多铁性复合陶瓷因兼具室温铁电/铁磁性能，且二者存在耦合调控，具有广泛的应用前景；但其机械结合的两相界面，在经历反复磁电耦合作用后容易失效；并且大量界面缺陷导致复合陶瓷本征铁电极化难以表达。层状Aurivillius相具有可调的周期性晶体结构，与CoFe2O4铁磁体结构相容，拟在二者之间构建共格铁性周期单元，实现相界面的化学键层次结合，开展如下研究：第一，采用精细化学路线调控层状Aurivillius相的铁性单元，以便与CoFe2O4铁磁单元通过特定晶面，在相界面实现周期性共格与键合作用；第二，采用低温快速烧结技术实现复合陶瓷致密化，揭示陶瓷致密化机理；第三，考察多铁性复合陶瓷的宏观铁性性能，阐明铁性强化机制，建立化学键状态与自发极化的关联；第四，探索基于共格铁性周期单元的磁电耦合新机制。通过以上研究，期望一方面为多铁性的基础研究提供帮助，另一方面也为多铁性复合陶瓷的应用打下技术基础。

Multiferroic composite ceramics, which contain both ferroelectricity and ferromagnetism at room temperature，possess magetoelectric effect and have a wide prospect on the application of electromagnetic devices. However, the mechanical bonding in interface regions of composite ceramics would have to face the fatigue failure after repeated magnetoelectric coupling interaction. The accompanying interface defects limit the intrinsic ferroelectric polarization of multiferroic composite ceramics. Considering the periodic crystal structure of layered Aurivillius phase is highly adjustable and compatible with the spinel CoFe2O4, this project plans to construct coherent ferroic periodic units between Aurivillius phase and CoFe2O4 ferromagnetic phase realizing a chemical bonding interface. The following researches will be carried out: Firstly, control the ferroic units of Aurivillius phase through an elaborate chemical route and form the periodic coherent bonding with ferromagnetic units of CoFe2O4 at the phase interfaces along certain planes; secondly, densify the multiferroic composite ceramics via rapid low-temperature sintering technology, and reveal the densification mechanism of the composite ceramics; thirdly, study the macroscopic ferroic properties of multiferroic composite ceramics to illuminate the strengthening mechanism and build the relationship between complex chemical bonding state and spontaneous polarization; lastly, explore new mechanism of magnetoelectric coupling based on coherent ferroic periodic units. Through all the studies above, the project expects to contribute fundamental researches for multiferroics on one hand, and on the other hand, lay the technical foundation for applications of multiferroic composite ceramics.