Sintering-dependent mechanical and magnetic properties of spinel cobalt ferrite (CoFe2O4) ceramics prepared via sol-gel synthesis

Abstract Despite increasing interest in cobalt ferrites as advanced ceramics, there is still much uncertainty regarding the relationship between sintering temperature and the magnetic and mechanical properties of CoFe2O4. Precursors prepared via sol-gel synthesis were treated at 750, 800, 850 and 900 °C, pressed into pellets and fired at 1150 and 1200 °C. Samples were analyzed via XRD, Raman spectroscopy, SEM, VSM and Vickers microhardness. Pure CoFe2O4 ceramics were produced from hematite-containing precursors. While magnetic parameters remained unaffected, a significant influence was observed for CoFe2O4 grain size and morphology. The highest hardness, obtained for the 1150 °C samples, was directly associated to smaller grain sizes. Mechanical behavior diverged from the classical Hall-Petch mechanism, likely due to lower grain size homogeneity. Our study achieved a thorough understanding of the magnetic and mechanical behavior of CoFe2O4 ceramics, enabling the optimized selection of processing according to the desired final properties of these materials.