Pressure-induced coupled structural–electronic transition in SnS₂ under different hydrostatic environments up to 39.7 GPa

Abstract

A pressure-induced coupled structural–electronic transition of SnS2 was disclosed by high-pressure Raman scattering and electrical conductivity measurement at ∼30.0 GPa under different hydrostatic environments.

High-pressure structural phase transitions and metallization in layered HfS2under different hydrostatic environments up to 42.1 GPa

“…As is known, semiconductors are characterized by a positive temperature dependence of the electrical conductivity relationship, whereas metals show a negative correlation between temperature and electrical conductivity. 18,19,21,22,28–31 And thus, our variable-temperature electrical conductivity results confirmed the occurrence of a semiconductor-to-metal transition at 22.7 GPa for HfS 2 . Obviously, the metallization pressure point of HfS 2 is considerably higher than that of HfSe 2 (∼10.0 GPa), 12 which is possibly related to the stronger electronic coupling effect in HfS 2 resulting from the smaller atomic radius and tighter electron orbitals of sulphur compared with those of selenium.…”

“…15 However, there exist some obvious discrepancies, including the identification of pressure-induced structural transitions and the reversibility of high-pressure structural phase transition for HfS 2 . All of these discrepancies are possibly related to (i) the difference in the hydrostatic environment, the use of crystallographic oil as the pressure medium by Grzeszczyk et al (2022), and the use of helium as the pressure medium in our present study (helium as a pressure medium can provide good hydrostatic conditions, which has been widely applied to explore the physicochemical properties of many materials at high pressure in diamond anvil cells); [16][17][18][19]21,22 (ii) the difference in the degree of decompression (previous Raman scattering measurements were conducted on HfS 2 decompressed from 27.0 to 1.7 GPa at a pressure interval of B3.5 GPa, and we conducted Raman spectroscopy experiments of a sample decompressed from 36.1 GPa to 1 atm at a pressure interval of B1.2 GPa).…”

“…Helium exhibits stable physicochemical properties and high hydrostaticity, and thus has been widely applied in previous high-pressure investigations. [16][17][18][19]21,22 The uncertainties of pressure calibration were less than 5% and 3% under non-hydrostatic and hydrostatic conditions, respectively. The Raman spectra of HfS 2 were measured using a Renishaw 2000 Micro-Confocal Raman spectrometer (TCS SP8, Leica, Renishaw) equipped with an Olympus charge coupled device (CCD) camera.…”

“…The uncertainty of the temperature calibration was not more than B5 K. More detailed sample assembly and experimental procedures for the measurement of electrical conductivity have been described in our previous investigations. 18,19,21,22…”

Superconductivity Induced by Lifshitz Transition in Pristine SnS2 under High Pressure

“…In general, pressure will decrease the interatomic distances and increase the bandwidth, leading to FS modification. Our high-pressure XRD measurement results show a discontinuity in the pressure dependence of the axial ratio c / a , which has been theoretically predicted and experimentally observed associated with the Lifshitz transition in several materials (e.g., Co and BiTeI). , A recent report by Zhang et al showed that the pressure-dependent Raman shifts and Raman full width at half-maximum of SnS 2 show discontinuity at around 33.4 GPa under the hydrostatic condition . We note that pressure discontinuities on the Raman spectrum are known to be one signature of the pressure-induced Lifshitz phase transitions, or so-called electronic phase transition, which is also observed in NbP and NiTe 2 . , Our DFT calculations also confirm this Lifshitz transition with a new FS around the Γ point and indicate the drastic increase of the DOS.…”