Synthesis of niobium nitride porous nanofibers with excellent microwave absorption properties via reduction nitridation of electrospinning precursor nanofibers with ammonia gas

Abstract

In order to solve the pressing issue of electromagnetic interactions, such as radar detection, communications, information processing and transport originates from civil and military fields, the niobium nitride porous nanofibers as novel microwave absorption materials have been prepared by electrospinning method followed the ammonia reduction nitriding process in the present work. The chemical composition, phase composition and pore structure of niobium nitride fibers are related with the reduction nitriding temperature. It was found that the phase of as-prepared nanofibers was quadrate Nb 4 N 5 phase and Nb 5 N 6 phase formed with the increase of reduction nitriding temperature. Meanwhile, the O atoms were still existed in the form of NbN x O y solid solution. The XPS results also demonstrate that niobium nitride nanofibers had residual oxygen element and abundant valence state, which were positive to impedance matching and interface polarization. The nitrogen content increased and the oxygen content decreased with the increase of reduction nitriding temperature. It was verified that the fibers were composed of niobium nitride nano-crystallite and a large number of holes. The average size of niobium nitride nanoparticles and the pore diameter in nanofibers increase as the reduction nitriding temperature increases. The as-prepared niobium nitride nanofibers with characteristic porous fibrous structure would provide the outstanding conductivity loss, magnetic loss, Debye relaxation, multiple reflections and scatterings, and suitable impedance matching. Hereby, the niobium nitride porous nanofibers were synthesized at 800 ℃, it exhibited excellent electromagnetic wave absorption ability and its optimal reflection loss value was − 49.5 dB at 8.9 GHz when matching layer thickness was only 2.04 mm. • A novel niobium nitride porous fibers as microwave absorbing materials were synthesized via electrospinning method followed the ammonia reduction nitriding process. • The optimal reflection loss was as high as − 49.5 dB at a thin thickness was 2.04 mm. • The residual oxygen and porous fibrous structure improved the impedance matching, multiple reflections and scatterings, conductivity loss, and Debye relaxation through the synergistic effect.