Magnetic nanoparticles based on iron and its oxides are promising in various biomedical applications. Currently, as a rule, ferromagnetic iron oxide particles with a low specific magnetic moment are used for medical purposes. In the present work, a new method for the synthesis of magnetic nanoparticles based on the electric explosion of a Fe wire is proposed. When wires are dispersed by high current electric pulse in an inert atmosphere containing less than 5% oxygen, nanoparticles with a core-shell structure are formed, where the core is α-Fe and the shell is formed by a mixture of oxides Fe 3 O 4 and FeO. The oxygen concentration in the buffer gas has been found to determine the size of the resulting nanoparticles, their shape, and iron content. The iron oxide shell protects the iron core from the external environment, preventing the rapid dissolution of Fe containing in the nanoparticles, in contrast to nanoparticles obtained in argon atmosphere. The specific magnetic moment of nanoparticles, depending on the content of iron oxides, varies from 90 to 180 emu/g. Keywords Fe-Fe 3 O 4 nanoparticles . Electrical explosion of a wire . Oxidation . Core-shell structures . Magnetic properties

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The paper studies patterns of interaction of electroexplosive Co nanoparticles with air oxygen during heating. The characteristics of Co nanoparticles and composite Co/CoO/Co3O4 nanoparticles formed as a result of oxidation were studied using transmission electron microscopy, X-ray phase analysis, thermogravimetric analysis, differential scanning calorimetry, and vibrating sample magnetometry. It was established that nanoparticles with similar morphology in the form of hollow spheres with different content of Co, CoO, and Co3O4 can be produced by varying oxidation temperatures. The influence of the composition of composite nanoparticles on their magnetic characteristics is shown.