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The exothermic reduction of oxides mixture (MoO 3 +2SiO 2 ) by magnesium in NaF melt enables the synthesis of nanocrystalline MoSi 2 powders in near-quantitative yields. The combustion wave with temperature of about 1000–1200 °C was recorded in highly diluted by NaF starting mixtures. The by-products of combustion reaction (NaF and MgO) were subsequently removed by leaching with acid and washing with water. The as-prepared MoSi 2 nanopowder composed of spherical and dendritic shape particles was consolidated using the spark plasma sintering method at 1200–1500 °C and 50 MPa for 10 min. The result was dense compacts (98.6% theoretical density) possessing submicron grains and exhibiting hardness of 8.74–12.92 GPa. [ABSTRACT FROM AUTHOR]

A melt-assisted solid flame synthesis approach was applied to synthesize boron nanoparticles in argon gas and air atmospheres. For this purpose, we investigated the characteristics of a thermally induced combustion wave in B 2 O 3 + α Mg mixtures ( α = 1.0–1.5 mol) in argon and air atmospheres. Utilizing stoichiometrically insufficient amounts of magnesium ensured that a large portion of molten B 2 O 3 remained in the sample, which reduced the combustion parameters and favored the formation of boron nanoparticles. Under these conditions the combustion temperature and burning velocity were controlled in the range of 1300–1580 °C and 0.065–0.18 cm/s, respectively, and boron nanoparticles in a ∼20–200 nm size range were obtained. The characteristics of boron nanoparticles (morphology, purity, specific surface area, oxidation activity, etc.) were analyzed and a reaction pathway leading to boron nanoparticles synthesis was proposed. [ABSTRACT FROM AUTHOR]