Intrinsic thermal conductivities of BC₃-C₃N superlattice nanoribbons: A molecular dynamics study

Superlattice nanostructures enable controllable thermal conductivity minimization in nanodevices for thermoelectric applications. This is especially true regarding recently developed carbon nitride (C₃N) and boron carbide (BC₃) nanostructures. In this study, we explored phonon heat transport in a superlattice nanoribbon with C₃N and BC₃ domains using non-equilibrium molecular dynamics (NEMD) simulation. Specifically, we investigated the impacts of changing the unit cell length, nanoribbon length, average temperature, and temperature difference between the hot source and cold sink on the thermal conductivity of the nanoribbon. Based on our results, the value of the intrinsic thermal conductivity (k_∞) reaches a minimum of 206 W m⁻¹ K⁻¹ at room temperature for a superlattice nanoribbon unit cell length of 8.5 nm. At infinite total length, the minimum thermal conductivity obtained for the BC₃-C₃N superlattice nanoribbon is about 40 % and 25 % of the thermal conductivities of pristine BC₃ and C₃N nanoribbons, respectively. The observed minimum thermal conductivity in the nanoribbons is attributed to the phonons transitioning from coherent to incoherent transport, where the unit cell length is comparable to the phonon coherence length. The results of this work provide atomistic insights into the development of low-thermal-conductivity nanomaterials for thermal insulation applications.