Tuning the shell thickness of core-shell α-Fe2O3@SiO2 nanoparticles to promote microwave absorption

Various advanced microwave absorbing materials have been developed for reducing/avoiding the harm of microwave radiation. Among them, core-shell structural nanomaterials have been widely fabricated for microwave absorption. However, the "structure-performance" relationship between shell thickness and microwave absorption performance is rarely reported. In this paper, we first explored the "structure-performance" relationship between shell thickness and microwave absorption performance, based on the core-shell alpha-Fe2O3@SiO2 nanoparticles with a constant alpha-Fe2O3-core size and changeable SiO2-shell thickness. With increasing the SiO2-shell thickness, the microwave absorption ability first increased, then decreased. Under a proper SiO2-shell thickness of 35 nm, alpha-Fe2O3@SiO2 sample achieved the strongest microwave absorbing ability with a reflection loss minimum value of -4.3 dB, better than that of pure alpha-Fe2O3 (-3.8 dB). This enhanced microwave absorption performance was mainly derived from the dielectric loss. Although the absolute value of the reflection loss was relatively low (-4.3 dB), this study shed an important reference on designing next-generation advanced iron oxide-based materials for microwave absorption. (C) 2021 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.