High-performance microwave absorbers based on (CoNiCuZn)1-xMnxFe2O4 spinel ferrites

(CoNiCuZn)(1-x)MnxFe(2)O(4) ferrite powders (x = 0.05, 0.1, 0.2, and 0.3) were easily prepared by the solution combustion method for absorption of electromagnetic microwaves. The effects of Mn contents on the structure, microstructure, and magnetic and microwave absorption properties were studied by various characterization methods. Single-phase spinel ferrites with a space group of Fd 3 m were directly formed by the combustion method without further heat treatment. The lattice parameter increased with adding the Mn2+ ions, and the fraction of Fe3+ cations in (A) sites decreased because of the redistribution of various cations. The average size of spherical nanoparticles increased from 55 to 130 nm for x = 0.1 and decreased up to 70 nm for x = 0.3. The saturation magnetization first decreased from 69 to 54 Am-2/kg for x = 0.2 and then increased to 70 Am-2/kg for x = 0.3. The coercivity decreased from 17.9 to 11.6 kA/m with Mn2+ substitution. The (CoNiCuZn)(0.95)Mn0.05Fe2O4/paraffin composite sample exhibited the maximum reflection loss of - 40 dB at Ku band (17 GHz) in the matching thickness of 5.3 mm. With the increase of Mn2+ content, the reflection loss decreased to - 33 dB at the matching frequency of 4.2 GHz (C2 band). However, the (CoNiCuZn)(0.7)Mn0.3Fe2O4 sample had a wide effective bandwidth of 3.2 GHz at the matching thickness of 4.3 mm because of its good impedance matching caused by the proper combination of permittivity and permeability values. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

(CoNiCuZn)(1-x)MnxFe(2)O(4) ferrite powders were prepared by the solution combustion method with different Mn contents for electromagnetic wave absorption. The effects of Mn contents on the structure, microstructure, and magnetic and microwave absorption properties were studied.