S.P. Gairola

Modified Composition of Cobalt Ferrite as Microwave Absorber in X-Band Frequencies

The magnetic and electromagnetic wave absorbing properties were investigated in the Ni substituted cobalt ferrites, Co1-xNixFe1.9Mn0.1O4 (0≤ x ≤ 1.0), prepared by solid state technique with the increase in concentration of Ni doping uniformly in grain size and densification have improved, while permeability increased remarkably. Saturation magnetization and coercivity both decreased with Ni concentration in cobalt ferrite. Electromagnetic parameters of ferrite samples were measured in X-band frequency range (8–12 GHz) by vector network analyzer (VNA) and their absorbing properties were calculated according to transmission-line theory. Phase formation of all samples has been confirmed by XRD. Ferromagnetic resonance frequency shift has been observed with concentration of Ni concentration which is an important phenomenon of cobalt ferrite to absorb microwave at higher frequencies in X-band. Based on magnetic and microwave measurements Co1-xNixFe1.9Mn0.1O4 (x = 0.8) may be a good potential candidate for electromagnetic compatibility and for other practical applications at high frequencies.

Nanoferrite Embedded in Poly(O-Toluidine) and Polyaniline Matrix for EMI Shielding

Nanoparticles of barium ferrite were synthesized by citrate precursor method and nanocomposite of barium ferrite@poly(o-toluidine) and barium ferrite@polyaniline were prepared by in situ polymerization. The electromagnetic properties were investigated in the frequency range of 8–12 GHz. Shielding effectivenesses of nanoferrite/poly(o-toluidine) and nanoferrite/polyaniline composites were obtained as 10.9 dB and 42.5 dB, respectively. The value of SE suggests that the barium ferrite@polyaniline composite shows much better electromagnetic interference (EMI) shielding results than barium ferrite@poly (o-toluidine).