Quantitative phase analysis of magnetic Fe@C nanoparticles

Substantial progress in the area of nanotechnology requires special quality of magnetic nanoparticles. Conventional methods of analysis are not always efficient to the study of nanoparticles. This paper is dedicated to the problem of quantitative analysis of the phase composition of ferromagnetic nanoparticles and the fundamental issue of transition to the single domain magnetic state. A comprehensive study of Fe@C nanoparticles has been carried out, including local Fe-57 NMR and MOssbauer spectroscopy methods. It has been found that the cores of nanoparticles contain phases of alpha-iron, iron carbides, ferromagnetic and paramagnetic phases of iron-carbon FeCx solid solutions. Annealing of the nanoparticles leads to a significant redistribution of the phase composition and leads to an increase in magnetization. Also, a nanoscale effect has been found. It consists in observation of two lines in NMR spectra corresponding to multidomain and single-domain state. The hyperfine fields obtained by NMR and Mossbauer spectroscopy methods are discussed.

Automated summary

This paper focuses on the quantitative analysis of the phase composition of ferromagnetic nanoparticles and the transition to the single domain magnetic state. Fe@C nanoparticles were studied comprehensively, revealing the presence of multiple phases in their cores. Annealing leads to redistribution of phase composition and increased magnetization, while also observing a nanoscale effect in the NMR spectra.