In-situ combustion synthesis of Ni1-xZnxFe2O4/FeNi3/ZnO composite powders for electromagnetic absorption

The magnetic (Ni1-xZnxFe2O4/FeNi3 (x = 0.5 and 0.7))/dielectric (ZnO) composites were designed as microwave absorbers. The composite absorbers with uniform phase distribution were in-situ prepared by mixing the precursor solutions of Ni1-xZnxFe2O4 and ZnO in solution combustion method. To tune the dielectric and magnetic properties, the amount of crystallized ZnO phase varied in the range of 0-54 wt % as a function of fuel contents and composition (x). The composite containing amorphous ZnO phase showed high microwave absorption performance, including a minimum reflection loss of -40 dB and effective absorption bandwidth of 3.4, 4, 3.8, and 1.8 GHz in Ku, X, C2, and C1 bands at matching thicknesses of 2.2, 3, 4.2, and 6.5 mm, respectively.