Experimental and Theoretical Investigation on the Relative Stability of the PdS₂- and Pyrite-Type Structures of PdSe₂

Abstract

Under ambient condition PdSe2 has the PdS2-type structure. The crystal structure of PdSe2 under pressure (up to 30 GPa) was investigated at room temperature by X-ray diffraction in an energy-dispersive configuration using a diamond anvil cell with a mixture of water/ethanol/methanol as a pressure transmitting medium. A reversible structural transition from the PdS2-type to the pyrite-type structure occurs around 10 GPa, and the applied pressure reduces the spacing between adjacent 2/proportional to [PdSe2] layers of the PdS2-type structure to form the three-dimensional lattice of the pyrite-type structure. First principles and extended Hückel electronic band structure calculations were carried out to confirm the observed pressure-induced structural changes. We also examined why the isoelectronic analogues NiSe2 and PtSe2 adopt structures different from the PdS2-type structure on the basis of qualitative electronic structure considerations.

Anisotropic Growth and Scanning Tunneling Microscopy Identification of Ultrathin Even‐Layered PdSe2 Ribbons

“…TEM, selected area electron diffraction (SAED), high‐angle annular‐dark‐field STEM (HAADF‐STEM), and energy‐dispersive X‐ray spectroscopy (EDS) characterizations were then performed to reveal the detailed structure of the CVD‐grown PdSe 2 . The top‐view crystal structure of PdSe 2 is shown in Figure a as a reference, with the lattice vectors and along [010] and [100] directions, and the corresponding lattice constants a = 5.7457 Å and b = 5.8679 Å, respectively . Notably, each Pd atom binds to four Se atoms, and the two adjacent Se atoms from the top and bottom sublayers form a SeSe bond crossing the Pd sublayer, resulting in a pentagonal network with a puckered structure .…”

“…The as‐grown edge of PdSe 2 (Figure a) shows a 2L thickness difference ≈0.70 nm on the open edge, according to the height profile analysis (Figure a). This height difference is similar to the 2L thickness of PdSe 2 , according to both experimental and calculation values . While the scratched edges (Figure d) exhibit two separate height differences ≈0.35 and ≈0.30 nm, respectively, similar to the monolayer thickness of PdSe 2 .…”

Strain-Modulated Electronic Structure and Infrared Light Adsorption in Palladium Diselenide Monolayer

“…Both atomic positions and lattice vectors were fully optimized using the conjugate gradient (CG) algorithm until the maximum atomic forces were less than 0.0005 eV/Å. The lattice constants of the orthorhombic PdSe 2 crystal (a = 5.752 Å, b = 5.926 Å) obtained from our calculations agree well with the experimental data (a = 5.746 Å, b = 5.868 Å)12, confirming the validity of this strategy.…”

“…Under ambient conditions, PdSe 2 crystal appears in an orthorhombic structure with a space group of Pbca similar to the case of PdS 2 1112. Using first-principles calculations, Sun et al ., proposed a PdSe 2 monolayer with semiconducting nature and high Seebeck coefficients11.…”

Not your familiar two dimensional transition metal disulfide: structural and electronic properties of the PdS2monolayer

“…Interestingly, the TMDs 35. For example, MoS 2 and WS 2 monolayers prefer to adopt the 2H configuration, while the most stable configuration of TiS 2 and SnS 2 monolayers is 1T.…”