Thermal transport across few-layer boron nitride encased by silica

Two dimensional hexagonal boron nitride (h-BN) attracted attention for use in applications. Using equilibrium molecular dynamics, we examine the phonon transport in few-layer h-BN encased by silica (SiO₂). We report large interfacial thermal resistances, of about 2.2 × 10^-8 m² K W^-1, which are not sensitive to the number of h-BN layers or the SiO₂ crystallinity. The h-BN/SiO₂ superlattices exhibit ultra-low thermal conductivities across layers, as low as 0.3 W/m K. They are structurally stable up to 2000 K while retaining the low-thermal conductivity attributes. Our simulations indicate that incorporation of h-BN layers and nanoparticles in silica could establish thermal barriers and heat spreading paths, useful for high performance coatings and electronic device applications.