Understanding the efficient microwave absorption for FeCo@ZnO flakes at elevated temperatures a combined experimental and theoretical approach

Considerable microwave absorption performance at elevated temperatures is highly demanded in both civil and military fields. Single dielectric or magnetic absorbers are difficult to attain efficient and broad-band microwave absorption at the high temperature range of 373 K-573 K, and the evolution mech-anism of the microwave absorption is still unclear especially for the magnetic absorbers. Herein, ZnO coated flaky-FeCo composite is proposed to break through the bottleneck, which possesses microwave absorption (RL <-10 dB) that covering the whole X band (8.2 GHz-12.4 GHz) at the temperature range of 298 K-573 K with a thickness of only similar to 2 mm. Moreover, attenuation mechanism and evolution of the microwave absorption properties for the FeCo@ZnO flaky material at elevated temperature has been clearly disclosed by the composition and microstructure characterizations, electromagnetic performance measurements and first principles calculations for the first time. Moreover, the Poynting vector, volume loss density, magnetic field ( H ) and electric field ( E ) are simulated by HFSS to understand the interac-tion between EM waves and the samples at different tem peratures, further elaborating the attenuation mechanism in high-temperature environment. This study provides guidance in designing and developing high-temperature microwave absorbers for the next generation. (c) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

This study proposes a zinc oxide-coated flaky FeCo composite with efficient and broad-band microwave absorption at high temperatures. The composition, microstructure, and electromagnetic performance of the material are investigated, revealing the attenuation mechanism and evolution of microwave absorption at elevated temperatures.