Search

The spinel ferrites are famous due to their unique electrical and magnetic performance. The composition Co1-xSrxFe2O4 (x = 0.00, 0.20, 0.40, 0.60, 0.80, and 1.0) was prepared by sol–gel technique. The pattern of X-ray diffraction (XRD) exhibited the cubic spinel phase of all samples. The values of the lattice constant are improved, whereas the porosity and densities are decreased by the substitution of strontium ions. The addition of strontium ions increased activation energy and dc resistivity. The increase in the strontium ions also created the decreasing trend in the temperature-dependent resistivity, which proved the semiconducting nature of spinel ferrites. The substitution of strontium ions enhanced the coercivity while magnetization decreased by changing the applied field. The dielectric parameters were also found in the frequency range of 3 Mega Hertz to 1 Giga Hertz. The low dielectric loss and enhanced value of direct current resistivity made such samples appropriate for high-frequency applications.

Conducting polymers and their composites are receiving considerable attention due to their applications in commercial and domestic appliances based on their electrical, optical and thermal properties. Also the magnetic and conducting properties of ferrite/polypyrrole (PPy) composites have opened a new horizon in multifunctional materials. In the present study, different properties of PPy, holmium substituted ferrite and their composites have been investigated. Prior to that, PPy was prepared by the chemical polymerization method of pyrrole in the presence of FeCl3⋅6H2O. Holmium substituted ferrite Co0.02Ho1.98Fe2O4 was prepared by using co-precipitation technique. The X-ray diffraction (XRD) pattern showed crystalline ferrite phase having an average crystallite size of 27 nm. Composites with different ratios of ferrite and PPy were fabricated using solid state reaction technique. The structural and morphological properties of PPy/Ferrite composites were studied by XRD and scanning electron microscopy (SEM), respectively. Frequency dependent dielectric properties were studied in the range of 1 MHz-3 GHz; the dielectric constant value for composite is higher than that for the holmium ferrite. The higher dielectric constant of the composite indicates that these materials have better ability to store potential energy under the influence of alternating electric field.