Out-of-Plane Deformations Determined Mechanics of Vanadium Disulfide (VS₂) Sheets

Abstract

The rapid development of two-dimensional (2D) materials has significantly broadened the scope of 2D science in both fundamental scientific interests and emerging technological applications, wherein the mechanical properties play an indispensably key role. Nevertheless, particularly challenging is the ultrathin nature of 2D materials that makes their manipulations and characterizations considerably difficult. Herein, thanks to the excellent flexibility of vanadium disulfide (VS2) sheets, their susceptibility to out-of-plane deformation is exploited to realize the controllable loading and enable the accurate measurements of mechanical properties. In particular, the Young’s modulus is estimated to be 44.4 ± 3.5 GPa, approaching the lower limit for 2D transition metal dichalcogenides (TMDs). We further report the first measurement of thickness-dependent bending rigidity of VS2, which deviates from the prediction of the classical continuum mechanics theory. Additionally, a deeper understanding of the mechanics within two dimensions also facilitates the modulation of strain-coupled physics at the nanoscale. Our Raman measurements showed the Grüneisen parameters for VS2 were determined for the first time to be γE2g 1 ≈ 0.83 and γA1g ≈ 0.32.

Layered Metallic Vanadium Disulfide for Doubly Q-Switched Tm:YAP Laser with EOM: Experimental and Theoretical Investigations

“…The large interlayer spacing and high surface activity of 2D VS 2 render it suitable for application as an electrode material [25]. Moreover, VS 2 is the softest candidate of the TMDs to date, revealing its inherent advantage in the application of nanomaterial-based flexible electronics [26]. The remarkable nonlinear optical responses of layered VS 2 have already been reported in previous works [27,28].…”

An Atomically Thin and Photosensitive Vanadium Disulfide Memtransistor

“…VS2 exhibits two unique phases, that is, a metallic trigonal prismatic T-phase and the semiconducting octahedral H-phase. While the T-phase VS2 is relatively well known and explored for its excellent interfacial [23,24], electrolytic [25], and ferromagnetic [26] properties, the H-phase has only recently aroused widespread interest due to its semiconducting properties and larger magnetic moment [27], As per a recent report involving theoretical ab-initio calculations based on density functional theory (DFT), H-phase VS2 possesses an indirect bandgap of 0.6 eV [28].…”

Utilising buckling modes for the determination of the anisotropic mechanical properties of As2S3 nanosheets

“…Therefore, these buckling instabilities can provide a tool to measure these mechanical properties. [24][25][26][27][28][29] For example, the Young's modulus of transition metal dichalcogenides has been determined by observing the periodicity of the wrinkles formed in a nanosheet on a pre-stretched polydimethylsiloxane (PDMS) substrate. 24 Buckling delamination (induced by compressive strain) has also been used to determine the interfacial adhesion of MoS 2 on a stiff SiO 2 /Si substrate 27 and on a soft PDMS substrate.…”