Few-atomic-layer boron nitride nanosheets synthesized in solid thermal waves

Abstract

In this study, we demonstrate the synthesis of few-atomic-layer hexagonal boron nitride (h-BN) sheets in a solid thermal wave implemented in a B₂O₃ + (3 + 0.5k)Mg + kNH₄Cl exothermic mixture (here, k is the mole number of NH₄Cl). The maximum synthesis temperature, developed using a thermal wave, was between 1030 and 1250 °C as k was changed from 5 to 7 moles. The phase content, morphology, and optical properties of the products were characterized. It is shown that BN sheets synthesized at the given k were 1.5–3 nm thick and had a hexagonal structure. The number of atomic layers in one sheet ranged from 5 to 10; the lateral dimension of individual sheets ranged from 50 to 1000 nm. The developed method allowed the synthesis of a large amount of uniform and high quality BN nanosheets (tens of grams in laboratory-scale experiments); this method will reduce the overall production cost.