Flexible ferroelasticity in monolayer PdS₂: a DFT study

Abstract

As an unusual mechanical response, the ferroelastic phenomenon in two-dimensional materials has been reported both experimentally and theoretically in recent years. Here, we present the theoretical findings of ferroelastic switching...

Two-Dimensional β-PdX2 (X=S, Se, and Te) Monolayers with Promising Potential for Thermoelectric Applications

“…The β-PdX 2 (X = S, Se, and Te) structures contain one Pd atom and two X atoms in the unit cell and possess trigonal symmetry with the P 3 1 21 space group, as shown in Figure a. The optimized lattice constants and atomic bond lengths of β-PdX 2 monolayers are summarized in Table , which are in good agreement with the previously reported values. , β-PdX 2 have helical chains parallel to the y direction, where these atoms are connected by the covalent bond within the chain and the chain is stacked in the x direction.…”

“…The optimized lattice constants and atomic bond lengths of β-PdX 2 monolayers are summarized in Table 1, which are in good agreement with the previously reported values. 37,38 β-PdX 2 have helical chains parallel to the y direction, where these atoms are connected by the covalent bond within the chain and the chain is stacked in the x direction.…”

Layer-dependent electronic structures and optical properties of two-dimensional PdSSe

“…[44][45][46][47][48][49][50] Owing to the low-symmetry pentagonal layer structure, PdX 2 materials show intriguing properties including layer-related band gaps, bipolar charge transport with high carrier mobility, excellent thermoelectric performances, and pressure/strain modulated superconducting and ferroelastic phenomena. 23,[26][27][28][29][30][51][52][53][54][55][56] Furthermore, the bulk phases of PdX 2 hold the Pbca space group and the D 2h (mmm) point group, while the symmetries of few-layer PdSe 2 differ from those of the bulk phase. 57 The evenlayer PdSe 2 belongs to the Pca2 1 space group and C 2v (mm2) point group without inversion symmetry, whereas the odd-layer PdSe 2 belongs to the P2 1 /c space group and C 2h (2/m) point group with inversion symmetry.…”

“…44–50 Owing to the low-symmetry pentagonal layer structure, PdX 2 materials show intriguing properties including layer-related band gaps, bipolar charge transport with high carrier mobility, excellent thermoelectric performances, and pressure/strain modulated superconducting and ferroelastic phenomena. 23,26–30,51–56…”

Penta-OsP2 and penta-Rhs2 sheets derived from marcasite and pyrite with low lattice thermal conductivity

“…Since the proposal of penta-graphene, 1 a pentagon-based two-dimensional (2D) carbon allotrope, a family of over 100 pentagon-based 2D materials has been reported with novel physical properties and vast potential applications. 2,3 For instance, a negative Poisson's ratio (NPR) has been found in penta-BN 2 , 4,5 penta-ZnO 2 , 6 and penta-PdSe 2 , 7,8 topological electronic states have been reported in penta-RuS 4 , 9 MoS 2 , 10 and p-PbS 2 , 11 ferromagnetism and antiferromagnetism have been found in penta-MnN 2 , 12 and CoS 2 , 13 ferroelasticity was reported in penta-PdS 2 , 14 piezoelectric responses have been found in penta-BCN, 15,16 penta-CNP 17 and some transition metal-based ternary pentagonal sheets, 18 and second harmonic generation was predicted in penta-ZnS 2 . 19 Meanwhile, considerable effort has been made to synthesize such pentagon-based materials.…”