Electromagnetic response mechanism of BaTiO₃-based metamaterials: Transition between microwave absorption and shielding capacity

As a classical ferroelectric material, the BaTiO₃-based electromagnetic metamaterials for microwave absorption/shielding have not been investigated. In this paper, triply-periodic minimal surface structures with varied unit cell dimensions (UCD) and relative densities (RD) are firstly constructed to investigate the relationship between macrostructure and electromagnetic response, and the single-step fabrication of BaTiO₃-based metamaterial microwave absorber is then achieved by 3D printing technology. The optimal microwave absorption performance with a minimum reflection loss of –59.06 dB and an effective absorption bandwidth of 1.7 GHz is achieved in X-band when the UCD is 1 T (taking the UCD in the direction of microwave incidence 1 T=1.47 mm as the standard, and enlarging the UCD as a whole to 5 T in 1 T steps) and the RD is 10 %. In contrast, when the UCD is 2 T, the total shielding effectiveness of BaTiO₃ metamaterial is 15.98 dB, which indicates that the transition from shielding to microwave-absorbing materials can be achieved through the optimization of the macrostructure. This study shows that by tailoring structural parameters, completely different electromagnetic responses can be obtained. Macrostructural design ideas for ferroelectric metamaterials can be explored in more depth based on the above studies.