Enhancement of piezoelectric and flexoelectric response of boron nitride sheet superlattices via interface and defect engineering

Abstract

In this work, the piezoelectric, flexoelectric and elastic coefficients of boron nitride sheet/s (BNS) with graphene stripes were determined via molecular dynamics simulations (MDS) with a Tersoff potential force field. The external electric-field (E-field) was applied in the two most relevant orientations of BNS: armchair and zigzag. Our results reveal that the coherent interface engineering of zigzag stripe and hexagonal ring of graphene with BNS can be utilized to enhance the total electronic response of resulting hybrid BNS. For instance, the increase in total polarizations when the E-field applied in the armchair and zigzag directions of hybrid BNS are found to be 17% and 21%, respectively, compared to pristine BNS due to the interface engineering of BNS/zigzag graphene stripe. Moreover, we determined the elastic properties of hybrid BNS and found that its Young's and shear moduli enhanced by 17.5% and 12%, respectively. The other cases, interface engineering of BNS/hexagonal ring of graphene and defect engineering of Stone-Wales (SW) defected BNS also improved the total polarization of BNS compared to the pristine BNS but lower than the first case. Comparisons of the (i) axial piezoelectric and flexoelectric coefficients of pristine BNS, and (ii) elastic coefficients of pristine and hybrid BNS with the existing results are found to be in good agreement. This study opens up an avenue for enhancing the net polarization as well as the elastic properties of existing BN sheets via integration of graphene stripes in them and defect engineering in general. © 2020 Elsevier B.V.