Contrasting Elastic Properties of Heavily B- and N-doped Graphene with Random Impurity Distributions Including Aggregates

Abstract

We focused on elastic properties of B- and N-doped graphene in a wide range of concentrations up to 20%. The Young’s, bulk, and shear moduli and Poisson’s ratio have been calculated by means of density functional theory for a representative set of supercells with disordered impurity patterns including aggregates. In contrast to earlier work, it is demonstrated that doping with nitrogen strengthens the graphene layers, whereas incorporation of boron induces large structural and morphological changes seen in simulated STM images. Young’s and shear moduli increase or decrease with the doping concentration for nitrogen or boron, respectively, while bulk modulus and Poisson’s ratio exhibit opposite trends. Elastic properties of samples for both types of impurities are strongly related to the electronic structures, especially for heavy doping (>12%). Local arrangements of dopants and an aggregation or separation of impurities play crucial roles in the determination of stiffness in the investigated systems. Interestingly, these findings are different for B- and N-contained samples.