铋层状压电材料的可控制备、共生/复相结构特征及性能调控研究

The present proposal is focused on the technique improvement and chemical design of the intergrowth and composite structure of new lead-free piezoelectric ceramics. From the viewpoint of chemical component, preparation technique and structure control, a sol-gel combustion route would be adopted for the preparation of bismuth layer oxide powders and the screen-printing multilayer grain growth technique would be used to obtain textured bismuth layer ceramics with intergrowth/composite structure. The effect of the chemical composition and process on the grain orientation and the nanocrystalline structure will be studied systematically, revealing new insights into bismuth layer complex oxides: the relations between composition, processing, microstructure and properties. The intergrowth/composite phases, lattice distortion, textured structure and the grain size effect will be investigated. Further improvements in the piezoelectric, ferroelectric properties are ecpected to be achieved by an understanding of the interaction mechanism of intergrowth/composite phases, textured structure and properties. The document presents an alternative approach to optimized properties via controlling composition, processing and microstructure, provides experimental evidence and theoretical direction on approaches to design and preparation for next-generation multi-functional, integration and high performance microwave materials and devices.

对新型无铅压电材料进行共生/复合结构设计及制备技术改进：从基元组成、制备工艺与结构调控角度出发，开展铋层状氧化物的溶胶-凝胶自蔓燃合成工艺研究，结合厚膜晶粒定向生长技术制备具有共生/复合结构的织构化铋层状陶瓷，获得高取向度的纳米晶陶瓷材料，分析晶粒取向度的工艺调控机制及纳米晶粒尺寸效应，探寻共生相结构的形成机理及复相共存区结构特征，研究压电活性与晶粒定向结构及陶瓷切向的规律，关注铁电特性、介电非线性特征及高温电导机制等诸多性能与结构及制备工艺的关联性。探索高性能铋层状共生/复合材料的制备新途径，获得织构化的共生相和复相铋层状陶瓷，阐明材料组成设计、工艺方法与材料性能的关系，为设计制作高性能实用性的压电及铁电器件奠定良好的学术基础。

本项目研究针对新型无铅压电材料进行共生/复合结构设计及制备技术改进，从基元组成、制备工艺与结构调控角度出发，探索高性能铋层状材料的制备新途径，获得共生和复相铋层状陶瓷，阐明材料组成设计、工艺方法与材料性能的关系，为设计制作高性能实用性的压电器件提供科学技术支持。.发展了不同层数与组成的BLSF纳米材料形貌可控化学法制备技术，提供了片层纳米结构SBN、纳米花球状BTO，及四层薄片状SBT纳米颗粒的制备方法。构建并制备了2/3层共生结构MBi2Nb2O9-Bi4Ti3O12和3/4层共生结构的Bi4Ti3O12-MBi4Ti4O15的新型BLSF材料。基于复相结构模型和分子力学计算，设计研究了SBN-NBT/NKBT复相材料结构与组成，采用水热负载法在SBN基体上修饰NBT/NKBT颗粒，进一步优化其介电与压电性能。.基于相场理论模拟研究了气孔相对多孔陶瓷晶相结构的影响规律，利用Zener理论计算了不同特性气孔对晶界的拖曳力，获得了气孔相对晶粒相影响规律，提出了耦合传统介电复合关系及晶粒-气孔相互作用关系的多孔材料介电性能预测模型，为多孔材料的介电性能与其微观组织间作用规律提供了新思路。添加两种不同性质造孔剂PMMA和SA制备多孔陶瓷。通过调整孔隙率改善其电性能：无规则孔形结构将有效提升水声换能器用多孔陶瓷的性能；添加PMMA构造球形孔结构则显著提升静水压特性。以海藻酸钠为粘结剂，通过冷冻干燥法制备的直通型多孔无铅压电陶瓷，压电活性显著提高。.选取Bi4Ti3O12和Bi2MoO6为基础体系，利用不同半导体导带和价带能级的差异，与Ag、MoS2和Bi2S3等复合形成异质结，及在其表面负载Bi2S3纳米棒制得Bi4Ti3O12/Bi2S3异质结，可有效提高了光生电子−空穴对的分离，增加了半导体光催化剂的稳定性和光催化性能。采用静电纺丝技术制备的Bi4Ti3O12/MoS2异质结具有更好的可见光光催化性能。.本课题研究成果将铋层状无铅压电材料及其应用向着纳米化、精细化、多功能、高可靠、高性能、智能化、和复合结构方向发展，开拓探索了无铅压电材料在传感器、能量收集器、驱动器等领域的应用，初步研究表明无铅压电材料在压电器件领域的应用具有广阔前景。