Electromagnetic wave absorption performance of NiCo2X4 (X = O, S, Se, Te) spinel structures

With the extensive development of electrical communication equipment, the requirements for electromagnetic (EM) wave absorption materials have become more stringent to eliminate electromagnetic interference issues. Rational regulation of permittivity is an efficacious path to optimal EM wave absorption performance. NiCo based spinel materials (NiCo2X4, X = O, S, Se, Te) have been regarded as promising EM wave absorbing materials due to the advantage of controllable structure, inexpensive procedure and excellent dielectric property. Particularly, the element of anionic sites acts as a considerable role in determining the conductivity and permittivity of materials. Herein, spiny globose like NiCo2X4 (X = O, S, Se, Te) are successfully prepared through hydrothermal and subsequent oxidation, sulfidation, selenization and tellurization methods, respectively. Due to the difference in electronegativity of the anion site elements, NiCo2Se4 and NiCo2Te4 show ameliorative conductivity and dielectric loss. An optimal reflection loss (RL) of −78.5 dB at 2.8 mm and an effective absorption bandwidth (EAB) of 5.28 GHz at 2.3 mm can be achieved for NiCo2Se4. Moreover, due to enhanced dielectric performance, the matching thickness of NiCo2Te4 is greatly improved, which the RL is −54.3 dB at 1.8 mm and EAB of 4.88 GHz at 1.6 mm. The synthesis of NiCo2Se4 and NiCo2Te4, with remarkable absorption performance, is expected to provide an important reference for broadening the application of NiCo-based spinel in the field of EM wave absorption.