Synthesis of novel nanostructures by metal-polytetrafluoroethene thermolysis

Novel ceramic and carbon nanostructures have been created by thermolysis of mixtures containing polytetrafluoroethene (PTFE) and a pure metal or metal alloy in a calorimetric bomb. The influence of the stoichiometry was studied for Si-containing reactants for which the yield of the nanofibers was the highest. The process was monitored by measuring the heat of reaction and by differential thermal analysis/thermogravimetric techniques. The reaction temperatures were measured, and the heating rates of the reactants during thermal wave propagation were estimated. Elemental analysis, X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray spectrometry were employed to characterize the chemical composition and structural features of the products. Well-crystallized elongated single-crystal Si nanofibers, coated with a thin SiO2 amorphous layer, and crystallized carbon nanoparticles containing metals (e.g., Fe) and Si dominate. The highest yields of nanofibers and carbon particles were obtained from PTFE and Si-containing precursors, due to the volatility of SiF4.