First-Principles Calculations of a New Semi-Conductive Carbon Allotrope Named ABF-Carbon

Felipe Lopes Oliveira ,Pierre M Esteves

doi:10.21577/0103-5053.20200238

Abstract

Carbon is an extremely versatile element and can generate a plethora of structures with distinct properties. Proposing new possible metastable allotropic structures for carbon has been the subject of increasing interest over the past few years. In this contribution, we present a new carbon allotrope, named ABF-Carbon, based on the connection of spiropentadiene molecular motif and sp3 carbon atoms. This new structure is a metastable carbon allotrope formed by 6 carbon atoms, being 2 sp2 and 4 sp3, in a body-centered tetragonal with space group I4m2 (space group 119) and point group D2d11. By first-principles calculations using the density functional theory (DFT), we predict that this new structure is mechanically and structurally stable and presents thermal stability up to 900 K. The calculations also show that ABF-Carbon presents a direct bandgap of 2.39 eV and higher cohesive energy than other carbon allotropes, such as T-Carbon and Y-Carbon/1-diamondyne.

Highlights

Carbon is one of the most versatile elements of the periodic table
In a previous publication,[30] we showed that it is possible to use the spiropentadiene molecule as a structural motif to build a new carbon allotrope composed of sp[2] and sp[3] carbon atoms, called Spiro-Carbon, directly connecting the spiro units throughout double bonds.[22]
All ab initio calculations were carried out based on density functional theory (DFT) calculations under periodic boundary conditions approach as implemented in the PWscf code of Quantum ESPRESSO version 6.4.31,32 Exchange and correlation effects are treated with generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) functional[33] and ultrasoft pseudopotentials[34] was used to describe the nuclei and core electrons

Summary

Introduction

Due to its ability to present itself in different hybridizations several distinct structures, which are denominated allotropes,[1] can be conceived using only carbon atoms. The most remarkable examples include graphene,[2] fullerenes,[3] nanotubes,[4] carbyne,[5,6] graphdiyne,[7] T-Carbon,[8,9] cyclo[18]carbon,[10,11] and many other nanoallotropes.[12] Besides those structures, several other allotropic forms such as Y-Carbon,[13] hexagonal carbon foams,[14] biphenylene carbon,[15] tetragraphenes,[16,17] K6 carbon,[18] C3,19 schwarzites,[20] Pentagon-Carbon,[21] Spiro-Carbon,[22] n-diamondynes,[23] and many others have been theoretically proposed and their properties computationally studied. Most of these structures are compiled in the Samara Carbon Allotrope database (SACADA).[24]

Methods

Results

Conclusion