随着功能陶瓷向轻量化、智能化、多功能耦合方向发展，结构功能一体化的多孔压电陶瓷因其比表面积大、孔隙率高、能有效促进能量转化，逐渐成为功能陶瓷领域研究的热点。Bi_0.5Na_0.5TiO₃(BNT)基陶瓷因其环保、压电系数高、机械性能好及机电耦合系数各向异性明显等优势被认为是最有潜力的无铅压电陶瓷体系之一。本论文以BNT基陶瓷为研究主体，优选0.94Bi_0.5Na_0.5TiO₃- 0.06BaTiO₃(BNBT6)体系为研究对象，研究材料组成和多孔结构对其介电、压电性能的影响规律，为多孔压电陶瓷在声学换能器、压电谐振式传感器等领域的应用提供科学依据和技术支撑。

选取准同型相界处的BNBT6陶瓷为研究对象，通过固相法制备BNT基陶瓷，研究了材料组成对其性能的影响，并基于第一性原理，模拟研究了其晶体结构、电子结构对性能的影响。结果表明，准同型相界处的BNBT6陶瓷的介电性能和压电性能明显提高。模拟计算结果显示，BNBT6的带隙明显减小，导带降低，能量范围在一定程度上略有减小，介电峰的宽度增加，介电稳定性提高。

采用海藻酸钠离子凝胶法制备BNBT6多孔陶瓷，通过控制固含量和阳离子溶液浓度控制多孔结构，研究了多孔结构对陶瓷介电、压电性能的影响规律及作用机制。结果表明孔隙率增加使多孔陶瓷的介电常数减小，介电常数温度稳定性明显提高。孔隙率增加使多孔陶瓷的压电性能逐渐减小，声学性能得到较好的改善。当固含量为15 %，Ca²⁺浓度为1 mol/L时，BNBT6多孔陶瓷的声阻抗与水声组织的声阻抗匹配度高，有望应用在水声换能器等领域。

优选Ta₂O₅作为掺杂剂，采用固相法制备(1-x)(Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃-xTa(BNBT6-x wt.%Ta)陶瓷粉体，通过海藻酸钠离子凝胶法制备多孔陶瓷。研究了Ta掺杂对BNBT6多孔陶瓷微观结构、介电性能、压电性能及谐响应特性的影响。结果表明适量Ta掺杂明显改善了BNBT6-x wt.%Ta多孔陶瓷的电学性能和工作温度范围。通过设计圆形片状BNBT6-x wt.%Ta多孔陶瓷的尺寸，使其在横向伸缩振动下，不易产生谐振耦合，易激发，为其在压电谐振式传感器等领域的应用提供科学指导。

With the development of functional ceramics towards lightweight, intelligent, and multifunctional coupling, porous piezoelectric ceramics with integrated structure and function have gradually become a hot research topic in the field of functional ceramics due to their large specific surface area, high porosity, and effective promotion of energy conversion. Bi_0.5Na_0.5TiO₃(BNT)-based ceramics are considered one of the most promising lead-free piezoelectric ceramic systems due to their environmental friendliness, high piezoelectric coefficient, excellent mechanical properties, and significant anisotropy of electromechanical coupling coefficient. BNT based ceramics were selected as the research subject, and the 0.94Bi_0.5Na_0.5TiO₃-0.06BaTiO₃(BNBT6) system was selected as the research object to study the influence of material composition and porous structure on its dielectric and piezoelectric properties, providing scientific basis and technical support for the application of porous piezoelectric ceramics in fields such as acoustic transducers and piezoelectric resonant sensors.

BNBT6 ceramics at the quasi-homotypic phase boundary were selected for the study. The BNT-based ceramics were prepared by the solid-phase method to investigate the influence of material composition on their properties. The effects of their crystal structure and electronic structure on their properties were studied by simulation based on the first-nature principle. The results show that the dielectric and piezoelectric properties of BNBT6 ceramics at the morphotropic phase boundary are significantly improved. The results of the simulations show that the band gap of BNBT6 decreases significantly, the conduction band decreases, the energy range decreases to some extent, the width of the dielectric peak increases, and the dielectric stability improves.

BNBT6 porous ceramics were prepared by the sodium alginate ionic gelation method. The pore structure was controlled by controlling the solid content and cation solution concentration, and the law and mechanism of porous structure on the dielectric and piezoelectric properties of ceramics were investigated. The results show that the increase in porosity leads to a decrease in the dielectric constant of porous ceramics and a significant increase in the temperature stability of the dielectric constant. The increase in porosity causes the piezoelectric properties of porous ceramics to gradually decrease, and the acoustic properties are better improved. When the solid content is 15 % and the Ca²⁺ concentration is 1 mol/L, the acoustic impedance of BNBT6 porous ceramics is closer to the hydroacoustic tissues, which is expected to be applied in fields such as hydroacoustic transducers.

In this paper, Ta₂O₅ was preferably selected as the dopant, (1-x)(Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃-xTa(BNBT6-x wt.%Ta) ceramic powder was prepa- red by the solid phase method, and porous ceramics were prepared by the sodium alginate ionic gel method. The effects of Ta doping on the microstructure, dielectric properties, piezoelectric properties, and harmonic response of BNBT6 porous ceramics were investigated. The results indicate that the appropriate amount of Ta doping significantly improves the electrical properties and operating temperature range of porous ceramics. By designing the dimensions of the circular sheet porous BNBT6-x wt.%Ta ceramics to be less susceptible to resonant coupling and easy to excite under transverse stretching vibration, scientific guidance is provided for their applications in fields such as piezoelectric resonant sensors.