Effect of La3+ doping on the electric, dielectric and magnetic properties of cobalt ferrite processed by co-precipitation technique

Lanthanum doped cobalt ferrite ferrites with improved dielectric and magnetic properties have been synthesized by co-precipitation technique. The nano-structures, dielectric and magnetic properties have been investigated by means of X-ray diffraction, impedance analyzer and VSM respectively. The dielectric properties and magnetic properties of CoLaxFe2−xO4 (x = 0, 0.1, 0.15, 0.2) ferrites have been studied as a function of frequency and applied field. The values of dielectric constant and dielectric loss have been reduced significantly due to the doping of La3+ ions in cobalt ferrite. The dielectric loss of the investigated ferrite is 1.9 × 10−3 at 9 MHz. The dc electrical resistivity of CoLa0.1Fe1.9O4 ferrite was found to increase up to 30 times more as compared to pure cobalt ferrite at room temperature. Low values of dielectric constant, dielectric loss and magnetic loss can be correlated with better compositional stoichiometry and Fe ions concentration. The mechanisms responsible to these processes have been discussed.

Research highlights▶ The room temperature saturation magnetization for pure cobalt ferrite is about 60 emu/g which is higher than achieved by sol–gel method. It has been reported that remanence and coercivity is not observed at 300 K for rare earth doped cobalt ferrite, however, we have been able to observe it at the temperature. In addition, we have been able to prepare La3+ doped samples with higher resistivity, low dielectric and magnetic losses.