Development of electrical and magnetic properties of Gd substituted Ba0.75Sr0.25Fe12O19 nanoparticles

Nanoparticles of Gadolinium substituted barium-strontium hexaferrite of composition Ba0.75Sr0.25Fe12-xGdxO(19) (x = 0.0-0.4 with a step size of x = 0.1) were synthesized using WOW sol- gel method. Pallets were sintered at 920 degrees C for 20 min. XRD of calcined and sintered samples showed pure hexagonal structure. SEM micrographs showed agglomerated nanoparticles of the nano-size. Dielectric properties like dielectric constant, dielectric loss tangent, AC conductivity, impedance (real Z ' and imaginary part Z") were measured at room temperature with respect to frequency. Gd (x = 0.3) substituted sample showed the highest value for dielectric constant of the order of 2136. The ac electrical conductivity increased with increase in frequency. AC conductivity and dielectric constant increased with substitution concentration. The obtained results are explained by Maxwell Wagner model. Impedance decreased as a function of frequency. The highest impedance value was observed for the 0.4 Gd substituted sample and it is 2500 k Omega. Complex impedance spectroscopy analysis for samples showed effect of grain and grain boundary resistance. Magnetic properties were measured using VSM. Gd (x = 0.3) substituted sample showed maximum value of coercivity i.e. 5413 Oe. Gd (x = 0.2) substituted sample showed maximum saturation magnetization and remanence magnetization.