本项目拟利用原位XRD、中子衍射NPD、拉曼光谱、EPMA、扫描电镜SEM、投射电镜TEM等技术测试分析，开展RxOy-Bi2O3-Fe2O3体系的化合物晶体结构、磁结构及相关系的研究，测定其相图，构建多铁材料设计平台。在此基础上，为解决多铁材料磁电性能的调控问题，重点研究晶体结构和相关系随成分、温度变化的演变规律。优化制备工艺，实现对微观结构的调控。通过Rietveld对化合物的晶体结构进行精修，计算晶胞参数、各原子间键长、键角、占位及占有率等结构参数。结合热力学测试及计算，研究该体系化合物稳定性和成相规律。采用PPMS测试其磁电性能，分析双（多）主相耦合的协同效应，阐明相组成和组织结构对磁电性能影响规律,为多铁材料设计提供理论依据。通过本项目的研究，深入理解多铁材料的磁电耦合机理，建立多铁材料的现代设计方法，加速多铁材料的开发。

In the project，the crystal structures 、magnetic structure and phase relationships of the RxOy-Bi2O3-Fe2O3 system will be investigated by XRD, PND, Raman spectroscopy, EPMA, SEM and TEM. The phase diagrams will be developed to support the composition design of the multiferroic materials. After that, an emphasis will be put on the composition, temperature evolution of the crystal structure and phase relationships in order to solve the magnetoelectricity performance control of multiferroic materials. The microstructure of multiferroic materials will be regulated by optimizing the preparation technology. Crystal structure parameters of the compounds, including cell parameters, bond lengths and bond angles between atoms, atomic positions and occupancy, will be calculated by the Rietveld program. Combined with thermodynamic test and optimization, the stability and forming the phase rule of the compounds will be systematically studied. The magnetoelectric properties will be tested by PPMS. The synergistic effect of double (multiple) main phase coupling is analyzed. The effect of the microstructure and phase composition on magnetoelectric properties will be illuminated. A theoretical foundation for the design of multiferroic materials based on phase diagram and microstructure will be constructed. The ultimate goal of the project is to provide a good deal of magnetoelectric coupling mechanism of multiferroic materials and to establish a modern design method for multiferroic materials. The research results can also accelerate the development of advanced multiferroic materials.