Structural and tunable dielectric properties of cobalt ferrite-based nanocomposites

Abstract

Nanocomposites C:S-1:4 comprising cobalt ferrite (CoFe₂O₄), strontium ferrite (SrFe₁₂O₁₉) and C:B-1:4 containing cobalt ferrite (CoFe₂O₄), barium ferrite (BaFe₁₂O₁₉) were synthesized in weight ratios of 1:4 by chemical co-precipitation route with higher content corresponding to SrFe₁₂O₁₉ and BaFe₁₂O₁₉. Rietveld refinement was employed to confirm the presence of independent CoFe₂O₄, SrFe₁₂O₁₉ and BaFe₁₂O₁₉ phases. The average crystallite size of CoFe₂O₄ and SrFe₁₂O₁₉ in C:S-1:4 was observed as 20 nm and 56 nm which depicts an increase as compared to individual components. The observed lattice strain in C:S-1:4 was 0.05% and 0.03% for CoFe₂O₄ and SrFe₁₂O₁₉. In C:B-1:4, the value of strain was 0.06% and 0.04% for CoFe₂O₄ and BaFe₁₂O₁₉. Increased lattice strain was observed in the prepared composites. Increase in impedance for the prepared composites was observed from measurements performed in the frequency range 20 –10⁶ Hz. Conduction mechanism was explained by overlapping large polaron tunneling model. Dielectric loss measurements for the prepared composites were observed to decrease establishing their usage in microwave applications.

Keywords:

• Co-precipitation
• ferrite
• conductivity
• polarization