Ferroelectric ceramics have the potential to be widely applied in the modern industry and military power systems due to their ultrafast charging/discharging speed and high energy density. Considering the structural design and electrical properties of ferroelectric capacitor, it is still a challenge to find out the optimal energy storage of ferroelectric ceramics during the phase-transition process of amorphous/nanocrystalline and polycrystalline. In this work, a finite element model suitable for the multiphase ceramic system is constructed based on the phase field breakdown theory. The nonlinear coupling relationship of multiple physical fields between multiphase ceramics was taken into account in this model. The basic structures of multiphase ceramics are generated by using the Voronoi diagram construction method. The specified structure of multiphase ceramics in the phase-transition process of amorphous/nanocrystalline and polycrystalline was further obtained through the grain boundary diffusion equation. The simulation results show that the multiphase ceramics have an optimal energy storage in the process of amorphous polycrystalline transformation, and the energy storage density reaches the maximum when the crystallinity is 13.96% and the volume fraction of grain is 2.08%. It provides a research plan and idea for revealing the correlation between microstructure and breakdown characteristics of multiphase ceramics. This simulation model realizes the nonlinear coupling of the multiphase ceramic mesoscopic structure and the phase field breakdown. It provides a reference scheme for the structural design and performance optimization of ferroelectric ceramics.

弛豫铁电材料因具有高的介电常数和压电系数而广泛应用于致动器、换能器等领域。实际使用中往往需要施加大信号激励驱动谐振，因此了解掌握大信号激励下的谐振特性变化极为重要。然而，目前这方面的研究却少有文献报道。针对这一问题，以二步氧化物固相反应法制备了高压电性Pb0.9625Sm0.025［(Mg1/3Nb2/3)0.71Ti0.29］O3陶瓷材料，用本人搭建的大信号谐振响应测试系统研究了驱动场幅值和温度对径向谐振特性的影响。结果表明：低驱动场下谐振响应能保持单一谐振峰直至完全退极化，但随着驱动场的增大谐振响应变得复杂，即使在低温也呈现多个谐振峰。谐振特性的变化与机械品质因子Qm、铁电宏畴尺寸及相组成密切相关，低Qm材料在大驱动场下产生的内热加速了宏畴裂解并引发了二级铁电相变。谐振特性的不稳定及较大谐振频率温度系数限制了Sm改性PMN-PT弛豫铁电陶瓷的应用，尤其是在大信号下。

The purpose of this work is to study the processes of interfacial interactions, their influence on the piezoelectric properties in highly elastic composite structures, to establish the patterns that determine the volume-sensitive piezoelectric characteristics of composites and to create effective piezoelectric materials for hydroacoustic receiving devices. In the process of this work, the development of a method for obtaining anisotropic ferropiezoelectric ceramics, the development of methods for the preparation of perfect ceramic powders and composite materials based on thermoplastic fluoropolymers and the study of composite materials based on lead–calcium titanate were carried out. As a result of the study, the dependences of the hydrostatic parameters of the composites on the degree of filling, particle size distribution, piezoelectric anisotropy of the active phase and the elastic properties of the polymer matrix were established. Composite materials were based on ceramics of the PT–CT system and thermoplastic fluoropolymers F-2ME, F-62, F-2N with a degree of filling with a ceramic phase from 30 to 60% vol. The dependences of the hydrostatic piezoelectric moduli gh and dh, and the quality factor gh⋅dh on the degree of filling of the composite for polymers F-62 and F-2ME with different average sizes of ceramic particles are plotted. It has been established that the maximum values gh = 119.1⋅10−3V⋅m/N and the quality factor gh⋅dh = 6074⋅10−15 m²/N are achieved for a polymer with a higher elastic compliance (F-62) at a degree of filling of 60% vol. and the use of granular filler.

