Past Events

Abstract
 

Due to the novel and excellent mechanical, electrical and optical properties, two-dimensional transition metal dichalcogenides (TMDs) have attracted tremendous attention. Among dozens of TMDs, vanadium dichalcogenides (VX₂, X=S, Se and Te) deserve to be extensively studied owing to their intrinsic magnetism and potential applications as high-performance functional nanomaterials. Different from other 2D materials like graphene, VX₂ potentially have more than one crystal structures and diverse electronic structures, which theoretically vary from metallic to semiconducting behavior. Recently the phase stability and electronic properties of the probable crystal structures of both monolayer and bulk VX₂ were investigated based on first-principle calculations, but experimentally structural phase transitions in VX₂ have not yet been realized. In this project, according to the thermodynamic calculations from previous reports, thermally induced means can be the dominant methods to obtain structural phase transitions between H-VX₂ and T-VX₂ for monolayer and between 1T-VX₂ and 2H-VX₂ for fewer layers. The phase transition phenomena can be detected by Raman spectroscopy and the critical temperatures of different phase transitions and another way based on size effect to change phases will be carefully investigated. Exploring the physics of transitions between these different structures of VX₂ may provide an approach to switching material properties and extend application range.

Anyone interested is welcome to attend.