Influence of La doping and synthesis method on the properties of CoFe₂O₄ nanocrystals

Nanocrystals of La doped CoFe₂O₄ were synthesized using three different techniques: flash autocombustion, citrate–nitrate and the standard ceramic technique. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the obtained nanocrystals. All samples were crystallized in a spinel structure with cubic symmetry. The decrease in the lattice constant was endorsed to the large difference in ionic radii of both La⁺³ (1.216 Å) and Fe (0.65 Å) in 6-f coordination. The citrate method displayed superior M_s values amongst all techniques. The coercivity was found to exhibit largest values for the citrate method and then the flash while smallest values are associated with ceramic technique. - Highlights: • CoLa_xFe_2−xO₄ nanocrystals crystallized in spinel cubic structure using 3 techniques. • The decrease in the lattice constant is due to the difference in ionic radius of La⁺³ and Fe³⁺. • The citrate method exhibit largest values of M_s amongst all techniques. • Coercivity exhibits largest values for citrate and then flash, smallest for ceramic technique.