Constructing three-dimensional reticulated carbonyl iron/carbon foam composites to achieve temperature-stable broadband microwave absorption performance

Microwave absorbing materials with stable-wide effective absorbing bandwidth (EAB) are regarded as desirable candidates for eliminating electromagnetic interference at high temperatures. However, it still remains a challenge to simultaneously regulate the dielectric and magnetic losses in wide temperature ranges for the above excellent microwave absorption performance. Herein, a novel magnetic-dielectric composite of carbonyl iron (CI)/carbon foam (CF) with three-dimensional (3D) reticulated structure is fabricated for the first time by carbonization and vacuum impregnation. 3D reticulated structure not only provides well-defined conductive paths and controlled electrical conductivity-temperature characteristics for optimizing dielectric loss, but also induces structural magnetic loss through induced currents to retard the attenuation of magnetic loss at high temperatures. Benefiting from the synergistic regulation of dielectric and magnetic losses, CI/CF composites show the ultra-stable wide EABs at a thickness of only 1 mm, maximum EAB of 8.48 GHz and minimum EAB of 8.32 GHz in the temperature range of 298-573 K. This work provides inspirations for construction of high-temperature microwave absorbing materials with tunable magnetic and dielectric losses.