The maximum values were obtained for the materials treated at 873 K (a¼8.46 Å), while the minimum values corresponded to those treated at 573 K (a¼8.40 Å).
All these calculated lattice parameters were higher than the reported value of 8.3919 Å (JCPDS No. 22-10086) for MgFe2O4 bulk material and also higher than those reported by O'Neill et al.