Boron nitride nanocages synthesized by a moderate thermochemical approach

The synthesis of boron nitride (BN) nanogages of less than 100 nm, was investigated. When NH₃/N₂ was introduced at 750 °C, NH₃ dissociated into the Fe-B catalyst surface where it formed N atoms, which then combined with B atoms from the Fe-B nanoparticles to form BN species on the catalyst surface. With the consumption of the surface B atoms, the inner B atoms of the catalyst diffused outwards to the particle surface due to concentration gradient, and the h-BN shell gradually grew inward around the Fe-B particle. High resolution transmission electron microscopy (HRTEM) indicated that the polyhedral nanocages were crystalline h-BN nanostructures characterized by the 0.34-nm spacing between neighbouring lattice fringes, which corresponded to the d₀₀₀₂ spacing of h-BN.