Numerical simulation of effective dielectric constant of MXene films

Abstract

MXenes are two-dimensional carbides and nitrides that are relatively simple to manufacture. Even when very thin and flexible, their films can replace metals in many devices, such as electromagnetic shields and antennas, offering excellent performance. The lack of models for predicting their nanostructure-dependent homogenized electromagnetic properties hinders the design and optimization of such devices. Classical linear homogenization models, related to the Maxwell–Garnett approach, are useful for relatively low inclusion volume fractions and the dipolar field approximates the inclusion field well. Neither of these assumptions holds well for MXenes, which can be treated as layers of high-aspect-ratio conducting flakes. A numerical linear homogenization model and an analytical model useful for understanding the effects of the MXene nanostructure on the effective dielectric constant are presented. Numerical estimates are obtained using integral equations for the induced charges on the surfaces of MXene flakes. Parametric studies over varying aspect ratios, inter-flake spacing, and stacking configuration reveal that interleaved stacking can yield higher dielectric enhancement. The effective permittivity increases significantly with increasing aspect ratios in a linear fashion. The findings are consistent with experimental reports of high permittivity in MXene-based composites and offer design insights for engineering high-dielectric constant nanomaterials for electromagnetic interference shielding and communication applications.