High magnetostrictive cobalt ferrite for sensor applications

Manganese substituted cobalt ferrites are promising materials for stress and torsion sensor applications. The substitution of manganese for iron can decrease the Curie temperature and consequently the temperature of magnetomechanical effect. In the present study we investigated the influence of the manganese substitution on the magnetostrictive coefficient of ferrite samples with compositions of CoFe_2-x Mn_xO₄ where x ranges from 0 to 0.6. The samples were made using standard powder ceramic technique. Microstructures of the samples were characterized using a scanning electron microscope. The spinel structure and the presence of residual phases were checked by X-ray diffraction analysis. Saturation magnetization, Curie temperature and magnetostriction measurements were performed on the samples to determine the influence of the substitution. By adjusting the manganese content and the sintering process, the material properties could be optimized for use in magnetomechanical stress sensors.