Ms. Shiyu Feng - M.Sc. Candidate
19/02/2025
ZOOM
12:30 - Jerusalem time / 18:30 - Beijing time
In searching for ultrathin and robust ferroelectric two-dimensional materials, ฮฑ-In2Se3 has drawn special attention owing to the existence of intercoupled in-plane and out-of-plane ferroelectricity. This makes ฮฑ-In2Se3 a potential candidate for emerging artificial intelligence, information processing, and memory applications. It is expected that pressure will significantly affect the physicochemical properties of ฮฑ-In2Se3 and recent research results on other layered compounds, such as graphene and Transition Metal Dichalcogenides, further support this hypothesis. However, to our knowledge, the overall structural behavior and the optical properties of the ฮฑ-In2Se3 phase under high pressure have not been systematically investigated.
In this study, the overall structural evolution was explored by performing a concomitant in-situ Raman Spectroscopy and X-ray diffraction study. Below 10GPa, the ฮฑ-In2Se3 first transforms to the ฮฒโฒ phase at around 1GPa, that remains stable up to to 45GP. With further pressure increase another phase transition was observed towards a solid solution structure based on density and enthalpy arguments. A few-layer ฮฑ-In2Se3 has also been investigated under pressure. A novel straightforward approach was developed to estimate the thickness of the sample from Raman spectra. Moreover, a procedure for loading few-layer ฮฑ-In2Se3 inside a typical diamond anvil cell was developed. Finally, high-pressure Raman measurements were performed and the comparison between the Raman spectroscopy measurements between the few-layer and the bulk samples was discussed.