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, Fex(CoyNi1-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 Fex(CoyNi1-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 (RL) of the Fe23(Co0.5Ni0.5)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(Co0.5Ni0.5)77. Overall, this work is promising for the future design of high-performance microwave absorbing materials in a wide bandwidth.