Nickel/yttrium iron garnet metacomposites with adjustable negative permittivity behavior toward electromagnetic shielding application

Recent advancement of metacomposites with negative permittivity has provided a new research approach for the design and construction of electromagnetic (EM) shielding materials. Here, we fabricated nickel/yttrium iron garnet (Ni/YIG) metacomposites by a convenient liquid impregnation approach and explored their electromagnetic properties at MHz and Ku bands. As the Ni content increased, some isolated Ni particles formed threedimensional interconnected networks in the composites, leading to the changes of conducting mechanism and reactance characteristic. A negative permittivity behavior was observed in the composites with high Ni contents, which was put down to low-frequency plasma state of free electrons in the completed Ni networks. The dispersion of negative permittivity at frequencies below 10 MHz was affected by the isolated metal particles and could be well described by the Drude-Lorentz model. An impressive shielding effectiveness of 33.1 dB was achieved at Ku band with a reflection-dominated mechanism, which was ascribed to the negative permittivity induced impedance mismatch. The inductive conducting networks were vital building blocks in the metacomposites for realizing negative permittivity and improving EM shielding performance. This work offered guidance for designing EM shielding metacomposites and promoted the next development of this field.

Automated summary

The recent advancement of metacomposites with negative permittivity provides a new research approach for the design and construction of electromagnetic shielding materials. In this study, Ni/YIG metacomposites were fabricated using a liquid impregnation approach and their electromagnetic properties were explored at MHz and Ku bands. With an increase in Ni content, isolated Ni particles formed interconnected networks in the composites, resulting in changes in conducting mechanism and reactance characteristic. The composites with high Ni contents exhibited a negative permittivity behavior, attributed to low-frequency plasma state of free electrons in the completed Ni networks. The dispersion of negative permittivity at frequencies below 10 MHz was influenced by isolated metal particles and could be well described by the Drude-Lorentz model. A notable shielding effectiveness of 33.1 dB was achieved at Ku band, primarily due to the impedance mismatch caused by the negative permittivity. The inductive conducting networks were crucial building blocks for achieving negative permittivity and improving electromagnetic shielding performance. This work provides guidance for designing electromagnetic shielding metacomposites and promotes further development in this field.