Role of Rare Earth Metal Ions Doping on Structural, Electrical, Magnetic, and Dielectric Behavior of Spinel Ferrites: a Comparative Study

In current studies, we have compared the doping effect of different rare earth metal ions on structural, electrical, magnetic, and dielectric properties in three different series of spinel ferrites. The cubic spinel structure for all the synthesized nanoferrites had been confirmed by XRD scans and further with FTIR analysis. Crystallite size, grain size, and lattice constant are found significantly affected by nature of dopant RE3+ ions and decrease with decreasing ionic radii of dopants. Lanthanum doping showed appearance of secondary phases at dopant concentration above 0.2 that was attributed to its larger ionic radii than cerium. The magnetic parameters for all the prepared samples were discussed by tracing hysteresis curves of all synthesized samples at room temperature. Decreasing crystallite size effected spin orders which associated with ionic radii of RE3+ ions resulted in decrease in magnetization. Dopants having smaller ionic radii greatly reduced coercivity and improved initial permeability. In the temperature range 423 to 823 K, the composition-dependent DC resistivity and activation energy ranges between 109 to ~ 1010 Ωcm and ~ 2.85 eV respectively. Both dielectric loss and dielectric constant decrease with decrease in frequency. The reported characteristics made these prepared nanoferrites suitable candidates for high-frequency and microwave absorber devices.