Piezoelectric and polarized enhancement by hydrofluorination of penta-graphene

Abstract

Hydrofluorination can efficiently enhance the piezoelectric response of 2D penta-graphene.

Penta-BCN: A New Ternary Pentagonal Monolayer with Intrinsic Piezoelectricity

“…We note that the d 21 and d 16 of penta-BCN are higher than the d 11 of h-BN and d 31 of H-PG-F. Usually, the softer the material, the larger the d coefficient. 45 Though the piezoelectric stress tensor e of penta-BCN is comparable to that of h-BN, its piezoelectric strain tensor d is larger, because penta-BCN possesses smaller elastic constants C. While in the functionalized pentagraphene sheet, 44 the polarization comes from the inequivalence of the H-and F-terminated surfaces. However, the small thickness of such a 2D sheet inhibits the full spatial separation of positive and negative charges, so the in-plane strain can hardly cause a significant change in polarization.…”

A penta-BCP sheet with strong piezoelectricity and a record high positive Poisson's ratio

“…4 Numerous penta-sheets can exhibit exceptional piezoelectric properties. [13][14][15][16][17] For example, although graphene exhibits no piezoelectricity, penta-graphene is piezoelectric. 15 Meanwhile, piezoelectricity is a general property of the semiconducting penta-graphene-like structures because they are all noncentrosymmetric with the space group symmetry of P% 42 1 m. 18 In addition, spontaneous polarization can be introduced in penta-sheets with enhanced piezoelectric responses.…”

“…15 Meanwhile, piezoelectricity is a general property of the semiconducting penta-graphene-like structures because they are all noncentrosymmetric with the space group symmetry of P% 42 1 m. 18 In addition, spontaneous polarization can be introduced in penta-sheets with enhanced piezoelectric responses. For instance, the out-of-plane spontaneous polarization has been found in hydrofluorinated penta-graphene, 13 penta-CoAsS, 14 and penta-CCB 15 due to the asymmetry along the out-of-plane direction. By contrast, in-plane spontaneous polarization can also be introduced through a small tilt of the Si-Si dimers 19 or the existence of B-N or P-N polarized bonds.…”

Enhanced vertical polarization and ultra-low polarization switching barriers of two-dimensional SnS/SnSSe ferroelectric heterostructures

“…[1][2][3][4][5][6] Fortunately, in some 2D materials, polarizations are weakly affected by the depolarization field, and then large piezoelectric coefficients can be found. [7][8][9][10][11][12] The positive charge center does not coincide with the negative charge center, which introduces the electric dipole moment in 2D materials and makes them undergo spontaneous polarization. Ferroelectric materials with switchable polarization can serve as potential materials in nonvolatile memory (NVM) devices and sensors.…”