Constructing multi-layer heterogeneous interfaces in liquid metal graphite hybrid powder: Towards microwave absorption enhancement.

Carbon based materials are widely used in the preparation of microwave absorption materials due to their low density, high attenuation loss and large specific surface area. However, their high conductivity usually leads to high reflection loss. In this study, multi-layer heterogeneous interfaces were constructed in liquid metal graphite hybrid powder to reduce reflection loss and enhance microwave absorption performance. Gallium oxide (GaO) layer was formed in Ga coated graphite powder to improve impedance matching and attenuation constant via an annealing treatment. Specifically, the hybrid particles with 50 wt% Ga and being annealed at 120 °C for 2 h have a minimum reflection loss (RL) value of -42.68 dB and a maximum effective absorption bandwidth (EAB) of 4.11 GHz at a thickness of 3.3 mm. The hybrid particles not only have multi-layer structures with different electrical conductivity, but also form heterojunctions between different interfaces, which can further enhance dipole and interfacial polarization.