Structural, electrical and magnetic properties of Co0.5Zn0.5Al Fe2−O4 (x= 0, 0.2, 0.4, 0.6, 0.8 and 1.0) prepared via sol–gel route

Abstract Nanoparticles of Co 0.5 Zn 0.5 Al x Fe 2− x O 4 ( x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) were synthesized by sol–gel method and the influence of Al 3+ doping on the properties of Co 0.5 Zn 0.5 Fe 2 O 4 was studied. X-ray diffraction studies revealed the formation of single phase spinel type cubical structure having space group Fd-3m. A decreasing trend of the lattice parameter was observed with increasing Al 3+ concentration due to the smaller ionic radii of Al 3+ ion as compared to Fe 3+ ion. TEM was used to characterize the microstructure of the samples and particle size determination, which exhibited the formation of spherical nanoparticles. The particle size was found to be increases up to ∼45 nm after annealing the sample at 1000 °C. Electrical resistivity was found to increase with Al 3+ doping, attributed to the decrease in the number of Fe 2+ –Fe 3+ hopping. The activation energy decreased with increasing Al 3+ ion concentration, indicating the blocking of conduction mechanism between Fe 3+ –Fe 2+ ions. The value of saturation magnetization decreased, when Fe 3+ ions were doped with Al 3+ ions in Co 0.5 Zn 0.5 Fe 2 O 4 ; however, the coercivity values increased with increasing Al 3+ ion content.