 Nb 过量的 0.54Bi0.5Na0.5TiO3-0.06BaTiO3-0.4Bi0.2Sr0.7Ti1-1.25yNb5yO3，通过 B 位调控研究了具有细长极化电滞回线的 BNT-BT-BSTN 无铅弛豫铁电体的介电和极化机 理。采用化学计量和过量的 Nb 含量取代，以阻碍氧空位的生成并增强绝缘性。复阻抗 谱表明，所有成分都具有 n 型主导导电机制。由于 Nb 含量过高，导致介电电阻率增加， 可进一步限制氧空位的产生和 Ti 4+的还原。有趣的是，由于极化的极大增强，在相对低 的电场和高掺杂剂浓度下同时提高能量存储密度（2.07 J/cm3）和效率（94.5 %），这可 能归因于 Nb 过量导致的杂质或畸变相。此外，介电和储能均具有增强的稳定性。所有 这些特性证实了 BNT 基电介质陶瓷的应用前景。 采用传统固相法制备 0.9Na1-3xBixNbO3-0.1SrTiO3 陶瓷，通过 Bi 取代对非化学计量 铌酸钠基反铁电（AFE）陶瓷的相变、介电行为和铁电性能进行了系统的研究。结果 表明掺杂Bi3+能够调节相变温度，同时加速极性纳米区的形成，而不是长程有序结构。 随着 Bi3+掺杂剂的增加，通过从正交 P 相到由正交 P 和 R 相组成的赝立方相的结构， 该结果通过 Rietveld 精修证实了相变的发生。组分调节将介电异常峰转移到较低的温度， 并有效地增强了弛豫特性。具体来说，由于与氧空位缺陷引起的介电弥散弛豫有关， 该此外，在中等电场下，有效储能密度和效率同时得到显著提高（Wrec=2.6 J/cm3， η=84.6 %）。这项工作使其成为高温电容器应用的可替代反铁电陶瓷策略之一。 采用钛酸锶铋固溶到钛酸钡及铌酸钠二元体系中，使用传统固相法及二步烧结法 制备（1-x）（0.55BaTiO3-0.45NaNbO3）-xSr0.85Bi0.1TiO3 陶瓷。结果表明，随着钛酸锶铋 的含量增多，陶瓷发生了由四方相至赝立方相的转变。随掺杂量增加成功破坏了铁电 的长程有序结构，导致弛豫特性增强，剩余极化得到有效降低。且较强的弛豫行为致 使陶瓷在外加电场下快速响应，从而减少损耗进一步优化储能特性。对陶瓷进行了阻 抗测试，当 x=0.04时，实部阻抗值大幅增加，电导率得到抑制，表明 BN-0.04BST可以 有效地提高陶瓷的绝缘性，有利于击穿场强的提高。所有陶瓷在-150-300 °C 的温度范 围介电损耗均低于 0.02。BN-0.04BST 在 275 kV/cm 的陶瓷中实现了 2.41 J/cm3的最优有 效储能密度和 76.1 %的储能效率。通过在 BN-0.06BST 中引入高熵成分，击穿场强提升 到 305 kV/cm，并且此时的储能密度为 2.56 J/cm3。该方法为钙钛矿陶瓷的发展提供了 一种新的思路。

Electronic components develop towards integration and miniaturization, and the investigation of high-performance dielectric capacitors with a wide operating range perform good application prospects. Perovskite functional ceramics possess many physical properties to meet the above requirements, but their low energy storage density and temperature stability further limit their development. The purpose of this study aims at improving the dielectric and ferroelectric properties of perovskite lead-free ceramics. Sodium bismuth titanate, barium titanate and sodium niobate systems were selected as the research objects. The ceramics were modified by introducing cationic vacancies and the structure and microstructure were characterized, specific contents are as follows: Sodium bismuth titanate-based ceramics 0.54Bi0.5Na0.5TiO3-0.06BaTiO3-0.4Bi0.2Sr0.7Ti1- 1.25xNbxO3 and Nb excess 0.54Bi0.5Na0.5TiO3-0.06BaTiO3-0.4Bi0.2Sr0.7Ti1-1.25yNb5yO3 are prepared by solid state reaction, the dielectric and polarization mechanism of BNT-BT-BSTN lead-free relaxor ferroelectrics with slim polarization hysteresis loops are investigated through B-site modulation. Substitution by stoichiometric and excessive Nb content is proposed to hinder the oxygen vacancies and reinforce the insulation. Complex impedance spectroscopy shows that all compositions possess n-type dominant conduction behavior. The generation of oxygen vacancies and Ti reduction can be further restricted caused by the excessive Nb content, leading to the increased dielectric resistivity. Interestingly, simultaneous improvement of energy storage density (2.07 J/cm3 ) and efficiency (94.5 %) is achieved at a relatively low electric field at the high dopant concentration as a result of the fascinating enhancement in polarization, which may attribute to the impurity or distorted phase caused by Nb excess. The enhanced stability against dielectric and energy storage performance is also obtained. All these features guarantee the promising prospects of application for BNT-based dielectrics. 0.9Na1-3xBixNbO3-0.1SrTiO3 ceramics are prepared by conventional solid-state method, systematic investigation on the phase transition, dielectric behavior, and ferroelectric property of non-stoichiometric sodium niobate-based antiferroelectric (AFE) ceramics is carried out via Bi-substitution. The results indicates that doping Bi3+ is capable of adjusting phase transition temperature meanwhile accelerating the formation of polar nanoregions instead of the long-range order structure. The phase transition is identified by the structural Rietveld refinement from the orthorhombic P phase to the pseudo-cubic phase consisting of the P and orthorhombic R phase as Bi3+ dopant increases. The composition regulation shifts the dielectric anomaly to a lower temperature and effectively enhances the relaxor nature. Specifically, associated with the diffuse dielectric relaxation aroused by oxygen vacancy defect, excellent thermal stability is achieved in a wide temperature range from -82 °C to 408 °C. Additionally, the simultaneously significant improvement of the recoverable energy density and efficiency is gained at moderate electric fields (Wrec=2.6 J/cm3，η=84.6 %). This work makes it an alternative AFE strategy for the application of high-temperature capacitor. (1-x)(0.55BaTiO3-0.45NaNbO3)-xSr0.85Bi0.1TiO3 ceramics are prepared by traditional solid phase method and two-step sintering method. The results show that with the increase of the content of strontium bismuth titanate, the ceramics change from tetragonal phase to pseudocubic phase. With the increment of doping amount, the long-range ordered structure of ferroelectric was successfully destroyed, resulting in the enhancement of relaxation characteristics and the effective reduction of residual polarization. The strong relaxation behavior causes the ceramic to respond quickly under the applied electric field, thereby reducing the dielectric loss and further optimizing the energy storage characteristics. The impedance analysis of the ceramics was carried out. When x =0.04, the impedance value increased significantly and the conductivity was suppressed, indicating that BN-0.04BST ceramic can effectively improve the resistivity, which is beneficial to the improvement of breakdown field strength. All ceramics exhibit a dielectric loss of less than 0.02 within the temperature range of -150-300 °C. BN-0.04BST ceramic achieves an optimal energy storage density of 2.41 J/cm3 and η of 76.1 % in the 275 kV/cm. By introducing a high entropy component into BN-0.06BST, the breakdown field strength is increased to 305 kV/cm, and the energy storage density is 2.56 J/cm3 . This method provides a new idea for the development of perovskite ceramics.