Liquid metal coated copper micro-particles to construct core-shell structure and multiple heterojunctions for high-efficiency microwave absorption.

Facing the inherent defects of magnetic materials, the research of non-magnetic absorbers has gradually become a new direction in the research of microwave absorbers to fit the requirements of a new generation for high strength, wide effective absorption bandwidth. Herein, the liquid metal and copper (LC) composite micro-particles with multiple heterojunctions and core-shell structure, which have an excellent performance of microwave absorption (MA), were prepared by simply coating liquid metal on copper and then annealing. These special LC composite micro-particles exhibit excellent MA performance with the optimal reflection loss of -39.6 dB at thickness of 2.1 mm and a maximum effective absorption bandwidth of 4.96 GHz at thickness of 2.5 mm. The high MA performance of the LC composite particles are due to the enhancement of dielectric loss, including dipolar, interfacial, and dielectric polarization, which is caused by the special core-shell structure, multiple interfaces and heterojunctions. Furthermore, the multiple reflection/scattering of microwaves among particles or on the surface of particles also benefit to the high MA performance. Therefore, this study provides a facile method to construct multiple metal heterojunctions which have great prospects in microwave absorption applications.