Unique dielectric dispersion induced ultra-broadband microwave absorption of tellurium doped black phosphorus nanoflakes/aramid nanofibers/carbonyl iron nanopowders ultra-lightweight aerogel

Abstract

With the development of microwave technology and the widespread use of high-frequency electronic equipment, electromagnetic pollution is becoming increasingly serious. The research and development of electromagnetic protection technology and lightweight broadband microwave absorption materials are urgent. In this work, the lightweight and porous tellurium-doped black phosphorus nanoflakes/aramid nanofibers/carbonyl iron nano-powder aerogel (TBAC) was prepared by vacuum extraction and freezing drying method. The low conductivity of TBAC aerogel exhibited a unique dielectric dispersion phenomenon, where the imaginary part of the permittivity spectrum displayed a strong resonance peak. It resulted in the wavelength of the microwave inside the medium no longer decreasing monotonically with frequency, providing new ideas for expanding the microwave absorption bandwidth. Strong magnetic carbonyl iron nanopowders were devoted to adjust the impedance characteristics of the composites by changing the content, achieving strong absorption. Aramid nanofibers were used to prepare porous aerogel, and acted as an adhesive instead of paraffin. Porous aerogel realized the material ultra-lightweight (0.02–0.043 g/cm3), while enhancing the polarization of the medium, as well as the multiple reflection of microwaves. By uniformly dispersing Te-BP and carbonyl iron in ANF aerogel, TBAC-1-3 aerogel exhibited the minimum reflection loss (RLmin) of −55.1 dB and an effective absorption bandwidth (EAB) of 6.55 GHz with the thickness of 1.7 mm. Additionally, the ultra-broadband EAB of 8.46 GHz under single thickness of 1.9 mm was obtained. Therefore, the ultra-lightweight TBAC aerogel offer a high-performance solution for ultra-broadband microwave absorption.