Facile synthesis of bud-like BaTiO3/CNT composite as a high-performance microwave absorber: Significantly boosted by a tunable spacer

Abstract

Wireless technology has facilitated world development and innovation, yet overutilization has led to interference, disruption, and safety concerns in microwave applications. The high electromagnetic wave dissipation capability of a lightweight absorber highlights its strong potential for advanced absorption applications. In the present study, the bud-like BaTiO₃/CNTs (BTO/CNTs) as absorbing materials were synthesized by a sol-gel method. The characteristics of BTO/CNT hybrid powders were investigated through a series of examinations, including scanning and transmission electron microscopy, X-ray diffraction, Raman spectroscopy, etc. The electromagnetic properties were revealed by filling 10 wt% absorbing hybrid powder in epoxy resin as an absorbing composite. The best BTO content was screened by their absorption performance in various amounts from 10 to 70 wt%. The 10BTO/CNT (i.e., 10 wt% of BaTiO₃ contained) exhibited the best absorption performance, due to the good impedance matching and the strong attenuation. The 10BTO/CNT composite exhibits superior reflection loss of −39.3 dB with a thickness of 2.2 mm at 11.52 GHz, and an effective maximum absorption bandwidth (EMAB) of 5.04 GHz at 1.6 mm. Furthermore, the 10BTO/CNT composite was used as an absorbing layer in combination with an air spacer to investigate the optimal composite and spacer thickness (d_s) for enhanced absorption performance. An optimized absorbing layer thickness of 1.8 mm, combined with a spacer thickness of 0.25 mm, results in a reflection loss of −56.1 dB at 12.96 GHz. A significantly boosted absorption was achieved by introducing the optimized d_s with 10BTO/CNT absorbing composite.