New Pressure Stabilization Structure in Two-Dimensional PtSe₂

Abstract

The frequency shifts and lattice dynamics to unveil the vibrational properties of platinum diselenide (PtSe2) are investigated using pressure-dependent polarized Raman scattering at room temperature up to 25 GPa. The two phonon modes Eg and A1g display similar hardening trends; both the Raman peak positions and full widths at half-maximum have distinct mutation phenomena under high pressure. Especially, the split Eg mode at 4.3 GPa confirms the change of the lattice symmetry. With the aid of the first-principles calculations, a new pressure stabilization structure C2/m of PtSe2 has been found to be in good agreement with experiments. The band structures calculations reveal that the new phase is a novel type-I Dirac semimetal. The results demonstrate that the pressure-dependent Raman spectra combined with theoretical predictions may open a new window for searching and controlling the phase structure and Dirac cones of two-dimensional materials.

In-Plane Seebeck Coefficients of Thickness-Modulated 2D PtSe2 Thin Films

“…Furthermore, the E g /A 1g ratios are significantly reduced with increasing PtSe 2 film thickness owing to the enhancement in the out-of-plane interactions among the increasing number of layers in the thicker films . These thickness-dependent Raman characteristics are consistent with those reported previously ,,, and confirm the complete selenization of the Pt films into 2D PtSe 2 thin films.…”

Interface-Induced Seebeck Effect in PtSe2/PtSe2 van der Waals Homostructures

“…The 2-nm-thick PtSe 2 sample exhibited two weak peaks at 176.8 and 205.5 cm −1 , which can be attributed to the in-plane (E g ) and out-of-plane (A 1g ) modes, respectively. 27,31,32 In contrast, two prominent peaks are observed in the spectrum of the PtSe 2 (10 nm) film, and the relative intensity of the A 1g peak with respect to that of the E g peak is higher than that of the PtSe 2 (2 nm) film. This high relative intensity, observed in the spectrum of the PtSe 2 (10 nm) film, can be attributed to increased out-of-plane interactions between the large number of layers in this comparatively thicker film.…”

Photocatalytic properties of anisotropic β-PtX2 (X = S, Se) and Janus β-PtSSe monolayers

“…43,44 Furthermore, they can form more than one stable phase, such as the T-phase with an hexagonal lattice 45 and puckered pentagonal structure with an orthorhombic lattice. 46,47 One phase can undergo a phase transition by external stimuli such as high pressure, 48,49 uniaxial strain, 50 and Li-adsorption. 51 Among the noble metal dichalcogenides, Pt-based layered structures such as PtSe 2 have emerged as promising 2D materials because of their experimental synthesis 52 and novel physical, chemical, and photonic properties.…”

“…43,44 Furthermore, they can form more than one stable phase, such as the T-phase with an hexagonal lattice 45 and puckered pentagonal structure with an orthorhombic lattice. 46,47 One phase can undergo a phase transition by external stimuli such as high pressure, 48,49 uniaxial strain, 50 and Li-adsorption. 51…”