Enhanced microwave absorption properties of Co-doped SiC at elevated temperature

Abstract

Here, Co-doped SiC powders with core/shell heterogeneous nanoarchitectures are synthesized through mechanically activation-assisted combustion method. Compared to undoped SiC, Co-doped SiC exhibits enhanced high-temperature dielectric and microwave absorption properties over 8.2–12.4 GHz. The Co dopants introduce abundant defects in SiC, such as VC, CoSi and CoSiVC, which can work as dipoles to promote the polarization loss, and create more carriers to increase the leakage loss according to the first-principle calculations. In addition, the core/shell nanoarchitectures of Co-doped SiC can result in interfacial polarization between the surface shell and the core to further enhance the dielectric loss and consequently improve the microwave absorption performance. The minimum reflection loss (RL) value of Co-doped SiC reaches up to −44.7 dB at a very thin thickness of 1.7 mm, more than 3 times the RL value of undoped SiC. This work provides new inspirations and insights that combining doping and fabricating core/shell nanoarchitecture would be an effective route for designing and exploiting novel high-temperature microwave absorption (MA) inorganic absorbers.