Magnetostrictive Cu0.1Co0.9RExFe2−xO4 (RE=Ho, Gd or Sm, x=0.0–0.25) nanocomposites were fabricated via sol-gel auto-combustion route using spent lithium-ion batteries as raw materials.
The RE elements doping had limited solubility.
The saturation magnetization (Ms) and maximum magnetostriction (λmax) were reduced and the lattice parameter (a) was increasing by increasing RE3+ substitution contents.
The relationship of maximum strain derivative (dλ/dHmax) after the incorporation of RE was Ho>Gd>Sm.