B-containing nanomaterial synthesis when a combustion wave moves within a packed bed of solid particles

This study deals with combustion behavior of B2O3/Mg/NH4Cl/C complex systems for the synthesis of amorphous boron (B), boron carbide (B4C), and boron nitride (BN) nanostructures. The raw mixtures used in the experiments were prepared on the base of a B2O3-Mg precursor mixture, which is sufficiently exothermic to maintain a self-propagating regime of the combustion reaction. Thermodynamic analysis of the combustion temperatures and experimental validation indicate that the 1000-1500 °C temperature range is very effective for synthesizing the nanostructures of B, B4C, and BN. It was found that B-containing functional nanostructures are mainly spherical nanoparticles (B) or nanosheets (B4C, BN). The phase composition and microstructural characteristics of the final products were evaluated based on the combustion temperature and solid/liquid phase changes.