Effect of synthesis temperatures on the composition, microstructure, and microwave absorption properties of titanium nitride porous nanofibers prepared using ammonia reduction nitridation process

In order to reveal the effect of synthesis temperatures on the capacity in tailoring the composition and morphology of titanium nitride nanofibers and their microwave absorption properties, the titanium nitride nanofibers have been prepared by the electrospinning method combined with ammonia reduction nitriding process in the present work. The composition and microstructure of titanium nitride nanofibers synthesized at different reduction nitriding temperatures were investigated and their microwave absorption properties were measured. It was found that the phase of as-prepared nanofibers translated from TiO₂ to TiN with the increase of reduction nitriding temperature. Meanwhile, the XRD, XPS, and EDS results demonstrated that the residual oxygen element still existed in the form of TiN_xO_1−x solid solution, which is beneficial to the improvement of impedance matching and interface polarization. The nitrogen content increased and the oxygen content decreased gradually with the increase of reduction nitriding temperature. The SEM and HRTEM results showed that the as-prepared nanofibers were accumulated by titanium nitride crystal particles, resulting in the formation of a large number of pores. The composition and microstructure of as-prepared titanium nitride nanofibers varied with the reduction nitriding temperature, which could provide the outstanding conductivity loss, Debye relaxation, multiple reflections and scatterings, and suitable impedance matching. As a result, the reflection loss value of as-prepared titanium nitride nanofibers decreased as the reduction nitriding temperature increased from 600 to 900 °C. Hereby, the microwave-absorbing properties of TiN nanofibers could be regulated via reduction nitriding reaction temperature and the optimal reflection loss value of TiN nanofibers was − 46.7 dB with matching layer thickness of 1.04 mm.