Relationship of Various Structural Parameters with Magnetic Behavior of Stoichiometric Tb3+ and Dy3+ Co-substituted NiFe2O4 Nanostructures

Abstract

In this study, we have successfully controlled the structural parameters of NiFe2-x-y TbxDyyO4 (x + y = 0, 0.1, 0.15, 0.2) of nickel ferrites with the substitution of rare earth metal ions (RE3+ = Tb3+, Dy3+) in order to optimize the magnetic properties. XRD reflections had ensured phase purity and single phase of FCC structure formation for all synthesized samples with no additional impurity peaks. It was found that crystallite size and lattice parameters are found to decrease from 28.13 to 25.2 nm and 8.43 to 8.41 Å, respectively, with increasing the amount of dopant ions. The magnetic parameters for NiFe2-x-yTbxDyyO4 (x + y = 0, 0.1, 0.15, 0.2) were measured by tracing the hysteresis curves for all synthesized samples at room temperature. VSM data suggested a decrease in magnetization which is attributed to increase in spin disorder due the decrease of crystallite size which was associated with increase in contents of Tb3+, Dy3+ ions in the host structure. Higher dopant concentrations have greatly reduced coercivity and improve initial permeability. Hence, size and shape of particles are the key features which govern the stability and magnetic properties of ferrite nanoparticles.