本论文围绕温度稳定型多层陶瓷电容器（MLCC）用介质材料的结构、性能及可靠性机理研究展开，结合模拟与实验，通过材料设计、烧结优化、元素掺杂、晶粒级配等调控手段，开发出具有优异介电性能、储能性能与高可靠性的温度稳定型陶瓷介质材料，为超薄层MLCC的发展奠定介质材料基础，为下一代超宽温MLCC介质材料的设计提供指导。首先，设计并制备出0.8(0.95Bi1/2Na1/2TiO3-0.05SrZrO3)-0.2NaNbO3（BNTSZNN）超宽温度稳定型多相复合陶瓷，在-55~545℃超宽温度范围内满足容温变化率小于±15%，该上限温度远超EIA X9R标准（200℃）。通过提高两段式烧结升温速率调控各相比例并细化晶粒，同步提升极化强度和击穿场强，最终升温速率为60℃/min的陶瓷样品在350kV/cm电场下获得了高达5.5J/cm3的放电储能密度，储能效率超过85%。系统研究了Mg元素掺杂对BNTSZNN陶瓷介电与储能性能的影响。适量Mg元素的引入可以有效抑制空间电荷的迁移，起到优化击穿场强和降低介电损耗的作用。掺杂0.2wt% MgO的BNTSZNN陶瓷可以在超宽温度范围内保持高储能密度、低介电损耗及稳定的介电常数，且兼具优异的频率、循环、偏压稳定性，这对于推动超宽温度稳定型MLCC的实际应用迈出了关键性的一步。采用固相法制备了平均晶粒尺寸约50nm的BaTiO3（BT）基陶瓷介质，是当前报道中晶粒尺寸最小的BT基抗还原陶瓷介质材料，为新型超薄层BME MLCC的研制奠定了基础。研究了纳米晶BT基陶瓷的尺寸效应，结合电滞回线的测试与模拟，揭示了纳米晶BT基陶瓷最佳储能性能的尺寸范围，可以实现储能密度的最大化，为超薄层MLCC在追求小型化的同时优化其储能特性提供了重要的指导。提出晶粒级配策略有效解决了晶粒尺寸与介电常数之间的相互制约的难题，制备出具有优异介电性能（介电常数>2000）的高可靠性抗还原纳米晶（平均粒径＜100nm）BT基陶瓷介质，为高介电、高可靠纳米晶陶瓷的设计提供指导。系统研究了超薄层BME MLCC的劣化机理，结合加速老化测试、高温阻抗谱、漏电流测试，揭示了抑制氧空位的迁移与富集是保证超薄层MLCC可靠性的重中之重。为此，应减小介质层内部的氧空位浓度，增大其迁移所需的激活能，提高界面肖特基势垒，从而提升超薄层MLCC的可靠性。

In this dissertation, we focus on the structure, performance and reliability mechanism study of the dielectric materials for temperature-stable multilayer ceramic capacitors (MLCC). Combing the simulation and experimental methods, temperature-stable cetamic dielectric materials with excellent dielectric properties, energy syorage performance and high reliablility have been developed via optimizing the material compositions, sintering methods and grain size distributions, which lays the foundation for the decelopment of ultra-thin MLCC and provides guidance for the design of the next-generation ultra-wide-temperature MLCC.Firstly, a kind of ultra-wide temperature-stable multiphase ceramics composed of 0.8(0.95Bi1/2Na1/2TiO3-0.05SrZrO3)-0.2NaNbO3 (BNTSZNN) is designed and prepared, which statisfies the variation in the dielectric permittivity less than ±15% over an ultra-wide temperature range from -55℃ to 545℃ and achieves an upper operating temperature much higher than the EIA X9R standard (200℃). Meanwhile, by further increasing the heating rate of the two-step sintering to control the phase compositions and refine the grains, the polarization and breakdown strength are enhanced synchronously. The ceramic sample with the heating rate of 60℃/min obtains an ultra-high discharge energy storage density of 5.5J/cm3 under the applied electric field of 350kV/cm, the corresponding energy efficiency is over 85%.The effects of Mg doping on the dielectric properties and energy syorage performance of BNTSZNN ceramics are systematically investigated. The introduction of an appropriate amount of MgO helps to suppress the space charge migration, strengthen the breakdown strength, and reduce the dielectric loss effectively. The BNTSZNN ceramics doped with 0.2wt%MgO maintain a high energy storage density, a low dielectric loss and a stable dielectric constant over an ultra-wide temperature range, together with excellent stabilities in terms of frequency, cycle number, and bias field, which promotes the practical applications of the ultra-wide temperature-stable MLCC.A mean grain size of 50nm is achieved in the BaTiO3（BT）based ceramics prepared by the solid state method, which is the smallest grain size in the current reports, laying the foundation for the development of the ultra-thin MLCC. Besides, the size effect of nanograined BT-based ceramics is studied. An optimal grain size range of nanograined BT-based ceramics for energy storage performance is revealed based on the measured and simulated hysteresis loops, providing important guidance for ultra-thin MLCC to optimize the energy storage properties when pursuing miniaturization. A grain gading design is proposed to solve the mutual constrain between the grain size and dielectric constant. Based on this, high-reliable anti-reduction nanograined BT-based ceramics (＜100nm) with superior dielectric properties (dielectric constant >2000) are prepared, which provides guidance for the design of high dielectric constant and high reliability nanograined ceramics.The reliability mechanism of ultra-thin MLCC is systematically investigated. Based on the results of accelerated aging tests, high temperature impedance spectroscopy, and leakage current measurements, the key to ensure the reliability of ultra-thin MLCC is to inhibit the migration and enrichment of oxygen vacancies. Thus, for the purpose of improving the reliability of ultra-thin MLCC, we should control the oxygen vacancies in dielectric layers, enhance the activation energy of the oxygen vacancy migration, and increase the Schottky barrier height at the interface between the electrodes and dielectrics.