Dependence of magnetic properties on crystallite size of CoFe2O4nanoparticles synthesised by auto-combustion method

Cobalt ferrite (CoFe2O4) nanoparticles were prepared through an auto-combustion method. The results of XRD show that the crystallite size of CoFe2O4 nanoparticles increases from 57 to 105 nm with a slight change in lattice constant as the annealing temperature increases from 300 to 1200°C. The magnetic measurements by vibrating sample magnetometer (VSM) show that M s increases monotonously by increasing the annealing temperature from 300 to 1200°C and C hB and M s reached a maximum when annealing temperature is about 400°C due to the change of the grain size.