High-pressure structural phase transitions and metallization in layered HfS2 under different hydrostatic environments up to 42.1 GPa. Issue 29 (8th July 2022)

• Record Type: Journal Article
• Authors: Hong, Meiling; Dai, Lidong; Hu, Haiying; Zhang, Xinyu; Li, Chuang; He, Yu
• Is Part Of: Journal of materials chemistry. Volume 10:Issue 29(2022)
• Page Start: 10541
• Page End: 10550
• Publication Date: 2022-07-08
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d2tc01669a
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : A series of structural, vibrational and electrical transport behaviors for HfS2 were systematically investigated upon compression and decompression under different hydrostatic environments. High-pressure structure and stability were deeply explored. Abstract : A series of structural, vibrational and electrical transport behaviors for HfS2 were systematically investigated by Raman spectroscopy, electrical conductivity, high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM) in conjunction with first-principles theoretical calculations in the processes of compression and decompression under different hydrostatic environments. High-pressure Raman scattering and electrical conductivity results revealed that HfS2 underwent two structural phase transitions and metallization at 8.0, 15.2 and 20.5 GPa under non-hydrostatic conditions. The first structural transition was characterized by the appearance of the M1 and M2 Raman peaks and the inflection point in the pressure-dependent electrical conductivity. The second structural transition was identified from the disappearance of the Eg, M1 and M2 Raman peaks, the emergence of the M3–M6 Raman peaks, and the discontinuities in the pressure coefficient of the A1g mode and electrical conductivity. As the pressure increased to 20.5 GPa, HfS2 underwent a metallization transition, which was attributed to the closure of the bandgap energy obtained from first-principles theoretical calculations. Under hydrostatic conditions, two structural transformations and metallization of HfS2 occurred at relatively high pressures of 8.2, 17.2 and 23.1 GPa due to different deviatoric stress. Upon decompression, the phase transition was revealed to be reversible under different hydrostatic environments, which was verified by the HRTEM and AFM results. Our acquired results of the crystalline and electronic structures of HfS2 facilitate the understanding of the high-pressure characterization of other HfX2 compounds (X = Se and Te) under different hydrostatic environments.