Adsorption of beryllium atoms and clusters both on graphene and in a bilayer of graphite investigated by DFT

Abstract

We herein investigate the interaction of beryllium with a graphene sheet and in a bilayer of graphite by means of periodic DFT calculations. In all cases, we find the beryllium atoms to be more weakly bonded on graphene than in the bilayer. Be 2 forms both magnetic and non-magnetic structures on graphene depending on the geometrical configuration of adsorption. We find the stability of the Be/bilayer system to increase with the size of the beryllium clusters inserted into the bilayer of graphite. We also find a charge transfer from beryllium to the graphite layers. All these results are analyzed in terms of electronic structure.

Absorption and diffusion of beryllium in graphite, beryllium carbide formation investigated by density functional theory

“…13,15,26,27 Thus, in case of beryllium evaporation and redeposition on graphite, the first step leading to beryllium carbide would be beryllium diffusion in graphite, then beryllium clustering, followed by a phase transition. As a consequence, we first start to investigate different models for beryllium diffusion into perfect and defective graphite.…”

“…20 The same methodology was carried on in a previous study. 13 Minimum energy path and the corresponding saddle-points were investigated using the nudged elastic band (NEB) method. 21,22 The surface and the bulk properties of graphite were modeled by a single graphene layer (64 carbon atoms) and a graphite bilayer (128 carbon atoms), respectively.…”

“…13 In the following, it is assumed that the subsequent diffusion and aggregation processes lead to the formation of complete layers of beryllium in the graphene bilayer.…”

“…From a fundamental point of view, the interaction of beryllium atom with the surface of graphite 13,14 and nanoribbons of graphite 15 was previously investigated by density functional theory (DFT). Beryllium was shown not to significantly bond on the graphite surface; this is the opposite to what happens in the bulk of graphite, where a tendency to beryllium clustering was established.…”

“…Beryllium was shown not to significantly bond on the graphite surface; this is the opposite to what happens in the bulk of graphite, where a tendency to beryllium clustering was established. 13 In the continuity of this work and also using DFT, the diffusion of beryllium in perfect and defective graphite is here investigated, and the impact of defects on the diffusion process and chemical reactivity of graphite is assessed. An upper bond to activation energies related to these mechanisms is proposed, and mechanisms leading to the growth of Be 2 C at the interface between beryllium and graphite as experimentally observed [2][3][4][5][6][7] …”