爆炸驱动铁电体脉冲电源利用铁电陶瓷在冲击压力作用下去极化释放电荷而产生电流，可以作为脉冲功率源的初始电源，也可直接驱动高阻抗负载产生脉冲高电压。通常情况下，铁电陶瓷可以看作理想的绝缘体，但在数GPa冲击波压力作用下，铁电陶瓷电阻率可能会明显下降并形成漏电导，使部分去极化释放电荷在铁电陶瓷内部流失，导致铁电陶瓷剩余极化电荷输出效率下降。以PZT95/5铁电陶瓷作为初始储能介质，以爆炸冲击波加载PZT95/5铁电陶瓷释放电荷对脉冲电容器充电，充电结束后电容器电压维持期间检测到明显的反向电流，根据铁电陶瓷输出电流和工作电压，得到冲击波作用过程中铁电陶瓷的瞬态电阻率曲线，并分析了电阻率下降对输出电荷的影响。进一步研究表明，冲击压力在铁电陶瓷边侧产生的稀疏波是引起电荷输出效率降低的主要因素，而铁电陶瓷电阻率下降对电荷输出效率的影响很小。

铁电陶瓷材料在外场加载下的畴变所引起的材料结构变化, 是导致材料性能衰变和破坏的主要原因, Raman光谱技术是一种研究铁电材料畴变和微结构变化的无损伤性及原位微区的观测方法。 采用传统固相法合成Zr/Ti原子比为53/478的掺镧锆钛酸铅(PLZT)铁电陶瓷材料 , 采用X射线衍射仪和扫描电子显微镜及Precision_LC铁电测试系统分别对试样进行结构形貌表征和铁电物理性能测试, 利用自制的应力加载装置与Raman光谱仪联用, 实现不同压应力场作用下试样的原位Raman谱测试, 考察和分析Raman谱软模E(2TO)和E(3TO+2LO)+B1的峰强和峰位随散射偏振方向的变化规律。 结果表明, 不同压应力场下Raman软模E(2TO)和E(3TO+2LO)+B1的峰强均随散射偏振角度呈现正弦式的变化规律, 在60°偏振角度上软模峰强最大, 在150°偏振角度上软模峰强最小。 随着压应力场的增加, 在0°和60°偏振角度获得的软模峰强随应力场的增加呈现明显的下降趋势, 而在90°和150°偏振角度获得的软模峰强基本不变。 压应力场变化对PLZT陶瓷的Raman软模E(2TO)和E(3TO+2LO)+B1的峰位均不产生影响。

基于铁电陶瓷材料90°畴变导致Raman光谱变化的原理, 自行设计并搭建了铁电材料原位测试分析和数据采集系统, 通过与Raman光谱仪的联用, 利用特制的样品旋转装置, 从实验上证实在外加电场作用下铁电材料中的90°畴变使平均电畴的择优取向发生改变, 从而导致Raman光谱强度的变化, 利用铁电材料原位测试分析和数据采集系统, 实现了外电场作用下或电疲劳作用下同时进行铁电陶瓷材料畴变的原位Raman观测及原位电滞回线的测试。结果表明原位Raman光谱技术可应用于铁电材料的电致畴变和电疲劳研究。

对激光烧结制备钛酸铋Bi4Ti3O12陶瓷进行了研究。采用CO2激光直接辐照Bi4Ti3O12陶瓷素坯表面, 激光功率密度为20～30 W/cm2, 烧结温度为1000 ℃左右。与传统固相反应烧结技术制备的Bi4Ti3O12陶瓷相比, 激光烧结制备的Bi4Ti3O12陶瓷致密度较高, 相对密度能达到95%, 压电性能提高了约60%, 铁电性能的增强表现在矫顽场的明显减小和易于极化。通过X射线衍射、扫描电镜分析了激光烧结Bi4Ti3O12陶瓷的物相、显微结构和电性能改变的机理。实验现象和结果表明, 激光烧结可以作为功能陶瓷烧结的方法之一。

铁电阴极材料,作为一种新型的功能材料,以其高的发射电流密度等优点而受到重视.鉴于目前研究的铁电阴极材料多局限于锆钛酸铅等含铅材料,作者采用无铅铁电陶瓷Na_1/2Bi_1/2TiO₃-BaTiO₃(BNBT),进行了电子发射实验,获得发射电流密度达20A/cm².初步实验结果表明,与锆钛酸铅相比,钛酸铋钠发射电流密度略低但性能稳定性较好.作为无铅铁电阴极,BNBT仍然具有良好的研究开发价值.