Tunable Negative Permittivity and Magnetic Properties of Ag/BLM Ceramic Metacomposites

Percolation composites with tunable negative permittivity have garnered significant attention due to their potential applications. However, studies on the magnetic property and negative permittivity of ceramic composites at a frequency range of 100 MHz to 1 GHz are relatively scarce. In this paper, the porous La-doped barium ferrite (BLM) ceramics were immersed in silver nitrate solution, then put the dried porous BLM ceramics loaded with silver nitrate into a box furnace and calcined at 400 °C for 30 min to decompose the silver nitrate. Ag content could increase by increasing the number of impregnation-calcinations, therefore Ag/BLM ceramic metacomposites with varying Ag content were prepared. We investigate the permittivity, reactance, and permeability of Ag/BLM ceramic metacomposites at 100 MHz ∼ 1 GHz. The findings indicate that the percolation threshold for Ag/BLM ceramic metacomposites is between 10 wt% and 19 wt%. When Ag content reaches 19 wt%, it creates a conductive network that generates a high number of free electrons. This leads to low-frequency plasma states and results in negative permittivity. Meanwhile, the permeability of Ag/BLM ceramic metacomposites shows the frequency dispersion due to the magnetic resonance and eddy current. Therefore, this work presents an effective approach for adjusting the value of negative permittivity and permeability in the frequency band of 10 MHz ∼1 GHz.