Modifications of structure and magnetocrystalline anisotropy due to Fe deficiency in Ni–Zn spinel ferrite ceramics

Two Ni–Zn spinel ferrites samples with different iron contents were investigated by quantitative X-ray diffractometry and magnetization measurements. The Fe-deficient sample was found to hold 34.4 wt% of halite phase Ni0.7Zn0.3O in addition to primary spinel ferrite phase with Ni0.6Zn0.4Fe2O4 composition, while the near-stoichiometric Ni0.7Zn0.3Fe2O4 sample contained only 5 wt% of Ni0.7Zn0.3O halite. Magnetization study indicated preferentially ferrimagnetic ordering in both samples. The coefficient of magnetocrystalline anisotropy K1 was calculated from the magnetization data using the law of approach to saturation. The results revealed significant increase of K1 in Fe-deficient sample that can be employed in microwave absorption applications.