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High Negative Poisson’s Ratio in a Flexible Two-dimensional Tungsten Carbide Monolayer

Abstract

Auxetic materials have numerous promising engineering applications such as fracture resistance and energy storage due to their negative Poisson’s ratios (NPRs). However, compared to materials possessing positive Poisson’s ratios (PPRs), auxetic materials are rare. In this paper, by employing first principles calculations, we found a high NPR two-dimensional (2D) material, tungsten carbide (W2C), in transition metal carbides (MXenes). Our results of the relatively moderate Young’s modulus and fracture strength as well as critical strain showed that the 2D monolayer W2C is an extraordinary flexible material. Our DFT results also demonstrated that W2C possesses high NPRs while Hf2C and Ta2C have PPRs. Further, mechanically induced deformation mechanism and NPR formation mechanism of W2C were proposed. Such intrinsic NPR in W2C is attributed to strong coupling between C-p and W-d orbitals in the pyramid structural unit. Mechanically induced deformation mechanism and PPR formation mechanism of Hf2C were also determined. The intrinsic NPR for W2C transforms to the PPR upon the surface functionalization induced. The behavior occurs due to the W-C interaction weakened. The excellent NPR in the 2D MXene material combining with other outstanding properties such as the metallic state would bring its promising engineering prospects, ranging from metal-ion battery, to automobiles and aircraft.

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Publication details

The article was received on 01 Mar 2018, accepted on 09 Apr 2018 and first published on 09 Apr 2018


Article type: Paper
DOI: 10.1039/C8CP01353E
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
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    High Negative Poisson’s Ratio in a Flexible Two-dimensional Tungsten Carbide Monolayer

    D. Wu, S. Wang, S. Zhang, J. Yuan, B. Yang and H. Chen, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP01353E

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