Influence of Er3+ substitution on the structural, magnetic, and magnetostrictive properties of cobalt ferrite synthesized from spent Li-ion batteries

This study presents the effect of Er3+ substitution for Fe3+ at low concentrations on the structural, magnetic, ant magnetostrictive properties of cobalt ferrite synthesized by sol-gel method using spent Li-ion batteries as rat materials. The XRD results confirm the formation of pure-phase cubic spinel structure with average crystallite sizes of 24.8-41.5 nm as obtained through the Scherrer formula. Although Er3+ substitution does not show an: observable changes in morphology, the magnetic and magnetostrictive properties are strongly affected. Density measurements obtained by the Archimedes method reveal that the bulk density decreases and the porosity: increases with Er3+ substitution because of the formation of intragranular pores during sintering. The saturation magnetization and coercivity of the samples obtained with a vibrating sample magnetometer are influenced by the incorporation of Er3+ at the B-sites. Magnetostriction and strain derivative curves show that Er3+ sub stitution makes cobalt ferrite more suitable for advanced magnetomechanical stress sensors and energy-efficient actuator devices.