Enhanced dielectric and magnetic properties of lanthanum doped cobalt ferrite nanoparticles synthesized by sol-gel method

Abstract Lanthanum doped Cobalt ferrite (Co)[La x Fe 2-x ]O 4 (x = 0, 0.02, 0.04, 0.06, 0.08) nanoparticles were synthesised using sol-gel auto-combustion method. Cubic spinel structure was validated by XRD. Lattice constant and porosity values increased with increase of lanthanum doping. The particles with agglomeration morphology and porous nature were observed from the SEM analysis. The vibrational bands observed in FTIR spectroscopy, in the range 350–600 cm-1, were attributed to Co-O and Fe-O stretching vibrations which confirmed ferrite formation. Further, there was a marginal shift of the band positions towards higher wave numbers with increasing lanthanum concentration. Dielectric parameters (dielectric loss and dielectric constant) were obtained in temperature range, 30–150 °C and in the frequency range, 100Hz–5.5 MHz. Dielectric constant increased with a decrease in dielectric loss value, with increase in lanthanum doping. The relaxation time was estimated using the Havriliak-Negami model. Magnetic analysis utilizing Vibrating Sample Magnetometer (VSM) at room temperature revealed that with the increase in Lanthanum concentration, the coercivity and remanence ratio values rise from 958–1395 Oe and 0.43–0.51, respectively. Overall, the present study suggests that the samples with their enhanced dielectric and magnetic properties are suitable for high frequency and magnetic recording devices.