Figure 4.21 shows the magnetic hysteresis loop of CoFe2-xZnxO4 powders at room temperature, with a maximum applied field of up to 8 kOe. The saturated magnetization, remanence and coercivity are summarized in Table 4.10. Also, Figure 4.22 presented variations of saturated magnetization and coercivities for CoFe2-xZnxO4 powders as a function of compositions calcined at 900 ºC for 48 h. The magnetization value of doped samples increased sharply with the external magnetic field strength at the low field region. The highest saturated magnetization can be obtained in x = 0.1 Zn doped cobalt ferrites. Increasing in saturated magnetization can be attributed to influence of the cationic stoichiometry and its occupancy in specific sites. The magnetic order in the cubic system of ferromagnetic spinels was due to occurrence of the super-exchange interaction mechanism between metal ions in the tetrahedral A-site and octahedral B-site [20]. …show more content…
The net result, due to antiferromagnetic coupling, was an increase in magnetic moment on the B lattice and an increase in saturated magnetization. However, at high levels of zinc substitution in x > 0.1, the A-site magnetic ion becomes so diluted that coupling between the two lattices was lost, and the saturated magnetization drops [21]. Furthermore, the changes in coercivity of the samples by increasing the Zn content can be attributed to the magnetic character and anisotropic nature of cobalt. Magnetic anisotropy strongly affected the shape of the hysteresis loops and controls the