Effect of rare-earth ytterbium doping on the microwave absorption performance of nickel–cobalt ferrite

Abstract

In order to investigate the effect of different doping proportions of Yb³⁺ on the structure and microwave absorption properties of ferrite, a sol–gel method was proposed to prepare spinel Ni_0.5Co_0.5Yb_xFe_2−xO₄. The crystal shape, particle size, elements, microstructure, electromagnetic loss and microwave absorption properties of Ni_0.5Co_0.5Yb_xFe_2−xO₄ were characterized by X-ray diffraction, inductively coupled plasma emission spectrometry, transmission electron microscopy, scanning electron microscopy and vector network analysis. Results show that nickel–cobalt–ytterbium ferrite microwave absorbing materials can be prepared under optimal conditions, with an average particle size of 38.00–45.00 nm. With the increase in the doping amount, the microwave absorption performance first increases and then decreases. When Yb³⁺ = 0.02, Ni_0.5Co_0.5Yb_0.02Fe_1.98O₄ has the best microwave absorption performance, the best reflection loss is −21.04 dB, and the effective microwave absorption bandwidth in the Ku band is 2.55 GHz (15.45–18.00 GHz). The prepared nickel–cobalt–ytterbium ferrite microwave absorbing material has the advantages of less thickness, light weight, strong reflection loss and simple synthesis method. The excellent absorbing properties of Ni_0.5Co_0.5Yb_0.02Fe_1.98O₄ are attributed to the interaction between natural resonance and exchange resonance.