Tunable natural resonances via synergistic effects of two phases in Fe (Co Ni1-)100- for multi-band microwave absorption

Multi-band microwave absorption is becoming ubiquitous owing to the increasingly complex electromagnetic environment driven by the diversity of electronic devices. However, research on efficient electromagnetic absorbers applicable in both centimeter-wave and millimeter-wave bands to address the electromagnetic interference in 5G networks is highly challenging. In this study, Fe_x(Co_yNi_1-y)_100-x particles with two phases (face-centered cubic (FCC) and hexagonal close-packed (HCP)) were synthesized and were found to exhibit excellent electromagnetic wave absorption. HCP phase with high magnetocrystalline anisotropy was introduced into FCC phase Fe_x(Co_yNi_1-y)_100-x, resulting in natural resonances in multi-band frequency. Prominent microwave absorption properties in ultra-wide bandwidth ranging from 6.9 to 39.5 GHz were obtained. The maximum reflection loss (R_L) of the Fe₂₃(Co_0.5Ni_0.5)₇₇ composite film reached −50 dB. Such a remarkable absorption performance is attributed to the synergetic effects of the multiple natural resonances generated by the coexistence of HCP and FCC phases in Fe₂₃(Co_0.5Ni_0.5)₇₇. Overall, this work is promising for the future design of high-performance microwave absorbing materials in a wide bandwidth.