Study on the strain-induced mechanical property modulations in monolayer Tellurene

Abstract

Two-dimensional monolayer Tellurium, termed as Tellurene (Te), has recently been fabricated in the experiment. In this work, under uniaxial strain applied along either the armchair or zigzag direction with strain strength varying from 0 to 40%, we have investigated the mechanical property of Te including three allotropes (α-Te, β-Te, and γ-Te). Our results show that the β-Te exhibits the most obvious anisotropy in the stress-strain curve, Young's modulus, and Poisson's ratio, which is thought to originate from its inherent structure characteristic. The stress-strain curve demonstrates that the β-Te can withstand relatively high critical strain up to 36% in the armchair direction and 35% in the zigzag direction. The calculated Young's modulus E(θ) of the β-Te is 55 GPa in the zigzag direction and that is 27 GPa in the armchair direction. The comparative high critical strain and small Young's modulus mean that β-Te has good flexibility. Moreover, under the strain range within 15%, the direction being easy to be stretched has a reversion, which is thought to be decided by the competition between the puckered structure and the transfer charge resistant to deformation. Furthermore, when the strain is applied along the direction parallel to the pucker of β-Te, it is interesting to find that Poisson's ratio is negative in the out-of-plane direction. The hinged structure of the β-Te contributes to the negative Poisson's ratio, which can be comprehended by the hypothetical step-by-step evolution process.