Pomegranate-like ATO/SiO2 microspheres for efficient microwave absorption in wide temperature spectrum

High-performance microwave-absorbing materials (MAMs) should meet both impedance matching and attenuation performance. Commonly, it is hard to maintain excellent microwave absorption (MA) performance at an elevated temperature because the reliance on impedance matching and dielectric loss about temperature mutually restricts. In this work, the pomegranate-like antimony-doped tin dioxide (ATO)/ silica dioxide (SiO2) spheres were fabricated via a simple spray drying process. When the spheres were used as functional units and dispersed in the matrix, the corresponding composites exhibit an outstanding anti-reflection effect on microwaves. Moreover, the unique pomegranate-like structure of the ATO/SiO2 spheres provides both the effective local eddy current and abundant heterogeneous interface, which therefore contribute harvest enhanced dielectric relaxation and improved absorption performance when compared with that of the corresponding ATO/SiO2 composition. As a result, the maximum reflection loss of the ATO/SiO2 spheres composites can reach –47.8 dB at 9.7 GHz with a thickness of 1.8 mm, while the reflection loss could reach –47.3 dB at 573 K and the effective absorption bandwidth is 2.4 GHz. This work reveals the importance of local eddy current loss in optimizing the electromagnetic wave (EMW) absorption performance and impedance matching, providing novel guidance on designing advanced high-temperature MAMs.