Iron oxide nanopowders prepared by the electroexplosion of wire

Synthesis of Fe/Fe3O4 core-shell nanoparticles by electrical explosion of the iron wire in an oxygen-containing atmosphere

“…In contrary to the work (Kotov et al 2007), in our study, the formation of particles proceeds under oxygenpoor conditions, which limits the rate of oxidation being determined by diffusion of oxygen to the particle surface (external diffusion limitation). At high temperatures and low oxygen partial pressures, iron is oxidized to FeO.…”

“…5 and in Table 2. From the presented data, it follows that as the Oxygen content in the buffer gas (argon), vol.% The phase composition of iron oxide nanoparticles obtained in our experiments differs from that of iron oxide nanoparticles obtained by the electric explosion of the iron wire (Kotov et al 2007). In the mentioned publication, the authors showed that the metastable γ-Fe 2 O 3 (98 wt.%) is formed in the electrical explosion of iron wires of diameter 0.35 mm, a gas pressure of a heliumoxygen mixture of 10 5 Pa, and an oxygen content in a gas mixture of 20 and 30 vol.%.…”

“…When EEW is carried out, the formation of a chemical compound can be realized through two scenariosthe diffusion of a reactive gas into the bulk of a nanoparticle or the evaporation of part or all of the metal phase due to the exothermic effect and the occurrence of a chemical reaction in the gas phase (Kotov et al 2007;Lerner et al 2016b). According to (Distin and Whiteway 1970), the oxidation of iron droplets levitating in helium-oxygen mixtures at 1750 °C occurs in the gas phase due to the evaporation of a part of the metal already at an oxygen content of 1.46%.…”

“…The exothermic effect of the iron oxidation reaction to oxides FeO and Fe 3 O 4 contributes to the intensification of the metal evaporation process. At a high oxygen concentration, small iron particle evaporation takes place (Kotov et al 2007), with incomplete oxidation observed only in large particles with a size of more than 10 μm. Upon subsequent rapid cooling of the gas phase, γ-Fe 2 O 3 nanoparticles are formed.…”

“…EEW with a wire from a corresponding metal in an oxygen-containing atmosphere yields metal oxide nanoparticles, for example, Al 2 O 3 , TiO 2 , ZrO 2 , and Fe 2 O 3 + Fe 3 O 4 (Kotov et al 1997;Kotov et al 2007;Lerner et al 2016a). During EEW, a mixture of superheated metal vapor and molten metal droplets (so-called explosion products) is formed in the form of a cylinder cloud with a much higher density than that of the surrounding gas (Kotov 2003).…”