不同于传统的2H相过渡金属硫属化物(TMDs),ReX2(ReS2或ReSe2)具有面内扭曲非对称Td相二维结构，展现出明显非层数依赖的电子和光学特性，成为最前沿TMDs二维材料。认识和调控这种非对称二维微结构，从而实现其它二维材料很难获得的多铁特性意义重大。本项目拟采用化学气相沉积、特定化学溶液腐蚀和超声剥离等方法，制备出不同层厚，具有阳离子空位、六角对称的亚稳态T相和非对称Td相共存的ReX2超薄片状结构(T@Td-ReX2)，借助已有微结构表征技术认识超薄T@Td-ReX2结构中阳离子空位存在状态、Td到T相演化过程，结合理论模拟深入揭示该复合体系中磁、光、电物性的微结构依赖性。以此为基础，拟通过T@Td-ReX2复合结构中Td到T相的转变首次实现二维层状材料中的铁电特性，通过阳离子空位引入获得室温铁磁性，最终实现铁磁和铁电性的耦合，为新型自旋电子存储器件设计提供全新方案。

Different from other traditional hexagonal two-dimensional (2D) transition-metal dichalcogenide semiconductors (TMDs), ReX2 (ReS2 or ReSe2) has a distorted T diamond-chain structure and behaves as an electronically and optically decoupled monolayer, becomes a frontier 2D TMDs material. Therefore, we expect to realize the 2D multiferroic characteristic in this asymmetrical ReX2 material via understanding and regulation about its microstructure. In this project, we will fabricate composite ReX2 nanosheets with Re vacancies, local T and Td phase interface (named as T@Td-ReX2), using chemical vapor transport method and ultrasonic chemical exfoliation method. Associated with theoretical simulation, we will disclose the existing state of Re vacancies and transformation between Td and T phase. Subsequently, the relationship between microstructural regulation and magnetic, optical, electric characteristic can be understood deeply. Based on this investigation, in this T@Td-ReX2 structure, we will realize 2D layered ferroelectric characteristics via phase transformation from Td to T and ferromagnetism by Re vacancy introduction, finally achieve expected magnetoelectric coupling. This novel strategy allows manipulation of spin electron by electric information and provides some new design schemes for spintronics and optoelectronic devices.