Phase stabilities and vibrational analysis of hydrogenated diamondized bilayer graphenes: A first principles investigation

• Published in: Carbon (New York) Vol. 146; pp. 468 - 475
• Main Authors: Pakornchote, T., Ektarawong, A., Alling, B., Pinsook, U., Tancharakorn, S., Busayaporn, W., Bovornratanaraks, T.
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01.05.2019; Elsevier BV
• Subjects: 2-Dimensional materials; Band gap; Bilayers; Crystal structure; Deformation resistance; Diamond-like carbon; Diamondized bilayer graphene; Diamonds; Elastic deformation; Elastic properties; First principles; Graphene; High resistance; Hydrogen storage; Hydrogenation; Indentation; Plastic deformation; Stability analysis; Stability criteria; Thermodynamics; Vibrational analysis; 2-Dimensional materials; Diamondized bilayer graphene; Vibrational analysis
• ISSN: 0008-6223; 1873-3891; 1873-3891
• DOI: 10.1016/j.carbon.2019.01.088

The phase stabilities as well as some intrinsic properties of hydrogenated diamondized bilayer graphenes, 2-dimensional materials adopting the crystal structure of diamond and of lonsdaleite, are investigated using a first-principles approach. Our simulations demonstrate that hydrogenated diamondized bilayer graphenes are thermodynamically stable with respect to bilayer graphene and hydrogen molecule even at 0 GPa, and additionally they are found to withstand the physical change in structure up to at least 1000 K, ensuring their dynamical and thermal stabilities. The studied hydrogenated diamondized bilayer graphenes are predicted not only to behave as direct and wide band gap semiconductors, but also to have a remarkably high resistance to in-plane plastic deformation induced by indentation as implied by their high in-plane elastic constants comparable to those of diamond and of lonsdaleite. The mechanical stability of the materials is confirmed though the fulfilment of the Born stability criteria. Detailed analysis of phonon vibrational frequencies of hydrogenated diamondized bilayer graphenes reveals possible Raman active and IR active modes, which are found to be distinctly different from those of hydrogenated diamond-like amorphous carbon and defective graphene and thus could be used as a fingerprint for future experimental characterization of the materials. [Display omitted]