Boron nitride nanostructures formed by ultra-high-repetition rate laser ablation

High-repetition rate (2 × 105 pulses/s), short-pulse (60 ps) laser was used for the first time for ablation of a hexagonal boron nitride (BN) target at nitrogen pressure of ∼ 100 Torr in search for the optimum conditions of BN nanostructure formation. High-resolution transmission electron microscopy, electron energy loss spectroscopy, and energy-filtered TEM analysis of the produced nanomaterial revealed a variety of BN nanostructures formed due to the interaction of BN plume with nitrogen ambient. Nanorods, multi-layered nanocages, double-layered 'nanohorns', and multi- and single-walled BN nanotubes were discovered in the product. BN nanotubes exhibiting various diameters and numbers of layers, including single-walled nanotubes, were frequently assembled in bundles.