Flexoelectricity in hexagonal boron nitride monolayers

Guo, Hanze; Yang, Tingfan; Xuan, Xiaoyu; Zhang, Zhuhua; Guo, Wanlin

doi:10.1016/j.eml.2022.101669

Cited by 16 publications

(8 citation statements)

References 55 publications

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“…Ceramics are essential in human civilization, with widespread applications in aerospace, automotive engineering, and medical engineering based upon their unique thermal, physical, and mechanical properties. − Compared with metals and polymers, ceramics possess higher strength, hardness, and better resistance to wear and corrosion. − But the working situations of ceramics are always limited by their brittleness at room temperature. Reducing the sample size to the nanoscale offers a feasible strategy to design ductile ceramics working at room temperature. − When the diameter was reduced to 18 nm, unusual strain plasticity of SiO 2 glass nanofibers around room temperature was observed.…”

Section: Introductionmentioning

confidence: 99%

Amorphization Toughening Induced by Microcracks in SiO₂ Thin Films

Gao

Zhang

et al. 2023

J. Phys. Chem. C

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Fused silica, a widely used facing material of transparent armor, was found to transform into stishovite under heavy shock compression. The ballistic-resistant performance of the partially transformed fused silica, which is highly correlated to the crack initiation and propagation processes, is important for multi-hit possibility. The ultra-high hardness and strength of stishovite are beneficial for the reduction of crack initiation. However, how the pre-existing cracks in stishovite propagate is an open question. Here, by combining molecular dynamics simulations and density functional theory calculations, we investigate the fracture behavior of crystalline stishovite with pre-existing cracks at room temperature. It is found that the crystalline stishovite phase transforms into an amorphous phase via a deformed phase under tensile loading, leading to a ductile fracture. Amorphization is localized on crack tips because of the strain concentration. Amorphization helps to inhibit crack propagation by volume expansion, increasing the final fracture strain. The amorphization mechanism and crack propagation path are robust when the shape of cracks changes. These results provide a reference for application of fused silica-based transparent armor systems.

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Section: Introductionmentioning

confidence: 99%

Amorphization Toughening Induced by Microcracks in SiO₂ Thin Films

Gao

Zhang

et al. 2023

J. Phys. Chem. C

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“…The B-tips of studied BNNT frameworks showed the negative electrostatic potentials in the work. In 2022, Guo et al studied the flexoelectric effect in h-BN nanosheet using the first principle DFT investigation [8]. The findings showed that the flexoelectric coefficient of h-BN is higher than that of graphene in the work.…”

Section: Introductionmentioning

confidence: 99%

Pristine and Group Iv Doped Boron Nitride Single-Wall Nanotubes for Hydrogen Storage: A Density Functional Theory Computational Investigation

et al. 2022

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In this report, a density functional theory (DFT) computational approach was used to investigate the structural and electronic properties of molecular hydrogens adsorbed on single-walled boron nitride nanotubes (BNNTs) with/without doped by group IV elements, such as carbon (C), silicon (Si), and germanium (Ge) atom. The twelve hydrogen molecules (H2) were added to the outer surfaces of BNNT frameworks. Geometry optimization calculations were performed to find the local energy minima of the BNNTs nanostructures with the molecular hydrogens at the DFT/B3LYP/6-31G level of theory. By employing single-point calculations at the B3LYP/6-31G* level of theory, the equilibrium geometric structures were then utilized to find the electronic structures of hydrogen molecules adsorbed on the surfaces of BNNT frameworks. The results showed that the bond lengths of B-N are in the range of1.44 Å – 1.48 Å. The optimized distances of hydrogen molecules from the surfaces of BNNTs were predicted to be 3.1 Å – 3.2 Å. Moreover, the computed HOMO-LUMO energies of molecular hydrogens adsorbed on the surface of BNNTs are about 2.2 eV – 4.3 eV. For the surface map of HOMO, the electron density distribution of hydrogen molecules adsorbed on the surface of pristine BNNT was localized in the N-tip. While in the case of doped BNNTs, the electron densities of HOMOs were focused on the group IV elements. The B-tips on the pristine and doped BNNTs possess the major contribution to the LUMO.

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“…Ferroic materials usually contain multiple ferroic orderings that are strongly coupled with each other . Typically, intrinsic coupling between ferroelectric polarization and FE strain can lead to important electromechanical phenomena, including piezoelectricity − and flexoelectricity, − which always have been among the dominant themes of multifunctional device applications, widely used in a rich variety of actuators and sensors. Unlike the piezoelectricity that occurs only in noncentrosymmetric polar materials, the flexoelectric effect, the coupling between polarization and a strain gradient (inhomogeneous structural deformation), can be universally present in any nonmetallic material. − Polarizations at FE domain boundaries in CaTiO 3 , − SrTiO 3 , − LaAlO 3 , Pb 3 (PO 4 ) 2 , and CsPbBr 3 represent the typical cases in which flexoelectricity arises from the parent nonpolar materials crystallizing in purely centrosymmetric FE phases.…”

mentioning

confidence: 99%

Two-Dimensional Ferroelasticity and Domain-Wall Flexoelectricity in HgX₂ (X = Br or I) Monolayers

Ding

Jia

Gou

2023

J. Phys. Chem. Lett.

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Electromechanical phenomena in two-dimensional (2D) materials can be related to sizable electric polarizations and switchable spontaneous ferroelasticity, allowing them to be used as miniaturized electronic and memory devices. Even in a parent centrosymmetric (nonpolar) ferroelastic (FE) material, non-zero polarization can be produced around the FE domain wall, owing to the strain-gradient-induced flexoelectricity. Compared with the negligibly weak flexoelectric effect in bulk compounds, significant electric polarizations can be expected in 2D FE materials that sustain a large elastic strain and a strain gradient. Using first-principles calculations, we predict that spontaneous 2D ferroelasticity and domain-wall flexoelectricity can be simultaneously realized in synthetic HgX2 (X = Br or I) monolayers. The FE phase renders three oriented variants, which form FE domain walls with a large strain gradient and the associated domain-wall flexoelectric polarizations. Our thermodynamic stability analysis and kinetic barrier simulations allow us to manipulate the domain-wall flexoelectricity via applied mechanical stress, thereby enabling future electromechanical applications in nanoelectronics.

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Flexoelectricity in hexagonal boron nitride monolayers

Cited by 16 publications

References 55 publications

Amorphization Toughening Induced by Microcracks in SiO₂ Thin Films

Amorphization Toughening Induced by Microcracks in SiO₂ Thin Films

Pristine and Group Iv Doped Boron Nitride Single-Wall Nanotubes for Hydrogen Storage: A Density Functional Theory Computational Investigation

Two-Dimensional Ferroelasticity and Domain-Wall Flexoelectricity in HgX₂ (X = Br or I) Monolayers

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Flexoelectricity in hexagonal boron nitride monolayers

Cited by 16 publications

References 55 publications

Amorphization Toughening Induced by Microcracks in SiO2 Thin Films

Amorphization Toughening Induced by Microcracks in SiO2 Thin Films

Pristine and Group Iv Doped Boron Nitride Single-Wall Nanotubes for Hydrogen Storage: A Density Functional Theory Computational Investigation

Two-Dimensional Ferroelasticity and Domain-Wall Flexoelectricity in HgX2 (X = Br or I) Monolayers

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Product

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Amorphization Toughening Induced by Microcracks in SiO₂ Thin Films

Amorphization Toughening Induced by Microcracks in SiO₂ Thin Films

Two-Dimensional Ferroelasticity and Domain-Wall Flexoelectricity in HgX₂ (X = Br or I) Monolayers