Synthesis and Characterization of Barium W-type Hexagonal Ferrites for EMI Shielding Applications

Abstract

Barium W-type hexagonal ferrites are significant materials having tremendous applications in microwave absorbing materials, high-frequency devices, and memory gadgets on account of soft magnetic nature, low priced, high efficiency, and high saturation magnetization. In the present research work, the single-phase and nanosized cobalt W-type hexaferrite with composition BaCo2-xNixFe16O27 (x=0.0, 0.5, 1.0, 1.5, 2.0) synthesized by chemical co-precipitation method. Powder specimens were calcined at 1250 ⁰C for four hours. The structural properties were investigated by XRD, SEM, and FT-IR instrumental techniques. The pure single phase of W-type hexaferrite was affirmed by XRD. Average crystallite size was measured in the range of 20-28nm that makes them good for EMI shielding applications. The FT-IR absorption peaks confirmed the metal-oxygen bending and stretching vibration of synthesized products. Magnetic measurements showed an increase in coercivity and remanent magnetization from 136.93-531.63Oe and 5.18- 22.42 emu/g with increasing concentration of substituent. The dielectric studies revealed enhancement of dielectric constant, dielectric loss, and tangent loss till x=1.5 and then decreased for x=2.0 due to cation distribution. The AC impedance spectroscopy confirmed the resistance caused by the contribution of grain boundaries. The decreasing trend of impedance with the incorporation of Ni2+ represents that conductivity increases in substituted samples which ultimately rise absorption of EM waves. High EMI shielding effectiveness for absorption (- 31.02dB) and low shield efficiency for reflection were measured (-3.7dB) in the frequency range of 12-18GHz with nickel substitution (x=1.5) which make nickel substituted W-type hexaferrites best coefficient for EMI shielding applications with SET > -20dB.