Study of magnetic, elastic and Ka-band absorption properties of Zn1-xCoxFe2O4 (0.00=x=1.00) spinel ferrites

Magnetic, elastic, electromagnetic, and microwave absorption properties of cobalt-substituted zinc spinel ferrites Zn1-xCoxFe2O4 (0.00 <= x <= 1.00, Delta x = 0.25) fabricated via the sol-gel citrate route are analyzed. The hysteresis loops of constituent ferrites revealed the rapid rise in saturation magnetization and coercivity with the doping of cobalt ions. The FT-IR spectra exhibit two vibrational bands in the scope of 521-560 cm(-1) and 397-404 cm(-1). Complex permittivity (epsilon(r)) and complex permeability (mu(r)) are analyzed using a vector network analyzer in Ka-band. The absorption is maximized by tuning the thickness of the sample from 0.8 mm to 3.5 mm using the quarter wavelength model. Maximum absorption of 99.14 % at a matching frequency of 34.60 GHz and a matching thickness of 1 mm is obtained by the composition with x = 0.75. The prepared ferrite composition proves to be an efficient microwave-absorbing material at high frequencies ranging from 26.5 to 40 GHz.