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

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.