CoFe₂O₄ magnetic ceramic derived from gel and densified by spark plasma sintering

Cobalt ferrite (CoFe₂O₄) has been successfully synthesized by sol–gel technique. Pellets were prepared by spark plasma sintering technique (SPS) from CoFe₂O₄ sol–gel derived powder. The rapid sintering of CoFe₂O₄ pellet by SPS at 950 °C, leads to a dense ceramic (97%ρ_theoretic) with average crystallite size of 71 nm. As revealed by X-ray diffraction and Mössbauer measurements, the obtained powder and SPS pellets are spinel ferrite with a cubic symmetry. Complex dielectric investigation performed on CoFe₂O₄ ceramic reveals multiple relaxation mechanisms while the magnetic measurements indicated a saturation magnetization value of ∼83 A m²/kg at room temperature, which make them useful for applications in microwave domain. - Highlights: • Cobalt ferrite (CoFe₂O₄) has been processed by sol–gel and spark plasma sintering technique (SPS). • CoFe₂O₄ ceramic shows low electrical conductivity (σ_AC∼0.0022 at 10⁴ Hz and room temperature). • CoFe₂O₄ ceramic shows complex dielectric relaxation phenomena. • CoFe₂O₄ ceramic shows values of Ms and Hc for microwave or radio frequency devices.