Dual driving strategy from micro-polarization to macroscopic conductance: Tailoring optimized low-frequency and wide-band microwave absorption in high-entropy oxides

Recently, the strategy of tuning the dielectric parameters of absorbers for their excellent electromagnetic wave absorption (EMA) performance has attracted much attention. Among those candidates used for EMA application, high-entropy oxides (HEOs) can be implemented with this strategy due to their rich composition modulability. In this work, a series of implementation approaches varying from elemental design to structural modulation are employed to modulate the dielectric parameters of HEOs, resulting in their excellent EMA performance. The addition of Ti element optimizes the dipole distribution at the microscopic scales, improving the dielectric polarization of the materials. Moreover, a composite material is constructed by physically blending HEO with acetylene black (ACET), which significantly improves the macroscopic conduction loss of the material. The optimization of the dielectric genes of HEO/ACET is achieved with the blending effect and excellent EMA performance could be obtained. Among them, HEO with 17.5% ACET addition exhibits dual-band absorption, while Ti-HEO containing Ti element exhibits not only low-frequency absorption with reflection loss (RL) up to −29.81 dB at C-band but broadband absorption over 6 GHz as well as an optimal RL value up to −52.31 dB. In addition to the development of innovative EMA materials, this study offers a new perspective on how the EMA characteristics can be effectively regulated.