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

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 BaTiO 3 /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 BaTiO 3 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. • A simple sol-gel route enabled the synthesis of bud-like BaTiO 3 /CNT hybrid powders. • 10BTO/CNT composite shows the best absorption by unique morphology and permittivity. • Optimal spacer thickness markedly improved the absorption performance in 10BTO/CNT. • Only 10 wt% of 10BTO/CNT achieves -39.3 dB, and spacer tuning boosts it to -56.1 dB.