Phase transformations as a result of thermal annealing of nanocomposite Fe–Ni / Fe–Ni–O particles

Abstract

The paper presents the results of a study of changes in structural and magnetic characteristics, as well as phase transformations in Fe–Ni/Fe–Ni–O nanoparticles obtained by chemical synthesis and subsequent thermal annealing. It was found that the initial nanoparticles are a three-phase system consisting of Fe–Ni–O oxide with a spinel structure and a Fe–Ni alloy with a face- and body-centered cubic lattices. As a result of thermal annealing, a decrease in the Fe–Ni phase was established with subsequent ordering of the Fe–Ni–O phase with a decrease in the crystal lattice parameter and an increase in the degree of crystallinity. During resurces tests, it was found that for single-phase Fe–Ni–O nanoparticles, the lifetime is close to 500 discharge/charge cycles, which is a good indicator of the working life and makes it promising to use Fe–Ni/Fe–Ni–O nanoparticles as anode materials for lithium-ion batteries.