Elasticity, Flexibility, and Ideal Strength of Borophenes

Abstract

ABSTRACT:We study the mechanical properties of two-dimensional (2D) boron-borophenes -by first-principles calculations. The recently synthesized borophene with 1/6 concentration of hollow hexagons (HH) is shown to have in-plane modulus C up to 210 N/m and bending stiffness as low as D = 0.39 eV. Thus, its Foppl-von Karman number per unit area, defined as C/D, reaches 568 nm -2 , over twofold higher than graphene's value, establishing the borophene as one of the most flexible materials. Yet, the borophene has a specific modulus of 346 m 2 /s 2 and ideal strengths of 16 N/m, rivaling those (453 m 2 /s 2 and 34 N/m) of graphene. In particular, its structural fluxionality enabled by delocalized multi-center chemical bonding favors structural phase transitions under tension, which result in exceptionally small breaking strains yet highly ductile breaking behavior. These mechanical properties can be further tailored by varying the HH concentration, and the boron sheet without HHs can even be stiffer than graphene against tension. The record high flexibility combined with excellent elasticity in boron sheets can be utilized for designing composites and flexible systems.

Molecular dynamics simulations for mechanical properties of borophene: parameterization of valence force field model and Stillinger-Weber potential

“…The yielding strain is about 0.15 and 0.1 in the x and y directions respectively at the low temperature of 1 K. These values agree with ab initio results at 0 K283850. The yielding strain decreases with increasing temperature.…”

“…28, or 163 Nm −1 and 399 Nm −1 in ref. 50. Figure 9 shows that the Young’s modulus decreases with the increase of temperature.…”

2 D MXene‐based Energy Storage Materials: Interfacial Structure Design and Functionalization

“…Unlike conventional2Dn anomaterials, such as graphene, [32][33][34][35] borophenes, [36][37][38] silicene, [39][40][41] and black phosphorene, [42,43] MXenesh ave an extremely wide varietyo fc hemical composi-tions and structural arrangements at the atomic scale, [44,45] which endow them with many unique characteristics, including high electrical conductivity, plastic layer structure, small band gap, andl arge redox-active surfacea rea. [46][47][48] In spite of this, it remains ag reat challenge to fully utilize the advantages of MXenes because these unique traits and properties are highly related to the preparation processes that significantly influence their chemical compositions, layer structures,a nd surface functional groups.…”

Freestanding χ3-borophene nanoribbons: a density functional theory investigation

“…A lot of research has been devoted to studying outstanding properties of the borophene sheets in recent two years. It was observed that the borophene sheets are stiffer than the steel and unlike graphene, its mechanical ability is anisotropic and dependent on the * Izadi@webmail.guilan.ac.ir † m bagheri@guilan.ac.ir load direction [18,19]. In addition, same anisotropy has been reported for its electrical conductance that makes the borophene sheet an ideal candidate for electronic devices [20].…”