Microwave absorption properties of Fe/Fe16N2 nanoparticles prepared from iron oxide

Fe/Fe
16
N
2
nanoparticles was prepared from Fe
3
O
4
nanoparticles by hydrogen reduction and subsequent low-temperature nitriding process. XRD analysis showed that Fe
3
O
4
phase was fully transformed into α-Fe phase after hydrogen reduction at 400°C. Fe
16
N
2
component was confirmed after nitriding of the Fe nanoparticles from 140°C to 160°C. Volume fraction of Fe
16
N
2
was increased by increasing nitriding temperature, leading to increase in coercivity. The electromagnetic properties showed that the resonance frequency of resin composite of reduced Fe nanoparticles was 6.9 GHz, and it shifted to 9.5 GHz for resin composite of subsequent nitridation nanoparticles due to crystal structure of Fe
16
N
2
with large anisotropic field. It suggests that the resin composite containing Fe
16
N
2
nanoparticles is a promising microwave absorption material for 5G applications.