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In this study, tantalum network nanoparticles are prepared from a Ta 2 O 5 + k Mg system via a liquid magnesium-controlled combustion reaction. Super-stoichiometric amounts of magnesium are used in the preparation of a reaction mixture to produce a liquid magnesium pool capable of lowering the combustion temperature and leading to the formation of Ta network structures. The heat transfer kinetics from the hot reaction zone of 'cold' Mg particles is determined using heat transfer-coupled fluid dynamics simulation software. The formation of network structures is characterized through SEM, TEM, XRD, and BET analysis techniques. The mechanism of network formation is explained based on solid particle collisions in liquid media. Our method is able to produce Ta network structures in which the size of individual particles ranges between 50 and 700 nm. [ABSTRACT FROM AUTHOR]

This study deals with combustion behavior of B 2 O 3 /Mg/NH 4 Cl/C complex systems for the synthesis of amorphous boron (B), boron carbide (B 4 C), and boron nitride (BN) nanostructures. The raw mixtures used in the experiments were prepared on the base of a B 2 O 3 –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, B 4 C, and BN. It was found that B-containing functional nanostructures are mainly spherical nanoparticles (B) or nanosheets (B 4 C, BN). The phase composition and microstructural characteristics of the final products were evaluated based on the combustion temperature and solid/liquid phase changes. [ABSTRACT FROM AUTHOR]