Effect of cobalt substitution on physical & electro-magnetic properties of SrAl4Fe8O19 hexa-ferrite

Cobalt substituted strontium hexa-ferrite (SrAl4Fe8-xCoxO19 where, x = 0, 0.2, 0.4, 0.6, 0.8, 1) were successfully prepared by sol-gel auto combustion synthesis method. The autocatalytic nature of the combustion process was studied by thermal analysis of the dried gels. The ferrite was characterized with respect to phase identification using X-ray diffraction. Saturation magnetization and hysteresis parameters were measured at room temperature with a maximum magnetic field of 70 kOe. As the cobalt concentration increased, the saturation magnetization was increased from 12.25 to 18.77 emu/gm, however, the coercivity decreased with the increase in cobalt concentration due to the spin canted structure was formed. The variation in the dielectric constant and dielectric loss factor were discussed in the frequency range of 20 Hz-20MHz. It was found that the dielectric constant & loss increased with the increase in Co content. The AC electrical resistivity was decreased with the increase of dopent concentration.