Controllable magnetic properties of cobalt ferrite particles derived from layered double hydroxide precursors

Cobalt ferrite CoxNi1−xFe2O4 (x = 0, 0.5, 1) particles with controllable magnetic properties have been prepared by calcination of co-substituted NiFe2+Fe3+-layered double hydroxide (NiFe2+Fe3+-LDH) precursors prepared via a scalable method involving separate nucleation and aging steps (SNAS). Their structural and magnetic characteristics were investigated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). Measurements of magnetic properties show that the saturation magnetization (Ms) and coercivity (Hc) of the calcined products increased with increasing cobalt content. The LDH precursor-based product obtained by calcination of a mixture of CoFe2+Fe3+-LDH and NiFe2+Fe3+-LDH powders with a Co/Ni molar ratio of 1:1, exhibits a moderate value of Ms and an increased value of Hc compared to the corresponding values for an Ni0.5Co0.5Fe2O4 material prepared by calcination of a Co0.5Ni0.5Fe2+Fe3+-LDH precursor, and a physical mixture of CoFe2O4 and NiFe2O4 with a Co/Ni molar ratio of 1:1. These results may provide a way to regulate magnetic anisotropy of ferrite spinels by varying the composition of the LDH precursors.